CN1966935A - Method and apparatus for locating well casings from an adjacent wellbore - Google Patents

Abstract

A wellbore tool for locating a target wellbore containing a conductive member from a second wellbore and directing the trajectory of the second wellbore relative to the target wellbore includes an electric current driver having an insulated gap; a three-axis magnetometer positioned within a non-magnetic housing that is disposed within a non-magnetic tubular, the three-axis magnetometer positioned below the electric current driver; a drill bit positioned below the three-axis magnetometer; a hollow tubular connected between the electric current driver and the three-axis magnetometer; and a measurement-while-drilling tool. The current driver generates an electric current across the gap to the portion of the tool below the insulated gap. In a method a current is generated across the insulated gap to the portion of the tool below the insulated gap to the conductive material in the target wellbore returning to a portion of the bottom hole assembly above the insulated gap thereby producing a target magnetic field. Measuring the target magnetic field at the bottom hole assembly and the earth's magnetic field; and determining the position of the second wellbore relative to the target wellbore. Then steering the bottom hole assembly to drill the second wellbore along a trajectory relative to the target wellbore.

Description

Come the method and the device of spitting drill casing according to adjacent wellbore

Related application

[0001] the application requires the senior interest of the U.S. Provisional Patent Application No.60/733347 of submission on November 4th, 2005.

Technical field

[0002] in general, the present invention relates to drill-well operation, and more particularly, relate to the sleeve pipe or the drill string of when creeping into second pit shaft, locating first pit shaft according to second pit shaft.

Background technology

[0003] in various drilling operations, wishes the location adjacent wellbore.The example that may need to locate the drilling operation of adjacent wellbore comprises that the U-shaped well is crept into, creeps in decompression and steam assisted gravity is drained (SAGD).Sometimes the top layer, down-hole is eliminated in well generation blowout and hope, thereby need accurately locate first well when creeping into the second blocking-up decompression pit shaft.At present, the location adjacent wellbore generally be applied in SAGD well for example in first pit shaft take place when creeping into second pit shaft substantially parallel.

[0004] the current method that is used to locate the sleeve pipe (or drill string) of first pit shaft adopts the steel cable instrument.Utilize the steel cable instrument position the exploration and rely on those results' operation to have remarkable shortcoming.For example, use steel cable equipment to increase installation time and cost.And, adopt these steel cable methods only can obtain shaft location information termly.So just can not constant, in time and accurately obtain data, may cause the mistake of serious and high cost.

[0005] therefore, expectation provides the positioner that overcomes prior art and the adjacent well positioner and the method for the shortcoming in the method in the industry.Also expectation provides and has adjacent well positioner and the method for measuring (" MWD ") function when creeping into.

Summary of the invention

[0006] below an embodiment who is used for locating the drilling tool of the target wellbore that comprises conductive member according to second pit shaft.This drilling tool comprise current driver with clearance for insulation and be arranged on the current driver or under at least one magnetometer.Current driver produces the electric current of crossing over the gap and arriving the upper and lower tools section of clearance for insulation.

[0007] in another embodiment, being used for locating the target wellbore and the relative target wellbore that comprise conductive member according to second pit shaft guides the drilling tool of the track of second pit shaft to comprise: the current driver with clearance for insulation; At least one magnetometer, magnetometer be arranged on the current driver or under; Be arranged on the drill bit under the magnetometer; Be connected the hollow section between current driver and the magnetometer; And survey tool when creeping into.Current driver produces the electric current of crossing over the gap and arriving the upper and lower tools section of clearance for insulation.

[0008] below an embodiment of method that comprises the target wellbore of conductive member according to second pit shaft location and guide the track of second pit shaft with respect to target wellbore.This method may further comprise the steps: the bottom hole assembly that comprises the current driver with clearance for insulation is provided, be arranged on the current driver or under at least one magnetometer and be arranged on drill bit under the magnetometer; Adopt bottom hole assembly to creep into and isolated second pit shaft of target wellbore; The low-frequency current that generation is flowed out from current driver; The magnetic field of the goal at measuring well bottom component place; And determine the position of second pit shaft with respect to target wellbore according to the magnetic field of the goal measured value.

[0009] more than feature of the present invention and technological merit are summarized detailed description of the present invention below understanding better.Below other characteristics of the present invention and advantage are elaborated, they constitute the theme of claim of the present invention.

Description of drawings

[0010] in conjunction with the accompanying drawings with reference to following detailed description to a specific embodiment of the present invention, will thoroughly understand the present invention above-mentioned feature and the form that reach other, accompanying drawing comprises:

[0011] Fig. 1 is the schematic diagram of the embodiment of pit shaft navigation system of the present invention;

[0012] Fig. 2 is the sectional view of the embodiment of pit shaft orientation tool, shows magnetometer;

[0013] Fig. 3 is the schematic diagram of the embodiment of data acquisition sequence;

[0014] Fig. 4 is the sectional view of the pit shaft orientation tool on magnetometer, and the magnetic field when having asymmetric drill collar is described;

[0015] Fig. 5 A-5D is the diagram of magnetometer on the various position of rotation and the average magnetic field measured value that is associated;

[0016] Fig. 6 is the schematic plan view of the track of the target sleeve pipe and second pit shaft;

[0017] Fig. 7 is a schematic diagram, and creeping into of first pit shaft in the SAGD operation is described; And

[0018] Fig. 8 is a schematic diagram, and creeping into respect to second pit shaft of first pit shaft of Fig. 7 is described.

[0019] Fig. 9 is a schematic diagram, illustrates that an example creeps into the situation of SAGD well on cased well, shows sense of current.

[0020] Figure 10 represents the example orientation and the angle between them of two SAGD wells.

[0021] Figure 11 is with the axle of two wells of example shown and the radial vector between them.

The axle of two wells and an example of the radial vector between them when [0022] Figure 12 represents on second well is located immediately at first well.

[0023] Figure 13 is for tan γ ₀=-0.4,0 ,+0.4 (tan γ as theta function ₀Cos θ-sin θ) curve map.

[0024] Figure 14 is parallel with first well for second well and the curve map of the magnetic-field component of the example when having the well interbody spacer of 5m and 10m.Magnetic-field component when first well also being shown not existing.

[0025] Figure 15 is for the curve map of second well with the magnetic-field component of the angle  and first well inclined and the example when having the well interbody spacer of 5m.

The specific embodiment

[0026] referring now to accompanying drawing, therein, shown in parts not necessarily be shown to scale, and same or analogous parts are represented with identical reference number in some views.

[0027] term as used herein " upper and lower ", " top " and " bottom " and show that other similar terms for the relative position of set point or parts is used for more clearly describing some parts of embodiments of the invention.These terms are usually directed to reference point, for example from the surface that wherein begins drilling operation as the total depth of summit and well as minimum point.

[0028] Fig. 1 is the schematic diagram of an embodiment of pit shaft navigation system 10, it comprises that outfit is used for the bottom hole assembly (" BHA ") 12 of the 5 localizing objects pit shafts 14 on the stratum, simultaneously BHA 12 is used on the stratum 5 and creeps into second pit shaft 16, makes second pit shaft 16 can locate as required and along the guiding of expection track.Target wellbore 14 has been furnished with target sleeve pipe 18.

