EM-guided drilling relative to an existing borehole
First Claim
1. A parallel drilling method that comprises:
- gathering azimuthally-sensitive measurements of electromagnetic signals while drilling a new borehole near an existing borehole, said measurements being indicative of a formation resistivity; and
steering a drill string along a path at a substantially constant distance from the existing borehole, wherein the drill string includes both transmit and receive antennas for making the azimuthally-sensitive measurements, and determining the substantially constant distance based at least in part on the formation resistivity measurements.
2 Assignments
0 Petitions
Accused Products
Abstract
Parallel drilling systems and methods suitable for drilling wells for steam-assisted gravity drainage (SAGD). In some method embodiments, a tilted-antenna tool gathers azimuthally-sensitive electromagnetic signal measurements. Such measurements enable accurate measurement of inter-well distance and direction, thereby providing, the necessary information for drilling accurately-spaced wells having reduced vulnerability to “short-circuits” that inhibit effective reservoir exploitation. In some other method embodiments, a tilted-antenna tool transmits azimuthally non-uniform signals as it rotates. The attenuation and azimuthal variation detected by one or more receivers enables accurate direction and distance determination. The transmitter and receiver antennas can in some cases be combined into a single tool, while in other cases the transmitters and receivers are placed in separate wells to increase detection range.
359 Citations
24 Claims
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1. A parallel drilling method that comprises:
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gathering azimuthally-sensitive measurements of electromagnetic signals while drilling a new borehole near an existing borehole, said measurements being indicative of a formation resistivity; and steering a drill string along a path at a substantially constant distance from the existing borehole, wherein the drill string includes both transmit and receive antennas for making the azimuthally-sensitive measurements, and determining the substantially constant distance based at least in part on the formation resistivity measurements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A parallel drilling system that comprises:
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a steerable drill string that includes a tool having at least one tilted transmitter antenna, wherein the tool comprises at least one receive antenna, gathers formation resistivity measurements acquired using the receive antenna and determines distance to an existing borehole based at least in part on the formation resistivity measurements. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A parallel drilling method that comprises:
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transmitting an azimuthally non-uniform electromagnetic signal from a source in a drill string while creating a new borehole; and detecting the signal with at least two receivers in an existing borehole to determine distance from the existing borehole to the source, said signal being indicative of a formation resistivity and said distance being determined based at least in part on said formation resistivity. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification