CN115680492A - Casing pipe internal magnetization method for adjacent well passive magnetic positioning - Google Patents

Abstract

The invention provides a method for magnetizing inside a drilled casing for magnetic steering, which comprises a magnetizing device consisting of a magnetic source and a transmission mechanism, a probe, a steering module, a control module and a downhole power drilling tool. The magnetic field intensity of the casing is increased by internally magnetizing the drilled casing, so that relative position parameters such as the distance, the azimuth and the like of a finished well and a drilled well bore are determined. Compared with the traditional magnetic guiding method, the method has the advantages that the inside of the completed adjacent well with the metal casing pipe is magnetized only by utilizing the magnetizing device, the adjacent well shaft does not need to be occupied for a long time, the positioning precision can be improved by using the magnetic gradient sensor and the triaxial fluxgate in a matched manner, the process of collision prevention, positioning or distance measurement in the drilling process is further simplified for the magnetization of the adjacent well casing pipe, the working efficiency is improved, and the drilling cost is reduced.

Description

Casing pipe internal magnetization method for adjacent well passive magnetic positioning

Technical Field

The invention relates to a method for magnetizing an underground casing in drilling engineering in the field of oil and gas exploration, in particular to a method for magnetizing inside of a casing for passive magnetic positioning of an adjacent well.

Background

The magnetic distance measurement in the guided drilling is to place a magnetic source or a magnetic sensor in the drilling or an adjacent well respectively, and to adopt a distance measurement algorithm to realize the distance measurement between the adjacent well and the drilling according to the magnetic field intensity detected by the magnetic sensor and the magnetic field distribution around the magnetic source. The magnetic source may be a sleeve magnetized by the earth's magnetic field, a sleeve with residual magnetism, a magnetized sleeve, a permanent magnet with greater magnetic field strength, or an energized solenoid. For example, a measurement method using residual magnetism of a casing or a drilling tool as a signal source is called a passive distance measurement technology, an electromagnetic distance measurement technology using an artificially created magnetic field as a transmission source, for example, using a permanent magnetic joint, an energized solenoid, an energized cable or an energized casing, and a transmission source for artificially controlling field intensity as a magnetic source is called an active distance measurement technology or an active distance measurement technology.

The existing active magnetic steering technology is mature and enters a large-scale commercial stage. However, most of the active magnetic steering techniques require long term occupation of the target wellbore, making it unable to achieve its normal working regime during drilling while drilling, and are almost impractical due to the presence of downhole seawater during marine drilling if the excitation is applied by passing current through the downhole casing to create a magnetic field.

The existing passive magnetic guiding technology is mainly characterized in that a sleeve is magnetized by utilizing a geomagnetic field or a flaw detector or special magnetizing equipment before the sleeve is put into a well, then the pre-magnetized sleeve is put into a well shaft, and the magnetized sleeve is used for preventing collision and guiding of adjacent well drilling. However, due to the small intensity of the earth magnetic field, the detection distance is very limited and the accuracy is poor due to the existence of magnetic interference under the prior art. Although the problems of magnetizing the sleeve by the geomagnetic field can be solved when the sleeve is magnetized by using magnetizing equipment on the ground and then put into the well, if the encryption well is drilled in an old block, the sleeve in the existing well is not always magnetized before being put into the well, and the problem of demagnetization can also exist after a long time even if the sleeve is magnetized, so that the method is not suitable for the anti-collision situation when the encryption well is drilled in the old block; even if the pre-magnetization is carried out on the ground, the pre-magnetized sleeve is demagnetized under the conditions of a series of collisions between the sleeve and a well wall and high temperature in the well inevitably in the process of going into the well, so that the magnetic field intensity of the pre-magnetized sleeve is reduced, and the measurement accuracy is influenced; under some extreme conditions, if the well under drilling is located in the influence range of the superposed magnetic field of the pre-magnetized casings of two wells, the magnetic field data measured by the well under drilling is the vector sum of the superposed strength of the magnetic fields of the pre-magnetized casings of the two wells, and the distance and the direction from the well under drilling to the two wells are not true values, so that the data of another well is measured after one well is demagnetized, which cannot be realized.

Chinese patent document "magnetized casing method for dual horizontal well distance measurement and method for drilling dual horizontal well" (CN 201711297206.5). The technology is only suitable for double horizontal well distance measurement, and has the technical characteristics that: magnetizing a casing at three or more discrete locations on a first wellbore casing such that at least one pair of opposing magnetic poles is included between longitudinally opposing ends of the casing, interconnecting lengths of the magnetized casing to form a casing string, then running the casing string in the first wellbore, measuring a magnetic field generated by the casing string in the first wellbore in a second wellbore, processing the measured magnetic field to determine a direction for subsequent drilling of the second wellbore, and drilling the second wellbore in that direction. The method for magnetizing the casing pipe in the method is that the electromagnetic coil is wound outside the casing pipe for segmented magnetization, the magnetization mode determines that the magnetization process needs to be completed on the ground before the casing pipe is put into a well, and the method is not suitable for the conditions that the well is prevented from being collided in the well completion encryption process, the guided drilling of a relief well, and the steam injection well is additionally drilled in the later period of a thick oil block horizontal well to be transformed into the SAGD well, and has poor adaptability and flexibility and narrow application range.

