Key information

Title: Method of extending a borehole of a relief well, bottomhole assembly, drill string, and other apparatus
Application number: 20181353
Case type: National
Status: 14.12.2020 Patent meddelt (B1)
Filed: 22.10.2018
Effective date: 22.10.2018
Publicly available: 23.04.2020
Next annual fee due: 31.10.2027
Applicant: WELL INTERCEPT AS (NO)
Owner: WELL INTERCEPT AS (NO)
Inventor: Arild Saasen (NO) et al.
Agent: HÅMSØ PATENTBYRÅ AS (NO)
Granted: 14.12.2020
Patent number: 345338
Expiry date: 22.10.2038

Abstract and drawing

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content.

There is described a method of extending a borehole for a relief well in a subsurface of the Earth where in various embodiments a rotary drill string is provided in the borehole. The drill string includes a bottomhole assembly, and the bottomhole assembly includes a drill bit. Current into the subsurface using at least one electrode disposed on the drill 5 string, thereby generating current in a casing of a mother well which is located a distance away from the borehole of the relief well. At least one component of a magnetic field which is associated with the current generated in the casing is detected using at least one sensor disposed on the drill string. Data is obtained from the sensor for determining either or both the proximity and direction to the mother well, and the drill string is advanced into 10 the subsurface based upon the obtained data to extend the borehole. A related drill string, bottomhole assembly, drill bit, and insert is also described.

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Date	Doc. No.	Process	Case number	In/Out	Journal description	To/from
18.12.2020	15-01	Saksbehandling	20181353(345338)	UT	PT Registreringsbrev Nasjonal Patent (15) (PT20181353)
29.09.2020	14-01	Saksbehandling	20181353	UT	Intention to grant	HÅMSØ PATENTBYRÅ AS
05.09.2020	02-01	Overdragelse av søknad/rettighet	2020/10596	UT	GH Forespørsel	HÅMSØ PATENTBYRÅ AS
01.09.2020	13-01	Saksbehandling	20181353	UT	PT Varsel om betaling av første årsavgift (3317) (PT20181353)
20.08.2020	01-03	Overdragelse av søknad/rettighet	2020/10596	INN	P28734NO00_Overdragelse	HÅMSØ PATENTBYRÅ AS
20.08.2020	01-02	Overdragelse av søknad/rettighet	2020/10596	INN	P28734NO00_Gen.flm.	HÅMSØ PATENTBYRÅ AS
20.08.2020	01-01	Overdragelse av søknad/rettighet	2020/10596	INN	Generell henvendelse	HÅMSØ PATENTBYRÅ AS
26.06.2020	12-07	Saksbehandling	20181353	INN	Krav - Claims w corrections print ready 26.06.2020	HÅMSØ PATENTBYRÅ AS
26.06.2020	12-06	Saksbehandling	20181353	INN	Krav - Claims translated Norwegian	HÅMSØ PATENTBYRÅ AS
26.06.2020	12-05	Saksbehandling	20181353	INN	Beskrivelse - Additional sheets description markup 26.06.2020	HÅMSØ PATENTBYRÅ AS
26.06.2020	12-04	Saksbehandling	20181353	INN	Krav - Additional sheets claims mark-up 26.06.2020	HÅMSØ PATENTBYRÅ AS
26.06.2020	12-03	Saksbehandling	20181353	INN	Hovedbrev	HÅMSØ PATENTBYRÅ AS
26.06.2020	12-02	Saksbehandling	20181353	INN	Beskrivelse - Description w corrections print-ready 26.06.2020	HÅMSØ PATENTBYRÅ AS
26.06.2020	12-01	Saksbehandling	20181353	INN	Korrespondanse (Hovedbrev inn)	HÅMSØ PATENTBYRÅ AS
27.05.2020	11-01	Saksbehandling	20181353	UT	Realitet patent	HÅMSØ PATENTBYRÅ AS
18.03.2020	10-07	Saksbehandling	20181353	INN	Krav ren	HÅMSØ PATENTBYRÅ AS
18.03.2020	10-06	Saksbehandling	20181353	INN	Beskrivelse ren	HÅMSØ PATENTBYRÅ AS
18.03.2020	10-05	Saksbehandling	20181353	INN	Patenttegninger	HÅMSØ PATENTBYRÅ AS
18.03.2020	10-04	Saksbehandling	20181353	INN	Hovedbrev	HÅMSØ PATENTBYRÅ AS
18.03.2020	10-03	Saksbehandling	20181353	INN	Krav merket	HÅMSØ PATENTBYRÅ AS
18.03.2020	10-02	Saksbehandling	20181353	INN	Beskrivelse merket	HÅMSØ PATENTBYRÅ AS
18.03.2020	10-01	Saksbehandling	20181353	INN	Korrespondanse (Hovedbrev inn)	HÅMSØ PATENTBYRÅ AS
13.02.2020	09-01	Saksbehandling	20181353	UT	PT Bekreftelse på fristutsettelse	HÅMSØ PATENTBYRÅ AS
10.12.2019	08-01	Saksbehandling	20181353	UT	PT Bekreftelse på fristutsettelse	HÅMSØ PATENTBYRÅ AS
13.08.2019	07-02	Saksbehandling	20181353	UT	PT_report 01:18:18
13.08.2019	07-01	Saksbehandling	20181353	UT	Realitet patent	HÅMSØ PATENTBYRÅ AS
13.05.2019	06-04	Saksbehandling	20181353	INN	Hovedbrev	HÅMSØ PATENTBYRÅ AS
13.05.2019	06-03	Saksbehandling	20181353	INN	Krav merket	HÅMSØ PATENTBYRÅ AS
13.05.2019	06-02	Saksbehandling	20181353	INN	Krav ren	HÅMSØ PATENTBYRÅ AS
13.05.2019	06-01	Saksbehandling	20181353	INN	Korrespondanse (Hovedbrev inn)	HÅMSØ PATENTBYRÅ AS
25.02.2019	05-02	Saksbehandling	20181353	UT	PT_report 08:26:30
25.02.2019	05-01	Saksbehandling	20181353	UT	Realitet patent	HÅMSØ PATENTBYRÅ AS
18.01.2019	02-01	Overdragelse av søknad/rettighet	2019/00506	UT	GH Forespørsel	HÅMSØ PATENTBYRÅ AS
11.01.2019	04-04	Saksbehandling	20181353	INN	Fullmakt	HÅMSØ PATENTBYRÅ AS
11.01.2019	04-03	Saksbehandling	20181353	INN	Fullmakt	HÅMSØ PATENTBYRÅ AS
11.01.2019	04-02	Saksbehandling	20181353	INN	Fullmakt	HÅMSØ PATENTBYRÅ AS
11.01.2019	04-01	Saksbehandling	20181353	INN	Korrespondanse (Hovedbrev inn)	HÅMSØ PATENTBYRÅ AS
11.01.2019	01-03	Overdragelse av søknad/rettighet	2019/00506	INN	Generalfullmakt ALKAS Atlantic AS	HÅMSØ PATENTBYRÅ AS
11.01.2019	01-02	Overdragelse av søknad/rettighet	2019/00506	INN	P28734NO00_Patentoverdragelse_Saasen til ALKAS Atlantic AS	HÅMSØ PATENTBYRÅ AS
11.01.2019	01-01	Overdragelse av søknad/rettighet	2019/00506	INN	Generell henvendelse	HÅMSØ PATENTBYRÅ AS
24.10.2018	02-01	Saksbehandling	20181353	UT	Formalia 1	HÅMSØ PATENTBYRÅ AS
22.10.2018	03-01	Saksbehandling	20181353	INN	Korrespondanse (Hovedbrev inn)	HÅMSØ PATENTBYRÅ AS
22.10.2018	01-03	Saksbehandling	20181353	INN	Patenttegninger	HÅMSØ PATENTBYRÅ AS
22.10.2018	01-02	Saksbehandling	20181353	INN	Beskrivelse	HÅMSØ PATENTBYRÅ AS
22.10.2018	01-01	Saksbehandling	20181353	INN	Søknadsskjema Patent	HÅMSØ PATENTBYRÅ AS

Description, claims and drawings

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content.

Description

METHOD OF EXTENDING A BOREHOLE OF A RELIEF WELL, BOTTOMHOLE AS-SEMBLY, DRILL STRING, AND OTHER APPARATUS

The present invention relates to well construction and drilling, and in particular to relief well drilling. More specifically, it relates to a method of extending a borehole for a relief well, and related apparatus including a drill string and bottomhole assembly.

In various situations, it may not be possible to access a well directly. This might be the case where it may not be feasible to run equipment in through the top of the well to conduct work in the well. In the event of a blowout for instance, it may be desirable to plug the well by delivering cement into the wellbore at a specific location deep in the subsurface.

To deal with the problem of access to a “mother” well, a “relief” well may be drilled from another location to meet the mother well at the required depth. It may then be desired that the drill bit of the drill string used to drill the relief well be directed so as to pierce through the casing of the mother well. Access to the mother well deep in the subsurface can then be obtained through the relief well. In the case of the blow out for example, cement could be delivered from the relief well and into an annulus or bore within the subsurface casing of the mother well.

Drilling and constructing the relief well is traditionally time consuming and costly. Typical practice is to drill past the mother well and then turn back towards the mother well and intersect that close to the bottom of the casing. One of main challenges critical to success is to advance the drill bit at the end of the borehole into the correct position with respect to the mother well.

Although drill strings used for directional drilling often include compasses, the uncertainty as to the exact position of the drill bit is generally high, especially in regions where the Earth’s magnetic field is steeply inclined.

Conventionally, when the relief well reaches the vicinity of the mother well, the drill string is pulled out and a ranging tool is run in on a wireline. The patent publication US4372398 describes a typical ranging tool. The ranging tool is used for measuring the direction and distance to the casing of the mother well. The ranging tool injects electric current into the Earth, and a component of the magnetic field returned from the casing is detected.

Once measurement using the ranging tool has been performed, the ranging tool is pulled out, the drill string is run into the borehole, and drilling is resumed. The direction of drilling may then be corrected and the borehole extended into the subsurface based on the measurement from the ranging tool. This process is typically repeated several times. For “good” progress to be maintained, a significant period of drilling needs to be conducted to extend the borehole before pulling out again and running the ranging tool back in on the wireline. The drilling is thus performed based on previously collected data from the ranging tool at a location increasingly far away from the actual location of the drill bit in the end of the hole. Such “intermittency” may result in error or deviation of the borehole from desired trajectory of the relief well borehole in the subsurface. It may then be a challenge to intersect the casing of the mother well in the subsurface in proper or desired location.

The published patent application document WO2014/0895905 describes a system for ranging between two wellbores and published patent application document US2007/0126426 describes a wellbore tool for locating a target wellbore.

At least one aim of the invention is to obviate or at least mitigate one or more drawbacks associated with prior art techniques.

According to a first aspect of the present invention, there is provided a bottomhole assembly for a rotary drill string for drilling a borehole for a well in a subsurface of the earth, the assembly comprising: at least one tubular or sub comprising a wall; a drill bit connected to an end of the tubular or sub; at least one electrode for injecting electrical current into the subsurface into which the drill string penetrates and the bottomhole assembly is located in use, and thereby generating current in a casing of another well; wherein the electrode is disposed on an outer surface of the tubular or sub, and the tubular or sub has a length uphole of the electrode where an electrically conductive material of the wall of the tubular or sub has an outer insulative layer and a length downhole of the electrode where an electrically conductive material of the wall has an outer insulative layer, for localised current injection into the subsurface; and at least one sensor for detecting at least one component of a magnetic field; the bottomhole assembly being configured to provide electrical current communication through the conductive material of the wall for supplying electrical power from a power supply at surface to the electrode.

Upon use in connection with a relief well, the electrode can inject an electrical current into the subsurface that can generate an electrical current along a section of casing of the mother well located a distance apart from the relief well borehole within the subsurface. The sensor can then be arranged to detect the magnetic field associated with the current in the section of casing of the mother well. This can facilitate determination of the proximity and direction, e.g. azimuthal angle to the mother well casing. Magnetic north may be measured using a compass which may be included in the drill string or bottomhole assembly.

The bottomhole assembly may be configured to provide electrical current communication through a wall of the tubular or sub for return electrical current path from the subsurface.

The electrode may be disposed on an outer surface of a stabliliser, joint, centraliser, or collar.

First and second electrodes of the bottomhole assembly may be disposed on the tubular body and in different locations along the tubular body.

The drill bit may comprise or consist essentially of non-magnetic material or material of low magnetic susceptibility.

The sensor may be positioned in a length section thereof which may comprise or consist essentially of non-magnetic material or material of low magnetic susceptibility, e.g. which does not interfere with the detection of field by the sensor.

The sensor may be arranged in the drill bit or a drill bit sub. The tubular body may have a central long axis and the sensor may be positioned inside the tubular body on the central axis.

According to a second aspect of the present invention, there is provided a rotary drill string for drilling a borehole in a subsurface of the earth, the drill string including a bottomhole assembly in accordance with the first aspect of the invention.

According to a third aspect of the present invention, there is provided apparatus for drilling a borehole for a well, comprising: a rotary drill string in accordance with the second aspect of the invention; and a power supply at surface; wherein the electrode is connected to the power supply through the conductive material of the wall of the tubular or sub of the bottomhole assembly, for supplying electrical power from the surface to the electrode.

According to a fourth aspect of the present invention, there is provided tubular or sub for a drill string or bottomhole assembly for drilling a borehole, the tubular or sub comprising: a tubular body comprising a wall; at least one electrode disposed on the tubular body for injecting electrical current into a region surrounding the tubular body, in use, and thereby generating current in a casing of another well; a length uphole of the electrode where an electrically conductive material of the wall of the tubular body has an outer insulative layer, and a length downhole of the electrode where an electrically conductive material of the wall of the tubular body has an outer insulative layer, for localised current injection into the surrounding region in use; and the wall of the tubular body being configured for electrical current communication through the conductive material of the wall for supplying electrical power from a power supply at surface to the electrode.

According to a fifth aspect of the present invention, there is provided a method of extending a borehole for a relief well in a subsurface of the Earth, the method comprising the steps of: (a) providing a rotary drill string in the borehole, wherein the drill string includes a bottomhole assembly in accordance with the first aspect of the invention; (b) injecting current into the subsurface using the electrode, thereby generating electrical current in a casing of a mother well which is located a distance away from the borehole of the relief well, supplying the electrode with electrical power from a power source at surface through communicating electrical current in the material of the wall of the tubular or sub; (c) detecting at least one component of a magnetic field which is associated with the current generated in the casing, using at least one sensor disposed on the drill string; (d) obtaining data from the sensor for determining either or both the proximity of and direction from the bottomhole assembly to the mother well; and (e) advancing the drill string into the subsurface based upon the obtained data to extend the borehole.

