WO2014093096A1 - Appareil et procédés de mesure de la proximité de puits en cours de forage - Google Patents

Appareil et procédés de mesure de la proximité de puits en cours de forage Download PDF

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Publication number
WO2014093096A1
WO2014093096A1 PCT/US2013/073105 US2013073105W WO2014093096A1 WO 2014093096 A1 WO2014093096 A1 WO 2014093096A1 US 2013073105 W US2013073105 W US 2013073105W WO 2014093096 A1 WO2014093096 A1 WO 2014093096A1
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WIPO (PCT)
Prior art keywords
borehole
magnetic field
magnet
sensor
coil
Prior art date
Application number
PCT/US2013/073105
Other languages
English (en)
Inventor
Sheng Fang
Arcady Reiderman
Original Assignee
Baker Hughes Incorporated
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US13/713,960 external-priority patent/US9151150B2/en
Application filed by Baker Hughes Incorporated filed Critical Baker Hughes Incorporated
Priority to CA2894512A priority Critical patent/CA2894512C/fr
Publication of WO2014093096A1 publication Critical patent/WO2014093096A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
    • G01V3/10—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/09—Locating or determining the position of objects in boreholes or wells, e.g. the position of an extending arm; Identifying the free or blocked portions of pipes
    • E21B47/092—Locating or determining the position of objects in boreholes or wells, e.g. the position of an extending arm; Identifying the free or blocked portions of pipes by detecting magnetic anomalies

Definitions

  • This disclosure relates generally to apparatus and methods for determining a distance to a pre-existing wellbore and controlling drilling operations based on the determination.
  • the present disclosure discloses apparatus and methods for determining distance from a pre-existing wellbore without accessing the pre-existing well.
  • an apparatus for determining a distance between a first borehole and a second borehole during drilling of the second borehole includes a magnet on a drilling tool that rotates in the second borehole to induce a primary magnetic field in a magnetic object in the first borehole, a substantially stationary sensor on the drilling tool that detects a secondary magnetic field from the magnetic object responsive to the induced primary magnetic field, and a controller that determines the distance between the first borehole and the second borehole from the detected magnetic field.
  • Another embodiment of the disclosure is a method a method of determining a distance between a first borehole and a second borehole, the in one embodiment includes inducing a primary magnetic field in a magnetic object in the first borehole using a rotating magnet in the second borehole, detecting a secondary magnetic field from the magnetic object responsive to the induced primary magnetic field using a substantially stationary sensor in the second borehole, and determining the distance between the first borehole and the second borehole from the detected magnetic field.
  • FIG. 1 is a schematic illustration of an exemplary drilling system that includes an apparatus for determining distance between boreholes, according to one embodiment of the disclosure
  • FIG. 2 shows a simplified layout of the magnetometer and the coordinate system used for the calculations
  • FIG. 3 illustrates azimuthal dependence of the signal in the sensor coil
  • FIG. 4 is a schematic illustration of implementation of the rotational magnetometer
  • FIG. 5 shows an embodiment that utilizes a pair of additional differentially connected coils synchronously rotating with the magnetic coil
  • FIG. 6 shows an embodiment that utilizes switchable magnetic field source
  • FIG. 7 shows time diagrams of the switchable magnetic field and the transient responses (corresponds to the embodiment of FIG. 6);
  • FIG. 8 shows drilling a second borehole in close proximity to a cased production borehole
  • FIG. 9 shows an embodiment for a radial magnet-coil arrangement that includes two identical or substantially identical receiver coils symmetrically installed on the surface of the magnet for estimating distance between adjacent wellbore ore boreholes;
  • FIG. 10 shows yet another embodiment of a radial magnet-coil arrangement that includes two cols, each further containing a pair of radial oils, offset equally at two sides of the rotating magnet;
  • FIG. 11 depicts receiver coil magnetic flux as a function of receiver coil's axial offset as a function of distance between the coil and the casing having a five (5) meter offset;
  • FIG. 12 shows yet another embodiment of a magnet and coils arrangement wherein that includes three receiver coils placed with equal spacing
  • FIG. 13 shows another embodiment of a hybrid configuration of coils that includes six identical or substantially identical receiver coils forming two pairs of axial r or three pairs of radial measurements;
  • FIG. 14 shows an embodiment for a radial magnet-senor arrangement that includes a rotating magnet and a stationary or substantially stationary senor for detecting secondary magnetic waves for determining distance and inclination of wellbore relative to another borehole;
  • FIG. 15 shows yet another embodiment of a radial magnet-senor arrangement that includes a magnet and a sensor that rotate at different rotational speeds for determining distance and inclination of a one borehole relative to another borehole.
  • FIG. 1 shows a schematic diagram of a drilling system 100 with a drillstring 120 carrying a drilling assembly 190 (also referred to as the bottomhole assembly, or ABHA) conveyed in a "wellbore" or “borehole” 126 for drilling the wellbore.
  • the drilling system 100 includes a conventional derrick 1 1 1 erected on a floor 1 12 which supports a rotary table 1 14 that is rotated by a prime mover such as an electric motor (not shown) at a desired rotational speed.
  • the drillstring 120 includes a tubing such as a drill pipe 122 or a coiled- tubing extending downward from the surface into the borehole 126.
  • the drillstring 20 is pushed into the wellbore 126 when a drill pipe 122 is used as the tubing.
  • a tubing injector such as an injector (not shown), however, is used to move the tubing from a source thereof, such as a reel (not shown), to the wellbore 126.
  • the drill bit is used to move the tubing from a source thereof, such as a reel (not shown), to the wellbore 126.
  • the drillstring 120 breaks up the geological formations when it is rotated to drill the borehole 126.
  • the drillstring 120 is coupled to a drawworks 30 via a Kelly joint 121 , swivel, 138 and line 129 through a pulley 123.
  • the drawworks 130 is operated to control the weight on bit, which is an important parameter that affects the rate of penetration. The operation of the drawworks is well known in the art and is thus not described in detail herein.
  • a suitable drilling fluid 131 from a mud pit (source) 132 is circulated under pressure through a channel in the drillstring 120 by a mud pump 134.
  • the drilling fluid passes from the mud pump 134 into the drillstring 120 via a desurger 136, fluid line 128 and Kelly joint 121.
  • the drilling fluid 131 is discharged at the borehole bottom
  • the drilling fluid 131 circulates uphole through the annular space 127 between the drillstring 120 and the borehole 126 and returns to the mud pit 132 via a return line 135.
  • the drilling fluid acts to lubricate the drill bit 150 and to carry borehole cutting or chips away from the drill bit 150.
  • a sensor Si preferably placed in the line 138 provides information about the fluid flow rate.
  • a surface torque sensor S 2 and a sensor S 3 associated with the drillstring 120 respectively provide information about the torque and rotational speed of the drillstring.
  • a sensor (not shown) associated with line 129 is used to provide the hook load of the drillstring 120.
  • the drill bit 150 is rotated by only rotating the drill pipe 122.
  • a downhole motor 155 (mud motor) is disposed in the drilling assembly 190 to rotate the drill bit 150 and the drill pipe 122 is rotated usually to supplement the rotational power, if required, and to effect changes in the drilling direction.
  • the mud motor 155 is coupled to the drill bit 150 via a drive shaft (not shown) disposed in a bearing assembly 157.
  • the mud motor rotates the drill bit 150 when the drilling fluid 131 passes through the mud motor 155 under pressure.
  • the bearing assembly 157 supports the radial and axial forces of the drill bit.
  • a stabilizer 158 coupled to the bearing assembly 157 acts as a centralizer for the lowermost portion of the mud motor assembly.
  • a drilling sensor module 159 is placed near the drill bit 150.
  • the drilling sensor module contains sensors, circuitry and processing software and algorithms relating to the dynamic drilling parameters. Such parameters include bit bounce, stick-slip of the drilling assembly, backward rotation, torque, shocks, borehole and annulus pressure, acceleration measurements and other measurements of the drill bit condition.
  • a suitable telemetry or communication sub 172 using, for example, two-way telemetry, is also provided as illustrated in the drilling assembly 100.
  • the drilling sensor module processes the sensor information and transmits it to the surface control unit 140 via the telemetry system 172.
  • the communication sub 172, a power unit 178 and an MWD tool 179 are all connected in tandem with the drillstring 120. Flex subs, for example, are used in connecting the MWD tool 179 in the drilling assembly 190. Such subs and tools form the bottom hole drilling assembly 90 between the drillstring 120 and the drill bit 150.
  • the drilling assembly 190 makes various measurements including the pulsed nuclear magnetic resonance measurements while the borehole 126 is being drilled.
  • the communication sub 172 obtains the signals and measurements and transfers the signals, using two-way telemetry, for example, to be processed on the surface. Alternatively, the signals can be processed using a downhole processor in the drilling assembly 190.
  • the surface control unit or processor 140 also receives signals from other downhole sensors and devices and signals from sensors S 1 -S3 and other sensors used in the system 100 and processes such signals according to programmed instructions provided to the surface control unit 140.
  • the surface control unit 140 displays desired drilling parameters and other information on a display/monitor 142 utilized by an operator to control the drilling operations.
  • the surface control unit 140 preferably includes a computer or a microprocessor- based processing system, memory for storing programs or models and data, a recorder for recording data, and other peripherals.
  • the control unit 140 is preferably adapted to activate alarms 144 when certain unsafe or undesirable operating conditions occur.
  • the system also includes a downhole processor, sensor assembly for making formation evaluation and an orientation sensor. These may be located at any suitable position on the bottomhole assembly (BHA).
  • the system further includes a device 180 for determining distance between the wellbore 126 and a pre-existing wellbore, as described in more detail in reference to FIGS. 2-15.
  • a permanent magnet 203 is shown on a drill collar section 201 of the secondary well.
  • the magnet is transversely magnetized with the flux direction indicated by 221.
  • the pre-existing well casing is denoted by 205.
  • the coordinate axes x, y, and z are as indicated in FIG. 2.
  • the collar section is provided with a coil 213.
  • the coil rotates synchronously with the magnet, but the magnet-coil combination need not be synchronous with the rotation of the drill collar: this may be done by having the magnet-coil combination on a sleeve.
  • the rotating magnet generates a variable magnetic field at a magnetic object such as the casing 205 of the pre-existing well. This variable magnetic field induces magnetization in the casing that, in turn, generate a variable magnetic flux picked up by the rotating coil 213.
  • S C0IL is the sensitivity function of the coil and A C0IL is the effective area of the coil.
  • the rotating magnet generates variable magnetization in the casing.
  • the magnetization induces a variable magnetic flux in the coil.
  • the corresponding volta e can be expressed as:
  • M CASING is the magnetization of the casing
  • S C0IL is the coil sensitivity function
  • x eff xy and x eff z are the effective magnetic susceptibilities in the direction perpendicular and parallel to the casing axis respectively
  • a CASING is the effective area of the casing
  • r a represents points along the axis of the casing. Due to the shape of the casing we can use the following simlification: x eff xy « x eff z This then gives, for the coil voltage, the equation:
  • a CASING is the cross-sectional area of the casing.
  • the voltage induced in the rotating coil by the rotating magnetization of the casing has a frequency which is twice the rotation frequency of the magnet/coil assembly. This means that the measured proximity signal is relatively easy to separate from a parasitic signal induced in the rotating coil due to the earth's magnetic field.
  • the parasitic signal has a frequency equal to the magnet/coil rotation frequency.
  • the main sources of error in the measurement technique is due to the presence of some second harmonic in the magnet/coil assembly rotation.
  • the earth's magnetic field related signal would appear at the frequency 2 ⁇ thus giving a spurious signal at the same frequency as the expected proximity signal.
  • the second harmonic signal is easy to calculate from the accelerometer output, known value and direction of the earth's magnetic field, and measurements of borehole inclination and azimuth. A gyro survey may be needed to get the borehole inclination and azimuth.
  • FIG. 3 illustrates azimuthal dependence of the voltage on the rotating coil 213.
  • V SEF V m - ⁇ s[2((o - t + ⁇ p 0 )] . (9)
  • ⁇ 0 is the azimuth of the casing with respect to the secondary well.
  • phase of the signal on the coil 213 is sensitive to the azimuthal position of the casing 205 with respect to the secondary well 201.
  • FIG. 4 is a block diagram illustrating an implementation of the rotational magnetometer.
  • the magnetometer comprises a motor 401 rotating the magnet 203 and the coil 213.
  • the signal from the coil 213 transferred to the low noise preamplifier 409 via an adapter (e. g. sliding rings) 407.
  • Serving this purpose are also a controller 405, analog-to-digital converters 413, 417, 419, digital signal processor 415 and a variable gain amplifier 419.
  • the coil 213 it is sufficient for the coil 213 to be able to responsive to a component of the magnetic flux due to the induced magnetization that is transverse to the z- axis.
  • the configuration of the coil 213 shown in FIG. 2 is not the only arrangement that would provide a suitable signal, but it is one of the better designs.
  • an inclined planar coil on the BHA with the coil axis inclined to the z- axis would work.
  • the signal would be greatest when the coil axis is transverse to the z- axis.
  • the magnet does not have to be a transversally magnetized cylindrical magnet as indicated by 201.
  • the method would also work, albeit less efficiently, using a bar magnet with its magnetization direction having a component parallel to the z- axis.
  • a longitudinal coil spaced axially apart from the magnet 201 can be used to receive proximity signal originating from variable Z-component of the magnetization of the casing.
  • FIG. 5 illustrates an example of embodiment of the technique that utilizes a pair of additional differentially connected coils 217 synchronously rotating with the magnet/coil assembly.
  • the additional coil assembly is sensitive to non-parallel orientation of the wells, i.e., the output will be zero if the two boreholes are parallel.
  • Any differential pair of identical coils placed asymmetrically with respect to the magnet will also be sensitive to the DC magnetization of the casing (gives additional proximity information) and not sensitive to the Earth's magnetic field. This is particularly useful when it is desired to drill the secondary well to intersect the pre-existing well.
  • FIG. 6 depicts an embodiment of the transient magnetometer.
  • the magnetometer comprises a source of switchable magnetic field 601 having a switching coil 603 and a magnetic core 605.
  • the magnetic field source 601 generates magnetic field (the iso lines of the field are shown at 607) at a position of the target casing 205.
  • the magnetic core 605 preferably comprises a magnetic material with residual magnetization.
  • the residual magnetization is used to provide a strong magnetic dipole without the need for a DC current driving the switching coil and causing a significant energy loss if a strong magnetic field needs to be generated (the application of the magnetic material with residual magnetization in a source of a strong switchable magnetic field is described in US patent application Ser. No. 11/037,488).
  • Disclosed therein is a magnetic core having residual magnetization.
  • the magnetometer also comprises a longitudinal coil 609 to pickup a variable magnetic flux produced by the casing magnetization transient occurring in response to switching of the magnetization in the magnetic core 605.
  • the magnetometer further comprises a transversal coil 611, the signal induced in this coil is sensitive to the azimuthal position of the casing with respect to the secondary well 201 when the drill collar rotates.
  • FIG. 7 shows time diagrams of the switchable magnetic field and the transient responses in the coil 609.
  • the switchable magnetic field 703 is generated by switching polarity of the residual magnetization in the magnetic core 605.
  • the switching polarity is accomplished by driving the switching coil 603 with short pulses of electric current 701.
  • Decaying signals 705, 707, 709 (transients) in the coil 609 are generated in response to a fast switching off or changing polarity of a "static" magnetic field.
  • the signals are associated with direct coupling between the source and the sensing coil (transient at 705), the signal due to eddy currents in the surrounding rock formations and the conductive collar of the drill string (a conductive body) placed in the well 201 (transient at 707), and casing proximity signal due to variable magnetization of the magnetic casing 205 (transient at 709). It is important for the method that the proximity signal 709 is substantially longer than the undesired signals 705 and 707.
  • ⁇ is the wall thickness of the casing
  • ⁇ is the magnetic permeability, which is about 100 for a typical casing material
  • ⁇ is the conductivity of the material of the casing.
  • the process of building up of the magnetic flux in the coil 609 is exponential with the time constant given by eqn.(l 0). By the time approximately equal to the time constant of the casing magnetization process all other transients will substantially decay. Thus, by measuring the signal in a time window (at 71 1) starting after a time comparable with the time constant of building up of the casing magnetization (time window 711) one effectively eliminates all undesired signal.
  • the expected time constant of the direct coupling is of the order of the duration of the pulses 701.
  • the area within the window is used as a distance indicator.
  • Appropriate calibration is carried out.
  • the processes due to the eddy current in the conductive surroundings are in the range ⁇ - ⁇ .
  • the signal from the magnetic casing should last approximately 10-30ms.
  • practical acquisition window may be positioned between 1ms and 50 ms.
  • FIG. 8 illustrates an embodiment of the disclosure in secondary recovery operations.
  • a producing wellbore 820 has been drilled into a reservoir interval 801 that contains hydrocarbons. For various reasons, such as low formation pressure or high viscosity of the hydrocarbons in the reservoir, production under natural conditions of hydrocarbons may be at uneconomically low rates.
  • a second wellbore 822 is drilled, typically as a side bore from the wellbore 820 so as to be substantially parallel to the main wellbore within the reservoir.
  • the producing wellbore is typically cased with casing 830 that has perforations 834.
  • Fluid such as water, C0 2 or steam is then injected into the formation through the secondary wellbore 822 and the injected fluid drives the hydrocarbons in the formation towards the producing wellbore 820 where it may be recovered.
  • Such an operation requires careful positioning of the secondary borehole 822 in proximity to the production wellbore 820. This may be done by monitoring the voltage in the coil. As can be seen from eqn. (7), the voltage varies inversely as the fifth power of the distance. Thus, the voltage measurements may be used as either relative distance indicators based on voltage changes, or, with proper calibration, as absolute distance indicators.
  • FIG. 9 shows an embodiment for a radial magnet-coil arrangement 900 that includes two identical or substantially identical receiver coils symmetrically installed on the surface of the magnet for estimating distance between adjacent wellbore or boreholes.
  • the coil or coil arrangement 913 includes two coils 913a and 913b that are symmetrically or substantially symmetrically co-located (installed or placed) around or about the centerline of the magnet 203 and/or drill collar 201.
  • the radial magnetic field or flux 221 from the magnet 203 magnetizes the offset well casing 205.
  • the magnetic flux 223 from the casing 205 is received by both coils 913a and 913b.
  • This configuration may maximize the receiver signal and minimize the size of the rotational magnet/coil assembly.
  • a small size magnet/coil assembly may be installed on the drill bit or just above the drill bit and below (downhole) the mud motor.
  • such an arrangement is more desirable than attaching the magnet/coil on the drill collar because in high stick-slip situations the rotational speed of the drill collar 201 can induce large parasitic noise.
  • the magnet/coil arrangement With the magnet/coil assembly on the drill bit, the magnet/coil arrangement can still be rotated at a fairly constant speed using the mud motor. Pulling the drill bit a little uphole or back can be useful because the drill bit is then not be in contact with bottom of the borehole.
  • the configuration 900 continuously provided the distance between the drill collar 201 and the casing 205 while drilling the second borehole, which measurement may be used to monitor placement of the second borehole with respect to the first borehole.
  • signals from both the coils 913a and 913b are measured. Differential signals between coils 913a and 913b are obtained while rotating the drill collar 201. Due to the fact that the earth's magnetic field is spatially homogeneous while the signal from the rotating magnetization of the casing is spatially inhomogeneous, the parasitic signal from the earth's magnetic field is substantially removed from the differential signals, leaving a significant portion of signal from the rotating magnetization of the casing for further processing.
  • a controller downhole and/or at the surface may be utilized for processing the coil signals for determining the distance between the boreholes.
  • the controller may be a microprocessor based circuit and includes memory devices and programmed instructions for determining the distance. Such circuits are known in the art and are thus not described in detail herein.
  • the distance from the center of the coil 913 to the center of the casing is shown as "r" 2 while the distance between the surfaces of the drill color and the casing is shown as "d.”
  • FIG. 10 shows yet another embodiment of a radial magnet-coil arrangement 1000 that includes two coils, each coil further containing a pair of coils, radially
  • a first coil 1015 containing a first pair of identical or substantially identical coils 1015a and 1015b are placed a distance "dl" from the center of magnet 203 away from one end 203a and a second coil 1017 containing a second pair of coils 1017a and 1017b are placed at the distance dl away from the second end 203b of magnet 203.
  • the coils 1017a and 1017b are identical or substantially identical to coils 1015a and 1015b.
  • the magnet/coil configuration 1000 provides two distance-to-casing measurements (one corresponding to each pair) whose differentials may be utilized to estimate the distances and also determine the angle of the drill collar 201 with respect to the casing 205. Therefore, this configuration may be utilized intermittently when drilling is temporarily stopped (for example when drill pipe sections are being added) to determine the angle between the drill collar 201 and the casing 205 or the inclination of the drill collar 201 relative to the casing 205. The determined angle or relative angle or the inclination may then be utilized to steer or guide the next drilling section, i.e. till the next angle or inclination measurements.
  • the signal in the receiver coils 1015a, 1015b, 1017a and 1017b will generally be less than signals in the receiver coils 913a and 913b because the receiver coil voltage is now dependent also on the axial offset. This means the efficiency of this configuration will decrease as the axial offset increases.
  • FIG. 11 shows an exemplary graph 1100 of the magnetic flux 1110 at the receiver 215 or 217 as a function of the receiver axial offset 1120, i.e. (in this case two meters) between the receiver and the rotating magnet 203 shown in FIG. 10, wherein the distance between the drill collar 201 and the casing 205 (the casing offset) is five (5) meters.
  • the receiver magnetic flux at zero axial offset 1112 is 3.60e-l 1 Webb
  • the receiver magnetic flux at two (2) meters axial offset 1114 is 2.49e-l 1 Webb. Therefore, by taking differential signals between a pair of receivers at these two locations provides almost 31% of the remaining casing signal, which is significantly greater than the remaining signal (3.75%) for the radial signal.
  • FIG. 12 shows an exemplary axial coil configuration 1200.
  • three identical or substantially identical receiver coils 1213, 1215 and 1217 are installed on the drill collar 201 with equal spacing d2.
  • the middle coil 1213 is collocated with the rotating magnet 203, while coil 1215 is offset on one side of the magnet 203 and coil 1217 on the other side.
  • Two sets of differential signals between coil pairs 1215/1213, and 1213/1217 may be generated and utilized for determining the distance as well as the relative angle between the drill collar 201 and the casing 205.
  • An advantage of the axial configuration 1200 of FIG. 12 is that there is no physical limitation on the axial offset between the coils, while for the radial design the offset is limited by the diameter of the drill collar so the effectiveness of the radial gradiometer cannot be made very high.
  • a disadvantage may be that the bending/twisting/vibration of the drill collar may introduce relatively strong parasitic noise when the coils are axially separated. As a result, it may be more difficult to balance the magnetic moments of the coils for the axial configuration than for the radial configuration.
  • FIG. 13 shows an exemplary hybrid coil configuration 1300.
  • three identical or substantially identical receiver coils 1313, 1315 and 1317 are installed on the drill collar 201 with equal spacing d3.
  • Each such coil arrangement is shown to include a pair of two identical or substantially identical coils.
  • coil 1313 includes a pair 1313a and 1313b
  • coil 1315 includes a pair 1315a and 1315b
  • coil 1317 includes a pair 1317a and 1317b.
  • the middle coil 1313 is collocated with the rotating magnet 203, while coil 1315 is offset on one side of the magnet 203 and coil 1317 on the other side.
  • Two sets of differential signals between coil pairs 1315/1313, and 1313/1317 may be generated and utilized for determining the distance as well as the relative angle between the drill collar 201 and the casing 205. These measurements provide measurements for both the radial and axial configurations. For example, when differential signals are obtained, coil pairs 1313a and 1313b, 1315a and 1315b and 1317a and 1317b may be viewed as three radial configurations as shown in FIG. 9. However, when signals from each pair are combined, the three coil 3113, 1315 and 1317 would function as an axial configuration as, shown in FIG. 12.
  • coils such as coils 1015, 1017, 1313, 1315 and 1317 are shown to include two coils, more than two coils and suitable differential measurements may be utilized for the purposes of this disclosure. Also, the spacing from the magnet to the coils may be different. Additionally, the hybrid and other configurations provide more options and combinations of measurements so that the tool performance may be optimized for a particular drilling environment. Additionally, the embodiments discussed thus show the use of coils as detectors, magnetometers may also be used to detect the secondary magnetic field and the signals do detected may be processed to determine the distance between boreholes and the inclination a borehole.
  • the rotating magnet from a second borehole produces a time varying magnetic field in a first borehole.
  • a coil in the second borehole is then used to produce a signal responsive to a magnetic flux resulting from the magnetization of the casing from the first borehole. Since the signal induced by the rotating magnetization of the casing has a frequency which is twice the rotation frequency of the magnet/coil assembly, the measured proximity signal is separated from a parasitic signal induced in the rotating coil due to the earth's magnetic field, which has a frequency equal to the magnet/coil rotation frequency.
  • the parasitic signal from the earth's magnetic field may have spectral component at twice the rotation frequency of the magnet/coil assembly.
  • Such parasitic signal cannot be removed by a frequency-domain filter and may remain as a major source of noise in the final result.
  • the coil configurations shown in FIGS. 9, 10, 12 and 13 may reduce the parasitic signal from the earth's magnetic field and therefore improve the signal-to-noise ratio of the measurement.
  • the receiver coils with substantially equal magnetic moments are installed either radially-symmetrical or axially offset along the drill collar.
  • the magnetic moments of the receiver coils may be stabilized at (near) identical through surface or down-hole real-time calibration. Differential signal between a pair of receivers is processed for estimating the distance and the angle between two boreholes or objects. Since the earth's magnetic field is spatially homogeneous, the parasitic signal from the earth's magnetic field in the two substantially identical receiver coils should be substantially equal and therefore cancel out.
  • the signal induced by the rotating magnetization of the casing will not entirely cancel out because it is spatially inhomogeneous. Therefore, by taking the differential measurement, the noise from the earth's magnetic field is substantially removed, but a significant portion of the signal from the magnetized casing still remains for processing. The signal-to-noise ratio of the final measurement is thus improved.
  • V t o t (f) sin(cot) + V c sin(2eot + ⁇ 0 ), where (1 1)
  • V e a)A C0IL B e
  • V e is the amplitude of signal from the spatially homogeneous magnetic field of the Earth B e ;
  • V c is the amplitude of signal from the rotating magnetization of the target casing from the permanent magnet in the well being drilled, which has a strong spatial gradient;
  • ⁇ 0 is the angle between the Earth's magnetic field vector and the vector pointing from the well being drilled to the target casing, projected on the plane that is perpendicular to the surface of the receiver coils;
  • ⁇ 0 is the vacuum permeability
  • Xeff_ z is the effective magnetic susceptibility of the casing
  • ⁇ CASING is m e cross-sectional area of the casing
  • a COIL is m e area of the receiver coil
  • ⁇ is the angular frequency of the magnet/coil assembly
  • ri is the distance between the rotating magnet and the casing
  • r 2 is the distance between the casing and the receiver coil.
  • the magnet 203 is symmetric around the drill collar 201 so ri does not vary during rotation. If the distance between the center of the drill collar 201 and the casing 205 is five (5) meters, the diameter of the drill collar is 15 centimeters, then r 2 yaries approximately in the range of 5 ⁇ 0.075 m as the receiver coil rotates with the drill collar. In the radial configuration, two substantially identical coils mounted on opposite sides of the drill collar in a radially symmetric manner, and signals from the two coils are differentially combined.
  • Equation 13 shows that the signals due to the earth's magnetic field is removed by differentiating the measurements of the two coil signals, while a significant part of the casing signal remains for processing.
  • the signal-to-noise ratio may be further improved by better calibration of the receiver coil moments, and by using a drill collar with a greater diameter. It is also possible to implement an asymmetric magnet so ri varies in phase with r 2 during rotation, but this generally leads to a smaller total moment of the magnet and therefore a reduction of signal strength.
  • FIG. 14 shows an embodiment for a radial magnet-sensor arrangement 1400 for estimating distance between adjacent wellbore or boreholes.
  • the arrangement 1400 may be on a drill collar 1410 of a downhole tool, such as drilling assembly 190, FIG. 1, used for drilling a wellbore or may be in the form of a sub of the drilling assembly.
  • a magnetic member 1450 such as a metallic casing, in a preexisting wellbore is shown proximate the sub 1400.
  • the sub 1400 includes a magnet 1420 placed around a member 1410 of the sub 1400.
  • the magnet 1420 may be a permanent magnet placed around the member 1410 that generates uniform magnetic field 1422 that is induced the magnetic member 1450 when the drilling assembly (190, FIG. 1) is used to drill the wellbore.
  • the magnet 1420 rotates when the sub 1400 rotates with the drilling assembly (190, FIG. 1).
  • the magnet 1420 may be rotated independent of the drilling assembly rotation at a desired rotational speed that may be differ from the rotational speed of the sub 1400.
  • the magnet 1420 in one embodiment, may be rotated by an electrically- or hydraulically-operated motor.
  • the magnet 1420 when rotated independent of the sub 1400, is referred to herein as a detachable or detached magnet.
  • the sub 1400 further includes a sensor 1430 associated with the sub 1400.
  • sensor 1430 may include one or more magnetometers 1430a -1430n placed around the member 1410.
  • sensors 1430a- 143 On may be equally spaced. Any suitable number of sensors (for example 2-16) may be utilized.
  • sensor 1430 or sensors 1430a- 143 On may be placed on a non-rotating sleeve around member 1410 so that the sensors are stationary or substantially stationary relative to the rotation of the magnet 1420.
  • sensor 1430 or the sensors 1430a- 143 On may rotate relative to the magnet 1420 at a selected rotational speed that is different from the rotational speed of the magnet 1420.
  • the senor 1430 or sensors 1430a- 143 On may be rotated by any suitable device, including electrically- or hydraulically-operated motor.
  • a secondary or bucking magnet 1440 having a magnetic field Pb may be placed between the magnet 1420 and sensor 1430 or sensors 1430a- 143 On oriented in a manner to reduce or substantially cancel the effect of the magnetic field Pm on the sensor 1430 or sensors 1430a-1430n.
  • the distance between the sensor 1430 and the bucking magnet is shown as rb, while the distance between the magnet 1420 and the sensor 1430 is shown as r.
  • the magnet 1420 rotates, while the sensor 1430 or sensors 1430a-1430n remain stationary or substantially stationary relative to the magnet 1420.
  • Sensor 1430 or sensors 1430a- 143 On receive secondary magnetic field 1424 responsive to the primary magnetic field induced in the casing 1450 and provide signals representative of the received secondary magnetic field.
  • the secondary magnetic field ⁇ received at a particular sensor may be designated by its relative location, such as BO, B90, etc.
  • FIG. 15 shows an embodiment that utilizes electrical coils 1530a-1530n that provide electrical voltages V ⁇ (V0, V90, etc.) corresponding to the received secondary magnetic field.
  • Any suitable number of equispaced coils may be provided around the drill coil.
  • the coils may be stationary, substantially stationary or rotate at a rotational speed that differs from the rotational speed of the magnet 1420.
  • the magnet 1420 induces a primary magnetic field 1422 in the casing 1450.
  • the coils 1530a-1530n provide voltage signals corresponding to secondary magnetic field 1424.
  • the voltage signals are processed by a downhole and/or surface controller to estimate the distance D between the drilling assembly 1500 and the preexisting well 1450.
  • the distance D may ne determined as follows.
  • the bucked magnetic response for a rotating magnet and stationary sensor may be derived as follows:
  • B 0 A cos (cot + ⁇ - 2ip) + (A + ⁇ 3 ⁇ 4 ') cos (cot - ⁇ ) + B L cos(0 - ⁇ ) + 5 r (0) (14)
  • Acasing is the cross area of magnetic casing
  • ⁇ bucking is residual effect from imperfect bucking
  • S r (6>) is magnetic fields from residual magnetic charge distribution on casing
  • ⁇ azimuth angle of receiver moment direction
  • ⁇ is direction angel from a first borehole to a second borehole
  • ⁇ is direction angle of earth magnetic field
  • fl3 ⁇ 4 A cos ⁇ + 6j - 2 ⁇ ) + (A + B3 ⁇ 4 ) cos ⁇ - 0 y ) + B L cos(3 ⁇ 4 - ⁇ ) + ⁇ ⁇ ( ⁇ ,) (15)
  • the solution vector is then may be solved as follows:
  • the distance D can be determined from A.
  • V e V s 8 ⁇ ( ⁇ + ⁇ — 2 ⁇ ) + ⁇ V S + l3 ⁇ 4 sin( ⁇ ut + ⁇ ) (16)
  • ⁇ is angular frequency of rotation
  • ⁇ ⁇ is casing magnet permeability
  • Acasing is cross-section area of casing
  • Aeon is cross-section area of coil
  • D is distance to casing.
  • ⁇ bucking 1 is residual effect from imperfect bucking
  • the data processing relating to voltage signals to determine the distance may be performed as follows:
  • the solution vector can be solved as follows:
  • the processing of the data may be performed by a downhole processor to give corrected measurements substantially in real time. Implicit in the control and processing of the data is the use of a computer program on a suitable machine readable medium that enables the processor to perform the control and processing.
  • the machine-readable medium may include ROMs, EPROMs, EEPROMs, Flash Memories and Optical disks.

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Abstract

Un aspect de l'invention concerne un appareil permettant de déterminer une distance entre un premier trou de forage et un second trou de forage lors du forage du second trou de forage, appareil qui dans un premier mode de réalisation comprend un aimant sur un outil de forage qui tourne dans le second trou de forage pour induire un champ magnétique primaire dans un objet magnétique dans le premier trou de forage, un capteur sensiblement fixe sur l'outil de forage qui détecte un champ magnétique secondaire en provenance de l'objet magnétique en réponse au champ magnétique primaire induit, et un dispositif de commande qui détermine la distance entre le premier trou de forage et le second trou de forage d'après le champ magnétique détecté. Un autre aspect de l'invention concerne un procédé permettant de déterminer une distance entre un premier trou de forage et un second trou de forage, procédé qui dans un premier mode de réalisation comprend l'induction d'un champ magnétique primaire dans un objet magnétique dans le premier trou de forage en utilisant un aimant rotatif dans le second trou de forage, la détection d'un champ magnétique secondaire en provenance de l'objet magnétique en réponse au champ magnétique primaire induit en utilisant un capteur sensiblement fixe dans le second trou de forage, et la détermination de la distance entre le premier trou de forage et le second trou de forage d'après le champ magnétique détecté.
PCT/US2013/073105 2012-12-13 2013-12-04 Appareil et procédés de mesure de la proximité de puits en cours de forage WO2014093096A1 (fr)

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US13/713,960 US9151150B2 (en) 2012-10-23 2012-12-13 Apparatus and methods for well-bore proximity measurement while drilling

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CN105089519A (zh) * 2015-09-07 2015-11-25 山西风雷钻具有限公司 一种具有耐磨带的无磁钻铤
EP3469394A4 (fr) * 2016-06-09 2020-05-20 Optimal Ranging, Inc. Procédé et appareil d'excitation par induction et de localisation simultanées d'utilitaire
US10725191B2 (en) 2016-06-09 2020-07-28 Optimal Ranging, Inc. Method and apparatus for simultaneous inductive excitation and locating of utilities
US11762120B2 (en) * 2018-11-29 2023-09-19 Baker Hughes Holdings Llc Power-efficient transient electromagnetic evaluation system and method

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US5485089A (en) * 1992-11-06 1996-01-16 Vector Magnetics, Inc. Method and apparatus for measuring distance and direction by movable magnetic field source
US20050247484A1 (en) * 2001-11-15 2005-11-10 Brune Guenter W Locating technique and apparatus using an approximated dipole signal
US20070278008A1 (en) * 2006-06-05 2007-12-06 Vector Magnetics Llc Electromagnetically determining the relative location of a drill bit using a solenoid source installed on a steel casing
US20080018334A1 (en) * 2005-01-18 2008-01-24 Baker Hughes Incorporated Method and Apparatus for Well-bore Proximity Measurement While Drilling
US20090260879A1 (en) * 2008-04-18 2009-10-22 Schlumberger Technology Corporation Magnetic ranging while drilling using an electric dipole source and a magnetic field sensor

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Publication number Priority date Publication date Assignee Title
US5485089A (en) * 1992-11-06 1996-01-16 Vector Magnetics, Inc. Method and apparatus for measuring distance and direction by movable magnetic field source
US20050247484A1 (en) * 2001-11-15 2005-11-10 Brune Guenter W Locating technique and apparatus using an approximated dipole signal
US20080018334A1 (en) * 2005-01-18 2008-01-24 Baker Hughes Incorporated Method and Apparatus for Well-bore Proximity Measurement While Drilling
US20070278008A1 (en) * 2006-06-05 2007-12-06 Vector Magnetics Llc Electromagnetically determining the relative location of a drill bit using a solenoid source installed on a steel casing
US20090260879A1 (en) * 2008-04-18 2009-10-22 Schlumberger Technology Corporation Magnetic ranging while drilling using an electric dipole source and a magnetic field sensor

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105089519A (zh) * 2015-09-07 2015-11-25 山西风雷钻具有限公司 一种具有耐磨带的无磁钻铤
EP3469394A4 (fr) * 2016-06-09 2020-05-20 Optimal Ranging, Inc. Procédé et appareil d'excitation par induction et de localisation simultanées d'utilitaire
US10725191B2 (en) 2016-06-09 2020-07-28 Optimal Ranging, Inc. Method and apparatus for simultaneous inductive excitation and locating of utilities
US10809410B2 (en) 2016-06-09 2020-10-20 Optimal Ranging, Inc. Method and apparatus for simultaneous inductive excitation and locating of utilities
US11762120B2 (en) * 2018-11-29 2023-09-19 Baker Hughes Holdings Llc Power-efficient transient electromagnetic evaluation system and method

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CA2894512A1 (fr) 2014-06-19

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