CN108442915B - Method and device for determining oil well distance - Google Patents

Method and device for determining oil well distance Download PDF

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Publication number
CN108442915B
CN108442915B CN201810269535.7A CN201810269535A CN108442915B CN 108442915 B CN108442915 B CN 108442915B CN 201810269535 A CN201810269535 A CN 201810269535A CN 108442915 B CN108442915 B CN 108442915B
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China
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oil well
well
casing
magnetic field
current source
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CN108442915A (en
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梁华庆
张睿
范家怿
颜肖平
窦新宇
高德利
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China University of Petroleum Beijing
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China University of Petroleum Beijing
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/12—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
    • E21B47/13—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling by electromagnetic energy, e.g. radio frequency

Abstract

The invention provides a method and a device for determining the distance between oil wells, wherein the method comprises the following steps: after a current source supplies power to a casing of a first oil well so that the casing of the first oil well forms an alternating magnetic field, acquiring the amplitude of the alternating magnetic field detected by a magnetic sensor, wherein the first oil well is an oil well with a drilling process, the magnetic sensor is fixedly arranged in a second oil well, the second oil well is an oil well with a drilling process, and one end of the current source is electrically connected with the top end of the casing of the first oil well; the other end of the current source is electrically connected with the earth outside at least 50 meters, or the other end of the current source is electrically connected with the top end of a sleeve of a third oil well, wherein the third oil well is another oil well which has completed the drilling process and is separated from the first oil well by at least 50 meters; determining a distance between the second well and the first well according to the amplitude value; the effective detection distance is longer, and any tool does not need to be put into the drilled well, so that the normal production of the drilled well is not affected.