Chinese patent document "a double-solenoid group electromagnetic distance measurement while drilling guiding system" (CN 101852078B). A double-solenoid group electromagnetic distance measurement while drilling guiding system can provide accurate guiding measurement and calculation for borehole trajectory control of wells with complex structures such as double horizontal wells, communicated wells, U-shaped wells and encrypted wells. The system mainly comprises a short joint of a double-solenoid group, a modified MWD, a ground display system and ground equipment. The short section of the double-solenoid group is used as a magnetic signal emission source and is placed in a drilled well, so that two rotating magnetic fields with different frequencies can be generated; the magnetic field is matched with a modified MWD consisting of a traditional MWD, a three-axis alternating magnetic field sensor and a microprocessor solidified with data analysis and adjacent well spacing calculation programs, and the geomagnetic field vector and the gravity field vector of the well depth position of the short joint of the double-solenoid group are detected so as to calculate the placing posture of the short joint of the double-solenoid group. The magnetic field utilized in the positioning process of the technology is a magnetic field signal with different frequencies generated by an electrified double-solenoid, and needs to occupy an adjacent well for a long time. The three-axis alternating magnetic field sensor is used for detecting two magnetic signals with different frequencies generated by a short joint of a double-solenoid group at the position of the MWD, and a differential distance measurement method is not used.

Chinese patent document "method for improved active ranging and target well magnetization" (CN 103282601B). A method for magnetizing a portion of a pre-deployed casing string comprising: an electromagnetic array is deployed in a cased wellbore and power is supplied to the array. The array includes a plurality of electromagnets axially spaced apart and configured to generate a magnetic field pattern having at least first and second pairs of magnetically opposing poles. Passive ranging measurements of the induced magnetic field may be advantageously used to survey and guide the continued drilling of a twin well. Electromagnetic arrays may also be used in active ranging applications. Arrays of permanent magnets providing similar magnetic field characteristics may also be used in active ranging applications. The magnetic field measuring device mainly utilizes an electromagnetic array subsection magnetization sleeve pipe which is arranged at intervals and provided with a plurality of electromagnets, the magnetized sleeve pipe is composed of a plurality of pairs of repellent NN magnetic poles and SS magnetic poles, an underground logging instrument with a magnetic field measuring device measures the section of the magnetization sleeve pipe in a sensing range of a magnetic field, the position of the underground logging instrument is drilled with a drill bit, the position change of the underground logging instrument is changed continuously, and after the underground logging instrument is drilled for a certain distance, the electromagnetic array needs to move deeper into a target well. In the process, the electromagnetic array needs to occupy an adjacent well (a target well) for a long time, and demagnetization of the target well cannot be realized after complexity measurement of segmented magnetization is completed.

Disclosure of Invention

The invention aims to provide an in-casing magnetization method for passive magnetic positioning of an adjacent well.

In order to overcome the defects of the prior art, in a drilled and cased well, a magnetizing device or device is used for running into the well to magnetize a casing, the magnetic field intensity of the casing is increased, the magnetic field generated by the magnetizing casing is utilized to determine the relative position of a well shaft of an adjacent well and a well shaft of a well being drilled, the drilling process of the well being drilled nearby is guided, and the purposes of collision prevention, distance measurement, magnetic guiding and the like can be achieved. The technology can be used for cluster wells, encrypted wells and branch wells for collision prevention and rescue wells, coal bed gas horizontal wells are communicated with directional wells, and SAGD double horizontal wells are formed.

In order to solve the technical problems, the invention is realized by adopting the following technical scheme:

a casing internal magnetizing method for passive magnetic positioning of adjacent wells features that the casing of adjacent well is magnetized by an internal magnetizer to make the casing have uniform residual magnetism, and after the magnetization is finished, the magnetizer is removed from adjacent well to restore the normal working system of adjacent well.

The magnetic device in the sleeve comprises a transmission device and a magnetic source; the method comprises the following steps:

the transmission device is used for lowering the magnetic source to the bottom of the adjacent well, the sleeve at the corresponding position of the adjacent well is magnetized by the magnetized magnetic field generated by the magnetic source, and meanwhile, the transmission mechanism is used for lifting the magnetic source to the wellhead from the bottom of the well at a constant speed, so that the sleeve of the adjacent well is provided with the magnetic field;

and then, measuring related data by using an MWD probe in the drilling well, calculating a relative azimuth relationship between two wells by using a triaxial accelerometer and a triaxial fluxgate sensor in the probe, calculating the distance between the drilling well and an adjacent well by using the relationship between the data measured by a magnetic field gradient sensor and the magnetic induction intensity along with the distance, and communicating the MWD probe with a ground computer to guide the drilling of the drilling well or avoid the occurrence of well collision.

The adjacent well is a finished well which is already lowered into a metal casing, and the material of the metal casing is a ferromagnetic material.

The magnetic source is a part of the magnetization device in the sleeve and is a permanent magnet.

The magnetic source generates a magnetizing magnetic field through a magnetizing magnetic field generated by the magnetic source or by externally applying excitation to the magnetic source.

The magnetic source is an energized cable or an energized solenoid.

The transmission device is a winch with a steel wire rope, a crawling robot or a drill rod.

The MWD probe is used for measuring related data in the drilling well, an electronic measurement assembly, a battery short section, a driving short section and a pulse generator are arranged in the MWD probe, wherein the electronic measurement assembly is formed by electrically connecting a plurality of sensors and a circuit measurement short section, various sensors in the MWD probe are responsible for measuring magnetic field, gravitational field and temperature time data at the probe, the measured data are sent to the circuit measurement short section to calculate the temperature, magnetic field strength, well inclination angle, azimuth angle and tool face angle data of the point, a driving short section controller controls the opening time interval and pulse intensity of a pulse generator valve according to instructions from the electronic measurement assembly, and underground data are sent to a ground control system in the form of mud pulses.

The MWD probe at least comprises a magnetic gradient sensor, a three-axis fluxgate, a three-axis gravity accelerometer and a temperature sensor;

the MWD probe is used for collecting measurement data of a drilling well and transmitting the measurement data to a surface computer for processing, and the measurement data comprises: and the magnetic gradient sensor at the position of the MWD probe measures magnetic field gradient data of the magnetized sleeve, absolute magnetic field data measured by the triaxial fluxgate, gravitational field data measured by the triaxial accelerometer, and temperature data measured by the temperature sensor.

The magnetic gradient sensor measures magnetic field difference data used for the magnetized sleeve, measured absolute magnetic field data measured by the triaxial fluxgate, gravity data measured by the triaxial gravity accelerometer and temperature measured by the temperature sensor;

the triaxial fluxgate is formed by placing three orthogonal fluxgate sensors on the position of the axis of the probe tube, and respectively measuring magnetic field data in x, y and z directions;

the three-axis accelerometer is arranged at the position of the axis of the probe tube by three orthogonal acceleration sensors and respectively measures gravity field data in x, y and z directions;

the magnetic gradient sensor consists of an even number of three-axis fluxgates, two fluxgates are used as a group and are respectively arranged on the inner edge of the probe tube taking the axis of the probe tube as a symmetrical axis, the distance between every two three-axis fluxgates of the probe tube is known, and the magnetic field gradient generated by the adjacent well magnetization casing at the corresponding position can be obtained by the magnetic field intensity data measured by each fluxgate.

Obtaining the distance between the adjacent well and the probe tube in the forward drilling according to the rule that the magnetic field decays along with the distance by using the measured gradient value of the magnetic field and the known distance between two three-axis fluxgates of the magnetic gradient sensor, namely the distance between the forward drilling and two adjacent wells;

and obtaining the azimuth relationship between the two wells of the well under drilling and the adjacent well according to the magnetic field intensity data measured by the triaxial fluxgate and the gravity field data measured by the triaxial accelerometer.

Further comprising: the relation between the magnetic induction intensity and the distance measured when two fluxgates of the magnetic gradient sensor are collinear with the adjacent well casing can be obtained according to the rule that the magnetic field intensity of the magnetic field is in a square attenuation relation along with the increase of the distance:

when an included angle theta exists between the connecting line of the two fluxgates and the axial lines of the drilling well and the adjacent well, the relation is as follows:

the distance between the well and the adjacent well can be obtained by the relation.

Further, an internal magnetization method for the casing pipe of the adjacent well in the passive magnetic positioning mode is characterized in that an internal magnetization device is used for magnetizing the casing pipe of the adjacent well, so that the casing pipe is provided with uniform remanence, the magnetization device is removed from the adjacent well after the magnetization is finished, a normal working system is recovered, and then a MWD probe in a drilling well is used for measuring related data and communicating with a ground computer.

The magnetic device in the casing for the passive magnetic positioning of the adjacent well comprises a transmission device and a magnetic source.

The casing magnetization method for the passive magnetic positioning of the adjacent well comprises the following steps: the transmission device is used for lowering the magnetic source to the bottom of the adjacent well, the sleeve at the corresponding position of the adjacent well is magnetized by the magnetized magnetic field generated by the magnetic source, and meanwhile, the transmission mechanism is used for lifting the magnetic source to the wellhead from the bottom of the well at a uniform and proper speed, so that the sleeve of the adjacent well is provided with a magnetic field which guides the drilling of the drilling well or avoids the occurrence of well collision;

and calculating the relative azimuth relationship between the two wells by using a triaxial accelerometer and a triaxial fluxgate sensor in the probe, and calculating the distance between the drilling well and the adjacent well by using the relationship between the data measured by the magnetic field gradient sensor and the magnetic induction intensity along with the distance.

The beneficial effects of the invention are: compared with the traditional magnetic guiding method, the method has the advantages that the inside of the completed adjacent well with the metal casing pipe is magnetized only by the magnetizing device, the shaft of the adjacent well does not need to be occupied for a long time, the current does not need to be introduced into the casing pipe of the adjacent well, the problem of casing pipe demagnetization caused by the problems of vibration, collision, high temperature and the like when the ground pre-magnetized casing pipe is put into the well does not need to be worried, the positioning precision can be improved by the matching use of the magnetic gradient sensor and the triaxial fluxgate, the flow during collision prevention, positioning or distance measurement in the well drilling process is further simplified for the magnetization of the casing pipe of the adjacent well, the working efficiency is improved, and the well drilling cost is reduced.

Drawings

FIG. 1 is a schematic diagram of the anti-collision operation between an adjacent well and a normal well by the magnetization method in the casing of the present invention.

Fig. 2 is an operation schematic diagram of communicating a relief well with an accident well by using the magnetization method in the casing of the invention.

FIG. 3 is a schematic diagram of the communication operation between a horizontal well and a directional well or between a vertical well and a directional well by using the method of magnetization in a casing pipe of the present invention.

FIG. 4 is a schematic diagram of SAGD bi-horizontal well drilling operations using the in-casing magnetization method of the present invention.

FIG. 5 is a schematic diagram of solenoid magnetized sleeve operation.

Fig. 6 is a schematic diagram of the operation of the permanent magnet magnetizing sleeve.

Fig. 7 is a schematic view of a current magnetizer magnetizing sleeve.

Fig. 8 is a schematic diagram of the operation of the current magnetizer.

Fig. 9 is a schematic diagram of the probe of the magnetic device in the casing and the distribution of the internal sensors.

FIG. 10 is a schematic diagram of the attitude and position relationship between the connection line of two three-axis fluxgates of the magnetic gradient sensor of the probe and the connection line of two well axes.

FIG. 11 is a schematic diagram showing the attitude and position relationship between the connecting line of two three-axis fluxgates of the magnetic gradient sensor of the probe and the connecting line of the two well axes at an included angle θ.

In the figure: 1. the method comprises the steps of completing a well, 2. A casing, 3. A magnetic source, 4. An iron core, 5. A direct current power supply, 6. An electric wire, 7. A winch, 8. A steel wire rope, 9. A lubrication protection device of the magnetic source, 10. A drilling well, 11. A drilling platform, 12. A wellhead device, 13. A drill string, 14. A bottom drilling tool assembly, 15. A drill bit, 16. A probe tube, 17. A steering module, 18. A control module, 19. A downhole power drilling tool, 20. A magnetic casing magnetic field, 21. A direct current power supply, 22. A protection resistor, 23. An inflow cable, 24. An outflow cable, 25. A metal magnetic shielding device, 26. A circuit switch, 27. A cement ring, 28. A stratum, 29. A solenoid, 30. A magnetic gradient sensor, 30-a built-in flux gate, 30-b. A built-in flux gate, 31. A three-axis flux gate, 32. A three axis gravity accelerometer, 33. A probe tube shell, 34. A probe tube shell cover,

Detailed Description

The invention is described in further detail below with reference to the figures and the detailed description.

Referring to the attached figure 1, the magnetic source of the in-casing magnetizer magnetizes the inner casing of the finished well 1, measures the casing magnetic field of the finished well 1 through the probe 16 in the drilling well 10, measures and positions the distance of the finished well 1 and the drilling well 10, guides the drilling direction of the drilling well, and can realize the communication or collision prevention of the two wells.

Referring to fig. 5, the magnetic source 3 of the in-casing magnetizing apparatus generates a magnetizing magnetic field and magnetizes the nearby metal casing 2 using the magnetic field. The metal casing is made of ferromagnetic material, and is easy to be magnetized and can be saturated and magnetized under the action of a small magnetic field. The magnetic source 3 is a part of a magnetizing device in the casing, can generate a magnetizing magnetic field for magnetizing the casing of the adjacent well by the magnetizing magnetic field generated by the magnetic source itself or by externally adding excitation to the magnetic source, and the permanent magnet, the electrified cable and the electrified solenoid can be used as the magnetic source. The magnetizing magnetic field generated by the permanent magnet, the electrified cable and the electrified solenoid are electrified and excited to generate the magnetizing magnetic field. The magnetizing magnetic field generated by the magnetic source acts on the sleeve made of ferromagnetic material to magnetize the adjacent well sleeve at the corresponding position, and the transmission mechanism is used to move the magnetic source from the bottom of the well along the direction of the sleeve to magnetize the whole sleeve, so that the whole adjacent well sleeve has residual magnetism.

The operation process is as follows: a metal casing 2 is lowered into the completed well 1, outside the casing 2 in turn being a cement sheath 27 and a formation 28. Before the anti-collision operation, the metal casing 2 in the completed well 1 needs to be magnetized by an in-casing magnetizing device. The magnetic device in the casing comprises a magnetic source 3 and a transmission device, and a winch with a wire rope, a crawling robot, a drill rod and other devices or mechanisms which can realize that the magnetic source is lowered to the bottom of the well and can lift the magnetic source at a certain constant speed can be used as the transmission device of the internal magnetic device.

In order to prevent the magnetic source from contacting with the metal sleeve through magnetic attraction and moving relative to the sleeve 2 under the action of the winch, the magnetic source and the metal sleeve generate friction to damage the metal sleeve and the metal sleeve, a magnetic source lubricating and protecting device 9 which can not shield the magnetic field generated by the magnetic source 3 is added outside the magnetic source 3, so that the magnetic source 3 is not in direct contact with the sleeve 2, and the magnetic source is protected and lubricated.

The well drilling 10 is equipped with a passive magnetic positioning device, which mainly comprises a drilling system ground equipment and an underground equipment, wherein the ground equipment mainly comprises a drilling platform 11 positioned on the surface of the earth and a wellhead device 12, and the underground equipment mainly comprises a drill string 13 and a bottom hole assembly 14. The bottom hole assembly 14 basically includes a drill bit 15, a probe 16, a steering module 17, a control module 18 and a downhole motor 19. The drill bit 15 is the forward-most portion of the bottom hole assembly 14, and immediately behind the drill bit 15 in the drilling direction, is a probe 16, the probe 16 containing at least one magnetic gradient sensor or gradiometer, a triaxial accelerometer and a triaxial fluxgate for measuring the adjacent well magnetized casing field 20.

The probe 16 is close to the drill bit 15 as much as possible, so that the distance between the drill bit and the adjacent well bore can be measured more accurately and sensitively, and the signal delay caused by the distance and the risk caused by the signal delay are reduced.

The bottom hole assembly 14 includes, among other things, a downhole motor 19, a steering module 17, and a control module 18. The drill string 13 is used to connect drilling system surface equipment to the bottom hole assembly 14. The downhole motor 19 is driven by the drilling fluid and the downhole motor 19 in turn drives the drill bit 15 to extend the borehole 10 in the direction of the predetermined borehole trajectory. The steering module 17 enables the borehole being drilled 10 to be extended in a desired direction. Steering module 17 may be implemented with a ground based control system for directional control or programmed with control module 18. And the steering mechanism may be adjusted to direct the wellbore to extend along a desired trajectory according to specific drilling needs or changing formation needs.

The MWD is composed of an electronic measurement assembly, a battery short section, a driving short section and a pulse generator, wherein the electronic measurement assembly is composed of a probe and a circuit measurement short section, various sensors in the probe are responsible for measuring magnetic field, gravitational field and temperature time data at the position of the probe, the measured data are sent to the circuit measurement short section to calculate the temperature, magnetic field strength, well inclination angle, azimuth angle and tool face angle data of the point, a driving short section controller controls the opening time interval and pulse strength of a pulse generator valve according to instructions from the electronic measurement assembly, and underground data are sent to the ground control system in the form of mud pulses.

When a borehole is arranged, after collision risk between a positive drilling well 10 and a finished well 1 is obtained through a series of prediction methods or algorithms, a winch 7, a drill rod or a crawler is used for lowering a magnetic source 3 to the bottom of the finished well 1, the magnetic source 3 generates a uniform magnetic field with unchanged direction and size, the winch 7 is rotated, the winch 7 pulls a solenoid magnetizing device to move upwards at a constant speed, casing magnetization is realized, and a magnetized casing magnetic field 20 can be generated after the adjacent well casing 2 is magnetized.

After the adjacent well casing 2 is magnetized and meets the magnetization requirement, the magnetizing equipment can be removed to remove the occupation of the adjacent well and recover the original function and normal working system (if the adjacent well is a production well, the production can be recovered, and if the adjacent well is a water injection well, the water injection function can also be recovered).

During the drilling process of the well 10, a sensor in a probe 16 in the bottom hole assembly 14 receives a magnetic field signal of the magnetized casing 2, the distance and the direction between the well 10 and the finished well 1 can be inverted according to the magnitude and the direction of the signal after the signal is processed, when the distance is too small and well collision is likely to occur, the signal is transmitted to a control module 18, and the control module 18 controls a steering module 17 to enable the well 10 to drill in the direction far away from the finished well 1, so that the drilling direction is guided, two wells are communicated or the well collision is prevented.

Example 1:

referring to fig. 5, the magnetic source of the in-casing magnetizer is a solenoid magnetizer, and the principle of the solenoid magnetizer magnetizing the casing is to excite a solenoid 29 with a direct current to generate a magnetizing magnetic field and magnetize the nearby metal casing 2 with the magnetizing magnetic field.

The adjacent well anti-collision operation comprises the following specific operation processes: the completed well 1 is an adjacent well, most often a production or injection well, into which a metal casing 2 is lowered, outside of the casing 2 in turn a cement sheath 27 and a formation 28. Before the anti-collision operation, it is necessary to magnetize the metal casing 2 in the completed well 1 using a solenoid magnetizing apparatus including: solenoid 29, iron core 4 inserted in solenoid 29, dc power supply 5 for supplying power to solenoid 3, capstan 7 for lowering and lifting the solenoid magnetizer, and wire rope 8 for connecting the capstan and the solenoid magnetizer.

In order to prevent the solenoid 29 from contacting with the metal sleeve through magnetic attraction force after being electrified and generating relative movement with the sleeve 2 under the action of the winch, the solenoid 29 and the metal sleeve generate friction to damage, a magnetic source lubrication protection device 9 which does not shield the magnetic field generated by the solenoid is added outside the solenoid 29, so that the solenoid 29 is not in direct contact with the sleeve 2, and the protection and lubrication effects on the solenoid are achieved.

The well drilling 10 is equipped with a passive magnetic positioning device, which mainly comprises a drilling system ground equipment and an underground equipment, wherein the ground equipment mainly comprises a drilling platform 11 positioned on the surface of the earth and a wellhead device 12, and the underground equipment mainly comprises a drill string 13 and a bottom hole assembly 14. The bottom hole assembly 14 basically includes a drill bit 15, a probe 16, a steering module 17, a control module 18 and a downhole motor 19. The drill bit 15 is the forward-most portion of the bottom hole assembly 14, and immediately behind the drill bit 15 in the drilling direction, is a probe 16, the probe 16 containing at least one magnetic gradient sensor or gradiometer, a triaxial accelerometer and a triaxial fluxgate for measuring the adjacent well magnetized casing field 20.

The distance between the drill bit and the adjacent well bore can be measured more accurately and sensitively as far as the probe 16 is close to the drill bit 15, the signal delay caused by the distance and the well collision risk caused by the signal delay are reduced, and the purpose of preventing the adjacent well from collision is better realized.

When the well is arranged, after collision risk between a main drilling well 10 and a finished well 1 is obtained through a series of prediction methods or algorithms, a winch 7, a drill rod or a crawler is used for lowering a solenoid magnetizing device to the bottom of the finished well 1, at the moment, a power supply 5 is switched on, direct current is conducted to a solenoid 29 through a wire 6 to generate a uniform magnetic field with unchanged direction and size, the winch 7 is rotated, the solenoid magnetizing device is pulled by the winch 7 at a certain speed to move upwards at a constant speed, the casing pipe is magnetized, and after the casing pipe is magnetized, a magnetized casing pipe magnetic field 20 can be generated on an adjacent well casing pipe 2. In the process, the size of the introduced current and the rotation speed of the winch 7 can be adjusted according to the size of the magnetic field 20 of the magnetizing sleeve required by collision prevention. After the adjacent well casing 2 is magnetized and meets the magnetization requirement, the magnetizing equipment can be removed, the occupation of the adjacent well is removed, and the original function of the adjacent well is recovered (for example, the adjacent well can recover the production of the adjacent well for a production well, and can also recover the water injection function for a water injection well).

During the drilling process of the forward drilling well 10, a sensor in a probe 16 in a bottom hole assembly 14 receives a magnetic field signal of the magnetized casing 2, the distance and the direction between the forward drilling well 10 and the finished well 1 can be inverted according to the magnitude and the direction of the signal after the signal is processed, when the distance is too small, collision possibly occurs, the signal is transmitted to a control module 18, and a steering module 17 is controlled by the control module 18, so that the forward drilling well 10 is drilled in the direction far away from the finished well 1, and the drilling process is guided to prevent the collision.