The sensor may be positioned in the bottomhole assembly in any of: the drill bit; a drill bit sub, or a location along the drill string between the drill bit and the electrode.

The sensor may comprise at least one magnetometer, and the method may further comprise using the magnetometer to detect the component of the magnetic field.

The method may further comprise rotating the drill string to drill a section of the borehole and advance the drill string in the subsurface.

The method may further comprise pausing the rotation of the drill string, and injecting the current into the subsurface in the pause. The data from the sensor may be obtained in the pause.

The method may further comprises performing, simultaneously, the steps of: rotating the drill string to drill a section of the borehole; and injecting the current into the subsurface.

The method may further comprise rotating the drill string to drill a section of the borehole, wherein the data may be obtained from the sensor simultaneously to the rotation. The method may comprise communicating or streaming the data from the sensor toward surface using telemetry.

The method may further comprise processing the data to determine the proximity and/or direction to the casing of the mother well.

The method may further comprise transmitting correctional data based on the processed data to a directional drilling system to adjust a heading of the drill string.

The method may include injecting current alternatingly into the subsurface through first or second electrodes. Either or both of the first and second electrodes may be located in the bottomhole assembly.

The method may include conducting current from the subsurface through any of: at least one electrode; the drill bit; and a conductive outer wall portion of any of the drill string, the bottomhole assembly, and a tubular or a drill bit sub thereof.

The injected current may comprise an alternating current signal having a frequency of 1 Hz or lower, for example 0.5 Hz or lower, or 0.25 Hz or lower.

Any of the various aspects of the invention may include further features as described in relation to any other aspect, wherever described herein. Features described in one embodiment may be combined in other embodiments. For example, a selected feature from a first embodiment that is compatible with the arrangement in a second embodiment may be employed, e.g. as an additional, alternative or optional feature, e.g. inserted or exchanged for a similar or like feature, in the second embodiment to perform (in the second embodiment) in the same or corresponding manner as it does in the first embodiment.

Various further advantages of the embodiments of the invention and its features are described and will be apparent from the specification throughout.

There will now be described, by way of example only, embodiments of the invention with reference to the accompanying drawings, in which:

Figure 1 is an overview representation of a drill string in a relief well during use for determining proximity and direction to a mother well according to one example;

Figure 2 is a close-up representation of the bottomhole assembly of the drill string of Figure 1;

Figure 3 is a representation of another bottomhole assembly for the drill string of Figure 1 in close-up according to another example;

Figure 4 is a representation of an insert for a bottomhole assembly of a drill string; Figure 5 is a representation of the insert of Figure 4 inserted in a bottomhole assembly;

Figure 6 is a part sectional perspective representation of part of a box end of a tubular for a drill string according to an example;

Figure 7 is a sectional schematic representation of part of the tubular walling of the drill string according to an example;

Figure 8 is a sectional schematic representation of part of the tubular walling of a drill string according to another example; and

Figure 9 is a sectional schematic representation of part of the tubular walling of a drill string according to another example.

Referring to Figures 1 and 2, a rotary drill string 10 is located in a borehole 3 of a relief well 2 for extending the borehole.

The relief well 2 is sought to be extended by advancing the rotary drill string 10 into proximity of a mother well 1 and with such accuracy that at a desired depth beneath surface 5 the relief well 2, by way of further advancement of the drill string 10, can intersect the mother well 1. The drill bit 60 is typically advanced toward the casing 8 of the mother well 1 and directed to penetrate a wall of the casing to connect the relief well 2 to the mother well 1.

Once connected, the relief well 3 can be employed for example to perform a remedial operation on the mother well such as injecting high-density drilling fluid or cement through the relief well 2 for sealing off a section of the mother well 1. Such an operation may help to bring the mother well 1 under control, e.g. to stabilise pressure after a blowout or the like or other condition where access direct through the mother well 1 may not be practical, possible or desired.

In order to help direct the drill bit 60 in the correct heading toward the mother well, the bottomhole assembly of the drill string 10 includes an electric current transmitter 30 and a magnetic field sensor 40. The transmitter 30 has a first electrode 32 and a second electrode 33, which are operable to establish current flow in the subsurface. A “circuit” of current is generated from the first electrode to the second electrode 33 through the subsurface rock around the borehole 3 and the casing 8 of the mother well 1.

More specifically, an electric current is injected into the surrounding region of the subsurface at the first electrode 32 with suitable strength to affect the casing 8 of the mother well by propagation through the geological subsurface. As is typical of well design, the casing 8 of the mother well comprises a metal tubular with high electrical conductivity. Current resulting from the injection is generated in the casing 8 and takes a path of least resistance along the casing 8 of the mother well, some “leakage” of the current into the subsurface around the mother well also occurring. The flow of current that is established is indicated generally by arrows A and B, where arrows A indicate the propagation of current through the subsurface rock structure and arrow B indicates the propagation of current along the metal casing 8 of the mother well 1.

As a result of the current flow in the material of the wall of the casing 8, a magnetic field is produced that is associated with the current flow in the casing 8. The magnetic field emanating from the casing 8 propagates through the subsurface rock and is received at the drill string 10 in the relief well 2. Components of the magnetic field are detected by the sensor 40 in the drill string 10, which for purposes of specific examples herein comprises magnetometers, e.g. flux gate magnetometers, arranged to detect amplitude and phase components of the magnetic field in three orthogonal directions.

By way of the sensor 40 therefore, magnetic field data are obtained that permit the direction and proximity to the mother well to be determined. An amplitude time series signal is recorded. Amplitude and phase components of the field are used to obtain the strength and direction of the field. The strength of the field, and hence measured amplitude, are proportional to the distance from, i.e. proximity to, the casing.

With regard to determining the direction to the casing, it can be noted that the transmitter 30 is used to generate current in the casing of the mother well which produces an “additional” magnetic field to the ambient magnetic field of the Earth. In the absence of such transmission, i.e. no power being delivered from the power source to the electrodes 32,33, the magnetometers of the sensor 40 measure the ambient field of the Earth. The magnetometers are arranged to measure the field along three mutually perpendicular axes. The orientation of the magnetometers are determined relative to Magnetic North, which can be measured using a compass.

The components of the magnetic field from the magnetometers, e.g. in the direction along the borehole for the relief well, can thus also be determined with respect to magnetic north.

Upon transmission from the transmitter, the additional field from the casing of the mother well is produced, resulting in a total magnetic field which differs from that of the ambient field of the Earth which is originally measured. The measurements from the magnetometers in the presence of the new total field can be compared with those earlier obtained of the ambient field. The change in the field component 90 degree to the borehole before and after is indicative of where the mother well casing is located. This change can be measured as the azimuth (horizontal) angle relative to magnetic north.

The arrangement of the transmitter 30 and sensor 40 in the bottomhole assembly of the drill string, can thus provide for accurate determination of the location of the drill bit 60 with respect to the casing 8 of the mother well that the drill bit 60 may be required to penetrate. The drill string 10 can also provide for efficient construction of the relief well 2 as additional runs for measurements of the direction and proximity to the mother well may be avoidable.

The data for determining the direction and proximity to the casing 8 is acquired from the transmitter 30 and sensor 40 when the bottomhole assembly is in situ within the relief well. As drilling progresses, the bottomhole region of the borehole 3 is generally in greatest or best proximity to the mother well for measurement, and the provision of the acquisition transmitter and sensor in the bottomhole assembly (in the bottomhole region of the wellbore) facilitates early identification of the mother well, given electrical power and signal control constraints. Early acquisition data can be combined with later data and can further increase accuracy of determinations of the direction and proximity to the mother well casing. Time in the well for measurement can also be maximised, such that multiple measurements from the transmitter and sensor are possible and can further increase accuracy or data certainty in the determination of direction and proximity to the mother well. Repeat measurements can be combined to reduce signal to noise ratios.