[0029] in example shown in Figure 1, but BHA 12 is included in drill bit 20 guidance systems 22 that are coupled to each other in the operation, the current driver 28 that has the magnetometer instrument 24 of three axis magnetometer 26 and have clearance for insulation 30.BHA 12 preferably also comprises at least one drill collar 27 that is arranged between three axis magnetometer instrument 24 and the current driver 28.BHA 12 turns round on drilling pipe 32.Be noted that BHA 12 also can comprise well logging (LWD) instrument when creeping into, other down-the-hole instrument of measuring (MWD) instrument, remote measurement instrument and be used to creep into environment when creeping into.Be also noted that the magnetometer instrument can comprise other sensor, for example accelerometer.

[0030] for example, current driver 28 may be E-Pulse or the E-Pulse Express (additional reference patent) of Schlumberger.For the sake of brevity, current driver 28 can be called E-Pulse 28 in this article, but can adopt other current driver, and does not deviate from the scope of the present invention of its rights and interests of requirement.In described embodiment, magnetometer instrument 24 comprises measures (MWD) and remote measurement (mud-pulse or electromagnetism) parts when creeping into.Be noted that in certain operations, can adopt different configurations.For example, in an example, current driver can be the em telemetry device.In another example, BHA 12 can comprise mud-pulse telemetry device and current driver.

[0031] Fig. 2 is the sectional view of an example with magnetometer instrument 24 of three axis magnetometer 26.Three axis magnetometer 26 is arranged in the drill collar 34, and it may be made of the nonmagnetic substance such as stainless steel that is usually used in the drill collar material or beryllium copper.The wall thickness of drill collar 34 be generally one inch or more than.Three axis magnetometer 26 is enclosed in non magnetic pressure shell 36 placed in the middle in the drill collar 34.Passage 38 is arranged on and is used for the sludge slurry between the inwall of pressure shell 36 and drill collar 34.

[0032] see figures.1.and.2, current driver 28 produces the electric current 40a that crosses over clearance for insulation 30.For example, electric current 40a can have the frequency between about 1Hz and the about 100Hz, and has the amplitude that can reach about 17amps.Electric current 40a flows and carries out stratum 5 along BHA12, is expressed as electric current 40b.In oil-base mud (OBM), the major part of electric current 40a will be left and turn back to BHA12 with the drilling pipe 32 that contacts pit shaft 16 walls as the electric current 40d on the clearance for insulation 30 by the stabilizer (not shown) by drill bit 20.In water-base mud (WBM), electric current 40a will flow out BHA12 as electric current 40b along its length.In WBM, electric current 40a reduces in the approximately linear mode between clearance for insulation 30 and drill bit 20.When sleeve pipe 18 is near BHA12, the part of electric current 40b will concentrate on sleeve pipe 18, be expressed as electric current 40c, and on the top that turns back to BHA12 after sleeve pipe 18 conduction, be expressed as electric current 40d.

[0033] compare with stratum 5, target sleeve pipe 18 provides extremely low resistive path, because the conductance of sleeve pipe is usually than big six orders of magnitude of formation conductivity.For example, the resistance of 9-5/8 inch sleeve pipe roughly is equivalent to have the cylinder on the 1ohm-m stratum of 500 feet of diameters.When sleeve pipe 18 during near assembly 12, this big difference causes producing the electric current that returns in the stratum on sleeve pipe.

[0034] the electric current 40c on the sleeve pipe 18 produces magnetic field B ₁, it is to be the azimutal magnetic fields at center with target sleeve pipe 18.Magnetic field B ₁Existence show that target sleeve pipe 18 is positioned near, and magnetic field B ₁Intensity and orientation can be used to estimate from BHA12 to target sleeve pipe 18 and to the direction of pit shaft 14.

[0035] the electric current 40c on the target sleeve pipe 18 can be than a little less than the electric current 40a on the BHA12, but will have the frequency identical with it and with its homophase.Electric current 40c is expressed as I ', is the azimutal magnetic fields B at center with target sleeve pipe 18 ₁By equation 1 approximate representation:

[0036] (equation 1)

[0037] wherein, μ ₀=4 π 10 ^-7Henry/m, r are the radial distances (m) from the target sleeve pipe 18 to BHA12 of shaft position z, and ψ is the unit vector on the azimuth direction.Measure magnetic field B ₁Operation provide about target sleeve pipe 18 with respect to the direction of BHA12 and the information of distance.

[0038] as long as frequency is enough low, from the magnetic field B of target sleeve pipe 18 ₁To penetrate drill collar 34 and pressure shell 36.Skin depth with metal of conductivity and magnetic conductivity μ ' represents that by equation 2 f wherein is a frequency.

[0039] δ=(π f μ ' μ ₀σ) ^-1/2(equation 2)

[0040] for example, the non-magnetic steel (μ '=1) that is used for drill collar has conductivity=1.410 usually ⁶S/m.On 10Hz, skin depth is 5.3 inches (0.13m), so magnetic field B ₁Can arrive magnetometer 26 with few decay for 10Hz and following frequency.

[0041] magnetic field B ₁Will with from target sleeve pipe 18 to point of observation, be the radially vertical of magnetometer 26.Therefore, by analyzing magnetic field B ₁, three axis magnetometer 26 can be used to determine to point to or leave the direction of target sleeve pipe 18.The distance that needs only target sleeve pipe 18 is less than the skin depth in the stratum 5, then magnetic field B ₁Will with source electric current 40a homophase.This condition is easy to be met, because the skin depth in the 1ohm-m stratum is 5200 feet (1.6 kilometers) when 10Hz.

[0042] in Fig. 1, target sleeve pipe 18 is located at the left side of second pit shaft 16 and BHA 12, and electric current 40a flows downward in BHA 12.This points in the page magnetic field on three axis magnetometer instrument 24.If target sleeve pipe 18 is arranged on the right side of BHA 12, then magnetic field B ₁Outside the sensing page.Therefore, magnetic field B ₁Direction can be used to obtain the direction of target sleeve pipe 18.

[0043] Fig. 3 represents an embodiment of data acquisition sequence.Signal 42 is represented an electric current, this electric current stops circulation, continues circulation then in two cycles, therebetween current reversal polarity.Signal 42 can be used to by orientation tool 12 drive current 40a.For convenience of description, Fig. 3 supposes that BHA 12 is static in data acquisition period, but target sleeve pipe 18 can be provided with and the location with respect to BHA 12 when creeping into pit shaft 16, thereby for example along with BHA 12 moves, it may be rotated.

[0044] signal 42 in Fig. 3, be expressed as between time 0 and the time T very first time interlude at interval (0, have amplitude zero between T).The time interval (T, 2T) in, signal 42 is " connection ", wherein has amplitude I (t)=Io.The time interval, (T 2T) was second time interval between time T and the 2T.As time interval in the 3rd time interval between time 2T and the time 3T (2T, 3T) in, signal 42 is " connection ", wherein have negative amplitude I (t)=-Io.The measured corresponding magnetic vector of magnetometer is represented on the top of Fig. 3 in this three cycles.

[0045] for the very first time interval as the interval between time 0 and the time T, magnetometer 26 detects the vector B in expression magnetic fields of the earth _eBecause magnetometer 26 is three axis magnetometers, so vector B _eComprise the spatial orientation information relevant with amplitude with the magnetic field at magnetometer 26 places.In second time interval between time T and time 2T, magnetometer 26 detects the magnetic field and the magnetic field B of the expression earth ₁The vector of sum.The vector that is detected in second time interval is expressed as vector B in Fig. 3 ₁, and by B _t=B _e+ B ₁Expression.In the 3rd time interval between time 2T and time 3T, magnetometer 26 detect as from the vector B in the magnetic field that direction produced of reverse current 40a ' _tVector B ' _tBy equation B ' _t=B _e-B ₁

[0046] utilization by magnetometer 26 resulting data, can be calculated the magnetic field B from target sleeve pipe 18 in three time intervals shown in Figure 3 ₁Magnetic field B from target sleeve pipe 18 ₁Can be by counting magnetic-field vector of the earth B _eWork in order to vector B _tOr vector B ' _tObtain.Perhaps, magnetic field can be by equation B ₁=(B _t-B ' _t) determine.Note, do not need to allow the 28 pairs of positive polaritys in source and the negative polarity that produce electric current 40a produce identical amplitude, because B ₁Its amplitude of direction ratio even more important, and its direction do not depend on the amplitude of electric current, but depends on the relative position of orientation tool 12 and target sleeve pipe 18.

[0047] in an example, according to the relevant required time of good signal-to noise ratio of measurement of carrying out with magnetometer 26, period of time T can have the duration of scope between 10 milliseconds and 10 seconds.Signal strength signal intensity depends on a number of factors, the contact resistance in the resistance on, stratum 5 12 whether parallel comprising the distance between the amplitude of electric current 40a, target sleeve pipe 18 and the BHA 12, target sleeve pipe and BHA, the resistance of mud and the oil-base mud between BHA 12 and the stratum 5.Any noise depends on characteristic, the time of integration of magnetometer 26 and electronic component thereof and may be derived from defective on the electronic equipment related with target sleeve pipe 18 or BHA 12, is derived from the utensil vibration in the magnetic field of the earth or is derived from any parasitic signal in the magnetic field that causes because of electric current 40a on the BHA 12.

[0048] establish the locational axial current 40a that I (z) is a magnetometer 26, z wherein is the axial distance to the gap.This electric current produces azimutal magnetic fields Bo (z), as shown in Figure 2.If axial current is expressed as I (z), the inside radius r=a of drill collar 34, the outer radius r=b of drill collar 34 then can carry out the calculating of relevant magnetic field B o (z).When r=b, axial current I (z) produce by

The azimutal magnetic fields of expression, wherein Be the unit vector on the azimuth direction.Since I (z)＞I ' and d b, therefore | B ₀| | B ₁|.Importantly, 26 pairs of magnetic field B of magnetometer ₀Insensitive.

[0049] if the drill collar 34 of magnetometer 24 and pressure shell 36 are cylindrosymmetric, then axial current I (z) also will be cylindrosymmetric.This axial current will pass the section area of drill collar, and cylinder symmetrical current density

Can the amps/m of the unit of employing ²Define, wherein,

It is the unit vector on the z direction.By the cylinder symmetry, expression J (r) is not the function of azimuth angle theta.If for r＜a, J (r)=0, any position in drill collar then, magnetic field also will be zero for r＜a.This is by the electromagnetism equation of Maxwell and by calculating integration $\∫\stackrel{\→}{B}\·\mathrm{dl}={\mathrm{\μ}}_0\∫\∫\stackrel{-}{J}\left(r\right)\·\mathrm{zdxdy}$ Draw, wherein, the line integral in left side is calculated for the circle of radius r＜a, and the area integral on right side calculates for that round section area.If J (r) ≠ 0 on any position of drill collar 34 inside, then this result is not true.Therefore, importantly, do not allow electric current 40a process wire, lead-in wire or other path in drill collar 34.Specifically, between the inner member of current driver 28 and magnetometer instrument 24, there is not hardwire to be connected, for example on internal bus.In addition, be preferably at least one hollow section that has drill collar 27 between current driver 28 and the magnetometer 24.

[0050] as shown in Figure 4, if exist asymmetricly on a small quantity in the drill collar 34, then may have weak secondary magnetic field, as stray magnetic fields B ₂Pass magnetometer 26.The local magnetic field of magnetometer 26 may be influenced, cylinder symmetric magnetic field B can be modeled as ₀Add littler asymmetric stray magnetic fields B as the function of θ and r ₂Stray magnetic fields B ₂Be derived from Magnetic Dipole Source, for example from the hole of passing on the drill collar 34 (H.A.Beth.Phys.Rev.66, p163,1944).

[0051] if stray magnetic fields B ₂With magnetic field B ₁Compare not too big, magnetic field B then ₂Can adopt following process to overcome and from data, eliminate.The magnetic field of at first supposing the earth has been adopted and has abovely been eliminated in conjunction with the described communication method of Fig. 3.After this process, as shown in Figure 5, residual magnetic field B _SIt is magnetic field B ₁With stray magnetic fields B ₂Sum is by equation B _S=B ₁+ B ₂Expression.

[0052] in Fig. 5 A to 5D, bottom view represents to forward to 0 ° of four independent-angle, 90 °, 180 °, 270 ° the three axis magnetometer 26 (instrument 24) of Fig. 4 respectively, and these are called tool face azimuth or θ _TFThe orientation rather than the expression dissymmetrical magnetic field B of magnetometer 26 represented in the tool face azimuth ₂The source.The tool face azimuth is with respect to for example adopting the determined gravity of accelerometer in the magnetometer instrument 24 to measure.The residual magnetic field B that the upper view of Fig. 5 A to 5D is illustrated on the respective corners to be produced _SNote stray magnetic fields B ₂Orientation depend on the orientation of drill collar 34, and magnetic field B ₁Be constant aspect direction and the amplitude.Therefore, if residual magnetic field obtains as the function of the orientation (or tool-face) of drill collar 34, stray magnetic fields B then ₂Can handle via signal and eliminate.A simplified example shown in Fig. 5 A to 5D, therein, residual magnetic field B _S(0), B _S(90), B _S(180) and B _S(270) on 0 °, 90 °, 180 ° and 270 ° of four angle, measure respectively.The average of these four readings has been eliminated stray magnetic fields B ₂, and magnetic field B ₁By B ₁={ B _S(0)+B _S(90)+B _S(180)+B _S(270)+/ 4 expressions.

[0053] need not measure with the concrete angle shown in Fig. 5 A to 5D, be enough with several measurements of angle at random, as long as their are around 360 ° of distributions of tool-face.Be perfectly clear, the formation of the stray magnetic fields of angle is the circle at center with sleeve pipe magnetic field at random.Can adopt simple trigonometry method and utilize each example B _S(θ _TF) the given value of tool-face obtain magnetic field B ₁

[0054] or, if drill collar 34 smoothly rotates, then can obtain the continuous measurement value from magnetometer 26.If for several drill collar 34 rotations the magnetic field reading is asked on average, then stray magnetic fields B ₂With average out to zero.As long as it is not too big to creep into vibrations, tool-face can obtain from accelerometer.Therefore, possible process is to ask on average for the reading of the source electric current with positive polarity with regard to some rotations, asks average for the reading of the reversed polarity of source electric current then.If these two averages are＜B _tAnd＜B ' _t, magnetic field B then ₁By B ₁={＜B _tThe B ' of 〉-＜ _tExpression.Difference in last equation has been eliminated the magnetic field of the earth component.

[0055] blocking the operation of drawing pit shaft with second well is used to eliminate blowout and is used to creep into " U-shaped well ".In blowout, first well runs into the extremely high pressure stratum during creeping into.If the weight of drilling mud is too low, then strata pressure surpasses boring pressure, and enters pit shaft from the liquid on stratum with noncontrol system.Stratum liquid makes the anchor ring between drilling mud ejection stratum and the drill string.Because the stratum density of liquid is lower than mud, so the pressure on surface may become high.This is serious situation, and it may jeopardize human and environment, and may damage rig and fuel tank.(for example " weight and wait ") can not rebulid in boring than pressure bigger in the stratum if standard is crept into control method, then takes to creep into the extreme measures of relief well.Creep into second pit shaft from deviation post, and first well is blocked in the short distance of attempting on the blowout stratum.Use steel cable magnetic telemetry, therein, the BHA that creeps in second well regularly is removed, and steel cable instrument turn round in the open hole of relief well (referring to United States Patent (USP) 4372398).4372398 steel cable instrument has the electric current injecting electrode and the probe of two wide intervals, wherein has the magnetometer that is arranged between them.The electric current that injects concentrates on the drill string of first well, and gained magnetic field adopts magnetometer to measure, to determine the relative bearing of first well with respect to second well.By obtaining the some azimuths on the diverse location in the relief well, can also be determined to the distance of blowout.At last, relief well can be blocked blowout, but this may need a large amount of strokes, and promptly drill string is removed, and the steel cable magnetic ranging tool arrives open hole.Each stroke may need the installation time of a day or many days, so this process may be extremely slow and expensive.Relief well has extremely heavy mud, and it can come " elimination " blowout by the boring pressure that rebulids greater than strata pressure.

[0056] because that to determine from pit shaft be the steel cable magnetic survey to the process of the relative bearing of target sleeve pipe and distance is known apart from the technology, therefore is briefly described for BHA 12 with reference to Fig. 6.Fig. 6 provides second pit shaft 16 and the track of target sleeve pipe 18 or the plan view in path.BHA 12 (not shown) are arranged in the pit shaft 16, and determine with the trigonometry method to the distance of target sleeve pipe 18.When creeping into pit shaft 16, adopt the magnetometer 26 of BHA 12 on each position, to measure by the caused target sleeve pipe of the electric current in the target sleeve pipe 18 magnetic field.From seeing referring to figs. 1 through clear Fig. 5 description of this invention, BHA 12 can be used for creeping into pit shaft 16 and measures magnetic field B ₁Utilize the sleeve pipe magnetic field B ₁Various readings, can adopt the trigonometry method to calculate two distances between the well simply with all angles with respect to target sleeve pipe 18.

[0057] before the present invention, need pull out pit shaft to BHA, and operation steel cable magnetic ranging tool is with the localizing objects sleeve pipe.Adopt BHA to return pit shaft then to continue drilling operation.System 10 of the present invention can help the position of tracking target sleeve pipe 18 relative pit shafts 16, and need not to remove from pit shaft BHA, thereby significantly reduces the time, cost and improve the precision creep into second pit shaft.

[0058] being used for blocking from second well that second of first well uses is to set up " U-shaped " well.Creep into two horizontal wells from diverse location, and in underground carrying out " end on earth " blocking-up (referring to " a U pipe well connects horizontal well ", Drilling Contractor, in September, 2005-October).A purpose of creeping into the U-shaped well is cable laying or pipeline under water.Another purpose provides from land to the pipeline of coastal waters well, and therein, the stability in seabed can not be supported seabed pipeline.Another purpose may be by thermally showing the stratum rather than producing heavy oil by the seabed pipeline that is exposed to cold water.Cryogenic piping increases the viscosity of heavy oil, and stops its production.In order to creep into the U-shaped well, first well is crept into and is added sleeve pipe.When second well is crept into and during near first bottom, the steel cable instrument must be inserted into first well and be used for the magnetic survey distance.It is first aboveground that this needs boring tower to remain on, so that dispose the steel cable instrument in horizontal well.

[0059] example of the method for operation pit shaft navigation system 10 is described referring now to Fig. 1 to Fig. 5.For the starting data acquisition some possible strategies are arranged, this paper describes such process.(～50 feet/hour) are carried out in creeping into slowly of second pit shaft 16, and target sleeve pipe 18 can not change rapidly with respect to the distance and the direction of pit shaft 16.Therefore, may not need or not wish the relative bearing of continuous measurement to target sleeve pipe 18.

[0060] Once you begin data acquisition sequence, current driver 28 just stops circulating current 40a, continue circulating current 40a and electric current 40a is reversed with predetermined time interval T.In an example, this method is carried out as shown in Figure 3.Similarly, MWD instrument 24 can be when detecting acquisition sequence and begin initial measurement sequence.Magnetometer 26 reads the magnetic field of the earth at first.When 28 pairs of locator tool of current driver 12 send electric current 40a downwards, if there is sleeve pipe, then magnetometer will detect the variation in magnetic field.When electric current 40a is inverted, magnetometer will detect the variation in magnetic field once more.Directly communicate by letter between current driver 28 and the MWD instrument 24 and path synchronously, the MWD instrument will be derived and be broken, leads to and cycle of reverse current.This can be by carrying out the magnetic strength read data is relevant with known timing sequence.For example, (0, T) be the electric current disconnection to previous described sequence, (T be that electric current is connected 2T), and (2T 3T) is current reversal for the 3rd time interval for second time interval at interval for the very first time.This can repeat for the cycle of predetermined quantity.Then, MWD instrument 24 calculates interrelated between CURRENT DISTRIBUTION and the magnetic strength read data, to obtain three values in magnetic field.Adopt the unequal cycle, for example (0,2T) in electric current disconnect, (2T, 3T) in electric current connect, and (3T, 4T) in current reversal, the disconnection of mark electric current, connection and returing cycle clearly.Because current driver 28 is programmed for known phase (for example just) beginning electric current, therefore, do not have indeterminate property for the symbol of the direction of pointing to sleeve pipe.

[0061] in case deal with data to obtain magnetic field of the earth (B _e) and B _S(θ _TF), θ wherein _TFBe tool-face, then MWD instrument 24 can transmit this information earthward.BHA then can stop through rotation and in another tool face azimuth, and this process repeats to obtain another reading B in new tool face azimuth _S(θ ' _TF).If do not detect stray magnetic fields B ₂, then may not need to measure with a plurality of tool face azimuths.

[0062] pit shaft navigation system 10 of the present invention is relevant especially with steam assisted gravity drainage (SAGD) production operation.SAGD needs at least two horizontal wells to creep in parallel with each other.A well is set directly on another well, and has for example 3 to 5 meters constant interval usually.These wells can be furnished with sleeve pipe or slotted liner.In case finish drilling well, steam is injected into well, and hydrocarbon is from the output of going into the well.

[0063] referring now to Fig. 1 to Fig. 8 an embodiment who operates the method for creeping into first well 14 and second well 16 for SAGD is described.With reference to Fig. 7, first horizontal wellbore 14 adopts definite technology of developing for geosteering and interface, as heavy oil shale interface 52 parallel pit shafts to creep into.But the drilling assembly that is expressed as BHA 54 generally includes drill bit 20 guidance systems 22, LWD system 56 (for example comprise and be used for measuring resistance coefficient, gamma rays, sonic tool and/or nuclear tool) and mwd system 58, with the provider to, inclination and remote measurement, for example, LWD system 56 can comprise PeriScope15 or the similar system of Schlumberger, it can be measured and leave the formation resistivity coefficient on the orientation around the about altogether 15 feet formation resistivity coefficient of BHA, BHA, and can determine vertical and horizontal resistance coefficient on the stratum during for heterogeneous body.LWD 56 can measure the resistance coefficient on the drill bit 20, and the high-definition picture of drill hole wall is provided, and this can be used to provide the information about accurate bedding.Therefore, the resistance coefficient instrument of LWD 56 can provide the extremely detailed figure of the formation resistivity coefficient in the larger volume around the pit shaft.Pit shaft 14 is furnished with sleeve pipe 18.

[0064] as shown in Figure 8, second pit shaft 16 directly adopts in (or under) on first pit shaft 14 and comprises that the BHA 12 of orientation tool creeps into.See figures.1.and.2 and describe BHA 12, it also can comprise LWD system 56.As previously described, electric current 40 causes the magnetic field B of surrounding target sleeve pipe 18 ₁Magnetic field B ₁Can be by analysis to determine direction and the distance of target sleeve pipe 18 with respect to instrument 12.For the SAGD operation, preferably make second pit shaft 16 and target sleeve pipe 18 keep substantially invariable apart from S.Therefore, need make the triangulation method possibility of pit shaft 16 fluctuations unsatisfactory.Therefore, provide the alternative approach that is used for determining and keeping separation distance S.

[0065] provides an example of algorithm now, how to locate with respect to first well according to magnetic-field measurement so that the 2nd SAGD well to be described.First creeps into normally bottom producing well 14 (for example referring to Fig. 7) of well.After first well 14 adds sleeve pipe, be called top second well 16 and first well 14 that inject well again and crept into (Fig. 9) concurrently.As shown in Figure 9, second well 16 adopts BHA 22 to creep into, but it comprises drill bit 20 guidance systems 22, LWD instrument 56 and three axis magnetometer 58.

[0066] Figure 10 illustrates the azimuth of two wells and the related angle of two wells.(z) coordinate system is related with second well for x, y, wherein, Be to align with bore hole axis and point to the unit vector of " drill bit ".Unit vector

Point to (on the direction of gravity) down. Direction can be determined from the accelerometer of the MWD instrument that is used for creeping into second well.First well and unit vector Alignment.Angle between two wells is , and

Projection to (x, y, 0) plane forms angle θ with respect to the x axle.In an example, second well 16 directly is on first well 14.

[0067] establish that clearance for insulation 30 among the BHA 22 of second well is positioned at z=0 and drill bit is positioned at z=L, L wherein is the length of the BHA under the clearance for insulation.Electric current I (0) is crossed over clearance for insulation 30 and is produced in second well 16, and flows along the BHA in second well 16 22, is expressed as I (z).In conduction water-base mud (WBM), electric current I (z) is along with to the distance of clearance for insulation 30 and approximately linear ground reduces, and in the vanishing of bit face place, make between clearance for insulation 30 and drill bit 20 I (z) ≈ I (0) (L-|z|)/L.On clearance for insulation 30, electric current also reduces with linear mode, but further extends to drill string.In electrical insulation oil base mud (OBM), it is constant that electric current I (z) keeps under clearance for insulation 30, and only the surface by drill bit 20 enters the stratum.In OBM, the electric current under the clearance for insulation is represented by I (z) ≈ I (0).Electric current turns back to BHA by stabilizer on the gap, and contacts with the stratum by drill collar.

[0068] in the occasion of VBM or OBM, the major part of leaving the electric current of the BHA in second well 16 flows to first well 14, returns along target sleeve pipe 18 then.If the ammeter on the target sleeve pipe 18 is shown I '.In OBM, the electric current on the sleeve pipe is more constant along its length, and is represented by I '-I (0).In WBM, very little if the interval of two wells is compared with L, then electric current changes according to I '-I (z) along sleeve pipe.The electric current I (0) of crossing over clearance for insulation 30 and producing is measured and be sent to ground in real time.According to second well 16 is to adopt WBM or adopt OBM to creep into electric current I ' suitable approximation be used for following analysis.

3 magnetometers 58 in [0069] second well 16 be positioned at (x, y, z)=(0,0, z ₀), the magnetic-field component of returning on the target sleeve pipe 18 of its measurement by first well 14 that electric current produced.For abridged notation is represented, below do not represent subscript " 1 ", but be appreciated that following magnetic field represents the magnetic field that is produced by first well 14, promptly

For the sake of brevity, the magnetic field of the earth is left in the basket in following analysis, and the BHA 22 in second well 16 does not rotate.These restrictions can be eliminated.For example, alternating current will produce can with the distinguishing alternating magnetic field of the static magnetic field of the earth.Perhaps, the source electric current can be switched on and disconnect and reverse on direction, as previously described.In addition, if the BHA 22 in second well 16 can be magnetometer data static earth frame from the throw frame transform then with the given frequency rotation.

[0070] magnetic-field component is sent to ground in real time by the MWD instrument.Measure direction and the amplitude of B by the magnetometer among the BHA that adopts well #2, and by the electric current I on the sleeve pipe among the estimation well #1 ', can determine two distance and relative position and orientations between the well.

[0071] as long as electric current I ' there is not relative magmetometer too much to change, then magnetic field is by the following formula approximate representation

$\stackrel{-}{B}\left(z\right)=\frac{{\mathrm{\μ}}_0{I}^{\′}}{2\mathrm{\π}{r}^2}\hat{n}\×(-\stackrel{\→}{r})\·\·\·\left(1\right)$

Wherein, μ ₀=4 π 10 ^-7Henry/m.Here, It is the vector that points to the closest approach of cased well #1 from the magnetometer of well #2.This formula supposition is along the more constant electric current of the sleeve pipe of well #1.This hypothesis is correct for OBM, because source electric current I (z) is constant along BHA, thereby return current I ' will be constant near the sleeve pipe the magnetometer.In WBM, I (z) changes along BHA, thereby I ' is not constant along this sleeve pipe.But, if two well spacing distance r much smaller than L, then I ' should not change excessive near magnetometer.Therefore, still effective for the formula more than the magnetic field.

[0072] another analysis expression in the magnetic field of WBM occasion can comprise the variation of electric current with distance, promptly I ' (z) ≈-I (z) ≈-I (0) (L-|z|)/L.This CURRENT DISTRIBUTION is represented the characteristic of the linear electrical dipole antenna in the conducting medium." typical electrical kinetics " (John Wiley ﹠amp of the visible Jackson of analysis mode in magnetic field; Sons.Inc. publish, 1967, the 271-273 page or leaf).Analysis can be adopted from the expression formula of the books of Jackson and carry out, and it is followed and similar approach given here.But its basic conception is fully described by the simple formula of line current.Be appreciated that the present invention includes and utilize different formula that expression formula provided here is just as an example.

[0073] or, electric current on BHA 22 and the target sleeve pipe 18 and the magnetic field that is produced can adopt the three-dimensional numerical value code to come modeling, its allows model particularly including drill string, sleeve pipe, boring, drilling fluid and various layer attribute, for example bedding.In numerical method, computer model is used for simulating that BHA goes up, in the stratum and the CURRENT DISTRIBUTION on the sleeve pipe, and calculates the magnetic field that is produced.Relatively the modeling result in magnetic field and measured result's operation allows to be estimated to the distance and the direction of cased well.Be provided for a example after a while to a kind of like this value code of SAGD well modeling.

[0074] supposition first well is at position (x ₀, y ₀, z ₀) go up with $\frac{y_0}{x_0}\≡\tan {\mathrm{\γ}}_0$ Pass by z=z ₀Defined x-y plane, as shown in figure 11.Purpose is a quantification: x ₀, y ₀, θ and , they define position and the direction of first cased well with respect to the BHA in second well.Measurement or dose known amounts are: I (0), z ₀And B (0,0, z ₀).Mathematical analysis is for because of the electric current I on the target sleeve pipe of first well ' magnetic-field component that causes establishes an equation under producing,

$\mathrm{Bx}(\mathrm{0,0},z_0)=\frac{{\mathrm{\&mu;}}_0{I}^{\&prime;}}{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">r</figure-callout>}}_0^2}{\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">y</figure-callout>}}_0\cos \mathrm{\&phi;}\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

$\mathrm{By}(\mathrm{0,0},z_0)=-\frac{{\mathrm{\&mu;}}_0{I}^{\&prime;}}{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">r</figure-callout>}}_0^2}{x}_0\cos \mathrm{\&phi;}$ And (3)

$\mathrm{Bz}(\mathrm{0,0},z_0)=\frac{{\mathrm{\&mu;}}_0{I}^{\&prime;}}{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">r</figure-callout>}}_0^2}(x_0\sin \mathrm{\&theta;}-{\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">y</figure-callout>}}_0\cos \mathrm{\&theta;})\sin \mathrm{\&phi;}$ Wherein (4)

${\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">r</figure-callout>}}_0=\sqrt{x_0^2+{\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">y</figure-callout>}}_0^2-{\mathrm{\&beta;}}_0^2}$ And β ₀≡ (x ₀Cos θ+y ₀Sin θ) sin φ (5a, b)

[0075] for the SAGD well that correctly creeps into, | and By (0,0, z ₀) | be far longer than | and Bx (0,0, z ₀) | or | Bz (0,0, z ₀) |.The relative position of first well and direction can adopt above equation to derive from these quantity.Angle γ ₀By recently determining of Bx and By, wherein

$\frac{\mathrm{Bx}}{\mathrm{By}}=-\tan {\mathrm{\&gamma;}}_0=-\frac{y_0}{x_0}\&CenterDot;\&CenterDot;\&CenterDot;\left(6\right)$

Thereby eliminate a unknown quantity.If Bx ≠ 0, then γ ₀≠ 0, first well is not directly under second well.In case find the perpendicular separation (x of well ₀), horizontal movement (y ₀) just be determined.Bz gets with the ratio of By

$\frac{\mathrm{Bz}}{\mathrm{By}}=(-x_0\sin \mathrm{\&theta;}+{\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">y</figure-callout>}}_0\cos \mathrm{\&theta;})\tan \mathrm{\&phi;}=x_0(\tan {\mathrm{\&gamma;}}_0\cos \mathrm{\&theta;}-\sin \mathrm{\&theta;})\tan \mathrm{\&phi;}\&CenterDot;\&CenterDot;\&CenterDot;\left(7\right)$

If Bz ≠ 0, then possible  ≠ 0, two well is not parallel.At last, By is relevant with the well interbody spacer according to following formula with I '

[0076] equation 5a and 5b can be used for eliminating r from equation (8) ₀ ², obtain

These three equations (6), (7) and (9) are related to four unknown quantity x ₀, y ₀, θ and .Three equations are arranged in four unknown quantitys, therefore, do not have unique separating for having ordinary circumstance arbitrarily angled and that well location moves.But, only use so far from data along a single position of z axle.Provide abundant data to determine all unknown quantitys in two locational measurements along axle.

[0077] near parallel SAGD well, effectively carries out small angle approximation, cos  ≈ 1, and sin  ≈ .Normal MWD direction is fully accurate with the inclination measurement value for second well that will creep on the direction identical with second well, within the several years error.For example, 5 ° relative error is corresponding to =0.09.Therefore, for the approximation of cos  ≈ 1 and sin  ≈ , equation (7) and (9) are reduced to:

$\frac{\mathrm{Bz}}{\mathrm{By}}{\&ap;x}_0(\tan {\mathrm{\&gamma;}}_0\cos \mathrm{\&theta;}-\sin \mathrm{\&theta;})\mathrm{\&phi;}\&CenterDot;\&CenterDot;\&CenterDot;\left(10\right)$

$x_0^2+{\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">y</figure-callout>}}_0^2\&ap;-\frac{{\mathrm{\&mu;}}_0{I}^{\&prime;}}{2\mathrm{\&pi;By}}{\mathrm{<figure-callout\; id="0"\; label="x"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">x</figure-callout>}}_0\&CenterDot;\&CenterDot;\&CenterDot;\left(11\right)$

Equation (11) can be rewritten the perpendicular separation with definite well,

$x_0\&ap;-\frac{{\mathrm{\&mu;}}_0{I}^{\&prime;}}{2\mathrm{\&pi;}[1+{\left(\frac{\mathrm{Bx}}{\mathrm{By}}\right)}^2]\mathrm{By}}\&CenterDot;\&CenterDot;\&CenterDot;\left(12\right)$

Equation (6) provides y coordinate

${\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="A20061014456000272.png,A20061014456000291.png"\; state="\{\{state\}\}">y</figure-callout>}}_0=\frac{{\mathrm{\&mu;}}_0{I}^{\&prime;}\mathrm{<figure-callout\; id="2"\; label="Bx"\; filenames="A20061014456000331.png,A20061014456000361.png"\; state="\{\{state\}\}">Bx</figure-callout>}}{2\mathrm{\&pi;}[1+{\left(\frac{\mathrm{Bx}}{\mathrm{By}}\right)}^2]{\left(\mathrm{By}\right)}^2}\&CenterDot;\&CenterDot;\&CenterDot;\left(13\right)$

Therefore, for cos  ≈ 1, according to a magnetometer position (0,0, z ₀) measurement carried out, these coordinates (x ₀, y ₀, z ₀) on the axle of definition first well a bit.

[0078] angle θ and  can from second point (0,0, z ₁) on magnetometer survey determine.Two readings can adopt two different magnetometers among the BHA to obtain, and perhaps obtain by moving single magnetometer between the two positions.Repeat above process and produce first well at (x ₁, y ₁, z ₁) on second coordinate, x wherein ₁And y ₁From equation (12) and (13), obtain, and B (0,0, z ₁) be used for replacing B (0,0, z ₀).Two gained coordinate (x ₀, y ₀, z ₀) and (x ₁, y ₁, z ₁) axle of definition well #1; Therefore θ and  determine via following formula

$\tan \mathrm{\&theta;}=\frac{y_1-y_0}{x_1-x_0}:$ And (14)

$\tan \mathrm{\&phi;}=\sqrt{\frac{{(x_1-x_0)}^2+{(y_1-y_0)}^2}{{(z_1-z_0)}^2}}\&CenterDot;\&CenterDot;\&CenterDot;\left(15\right)$

Therefore, obtain describing second well with respect to the position of first well and all desired amounts of direction.

[0079] can also be from the release of the measured value on the single point some directional information about well #2.With reference to equation (10), two angle θ are relevant via following formula with 

$\mathrm{\&delta;}\&equiv;(\tan {\mathrm{\&gamma;}}_0\cos \mathrm{\&theta;}-\sin \mathrm{\&theta;})\mathrm{\&phi;}\&ap;-\frac{2\mathrm{\&pi;Bz}}{{\mathrm{\&mu;}}_0{I}^{\&prime;}}[1+{\left(\frac{\mathrm{Bx}}{\mathrm{By}}\right)}^2]\&CenterDot;\&CenterDot;\&CenterDot;\left(16\right)$

The right side comprises measured value.If Bz=0, δ=0 then, its expression

φ＝0，

Perhaps (17)

tanθ＝tanγ ₀θ＝γ ₀+nπ

(18’)

First condition (16) shows that two wells are parallel fully, and it is the ideal conditions of SAGD well.Second condition (17) expression direction vector Be positioned at (x ₀, y ₀, z ₀) in the defined plane.If well is not parallel, but they must all be arranged in same level, then can satisfy equation (18).In this case, they may be dispersed or convergence mutually mutually.

[0080] if Bz ≠ 0, then δ ≠ 0, and following condition is necessary for very:

φ≠0

And (19)

tanγ ₀cosθ-sinθ≠0

(20)

Equation (19) shows that two wells are not parallel, and equation (20) shows direction vector Be not positioned at

Axle and (x ₀, y ₀, z ₀) in the defined plane.Therefore, the nonzero value of δ can be used as the error indication, and this can be used for backfeed loop creeps into second well with control direction.

[0081] in order to describe, supposes γ ₀=0, make second well at point (x ₀, 0, z ₀) fully on first well, as shown in figure 12.Equation (16) is reduced to

δ＝-φsinθ

(21)

Note the edge Direction is arranged

Component be

Therefore, amount δ be two wells with respect to The direct measured value that does not overlap of direction.The trend that floats to a left side or the right side will detect by monitoring δ, and proofread and correct subsequently.But δ can not show upwards still drift downwards.

[0082] at tan γ ₀In ≠ 0 o'clock the ordinary circumstance, amount δ still can be used as feedback compensation., it corresponding to

Axle and point (x ₀, y ₀, z ₀) defined plane is vertical

Part.

For example, suppose tan γ ₀=0.4, corresponding to γ ₀=0.381 or 21.8 °.With reference to conduct (tan γ ₀Cos θ-sin θ) Figure 13, zero intersects 21.8 ° of appearance, makes that δ is driven into zero will make two wells reach Axle and (x ₀, y ₀, z ₀) defined plane.

[0083] automatic feedback and control system can be set in the shaft bottom, to guide second well.Suppose that two wells have suitable well interbody spacer (r=d), prograde orbit (=0) at first, and second well (γ on first well ₀=0), makes that error signal δ is zero.If δ offset from zero, then this expression trend from left to right.The direction of second well can be changed, so that δ gets back to zero, thereby proofreaies and correct drift from left to right.Because this is corresponding to just being driven into Bz zero, so without any need for additional shaft bottom information.Downhole processor among the BHA of second well can be monitored Bz, and controlling party is to remain on two wells in the same plane.

[0084] but still exist two wells to drift about mutually or mutually away from possibility.Correct interval can obtain by the amplitude of monitoring By.According to equation (12),

$x_0\&ap;-\frac{{\mathrm{\&mu;}}_0{I}^{\&prime;}}{2\mathrm{\&pi;By}}\&CenterDot;\&CenterDot;\&CenterDot;\left(23\right)$

For I ' is constant, and the variation of By may be interpreted as variation at interval.By can be used as error signal to the difference of its desired value.Processor among the BHA of second well can be monitored By and Bz, and controls the interval of two wells automatically.

[0085] analysis of front is intended to principle of specification rather than restriction the present invention.The simplification hypothesis in electric current and magnetic field is not main for this method.For example, a kind of alternative approach be to use full three-dimensional modeling code predict as well at interval, the electric current and the magnetic field of the function of the details of relative well orientation, BHA and sleeve pipe and variable formation characteristics.Market Electromagnetic Modeling code on sale, can be used to calculate electric current and magnetic field as Comsol Multiphsics.Its process is: 1) to various physical conditions (for example well interval, well orientation, formation resistivity coefficient, bore diameter, mud resistance coefficient, BHA diameter and length, casing diameter etc.) modeling, 2) modeling result and real-time measurement values are compared, 3) determine relative orientation and well interbody spacer, and 4) proofread and correct the track that creeps into well.

Three-dimensional numerical calculation such as Figure 14 and shown in Figure 15 of the BHA of [0086] for example, 6.75 inches (0.172 meter) diameters.The length of BHA under the clearance for insulation is 40 feet (12.2 meters), and the length of clearance for insulation is 28 inches (0.71 meters).The diameter of the sleeve pipe in first well is 12 inches (0.305 meters).The formation resistivity coefficient is 10ohm-m, and has supposed WBM.The leap that produces institute's electric current I (0) at interval is 1amp.

[0087] in Figure 14, for second well parallel with first well (=0) and (y on it fully ₀=0) situation the time is come the calculating magnetic field component.Two well interbody spacers that have modeling, 16.4 feet (5 meters) and 32.8 feet (10 meters).There is not the situation of sleeve pipe to be modeled yet.Magnetic field is as the z along BHA ₀Function calculate.Each data point is corresponding to the possible position of the magnetometer among the BHA.When not having sleeve pipe, three components in magnetic field are zero as estimating, because electric current returns symmetrically by the stratum.When in first well, having sleeve pipe, predict as equation 2 and 4, and Bx (0,0, z)=Bz (0,0, z)=0.Unique component in magnetic field is that (0,0, z), its amplitude depends on and interbody spacer By.Signal on 5 meters intervals is approximately the twice of 10 meters signals on the interval.Equation 3 provides the rough approximation in the magnetic field that is produced by numerical model

$\mathrm{By}(\mathrm{0,0},z_0)\&ap;-\frac{{\mathrm{\&mu;}}_{0}I\left(0\right)(L-|z\left|\right)}{2\mathrm{\&pi;L}{x}_0}\&CenterDot;\&CenterDot;\&CenterDot;\left(24\right)$

Electric current reduces with leaving clearance for insulation, well interbody spacer x ₀Can from amplitude, release.

[0088] in Figure 15, second well is added sleeve pipe, and not parallel with first well, but inclination different angles .Second well (x, y, z)=(x ₀, 0,0) with the Plane intersects of z=0, promptly it is crossing with the x axle.Second well and y-z plane parallel, wherein θ=pi/2.Well is separated 16.4 feet (5 meters).Three components in the magnetic field of calculating with the three-dimensional numerical value model are also followed by equation 2,3 and 4 predicted shape.Note, when y and z change, x ₀Be constant.Specifically, y=z tan  makes that y is a correlated variables, and z is an independent variable for the set-point of .The approximate equation of magnetic-field component becomes:

$\mathrm{Bx}(\mathrm{0,0},z)\&ap;-\frac{{\mathrm{\&mu;}}_{0}I\left(0\right)(L-|z\left|\right)}{2\mathrm{\&pi;L}{r}^2}y\cos \mathrm{\&phi;}=-\frac{{\mathrm{\&mu;}}_{0}I\left(0\right)(L-|z\left|\right)}{2\mathrm{\&pi;L}(x_0^2+{\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="A20061014456000331.png,A20061014456000361.png"\; state="\{\{state\}\}">z</figure-callout>}}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A20061014456000331.png,A20061014456000361.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&phi;})}z\sin \mathrm{\&phi;}.\&CenterDot;\&CenterDot;\&CenterDot;\left(25\right)$

$\mathrm{By}(\mathrm{0,0},z)\&ap;-\frac{{\mathrm{\&mu;}}_{0}I\left(0\right)(L-|z\left|\right)}{2\mathrm{\&pi;L}{r}^2}{x}_0\cos \mathrm{\&phi;}=-\frac{{\mathrm{\&mu;}}_{0}I\left(0\right)(L-|z\left|\right)}{2\mathrm{\&pi;L}(x_0^2+{\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="A20061014456000331.png,A20061014456000361.png"\; state="\{\{state\}\}">z</figure-callout>}}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A20061014456000331.png,A20061014456000361.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&phi;})}{x}_0\cos \mathrm{\&phi;}$ And (26)

$\mathrm{Bz}(\mathrm{0,0},z)\&ap;-\frac{{\mathrm{\&mu;}}_{0}I\left(0\right)(L-|z\left|\right)}{2\mathrm{\&pi;L}{r}^2}{x}_0\sin \mathrm{\&phi;}=-\frac{{\mathrm{\&mu;}}_{0}I\left(0\right)(L-|z\left|\right)}{2\mathrm{\&pi;L}(x_0^2+{\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="A20061014456000331.png,A20061014456000361.png"\; state="\{\{state\}\}">z</figure-callout>}}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A20061014456000331.png,A20061014456000361.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&phi;})}{x}_0\sin \mathrm{\&phi;}\&CenterDot;\&CenterDot;\&CenterDot;\left(27\right)$

(0,0, amplitude z) is approximate to be scaled cos  to Bx, and is antisymmetric for z=0.Antisymmetry is produced by z reindexing, and amplitude increases with z at first, accounts for space of top prominence up to the L-|z| item.By (0,0, the also approximate cos  that is scaled of amplitude z), but as be symmetrical for z=0 the expectation.It reaches peak value near z=0, but descends with distance when electric current reduces.Bz (0,0, amplitude z) is approximate to be scaled sin , and as above formula is predicted about the z=0 symmetry.