After the well completion is completed by the forward drilling 10, if special requirements exist, for example, when the magnetic field of the magnetic casing of the adjacent well is still in the other construction influence range when the next well is drilled for collision prevention, the magnetic field of the magnetic casing of the adjacent well needs to be demagnetized, at the moment, the current only needs to be reversed, and the step of magnetizing in the casing is repeated, wherein in the selection of the current, the existence of the magnetic coercive force is considered, and the demagnetizing current needs to be increased appropriately.

Referring to fig. 9, the probe 16 comprises a magnetic gradient sensor 30 (fig. 9 comprises 4 three-axis fluxgates 30-a, 30-b, 30-c, 30-d), a three-axis fluxgate 31, a three-axis gravity accelerometer 32, a probe housing 33 and a probe housing cover 34. The triaxial fluxgate is formed by placing three orthogonal fluxgate sensors on the position of the axis of the probe tube to respectively measure magnetic field data in the x direction, the y direction and the z direction. The triaxial accelerometer is arranged at the position of the axis of the probe tube by three orthogonal acceleration sensors and respectively measures gravity field data in x, y and z directions. The magnetic gradient sensor consists of an even number (4 in figure 9) of three-axis fluxgates, two fluxgates are arranged as a group and are respectively arranged on the inner edge of the probe tube which takes the axis of the probe tube as a symmetrical axis, the distance between each three-axis fluxgate of the probe tube is known, and the magnetic field gradient generated by the magnetized casing of the adjacent well at the corresponding position can be obtained by the magnetic field intensity data measured by each fluxgate. The x axis and the y axis of a magnetic gradient sensor in the probe tube, the x axis and the y axis of a triaxial fluxgate sensor and the x axis and the y axis of a triaxial acceleration sensor are respectively parallel and homodromous; the z-axes of the magnetic gradient sensor, the triaxial fluxgate sensor and the triaxial acceleration sensor are parallel and in the same direction, and the z-axes of the triaxial fluxgate sensor and the triaxial acceleration sensor are collinear with the central axis of the probe tube.

Referring to FIG. 10, the probe 16 includes a magnetic gradient sensor 30 (exemplified by a set of two tri-axis fluxgate sensors) having a tri-axis fluxgate 30-a and a tri-axis fluxgate 30-b, spaced apart by a distance R. When the two connecting lines are collinear, the rule of the square attenuation relation is established by the increase of the magnetic field intensity of the magnetic field along with the distance, and the relation between the magnetic induction intensity and the distance can be obtained:

referring to FIG. 11, the magnetic gradient sensor 30 of the probe 16 (taking the example of two tri-axial fluxgate sensors) incorporates a tri-axial fluxgate 30-a and a tri-axial fluxgate 30-b with a distance R between the two wells. When an included angle theta exists between a group of three-axis fluxgate 30-a of the magnetic gradient sensor 30 and a connection line of the three-axis fluxgate 30-b and a connection line of the normal drilling axis and the adjacent well casing 2, the relation between the magnetic induction intensity and the distance is as follows:

the distance between the drilling well and the adjacent well can be obtained according to the relation.

Example 2:

referring to the attached figure 2, the in-casing magnetization method for the passive magnetic positioning of the adjacent well has the following specific operation process when a relief well is drilled: the completed well 1 is an accident well in which the metal casing 2 is put in while the well is completed, but a downhole accident such as fire or blowout occurs due to some reason, and the metal casing 2 in the completed well 1 needs to be internally magnetized by the same magnetizing apparatus as that of the embodiment 1 before the rescue well is drilled.

The well bore 10 is a relief well. When the emergency well is dug when the accident happens to the well being drilled, the solenoid magnetizing device is lowered to the bottom of the accident well by using the winch 7, the drill rod or the crawler, the power supply 5 is switched on at the moment, the direct current is introduced into the solenoid 29 by using the wire 6 to generate a uniform magnetic field with unchanged direction and size, the winch 7 is rotated, the solenoid magnetizing device is pulled by the winch 7 to move upwards at a constant speed, the magnetization of the accident well casing is realized, and after the magnetization, a magnetizing casing magnetic field 20 can be generated on the accident well casing. In the process, the size of the introduced current and the rotation speed of the winch 7 can be adjusted according to the size of the magnetic field of the magnetized casing required by positioning the rescue well. And (4) after the accident well casing is magnetized and meets the magnetization requirement, the magnetization is stopped.

In the drilling process of the relief well, a sensor of a probe 16 in a bottom drilling assembly 14 receives a magnetic field signal of a magnetized casing of the accident well, the distance and the direction between the relief well and the accident well can be inverted according to the size and the direction of the signal after the signal is processed, when the relief well is drilled to a proper depth to be close to the accident well, the signal is transmitted to a control module 18 according to the signal of the magnetized casing detected by the probe 16, the control module 18 controls a steering module 17 to drill the relief well to the direction close to the accident well to be close to the accident well, the communication between the relief well and the accident well is realized, and therefore the relief for the accident well is realized.

After the rescue well is drilled and completed, if the accident casing 2 needs to be demagnetized, the current is reversed at the moment, and the steps of magnetizing in the casing are repeated, wherein in the selection of the current, the demagnetization current needs to be increased properly in consideration of the existence of the magnetic coercive force.

Example 3:

referring to the attached figure 3, the horizontal well and the directional well or the vertical well and the directional well are communicated by the magnetization method in the casing. The completed well 1 is a vertical or horizontal well, in most cases a production well. The metal casing 2 is put into the vertical well or the horizontal well, and before the communication operation, the metal casing 2 in the vertical well or the horizontal well needs to be internally magnetized by using an in-casing magnetizing device.

Referring to fig. 7, the magnetic source of the in-casing magnetizer is a current magnetizer.

Referring to fig. 8, the current magnetizer is composed of a dc power source 21, a protective resistor 22, an inflow cable 23, an outflow cable 24, a metallic magnetic shield 25, and a circuit switch 26. The switch 21 is closed to connect the circuit, the DC power supply 21 is used for supplying power, a magnetic field is generated around the cable when the current passes through the cable, in order to prevent the reverse magnetic field generated by the opposite directions of the current flowing into the cable 23 and the current flowing out of the cable 24, the two magnetic fields are offset, and the sleeve cannot be magnetized, therefore, a metal magnetic shielding device 25 is additionally arranged on the current flowing out of the cable 24 to shield the magnetic field on the cable, only the magnetic field generated by the current flowing into the cable 23 is reserved as the generation part of the magnetized magnetic field, and in addition, a protective resistor 22 is arranged in the circuit to prevent short circuit.

The well being drilled 10 is a directional well. In the coal bed gas exploitation process, a mode of communicating a vertical well with a directional well or communicating a horizontal well with the directional well is generally adopted, in the process, an effective positioning and guiding method is required to guide the communication of the two wells, and a magnetic guiding and positioning technology is a method with high feasibility, after the vertical well or the horizontal well is drilled, a metal casing 2 is put in, and a cave is built at a preset target point position, so that the target point area when the directional well is communicated with the well is increased. The current magnetizer is lowered to the bottom of the vertical well by a winch 7, a drill rod or a crawler, a power supply 5 is switched on at the moment, direct current is introduced into an inflow cable 23 of the current magnetizer by a wire 6 to generate a uniform magnetic field with unchangeable direction and size, the winch 7 is rotated, the current magnetizer is pulled by the winch 7 at a certain speed to move upwards in the vertical well 1 at a constant speed, the sleeve 2 is magnetized, and after magnetization, a magnetized sleeve magnetic field 20 can be generated on the vertical well sleeve. In the process, the size of the introduced current and the rotation speed of the winch can be adjusted according to the size of the magnetic field of the magnetized casing pipe required by the communication and positioning of the two wells. And (4) magnetizing the casing of the vertical well or the horizontal well and stopping magnetization after the casing of the vertical well or the horizontal well meets the magnetization requirement.

In the directional well drilling process, when the directional well is drilled to a depth close to a target point and a sensor of a probe 16 in a bottom drilling assembly 14 can receive a magnetic field signal of a magnetized casing, the signal is processed by a certain method, the distance and the direction between the directional well and the vertical well or the horizontal well can be inverted according to the size and the direction of the signal, the signal is transmitted to a control module 18 according to the signal of the magnetized casing detected by the probe 16, the control module 18 controls a steering module 17 to drill the directional well to a direction close to the vertical well or the horizontal well to be close to the target point position of the vertical well or the horizontal well, the point-to-line communication between the directional well and the vertical well is realized, and the point-to-point communication between the directional well and the horizontal well can be realized in the same way.

After the directional well is drilled and completed, if the vertical well or horizontal well casing 2 needs to be demagnetized, the current is reversed, and the steps of magnetizing in the casing are repeated.

Example 4:

referring to the attached figure 4, the casing magnetization method for the passive magnetic positioning of the adjacent well performs the concrete operation process of SAGD double horizontal well drilling: the finished well 1 is a production well, a metal casing 2 is put into the well, and before a steam injection well is drilled, the metal casing 2 in the production well 1 needs to be internally magnetized by a magnetizing device, and a magnetic source of the magnetizing device in the casing is a permanent magnet.

Referring to fig. 6, the principle of the permanent magnet magnetizing sleeve is to magnetize the nearby metal sleeve 2 by using the magnetizing field generated by the permanent magnet 3 itself.

The well 10 is a steam injection well. When thick oil is exploited, the SAGD double horizontal well technology is usually used, i.e. one horizontal well is drilled through an oil layer to serve as a production well, a steam injection well parallel to the production well is drilled 4-10m above the oil layer, steam is injected into the steam injection well during thick oil exploitation, the mobility of thick oil is enhanced by utilizing high temperature, and the thick oil in the oil layer flows into the production well, so that the effect of increasing the yield is achieved.

After the production well is drilled and the metal casing is put into the production well, the permanent magnet is put to the bottom of the production well by using a winch 7, a drill rod or a crawler, the permanent magnet is connected to generate a uniform magnetic field with unchanged direction and size, the winch 7 is rotated, the winch 7 pulls the electrified permanent magnet to move upwards at a constant speed, and the casing of the production well is magnetized to generate a magnetized casing magnetic field 20. In the process, the rotation speed of the winch can be adjusted according to the size of the magnetic field of the magnetized sleeve required by the magnetic guide positioning. After the casing pipe of the production well is magnetized and meets the requirement of magnetization intensity, the magnetizing equipment can be dismantled, the occupation of production is eliminated, and the original production function is recovered.

During the drilling process of the steam injection well, the sensor of the probe 16 in the bottom hole assembly 14 receives the magnetic field signal of the magnetized casing, and the distance and the direction between the steam injection well and the production well can be inverted according to the magnitude and the direction of the signal after the signal is processed, and when the distance between the horizontal section of the steam injection well and the horizontal section of the production well reaches the required distance, the horizontal section is extended according to the distance until the steam injection well is drilled.

Claims (12)

1. An in-casing magnetization method for passive magnetic positioning of an adjacent well is characterized by comprising the following steps: magnetizing the casing of the adjacent well by using the magnetizing device in the casing to enable the casing to have uniform remanence, withdrawing the magnetizing device from the adjacent well after the magnetization is finished, and restoring the normal working system of the adjacent well.