The current is transmitted into the subsurface as an alternating current signal with low frequency e.g.0.25 Hz. To do so, the polarity of power supply may be switched repeatedly back and forth such that the first and second electrodes 32, 33 are switched from injector and receiver to receiver and injector, and back. The transmission at low frequency can increase the range of operation compared with higher frequencies due to the frequency dependent skin depth effect and attenuation at higher frequencies. However, higher frequencies than 0.25 Hz may be preferred when close to the mother well to facilitate increased accuracy in the determination of the direction and proximity to the casing 8.

The alternating current allows the signal produced by the casing to be detected in the presence of the ambient magnetic field of the Earth. The current signal can be extracted e.g. by Fourier transformation of the applied to the data collected at the sensor. Components of both the ambient field of the Earth and the low frequency signal in response to the current transmission can be obtained from the data from the magnetometer 40. By measuring the field of the Earth with respect to a component of the drill string the compass trajectory of the borehole 3 and/or heading of the drill bit 60 can be determined.

Looking now at Figure 2 in more detail, the bottomhole assembly 100 of the drill string 10 has an elongate tubular 102 which is connected through pin and box connection (not shown) to a length of tubular drill pipe extending downhole from a drilling rig at a top of the well 2. Drilling fluid can be circulated from surface along an inside of the drill pipe, through an inside of the tubular 102, and into the borehole through an outlet in or near the drill bit 60. The drilling fluid can then flow upward along an outside of the drill string toward the surface.

The bottomhole assembly 100 includes first and second stabilisers 104, 105 which protrude outward from an outer surface of the tubular 102. The stabilisers 104, 105 can thus provide stand off for the tubular 102 from the inner wall of the borehole. The stabilisers 104, 105 are arranged to make contact against the formation of the inner wall of the borehole 3 and help to centralise the tubular 102 and attached drill bit 60 within the borehole 3.

The first and second stabilisers 104, 105 are positioned apart from one another along the tubular 102. In the example of Figure 2, the first electrode 32 is disposed on the first stabiliser 104, and the second electrode 34 is disposed on the second stabiliser 105. The electrodes are arranged on an outer part of the stabiliser. Provision of the electrode 32, 33 on the stabiliser 104, 105 can in this manner position the electrode close to the borehole wall and subsurface rock formation into which the current is to propagate. This can enhance the electrical coupling to the subsurface.

The first and second stabilisers 104, 105 each have ribs that extend along the tubular body and are spaced apart about the circumference of the tubular body 102. They can in this way permit return drilling fluid to pass along the outside of the tubular body 102 through flow passages between ribs. Providing the electrodes 32, 33 against or close to the wall of the borehole, e.g. on an outer part of a rib of the stabiliser so as to face the wall, effects of the drilling fluid upon the coupling and/or propagation of the current in the subsurface can also be minimised.

In practice, the electrode 32, 33 could comprise a conductive termination of bare metal wire, discrete metal area on outer surface of the tubular, metal rod, or metal ring or any other conductive termination structure providing suitable electrical coupling to the subsurface.

The first electrode 32 is connected to a first electric line 52 and the second electrode 33 is connected to a second electric line 53, the first and second electric lines 52, 53 are in turn connected to a power source 55. Depending on the switching state of the current signal to be transmitted into the subsurface, electrical power is supplied through the first or second electric line 52, 53 to the relevant one of the first and second electrodes 32, 33 for transmission of current into the subsurface.

It is sought to arrange the electrodes 32, 33 so that they each provide a localised point of injection or reception of current. This facilitates the proper emission and reception of cur rent signals. The outer surface of tubular body 102 at least in the region between and near the electrodes 32, 33 is arranged to be electrically insulated from its surroundings. The electrically insulated region is indicated by reference numeral 108 in Figure 2. This means that the tubular body 102 in the insulated region 108 does not interfere to any significant extent with the propagation and transmission and reception of the current at the electrodes.

In this example, the tubular body 102 in the region 108 consists essentially of nonconductive material. Hence, the region 108 provides the necessary insulation, with the electrodes 32, 33 being localised points of current communication and electrical coupling with the subsurface.

In other variants however, it can be appreciated that the tubular body 102 in the region 108 can comprise metal (e.g. conductive) pipe provided with insulating material on an outer surface of the metal pipe. The insulating or non-conductive material additionally prevents short circuiting between electrodes

In other variants also, it may be desirable for the tubular body 102 in region 108 to include wear surfaces of metal facing the wall of the wellbore for protection and/or resisting abrasion deterioration of the body 102. These surfaces can be provided by metal rings which circumferentially extend around the tubular body 102. They are insulated from the electrodes 32, 33 and from each other by virtue of being provided in discrete locations along the tubular body 102 and intermediate sections of the tubular body 102 consisting of nonconductive and insulative material. This avoids effects of the wear surfaces upon current transmission/reception.

The insulative region 108 is provided to avoid injected current establishing a conductive path in the tubular 102, or other parts of the string, rather than in mother well casing 8. By suitable configuration of wear surfaces or other metal parts of the string in combination with insulation between and from the electrodes, current conduction in the body 102 may be minimised whilst still allowing wear performance.

The magnetometers of the sensor 40 are located in the bottomhole assembly as close as possible toward the drill bit 60. In other variants, the sensor 40 is located in the drill bit or drill bit sub itself. In order to facilitate such positioning, the drill bit 60 is made and consists substantially of non-magnetic material, e.g. metal with low or no significant magnetic susceptibility, so as not to unduly affect the measurements of the magnetic field from the sensor 40. A suitable material for the drill bit or drill bit sub is for instance titanium, nonmagnetic steel or other non-magnetic metal or metal alloy. The sensor 40 is preferably disposed on and symmetrically about the central long axis of the drill string and bottomhole assembly. This can reduce asymmetry effects of surrounding drill string components upon propagation of the field that is to be measured using the sensor 40.

The supply of electrical power to the transmitter 30 can be carried out in various ways. It can be appreciated that the electrodes 32, 33 and first and second electric lines 52, 53 in Figure 2 are indicated schematically in Figure 2.

In Figure 3, a power supply 55 exemplified in the form of a turbine 55 is located in drill pipe 101 uphole from the bottomhole assembly 100. The bottomhole 100 assembly includes the tubular 102 which includes stabilisers 104, 105 on which the electrodes 32, 33 are disposed respectively. The bottomhole assembly 100 also includes a drill bit sub 103 which is to be coupled to the downhole end of the tubular 102. The sensor 40 is located near the drill bit in the drill bit sub 103. In this example, the first and second electric lines 52, 53 are wires embedded in the wall of the tubular 102. The first and second electric lines 52, 53 extend along the drill string to the power source 55. Electrical connection is obtained at joint locations 118, 119 to continue the electric lines along the string. As can be seen, the first electric line 52 is arranged to be continued between the tubular 102 and the drill bit sub 103, and both the first and second electric lines 52, 54 are arranged to be continued across the joint between the tubular 102 and the uphole drill pipe 101 of the string.