[0089] therefore, above-mentioned three-dimensional numerical value model produces the result who generally meets the more simple analysis model of deriving here.This three-dimensional numerical value model can be used for creating the database of various conditions (normal interval, normal orientation, casing size, BHA length and diameter, formation resistivity coefficient etc.) being made of magnetic-field component.Database then can be used for creating the various parameters equation relevant with magnetic field.For example, the form of this class equation may be similar with 27 to equation 25,26.Measured magnetic field can be used to inverting then in the hope of ideal parameters, particularly the well interbody spacer and the relative orientation of two wells.For example the independent measurement from the formation resistivity coefficient of LWD instrument also can be used to these parameters of refinement.

[0090] from the above detailed description of specific embodiments of the invention, is clear that, discloses novel equipment, the system and method that is used for during the creeping into of second pit shaft from the second pit shaft localizing objects pit shaft.Though this paper slightly at length discloses specific embodiments of the invention, this is just in order to describe the purpose of various feature of the present invention and aspect, rather than will limit for scope of the present invention.We consider, can include but not limited to various replacements, change and/or the modification of those realization variations that this paper may advise to the disclosed embodiments, and not deviate from the defined the spirit and scope of the present invention of appended claims subsequently.

Claims (22)

1. drilling tool, in order to determine to comprise the position from the target wellbore of the conductive member of second pit shaft, described drilling tool comprises:

Current driver with clearance for insulation; And

Be positioned at the magnetometer of described current driver below, wherein said current driver produces the electric current of crossing over described gap and arriving the described drilling tool part of described clearance for insulation below, and wherein said magnetometer is configured to the magnetic field that the electric current that flows through in the described conductive member in the described target wellbore causes is responded.

2. drilling tool as claimed in claim 1, wherein said electric current is a low-frequency current.

3. drilling tool as claimed in claim 1 also comprises the hollow section between described magnetometer and described current driver.

4. drilling tool as claimed in claim 1, wherein said magnetic strength is counted three axis magnetometer.

5. drilling tool as claimed in claim 1 also comprises survey tool when creeping into.

6. drilling tool as claimed in claim 1, wherein said magnetometer is positioned at non magnetic housing, and this non magnetic housing is located in the non magnetic pipe.

7. drilling tool as claimed in claim 1 also comprises:

Drill bit; And

But guidance system.

8. drilling tool as claimed in claim 7 also comprises the hollow section between described magnetometer and described current driver.

9. drilling tool as claimed in claim 7 also comprises survey tool when creeping into.

10. drilling tool as claimed in claim 9, wherein said magnetic strength is counted three axis magnetometer.

11. drilling tool as claimed in claim 3, wherein said electric current is a low-frequency current.

12. drilling tool as claimed in claim 11 also comprises survey tool when creeping into.

13. a drilling tool in order to determining to comprise the position from the target wellbore of the conductive member of second pit shaft, and is guided the track of described second pit shaft with respect to described target wellbore, described drilling tool comprises:

Current driver with clearance for insulation;

Be positioned at the three axis magnetometer of non magnetic housing, this non magnetic housing is located in the non magnetic pipe, and described three axis magnetometer is positioned at described current driver below;

Be positioned at the drill bit of described three axis magnetometer below;

Hollow section between described current driver and described three axis magnetometer; And

Survey tool when creeping into, wherein said current driver produces the electric current of crossing over described gap and arriving the described drilling tool part of described clearance for insulation below, and wherein said magnetometer is configured to the magnetic field that the electric current that flows through in the described conductive member in the described target wellbore causes is responded.

14. one kind is guided the method for the track of described second pit shaft in order to determine to comprise from the position of the target wellbore of the conductive member of second pit shaft and with respect to described target wellbore, said method comprising the steps of:

Setting comprises the bottom hole assembly of the current driver with clearance for insulation, the drill bit that is positioned at the three axis magnetometer of described current driver below and is positioned at described three axis magnetometer below;

Creep into second pit shaft that separates with described target wellbore with described bottom hole assembly;

The low-frequency current that generation is flowed out from described current driver;

Measure the magnetic field of the goal at described bottom hole assembly place; And

Determine the position of described second pit shaft with respect to described target wellbore.

15. method as claimed in claim 14 is wherein measured the step of described magnetic field of the goal and is carried out when creeping into described second pit shaft with described bottom hole assembly.

16. method as claimed in claim 15 is wherein measured the step of described magnetic field of the goal and is carried out when creeping into described second pit shaft with described bottom hole assembly.

17. method as claimed in claim 14, wherein said low-frequency current is crossed over described gap and is arrived the described bottom hole assembly part of described clearance for insulation below, arrive the conductive material in the described target wellbore again, turn back to the described bottom hole assembly part of described clearance for insulation top then, thereby produce magnetic field of the goal.

18. method as claimed in claim 14 also comprises the step of measuring the magnetic field of the earth, and the step of wherein determining the position of described second pit shaft part comprises the position of determining described second pit shaft according to the measured value in the measured value of magnetic field of the goal and magnetic field of the earth.

19. method as claimed in claim 14 also comprises along creeping into described second pit shaft with respect to the described bottom hole assembly of the railway guidance of described target wellbore.

20. method as claimed in claim 14, also comprise the step of measuring the electric current flow through described bottom hole assembly, and the step of wherein determining the position of described second pit shaft comprises the position of determining described second pit shaft according to the measured value of described magnetic field of the goal and the electric current that flows through described bottom hole assembly.

21. method as claimed in claim 14 also comprises:

The step of the electric current of described bottom hole assembly is flow through in measurement, and wherein

The measured value that the step of determining the position of described second pit shaft comprises measured value, current measurement value and magnetic field of the earth according to described magnetic field of the goal is determined the position of described second pit shaft.

22. method as claimed in claim 20 determines that wherein the step of the position of described second pit shaft comprises the following equation group of use:

$\frac{\mathrm{Bx}}{\mathrm{By}}=-\tan {\mathrm{\&gamma;}}_0=\frac{y_0}{x_0};$

$\frac{\mathrm{Bz}}{\mathrm{By}}=(-x_0\sin \mathrm{\&theta;}+y_0\cos \mathrm{\&theta;})\tan \mathrm{\&phi;}=x_0(\tan {\mathrm{\&gamma;}}_0\cos \mathrm{\&theta;}-\sin \mathrm{\&theta;})\tan \mathrm{\&phi;};$

$x_0^2[1-{\sin }^2\mathrm{\&phi;}(-\cos \mathrm{\&theta;}+\tan {\mathrm{\&gamma;}}_0\sin \mathrm{\&theta;}]+y_0^2=-\frac{{\mathrm{\&mu;}}_0{I}^{\&prime;}}{2\mathrm{\&pi;By}}{x}_0\cos \mathrm{\&phi;}.$

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