2. An in-casing magnetization method for passive magnetic positioning of an adjacent well according to claim 1, characterized in that: the magnetic device in the sleeve comprises a transmission device and a magnetic source; the method comprises the following steps: the transmission device is used for lowering the magnetic source to the bottom of the adjacent well, the sleeve at the corresponding position of the adjacent well is magnetized by the magnetized magnetic field generated by the magnetic source, and meanwhile, the transmission mechanism is used for lifting the magnetic source to the wellhead from the bottom of the well at a constant speed, so that the sleeve of the adjacent well is provided with the magnetic field; and then measuring related data by using an MWD probe in the drilling well, calculating the relative azimuth relationship between the two wells by using a triaxial accelerometer and a triaxial fluxgate sensor in the probe, calculating the distance between the drilling well and an adjacent well by using the data measured by a magnetic field gradient sensor and the relationship between the magnetic induction intensity and the distance, and communicating the MWD probe with a ground computer to guide the drilling of the drilling well or avoid the occurrence of well collision.

3. An in-casing magnetization method for passive magnetic positioning of an adjacent well according to claim 2, characterized in that: the adjacent well is a finished well which is already put into a metal casing, and the material of the metal casing is a ferromagnetic material.

4. A method of in-casing magnetization for passive magnetic positioning of an adjacent well according to claim 3, characterized in that: the magnetic source is a part of the magnetization device in the sleeve and is a permanent magnet.

5. A method of in-casing magnetization for passive magnetic positioning of an adjacent well according to claim 3, characterized in that: the magnetic source generates a magnetizing magnetic field through a magnetizing magnetic field generated by the magnetic source or by externally applying excitation to the magnetic source.

6. A method of in-casing magnetization for passive magnetic positioning of an adjacent well according to claim 3, characterized in that: the magnetic source is an energized cable or an energized solenoid.

7. An in-casing magnetization method for passive magnetic positioning of an adjacent well according to claim 2, characterized in that: the transmission device is a winch with a steel wire rope, a crawling robot or a drill rod.

8. An in-casing magnetization method for passive magnetic positioning of an adjacent well according to claim 2, characterized in that: the MWD probe is used for measuring related data in the drilling well, an electronic measurement assembly, a battery short section, a driving short section and a pulse generator are arranged in the MWD probe, wherein the electronic measurement assembly is formed by electrically connecting a plurality of sensors and a circuit measurement short section, various sensors in the MWD probe are responsible for measuring magnetic field, gravitational field and temperature time data at the probe, the measured data are sent to the circuit measurement short section to calculate the temperature, magnetic field strength, well inclination angle, azimuth angle and tool face angle data of the point, a driving short section controller controls the opening time interval and pulse intensity of a pulse generator valve according to instructions from the electronic measurement assembly, and underground data are sent to a ground control system in the form of mud pulses.

9. An in-casing magnetization method for passive magnetic positioning of an adjacent well according to claim 2, characterized in that: the MWD probe at least comprises a magnetic gradient sensor, a three-axis fluxgate, a three-axis gravity accelerometer and a temperature sensor;

the MWD probe is used for collecting measurement data of a drilling well and transmitting the measurement data to a surface computer for processing, and the measurement data comprises: and the magnetic gradient sensor at the position of the MWD probe measures magnetic field gradient data of the magnetized sleeve, absolute magnetic field data measured by the triaxial fluxgate, gravitational field data measured by the triaxial accelerometer, and temperature data measured by the temperature sensor.

10. The method of in-casing magnetization for passive magnetic positioning of an adjacent well according to claim 8, wherein: the magnetic gradient sensor measures magnetic field difference data used for the magnetized sleeve, measured absolute magnetic field data measured by the triaxial fluxgate, gravity data measured by the triaxial gravity accelerometer and temperature measured by the temperature sensor;

the triaxial fluxgate is formed by placing three orthogonal fluxgate sensors on the position of the axis of the probe tube to respectively measure magnetic field data in x, y and z directions;

the three-axis accelerometer is arranged at the position of the axis of the probe tube by three orthogonal acceleration sensors and respectively measures gravity field data in x, y and z directions;

the magnetic gradient sensor consists of an even number of three-axis fluxgates, two fluxgates are used as a group and are respectively arranged on the inner edge of the probe tube taking the axis of the probe tube as a symmetrical axis, the distance between every two three-axis fluxgates of the probe tube is known, and the magnetic field gradient generated by the adjacent well magnetization casing at the corresponding position can be obtained by the magnetic field intensity data measured by each fluxgate.

11. An in-casing magnetization method for passive magnetic positioning of an adjacent well according to claim 9, characterized in that: obtaining the distance between the adjacent well and the probe tube in the forward drilling according to the rule that the magnetic field decays along with the distance by using the measured gradient value of the magnetic field and the known distance between two three-axis fluxgates of the magnetic gradient sensor, namely the distance between the forward drilling and two adjacent wells;

and obtaining the azimuth relationship between the two wells of the well under drilling and the adjacent well according to the magnetic field intensity data measured by the triaxial fluxgate and the gravity field data measured by the triaxial accelerometer.

12. A method of in-casing magnetization for passive magnetic positioning of an adjacent well according to claim 10, wherein: further comprising: the relation between the magnetic induction intensity and the distance measured when two fluxgates of the magnetic gradient sensor are collinear with the adjacent well casing can be obtained according to the rule that the magnetic field intensity of the magnetic field is in a square attenuation relation along with the increase of the distance:

when an included angle theta exists between the connecting line of the two fluxgates and the axial lines of the drilling well and the adjacent well, the relation is as follows:

the distance between the drilling well and the adjacent well can be obtained according to the relation.

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