Figure 6 provides an example of how the electric lines 52, 53 may be embedded in the wall of the tubular 102 and connected to obtain the electrical connection across the joint 118 or 119. The end 171 of the tubular 102 has annular electrical contact surfaces 172, 173 which contact corresponding electrical contact surfaces of the adjacent tubular, e.g. drill pipe tubular 101, upon making up the joint 118. The wires of the electric lines 52, 53 are embedded in the wall and terminate at the upper end 171 of the tubular 102 in the respective electrical contact surfaces 172, 173. Both wires 52, 53 are included in Figure 6 for purposed of illustrating their relationship to the contact surfaces 172, 173, but can as in the example of Figure 3 in practice be placed in other positions such as on diametrically opposite sides of the tubular.

In examples where the material 177 of the wall of the tubular in which the wires are embedded is of conductive metal, the connectors 172, 173 can be insulated from one another and from the material 177 of the wall, e.g. by insulation layer. Alternatively, the one of the electrical contact surfaces 172, 173 can be coupled to the material 177 of the wall of the tubular 102 to transmit current in the material 177 of the wall, and through the joint 118, 119 to the adjacent section connecting to the end 171.

The wires 52, 53 are insulated from one another. In the example of Figure 3, they are insulated by virtue of the tubular body 102 and adjacent sections of the wall of the body 102 consisting of material 177 which is non-conductive. In this way, the tubular body 102 and conducting wires in regions above between and below the electrodes are also insulated from the surrounding region around the bottomhole assembly.

In various other examples, the tubular body 102 and its adjacent sections 101 and 103 up hole and downhole are conductive metal bodies, and in such cases, and more generally, the wires of the electric lines 52, 53 can be insulated wires sheathed with insulating sleeves. In such cases, as mentioned above, additional insulative layers or material may be applied to the outside of the tubular body and adjacent sections to obtain necessary electrical insulation from the surroundings.

With reference to Figures 7 to 9, some further examples are described to facilitate an understanding of the manner in which the transmitter 30 in particular could in some variants be employed in the drill string.

In Figure 7, walling of a tubular drill string is depicted generally at 180. The walling 180 has an upper wall section 181, an intermediate wall section 182, and a lower wall section 183 which together form a continuous length along the string. The walling 180 is generally configured similarly to that of the example of Figure 3 above. First and second electrodes 32, 33 of a current transmitter are depicted in different (downhole and uphole) positions along the string. In the region 108, the material of the intermediate wall section 182 consists of non-conductive material, e.g. titanium, non-magnetic steel, or the like, so that the electrodes are coupled to the surroundings of the drill string wall at discrete locations on the string. The non-magnetic region 108 extends downhole from the lower electrode 32, and uphole from the upper electrode 33. Electrical communication in the nonmagnetic section takes place through wires 52, 53 along the wall and embedded within the material in the intermediate wall section 182.

The material of the tubular in the upper and lower wall sections 181, 183 can conduct electrical current, but is not required in this particular example to utilise this ability as current is conducted through dedicated wires 52, 53.

In Figure 8, walling 180 of tubular drill string is arranged so as to conduct current in the material of the wall of the tubular in each of the wall sections 181, 182, 183. The outer surface of the drill string has an insulative layer 189 around the tubular and first and second electrodes 32, 33 are arranged to couple electrically with the surroundings for transmitting current into the subsurface. In this example, current return from the subsurface when injecting current from the upper, second electrode 33 is taken through the material of the wall of the tubular on current return path R1. This is achieved by virtue of the walling of lower wall section(s) 183 being in electrical coupling to the subsurface. The lower wall section 183 in effect acts as a receive electrode. Current return from the subsurface when injecting current into subsurface from the lower, first electrode 32 is taken through the material of the wall of the tubular on current return path R2. This is achieved by the walling of upper wall section(s) 181 being coupled electrically to the subsurface, e.g. in contact with subsurface fluid and/or rock. The upper wall section 181 then in effect acts as a receiver electrode.

The lower wall section(s) 183 can be a section of the drill bit sub 103. In practice, the drill bit sub or the drill bit itself, can be an electrode for the electrical return path R1, providing it is constructed of metal which is conductive and couples suitably to the subsurface. In such an implementation, the sensor 40 is placed in a non-magnetic section of the string, and sufficiently away from the bit as avoid effects of the material of the drill bit or drill bit sub interfere with the detection of the magnetic field.

An advantage of using the uninsulated sections to act as electrodes can be improved coupling to the Earth’s subsurface. In particular, the drill bit is designed to be in firm contact against the formation in use, and therefore may provide particularly good coupling to the subsurface for setting up the generation of the magnetic field to be measured.

In variants of this, a yet further return path may be provided, where instead of the R1 return through the drill pipe the return current is received by a section of casing in the relief borehole or by another component, e.g. a structure at surface such as on the seabed or on the wellhead of the mother well, providing that the section of casing or other compo nent couples electrically with the subsurface of the earth and connect to the power source 55.

In Figure 9, walling 180 of tubular drill string is arranged so as to conduct current in the material of the wall of the tubular to or from the second electrode 33 in the intermediate wall section 182. The electrode 33 is directly connected to the material 187 of the wall of the tubular in which current can propagate. The electrical power may be supplied through the wall to the electrode 33 to inject current into the subsurface and when oppositely polarised during the alternation of the signals may receive return current. The electrode 33 is provided as a discrete electrical surface, e.g. a break in the insulation layer 189, facing the surroundings of the subsurface into which the borehole of the relief well is drilled. The magnetic field produced from the generated current in the casing of the mother well is measured using the magnetometers. The direct coupling in this example may allow embedded wiring requirements to be reduced as the wall material 187 replaces the function of the second electric line 53. This can simplify components and reduce capital costs, or allow other an electric line to be employed for other purposes.

Electrical power and communication data is supplied to the magnetometers of the sensor 40 through the first electric line 52. The magnetometers run on DC. To this end, the current from electric line 52 may be converted from AC to DC, e.g. by rectifier. Communication with the magnetometer is superimposed high frequency information which can readily be extracted from the current signal. Data from the sensor can be communicated over separate data line (not shown) and/or by telemetry system (not shown) to surface.

Different power supplies or power supply systems may be utilised. In other variants, the power supply 55 is a battery that can be combined with a DC to AC and/or switching circuitry for producing suitable low-frequency transmission into the surface via transmitter 23. Electrical power from the power supply 55 may be supplied through the drilled wellbore through cables and/or tubular walls of string from surface power supply.

Electrical power can also be generated downhole in the relief well, e.g. using a turbine system which converts hydraulic flow to electrical current. A converter on the drill string can then be used to convert the generated power to a low-frequency AC, e.g. square pulse, which is transmitted via the electrodes 32, 33. It is desirable to be able to select to not send electrical power to the electrodes. This can be controlled from surface, e.g. by communication of control pulse to the power supply system. In examples where power is generated downhole, it is not necessary to supply power electrically through string from surface, and only telemetry is needed for data communication for control purposes.

Furthermore, an electrical accumulator can also be disposed downhole, e.g. on the drill string. The accumulator can be useful both in the example of supplying power from surface and downhole generation of power, if it is not possible to generate enough power. In such case, power can be produced and stored, and then used when enough power is available from the accumulator. Then, power can be generated and accumulated again, and so on repeatedly during the process.

In use, drilling progresses initially by rotating the string and a drill bit to cut through the rock and drill a section of borehole. Drilling fluid is circulated down the drill string through an inside of the connected sections of drill pipe and out into the wellbore through an outlet near the drill bit in the bottomhole assembly. When sought to determine precisely the direction and proximity to the mother well, the drilling, i.e. rotation and advancement of string, is paused, and while paused and in location in the borehole, power is delivered to the injector electrode in the bottomhole assembly, and the current is injected into the subsurface from the injector electrode. While paused however, drilling fluid may continue to circulate and power the power-generating turbine 55. The sensor 40 is used to detect components of the magnetic field from the current generated in the casing of the mother well, and the data from the sensor is used to determine the direction and proximity to the mother well by appropriate processing and /or analysis of the data.

