Well twinning techniques in borehole surveying
First Claim
1. A method for surveying a borehole, the method comprising:
- (a) providing a downhole tool including first and second magnetic field measurement devices disposed at corresponding first and second positions in the borehole, the first and second positions selected to be within sensory range of magnetic flux from a target subterranean structure;
(b) measuring local magnetic fields at the first and second positions using the corresponding first and second magnetic field measurement devices;
(c) processing (1) the local magnetic fields at the first and second positions, and (2) a reference magnetic field, to determine a portion of the local magnetic fields attributable to the target subterranean structure;
(d) generating interference magnetic field vectors at the first and second positions from the portion of the local magnetic fields attributable to the target subterranean structure; and
(e) processing the interference magnetic field vectors to determine a tool face to target angle at each of the first and second positions, the tool face to target angles representing a corresponding direction from each of the first and second positions to the target subterranean structure.
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Accused Products
Abstract
A method for surveying a borehole is provided. The method includes providing a tool having a magnetic field measurement device disposed thereon and positioning the tool in a borehole. Magnetic interference vectors are determined at at least two positions in the borehole by comparing the measured magnetic fields at those positions with a known magnetic field of the earth. The magnetic interference vectors indicate a direction to a target subterranean structure. Various embodiments of the invention compare the directions to the target subterranean structure with a historical survey thereof, so as to determine a distance between the borehole and the subterranean structure and an azimuth of the borehole. The surveying methodology of this invention may advantageously improve borehole surveying data obtained, for example, in relief well and/or well twinning drilling applications.
67 Citations
64 Claims
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1. A method for surveying a borehole, the method comprising:
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(a) providing a downhole tool including first and second magnetic field measurement devices disposed at corresponding first and second positions in the borehole, the first and second positions selected to be within sensory range of magnetic flux from a target subterranean structure;
(b) measuring local magnetic fields at the first and second positions using the corresponding first and second magnetic field measurement devices;
(c) processing (1) the local magnetic fields at the first and second positions, and (2) a reference magnetic field, to determine a portion of the local magnetic fields attributable to the target subterranean structure;
(d) generating interference magnetic field vectors at the first and second positions from the portion of the local magnetic fields attributable to the target subterranean structure; and
(e) processing the interference magnetic field vectors to determine a tool face to target angle at each of the first and second positions, the tool face to target angles representing a corresponding direction from each of the first and second positions to the target subterranean structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method for surveying a borehole, the method comprising:
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(a) providing a downhole tool including a magnetic field measurement device disposed at a first position in the borehole, the first position selected to be within sensory range of magnetic flux from the subterranean structure;
(b) measuring a local magnetic field at the first position using the magnetic field measurement device;
(c) re-positioning the tool at a second position in the borehole so that the magnetic field measurement device remains within sensory range of the magnetic flux from the subterranean structure;
(d) measuring a local magnetic field at the second position using the magnetic field measurement device;
(e) processing the local magnetic fields at the first and second positions and a reference magnetic field to determine a portion of the local magnetic fields attributable to the target subterranean structure;
(f) generating interference magnetic field vectors at the first and second positions from the portion of the local magnetic fields attributable to the target subterranean structure; and
(g) processing the interference magnetic field vectors to determine a tool face to target angle at each of the first and second positions, the tool face to target angles representing a direction from the first and second positions to the subterranean structure. - View Dependent Claims (27, 28, 29)
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30. A method for determining distance from a borehole to a target subterranean structure, the method comprising:
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(a) providing a downhole tool including first and second magnetic field measurement devices disposed at corresponding first and second positions in the borehole, the first and second positions selected to be within sensory range of magnetic flux from the target subterranean structure;
(b) measuring local magnetic fields at the first and second positions using the corresponding first and second magnetic field measurement devices;
(c) processing (1) the local magnetic fields at the first and second positions, and (2) a reference magnetic field, to determine a portion of the local magnetic fields attributable to the target subterranean structure;
(d) generating interference magnetic field vectors at the first and second positions from the portion of the local magnetic fields attributable to the target subterranean structure;
(e) processing the interference magnetic field vectors to determine a tool face to target angle at each of the first and second positions; and
(f) processing the tool face to target angles at the first and second positions to determine the distance from the borehole to the subterranean structure. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A method for determining a local azimuth of a borehole, the method comprising:
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(a) providing a downhole tool including first and second magnetic field measurement devices disposed at corresponding first and second positions in the borehole, the first and second positions selected to be within sensory range of magnetic flux from a target subterranean structure;
(b) measuring local magnetic fields at the first and second positions using the corresponding first and second magnetic field measurement devices;
(c) processing (1) the local magnetic fields at the first and second positions, and (2) a reference magnetic field, to determine a portion of the local magnetic fields attributable to the target subterranean structure;
(d) generating interference magnetic field vectors, at the first and second positions from the portion of the local magnetic fields attributable to the target subterranean structure;
(e) processing the interference magnetic field vectors to determine a tool face to target angle at each of the first and second positions; and
(f) processing the tool face to target angles at the first and second positions to determine a local azimuth of the borehole. - View Dependent Claims (44, 45, 46)
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47. A method for drilling a borehole along a predetermined course relative to a target subterranean structure, at least a portion of the borehole being within sensory range of magnetic flux from the target subterranean structure, the method comprising:
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(a) providing a downhole tool including first and second magnetic field measurement devices disposed at corresponding first and second positions in the borehole, the first and second positions selected to be within sensory range of magnetic flux from the target subterranean structure;
(b) measuring local magnetic fields at the first and second positions using the corresponding first and second magnetic field measurement devices;
(c) processing (1) the local magnetic fields at the first and second positions, and (2) a reference magnetic field, to determine a portion of the local magnetic fields attributable to the subterranean target well;
(d) generating interference magnetic field vectors at the first and second positions from the portion of the local magnetic fields attributable to the target subterranean target well;
(e) processing the interference magnetic field vectors to determine a tool face to target angle at each of the first and second positions;
(f) processing the tool face to target angles at the first and second positions determined in (e) to determine a direction for subsequent drilling of the borehole; and
(g) drilling the borehole along the direction for subsequent drilling determined in (f) such that the downhole tool is repositioned at a new locus in the borehole, and the first and second positions are repositioned at corresponding new loci, the first and second magnetic field measurement devices remaining within sensory range of magnetic flux from the subterranean structure; and
(h) repeating (b), (c), (d), (e), (f), and (g). - View Dependent Claims (48, 49, 50, 51)
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52. A system for determining the location of a target subterranean structure from within an adjacent borehole, said subterranean structure generating magnetic flux, the system comprising:
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a down hole tool including first and second magnetic field measurement devices deployed thereon, the tool operable to be positioned in a borehole such that the first and second magnetic field measurement devices are located at corresponding first and second positions in the borehole, the first and second positions selected to be within sensory range of magnetic flux from the subterranean structure; and
a processor configured to determine;
(A) local magnetic fields at the first and second positions as measured using the corresponding first and second magnetic field measurement devices;
(B) a portion of the local magnetic fields attributable to the subterranean structure at each of the first and second positions, said portion determined from the local magnetic fields in (A) and a reference magnetic field made available to the processor;
(C) an interference magnetic field vector at each of the first and second positions, each of the interference magnetic field vectors corresponding to the portion of the local magnetic fields determined in (B); and
(D) a tool face to target angle at each of the first and second positions, the tool face to target angles representing a corresponding direction from first and second positions in the borehole to the subterranean structure. - View Dependent Claims (53, 54)
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55. A computer system comprising:
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at least one processor; and
a storage device having computer-readable logic stored thereon, the computer-readable logic accessible by and intelligible to the processor;
the processor further disposed to receive input from first and second magnetic field measurement devices when said first and second magnetic field measurement devices are deployed on a downhole tool at corresponding first and second positions in a borehole, the first and second positions selected to be within sensory range of magnetic flux generated by a target subterranean structure located outside the borehole, the computer-readable logic further configured to instruct the processor to execute a method for determining the location of the target subterranean structure, the method comprising;
(a) determining a local magnetic field at each of the first and second positions based on input from the corresponding first and second magnetic field measurement devices;
(b) determining a portion of the local magnetic field attributable to the subterranean structure at each of the first and second positions, said portion determined from the local magnetic fields in (a) and a reference magnetic field made available to the processor;
(c) calculating an interference magnetic field vector for each of the first and second positions, each of the interference magnetic field vectors corresponding to the portion of the local magnetic fields determined in (b); and
(d) determining tool face to target angles at each of the first and second positions, the tool face to target angles representing a corresponding direction between the first and second positions in the borehole to the subterranean structure. - View Dependent Claims (56, 57, 58, 59, 60, 61, 62, 63, 64)
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Specification