The data are typically communicated in real time or near real time by telemetry from a telemetry transmitter in the bottomhole assembly to a telemetry receiver further uphole and/or at surface. Various telemetry techniques may be employed. For example, mudpulse telemetry or the like may be used. The mud pulse technique can typically involve transmitting about 20 pulses per second and requires full circulation of drilling fluid/mud to be possible. In this technique, one would typically need to wait a period of time for data to been sent uphole from the borehole, processed, and correctional information then sent back down to the directional drilling system for adjusting the heading of the drill bit.

Wired telemetry is another option which provides high-speed transmission of data typically in kHz band. Wireless telemetry is another alternative. Data transmission by telemetry can nowadays take place while the string rotates. Telemetry may also be used for communication of control signals to the power supply and magnetometers.

Based on the data and/or the direction or proximity determined for the mother well the drilling is resumed and the direction that the drill bit is headed is changed or performed accordingly, e.g. if needed to direct it toward the target location e.g. or “hit” the casing of the mother wellbore in the precise desired location.

Alternatively, the transmission of current and measurement of the magnetic field takes place when the string and drill bit is being rotated and advances into the subsurface.

High-speed real-time telemetry of data to surface and/or communication to the directional drilling system to provide correctional or steering information can facilitate accuracy and shorten the overall length of the drilling process further. Many data points can thus advantageously be obtained on the trajectory of the borehole of the relief well as it is drilled, for quick/immediate updating direction of drilling as the borehole of the relief well is extended in the subsurface.

In examples such as those described with reference to Figures 1 to 3, the electrodes 32, 33 are disposed on stabilisers. However, these are mere examples. The electrodes 32, 33 in other variants may be placed in other protruding structures with similar effect. For example, collars 116a, 116b, 117a, 117b on ends of the tubular sections to be joined at joints 118, 119 can be utilised. In one possible example, the collar 117a includes the first electrode 32 and the collar 116a includes the second electrode 34 on the outer surfaces of those collars 116a, 117a.

Acquisition of this “ranging data” by transmission of current and detection of the resulting magnetic field from the mother well is performed intermittently as the drill string advances subsurface towards its final intended location at or near the mother well. The determinations are generally more accurate the closer the mother well it comes, and the frequency may be increased the closer the mother well it comes to increase accuracy further of any determinations of the proximity and direction to the mother well.

Referring to Figure 4, an insert 200 is depicted for insertion into the bottomhole assembly 100. The insert 200 is removable from the bottomhole assembly, e.g. in the event the drill bit is to be replaced. The insert 200 is in the form of a tubular sleeve within which the sensor 40 is positioned centrally on longitudinal axis 220 within the end-to-end through bore 221 of the sleeve. An electric line 62 for supplying power to the sensor 40 is embedded in a wall 223 of the sleeve. The electric line extends upward to connector terminal 63.

In Figure 5, the insert 200 is shown in position within the bottomhole assembly where the connector terminal 63 is aligned with a corresponding connector in the wall of the tubular body 102 adapted to connect to the electrode or electric line 52 which is supplied with power from power supply 55. When the joint 119 is made up, the end 224 of the insert abuts a surface extending inward on the inner wall of the drill bit sub 116. In this way the insert can be inserted. In practice, the joint 119 could be made up before inserting the insert, and the insert 200 lowered into position through the tubular body 102. In other variants, the insert 200 may include other components necessary for transmission and reception of current through electrodes 32, 33 in addition to the sensor. In an embodiment the insert includes the power supply 55, e.g. battery, and termination and electric lines in the wall both for connecting to the first electrode (such as line 62) and the second electrode 33 when inserted into place.

In further embodiments therefore, the insert comprises an entirely self-contained tool including the transmitter, sensor, and power supply to be removably incorporated into the bottomhole as a removable insert for use in facilitating detection and drilling of the relief well.

The drill string tubulars into which the insert is inserted in such case preferably includes an electric connection and electrode in coupling relationship with the subsurface to enable injection and reception of current.

In further embodiments still, a dedicated self-contained tool sub comprises a tubular including the transmitter 30 with first and second electrodes 32, 33, sensor 40, and power supply 55, and connecting ends (e.g. box and pin sections) can be provided for incorporation of the sub into a bottomhole assembly or standard drill string.

In the above, a transmitter and sensor for “ranging” purposes is incorporated into drill string. This can have significant advantages in the reduction in cost and drilling time, and accuracy of ranging. The arrangement of electrodes of the transmitter on components such as drill bit, stabilisers, collars or the like which are to come into contact with the walls of the borehole can enhance coupling to subsurface to provide increased effectiveness. Placement in and adaptation of the bottomhole assembly accordingly can increase data accuracy as to the position of the bit relative to the mother well casing.

Claims

CLAIMS

1. A bottomhole assembly (100) for a rotary drill string (10) for drilling a borehole (3) for a well (2) in a subsurface of the Earth, the bottomhole assembly (100) comprising: at least one tubular (102) or sub comprising a wall;

a drill bit (60) connected to an end of the tubular (102) or sub;

at least one sensor (40) for detecting at least one component of a magnetic field; at least one electrode (32, 33) for injecting electrical current into the subsurface into which the drill string (10) penetrates and the bottomhole assembly (100) is located in use, and thereby generating current in a casing (8) of another well (1);

characterised in that:

the electrode (32, 33) is disposed on an outer surface of the tubular (102) or sub, and the tubular (102) or sub has a length uphole of the electrode (32, 33) where an electrically conductive material of the wall of the tubular (102) or sub has an outer insulative layer and a length downhole of the electrode (32, 33) where an electrically conductive material of the wall has an outer insulative layer, for localised current injection into the subsurface; and

the bottomhole assembly (100) is configured to provide electrical current communication through the conductive material of the wall for supplying electrical power from a power supply at surface (5) to the electrode (32, 33).

2. A bottomhole assembly as claimed in claim 2 configured to provide electrical current communication through a wall of the tubular or sub for return electrical current path from the subsurface.

3. A bottomhole assembly as claimed in claim 1 or 2, wherein the electrode is disposed on an outer surface of a stabiliser, joint, centraliser, or collar.

4. A bottomhole assembly as claimed in any preceding claim, wherein first and second electrodes are disposed on the tubular and in different locations along the tubular.

5. A bottomhole assembly as claimed in any preceding claim, wherein the drill bit comprises or consists essentially of non-magnetic material or material of low magnetic susceptibility.

6. A bottomhole assembly as claimed in any preceding claim, wherein the sensor is positioned in a length section thereof which comprises or consists essentially of nonmagnetic material or material of low magnetic susceptibility.

7. A bottomhole assembly as claimed in any preceding claim, wherein the sensor is arranged in the drill bit or a drill bit sub.

8. A bottomhole assembly as claimed in any preceding claim, wherein the tubular body has a central long axis and the sensor is positioned inside the tubular body on the central axis.

9. A rotary drill string (10) for drilling a borehole in a subsurface of the Earth, the drill string including a bottomhole assembly in accordance with any preceding claim.

10. Apparatus for drilling a borehole (3) for a well (2), comprising:

a rotary drill string (10) in accordance with claim 9; and

a power supply at surface (5);

wherein the electrode (32, 33) is connected to the power supply through the conductive material of the wall of the tubular (102) or sub of the bottomhole assembly (100), for supplying electrical power from the surface (5) to the electrode (32, 33).

11. A tubular (102) or sub for a drill string (10) or bottomhole assembly (100) for drilling a borehole (3), the tubular (102) or sub comprising:

a tubular body (102) comprising a wall;

at least one electrode (32, 33) disposed on the tubular body (102) for injecting electrical current into a region surrounding the tubular body (102), in use, and thereby generating current in a casing (8) of another well (1);

characterised in that the tubular or sub further comprises:

a length uphole of the electrode (32, 33) where an electrically conductive material of the wall of the tubular body (102) has an outer insulative layer, and a length downhole of the electrode (32, 33) where an electrically conductive material of the wall of the tubular body (102) has an outer insulative layer, for localised current injection into the surrounding region in use; and

the wall of the tubular body (102) is configured for electrical current communication through the conductive material of the wall for supplying electrical power from a power supply at surface (5) to the electrode (32, 33).

12. A tubular or sub as claimed in claim 11, further comprising at least one sensor for detecting at least one component of a magnetic field.

13. A method of extending a borehole (3) for a relief well (2) in a subsurface of the Earth, the method comprising the steps of:

(a) providing a rotary drill string (10) in the borehole (3), wherein the drill string includes a bottomhole assembly (100) in accordance with any of claims 1 to 8;

(b) injecting current into the subsurface using the electrode (32, 33), thereby generating electrical current in a casing (8) of a mother well (1) which is located a distance away from the borehole (3) of the relief well (2), supplying the electrode (32, 33) with electrical power from a power source at surface (5) through communicating electrical current in the material of the wall of the tubular (102) or sub;

(c) detecting at least one component of a magnetic field which is associated with the current generated in the casing, using at least one sensor (40) disposed on the drill string (10);

(d) obtaining data from the sensor (40) for determining either or both the proximity of and direction from the bottomhole assembly to the mother well (1); and

(e) advancing the drill string (10) into the subsurface based upon the obtained data to extend the borehole (3).

14. A method as claimed in claim 13, wherein the sensor is positioned in the bottomhole assembly in any of: the drill bit; a drill bit sub, or a location along the drill string between the drill bit and the electrode.

15. A method as claimed in claim 14, wherein the sensor comprises at least one magnetometer, and the method further comprises using the magnetometer to detect the component of the magnetic field.

16. A method as claimed in claim 14 or 15, which further comprises rotating the drill string to drill a section of the borehole and advance the drill string in the subsurface.

17. A method as claimed in any of claims 14 to 16, which further comprises pausing the rotation of the drill string, and injecting the current into the subsurface in the pause.

18. A method as claimed in claim 17, wherein the data from the sensor is obtained in the pause.

19. A method as claimed in any of claims 14 to 18, which further comprises performing, simultaneously, the steps of: rotating the drill string to drill a section of the borehole; and injecting the current into the subsurface.

20. A method as claimed in any of claims 14 to 19, which further comprises rotating the drill string to drill a section of the borehole, wherein the data is obtained from the sensor simultaneously to the rotation.

21. A method as claimed in any of claims 14 to 20, wherein the method comprises communicating or streaming the data from the sensor toward surface using telemetry.

22. A method as claimed in any of claims 14 to 21, which further comprises processing the data to determine the proximity and/or direction to the casing of the other well.

23. A method as claimed in any of claims 14 to 22, which further comprises transmitting correctional data based on the processed data to a directional drilling system to adjust a heading of the drill string.

24. A method as claimed in any of claims 14 to 23, which includes injecting current alternatingly into the subsurface through first or second electrodes.

25. A method as claimed in any of claims 14 to 24, which includes conducting return current from the subsurface through any of: at least one electrode; the drill bit; and a conductive outer wall portion of any of the drill string, the bottomhole assembly, and a tubular or a drill bit sub thereof.

26. A method as claimed in any of claims 14 to 25, wherein the injected current comprises an alternating current signal having a frequency of 1 Hz or lower, for example 0.5 Hz or lower, or 0.25 Hz or lower.

Patentkrav

1. Bunnhullssammenstilling (100) for en rotasjonsborestreng (10) for boring av et borehull (3) for en brønn (2) i en undergrunn i jorden, hvor bunnhullssammenstillingen (100) omfatter:

minst ett rør (102) eller overgangselement omfattende en vegg;

en borekrone (60) koplet til en ende av røret (102) eller overgangselementet; minst én sensor (40) for detektering av minst én komponent av et magnetfelt; minst én elektrode (32, 33) for injisering av elektrisk strøm i den undergrunnen som borestrengen (10) trenger inn i og bunnhullssammenstillingen (100) i bruk befinner seg i, og derved generering av strøm i et fôringsrør (8) i en annen brønn (1);

k a r a k t e r i s e r t v e d at

elektroden (32, 33) er anbrakt på en ytre flate av røret (102) eller overgangselementet, og røret (102) eller overgangselementet har en lengde i borehullet ovenfor elektroden (32, 33) hvor et elektrisk ledende materiale i rørets (102) eller overgangsstykkets vegg har et ytre isolerende lag, og en lengde i borehullet nedenfor elektroden (32, 33) hvor et elektrisk ledende materiale i veggen har et ytre isolerende lag, for lokalisert strøminjeksjon i undergrunnen; og bunnhullssammenstillingen (100) er konfigurert for å tilveiebringe overføring av elektrisk strøm gjennom veggens ledende materiale for å tilføre elektrisk kraft fra en kraftkilde på overflaten (5) til elektroden (32, 33).

2. Bunnhullssammenstilling som angitt i krav 2, konfigurert for å tilveiebringe overføring av elektrisk strøm gjennom en vegg i røret eller overgangselementet for returbane for elektrisk strøm fra undergrunnen.

3. Bunnhullssammenstilling som angitt i krav 1 eller 2, hvor elektroden er anbrakt på en ytre flate av en stabilisator, en skjøt, en sentreringsenhet eller en krage.

4. Bunnhullssammenstilling som angitt i hvilket som helst foregående krav, hvor det er anbrakt en første og en andre elektrode på rørlegemet og på ulike steder langs rørlegemet.

5. Bunnhullssammenstilling som angitt i hvilket som helst foregående krav, hvor borekronen omfatter eller består i det vesentlige av umagnetisk materiale eller materiale med lav magnetisk susceptibilitet.

6. Bunnhullssammenstilling som angitt i hvilket som helst foregående krav, hvor sensoren er anbrakt i et lengdeavsnitt av den som omfatter eller består i det vesentlige av umagnetisk materiale eller materiale med lav magnetisk susceptibilitet.

7. Bunnhullssammenstilling som angitt i hvilket som helst foregående krav, hvor sensoren er anordnet i borekronen eller et borekrone-overgangselement.

8. Bunnhullssammenstilling som angitt i hvilket som helst foregående krav, hvor rørlegemet har en sentral lengdeakse og sensoren er plassert på den sentrale aksen inne i rørlegemet.

9. Rotasjonsborestreng (10) for boring av et borehull i en undergrunn i jorden, hvor borestrengen innbefatter en bunnhullssammenstilling i overensstemmelse med hvilket som helst foregående krav.

10. Apparat for boring av et borehull (3) for en brønn (2), omfattende:

en rotasjonsborestreng (10) i overensstemmelse med krav 9; og

en kraftforsyning på overflaten (5);

hvor elektroden (32, 33) er koplet til kraftforsyningen gjennom det ledende materialet i veggen til røret (102) eller overgangselementet i bunnhullssammenstillingen (100) for å tilføre elektrisk kraft fra overflaten (5) til elektroden (32, 33).

11. Rør (102) eller overgangselement for en borestreng (10) eller bunnhullssammenstilling (100) for boring av et borehull (3), hvor røret (102) eller overgangselementet omfatter:

et rørlegeme (102) omfattende en vegg;

minst én elektrode (32, 33) anbrakt på rørlegemet (102) for i bruk å injisere elektrisk strøm i et område som omgir rørlegemet (102), og derved generere strøm i et fôringsrør (8) i en annen brønn (1);

k a r a k t e r i s e r t v e d at røret eller overgangselementet videre omfatter:

en lengde i borehullet ovenfor elektroden (32, 33) hvor et elektrisk ledende materiale i rørlegemets (102) vegg har et ytre isolerende lag, og en lengde i borehullet nedenfor elektroden (32, 33) hvor et elektrisk ledende materialet i rørlegemets (102) vegg har et ytre isolerende lag, for lokalisert strøminjeksjon i området i bruk; og

rørlegemets (102) vegg er konfigurert for overføring av elektrisk strøm gjen nom veggens ledende materiale for å tilføre elektrisk kraft fra en kraftforsyning på overflaten (5) til elektroden (32, 33).

12. Rør eller overgangselement som angitt i krav 11, videre omfattende minst én sensor for detektering av minst én komponent av et magnetfelt.

13. Fremgangsmåte for forlengelse av et borehull (3) for en avlastningsbrønn (2) i en undergrunn i jorden, hvor fremgangsmåten omfatter trinnene:

(a) å tilveiebringe en rotasjonsborestreng (10) i borehullet (3), hvor borestrengen innbefatter en bunnhullssammenstilling (100) i overensstemmelse med hvilket som helst av kravene 1 til 8;

(b) å injisere strøm i undergrunnen ved å bruke elektroden (32, 33) og derved generere elektrisk strøm i et fôringsrør (8) i en morbrønn (1) som er plassert i en avstand fra avlastningsbrønnens (2) borehull (3), hvor elektroden (32, 33) forsynes med elektrisk kraft fra en kraftkilde på overflaten (5) ved overføring av elektrisk strøm i materialet i rørets (102) eller overgangsstykkets vegg;

(c) å detektere minst én komponent av et magnetfelt som er knyttet til strømmen generert i fôringsrøret, ved bruk av minst én sensor (40) anbrakt på borestrengen (10);

(d) å innhente data fra sensoren (40) for å bestemme én av eller både nærheten og retningen fra bunnhullssammenstillingen til morbrønnen (1); og (e) å føre frem borestrengen (10) i undergrunnen basert på de innhentede dataene for å forlenge borehullet (3).

14. Fremgangsmåte som angitt i krav 13, hvor sensoren er plassert i bunnhullssammenstillingen i hvilken som helst av: borekronen, et borekrone-overgangselement eller på et sted langs borestrengen mellom borekronen og elektroden.

15. Fremgangsmåte som angitt i krav 14, hvor sensoren omfatter minst ett magnetometer, og fremgangsmåten videre omfatter å bruke magnetometeret for å detektere komponenten av magnetfeltet.

16. Fremgangsmåte som angitt i krav 14 eller 15, som videre omfatter å rotere borestrengen for å bore et avsnitt av borehullet og føre borestrengen videre i undergrunnen.

17. Fremgangsmåte som angitt i hvilket som helst av kravene 14 til 16, som videre omfatter å ta en pause i roteringen av borestrengen og injisere strømmen i undergrunnen i pausen.

18. Fremgangsmåte som angitt i krav 17, hvor dataene fra sensoren innhentes i pausen.

19. Fremgangsmåte som angitt i hvilket som helst av kravene 14 til 18, som videre omfatter samtidig utførelse av trinnene: å rotere borestrengen for å bore et avsnitt av borehullet; og å injisere strømmen i undergrunnen.

20. Fremgangsmåte som angitt i hvilket som helst av kravene 14 til 19, som videre omfatter å rotere borestrengen for å bore et avsnitt av borehullet, hvor dataene innhentes fra sensoren samtidig med roteringen.

21. Fremgangsmåte som angitt i hvilket som helst av kravene 14 til 20, hvor fremgangsmåten omfatter å overføre eller strømme dataene fra sensoren mot overflaten ved bruk av telemetri.

22. Fremgangsmåte som angitt i hvilket som helst av kravene 14 til 21, som videre omfatter å behandle dataene for å bestemme nærheten til og/eller retningen mot fôringsrøret i den andre brønnen.

23. Fremgangsmåte som angitt i hvilket som helst av kravene 14 til 22, som videre omfatter å overføre korreksjonsdata basert på de behandlede dataene til et retningsboringssystem for å justere en kurs for borestrengen.

24. Fremgangsmåte som angitt i hvilket som helst av kravene 14 til 23, som innbefatter å injisere strøm vekselvis i undergrunnen gjennom den første eller den andre elektroden.

25. Fremgangsmåte som angitt i hvilket som helst av kravene 14 til 24, som innbefatter å lede returstrøm fra undergrunnen gjennom hvilken som helst av: minst én elektrode; borekronen; og et ledende ytre veggparti av hvilken som helst av borestrengen, bunnhullssammenstillingen, og et rør eller et borekroneovergangselement i denne.

26. Fremgangsmåte som angitt i hvilket som helst av kravene 14 til 25, hvor den injiserte strømmen omfatter et vekselstrømsignal som har en frekvens på 1 Hz eller lavere, for eksempel 0,5 Hz eller lavere, eller 0,25 Hz eller lavere.

Drawings

Priority

No priority

Patent classes

IPC classes

E21B 47/022

G01V 3/26

G01V 3/30

CPC classes

E21B 47/02216

G01V 3/26

G01V 3/30

E21B 47/02224

Citations

US 2007126426 A1 (A1)

US 5230387 A (A)

US 2009078429 A1 (A1)

US 2007/0126426 A1 (A1)

US 5230387 A (A)

US 2009/0078429 A1 (A1)

WO 2014/089505 A1 (A1)

Applicants, owners and inventors

Owners

WELL INTERCEPT AS

Postboks 8034

4068 STAVANGER

NO (STAVANGER Municipality, Rogaland county)

Org. number: 820365682

Inventors

Arild Saasen

Gruveveien 1

3426 GULLAUG

NO (LIER Municipality, Buskerud county)

Jostein Tysse

Snorres Gate 42

4044 HAFRSFJORD

NO (STAVANGER Municipality, Rogaland county)

Espen Lea

Nonsbergtunet 13

4050 SOLA

NO (SOLA Municipality, Rogaland county)

Agent

HÅMSØ PATENTBYRÅ AS

Postboks 9

4068 STAVANGER

NO (STAVANGER Municipality, Rogaland county)

Org. number: 918752900

Reference: P28734NO00

Status history

Payment history

Oppositions and appeals

No oppositions or appeals

Administrative limitation

No administrative limitation

Liens and licences

No liens or licenses registered

Gazette entries

No Gazette entries found

Only events from 2024.03.04 and onwards are shown.

Method of extending a borehole of a relief well, bottomhole assembly, drill string, and other...

Key information

Abstract and drawing

Publications

Documents

Description, claims and drawings

Priority

Patent classes

Citations

Applicants, owners and inventors

Agent

Status history

Payment history

Oppositions and appeals

Administrative limitation

Liens and licences

Gazette entries