Description

Method and device for determining oil well distance
Technical Field
The invention relates to the technical field of petroleum development and drilling, in particular to a method and a device for determining the distance of an oil well.
Background
For oil development drilling, especially for cluster wells and freeze wells, it is necessary to perform a drilling process to obtain an oil well. During the drilling process, the well currently undergoing the drilling process is most likely to be in close proximity to other wells. Because of the complex well structure, the accident that the well bores of adjacent oil wells collide with each other is very easy to happen in the drilling process; and then the normal production process of the oil well is affected, and huge economic loss is caused. In order to prevent the collision accident of the wellbores of adjacent wells during the drilling process, the distances between the wells undergoing the drilling process and other wells having completed the drilling process can be detected in real time.
In the prior art, an active magnetic detection method can be adopted to detect the distance between adjacent oil wells, two electromagnets with equal magnetic moment and opposite directions are arranged in the oil well which is being drilled, and the two electromagnets can magnetize the casing pipes of the adjacent oil wells; and a magnetic field sensor is installed at the center of the two electromagnets, and the magnetic sensor can detect magnetic field intensity information of a magnetic field generated after the casing of the adjacent oil well is magnetized, so that the distance between the adjacent oil wells can be determined according to the magnetic field intensity information. However, the length of the detecting instrument in the technology is longer and needs to be more than 1.2 meters, which can adversely affect the guiding function of the well drilling; moreover, because the two electromagnets generate weak magnetizing fields due to the limitation of underground power supply and space, the effective detection distance is short and can only reach a few meters.
Disclosure of Invention
The invention provides a method and a device for determining the distance of an oil well, which are used for solving the problem of short effective detection distance.
In one aspect, the invention provides a method for determining a distance between oil wells, comprising:
acquiring the amplitude of the alternating magnetic field detected by a magnetic sensor after a current source supplies power to a casing of a first oil well to enable the casing of the first oil well to form the alternating magnetic field, wherein the first oil well is an oil well with a drilling process, the magnetic sensor is fixedly arranged in a second oil well, the second oil well is an oil well with a drilling process, and one end of the current source is electrically connected with the top end of the casing of the first oil well; the other end of the current source is electrically connected with the ground, or the other end of the current source is electrically connected with the top end of a sleeve of a third oil well, wherein the third oil well is another oil well with a drilling process; the distance between the other end of the current source and the ground is greater than or equal to 50 meters; the distance between the first oil well and the third oil well is greater than or equal to 50 meters;
and determining the distance between the second oil well and the first oil well according to the amplitude value.
Further, the distance between the second oil well and the first oil well isWherein H is the amplitude of the alternating magnetic field, pi is the circumference ratio, mu 0 For vacuum permeability, μ is the permeability of the surrounding formation of the casing of the first well, α for the included angle between the central axis of the second oil well and the central axis of the casing of the first oil well, θ is the included angle between a first straight line, which is the connecting straight line between the micro-ring on the casing of the first oil well and the position point of the magnetic sensor, and a second straight line, which is the straight line passing through the micro-ring on the casing of the first oil well and being parallel to the central axis of the second oil well, I l A current intensity at a depth l for a casing of the first well, and I l ＝I 0 e -l/k K is a preset coefficient, I 0 The depth l is the distance between the micro-ring on the casing of the first oil well and the top end of the casing of the first oil well, and is the current intensity value input into the casing of the first oil well by the current source.
Further, after the current source supplies power to the casing of the first oil well to enable the casing of the first oil well to form an alternating magnetic field, acquiring the amplitude of the alternating magnetic field detected by the magnetic sensor, including:
When the current source does not supply power to the casing of the first oil well, acquiring first magnetic field intensity information of a static magnetic field detected by the magnetic sensor, and performing Fourier transform on the first magnetic field intensity information to obtain a first amplitude of the static magnetic field;
when the current source supplies power to the casing of the first oil well, acquiring second magnetic field intensity information detected by the magnetic sensor, and carrying out Fourier transform on the second magnetic field intensity information to obtain a second amplitude;
subtracting the first amplitude from the second amplitude to obtain the amplitude of the alternating magnetic field.
Further, when the current source does not supply power to the casing of the first oil well, acquiring first magnetic field strength information detected by the magnetic sensor, including:
transmitting a first control signal to the current source, wherein the first control signal characterizes and controls the current source not to supply power to the casing of the first oil well, and acquires the first magnetic field intensity information;
when the current source supplies power to the casing of the first oil well, acquiring second magnetic field intensity information detected by the magnetic sensor, wherein the second magnetic field intensity information comprises:
and sending a second control signal to the current source, wherein the second control signal characterizes and controls the current source to supply power to the casing of the first oil well, and the second amplitude value is obtained.
Further, when the number of the first oil wells is N, the number of the current sources is N, N is a positive integer greater than or equal to 2, the first oil wells are connected with the current sources in a one-to-one correspondence manner, and accordingly, after the current sources supply power to the casings of the first oil wells so that the casings of the first oil wells form an alternating magnetic field, the method for obtaining the amplitude of the alternating magnetic field detected by the magnetic sensor comprises the following steps:
after each of the N current sources inputs current into the casing of the first oil well corresponding to the current source so that the casing of each first oil well forms an alternating magnetic field, acquiring an alternating magnetic field signal detected by the magnetic sensor, wherein the frequencies of the currents input into the casings of different first oil wells by different current sources are different;
performing Fourier transformation on the alternating magnetic field signals to obtain amplitude values corresponding to each first oil well;
accordingly, determining the distance between the second well and the first well according to the amplitude value comprises:
and determining the distance between the second oil well and each first oil well according to the amplitude corresponding to each first oil well.
In another aspect, the present invention provides an apparatus for determining a distance between wells, comprising:
A floor level, a magnetic sensor, and a current source;
one end of the current source is electrically connected with the top end of a sleeve of a first oil well, and the first oil well is an oil well with a drilling process completed; the surface instrument is electrically connected with the magnetic sensor, the magnetic sensor is fixedly arranged in a second oil well, and the second oil well is an oil well which is subjected to a drilling process; the other end of the current source is electrically connected with the ground, or the other end of the current source is electrically connected with the top end of a sleeve of a third oil well, wherein the third oil well is another oil well with a drilling process; the distance between the other end of the current source and the ground is greater than or equal to 50 meters; the distance between the first oil well and the third oil well is greater than or equal to 50 meters;
the current source is used for supplying power to the casing of the first oil well so that the casing of the first oil well forms an alternating magnetic field;
the surface instrument is used for acquiring the amplitude of the alternating magnetic field detected by the magnetic sensor and determining the distance between the second oil well and the first oil well according to the amplitude.
Further, the distance between the second oil well and the first oil well is Wherein H is the amplitude of the alternating magnetic field, pi is the circumference ratio, mu 0 Is vacuum permeability, μ is permeability of surrounding stratum of the casing of the first well, α is an angle between the central axis of the second well and the central axis of the casing of the first well, θ is an angle between a first straight line which is a connecting line between a micro ring on the casing of the first well and a position point of the magnetic sensor, and a second straight line which is a straight line passing through the micro ring on the casing of the first well and parallel to the central axis of the second well, I l A current intensity at a depth l for a casing of the first well, and I l ＝I 0 e -l/k K is a preset coefficient, I 0 A current intensity value input into the casing of the first oil well for the current source, wherein the depth l is the distance between a micro-ring on the casing of the first oil well and the top end of the casing of the first oil well;
the ground instrument is specifically used for:
when the current source does not supply power to the casing of the first oil well, acquiring first magnetic field intensity information of a static magnetic field detected by the magnetic sensor, and performing Fourier transform on the first magnetic field intensity information to obtain a first amplitude of the static magnetic field;
When the current source supplies power to the casing of the first oil well, acquiring second magnetic field intensity information detected by the magnetic sensor, and carrying out Fourier transform on the second magnetic field intensity information to obtain a second amplitude;
subtracting the first amplitude from the second amplitude to obtain the amplitude of the alternating magnetic field.
Further, the ground instrument is further configured to:
after each of N current sources inputs current into the casing of the first oil well corresponding to the current source so that the casing of each first oil well forms an alternating magnetic field, acquiring alternating magnetic field signals detected by a magnetic sensor, wherein the frequencies of the currents input into the casings of different first oil wells by different current sources are different, the number of the first oil wells is N, N is a positive integer greater than or equal to 2, and the first oil wells are connected with the current sources in a one-to-one correspondence manner;
performing Fourier transformation on the alternating magnetic field signals to obtain amplitude values corresponding to each first oil well;
and determining the distance between the second oil well and each first oil well according to the amplitude value of the alternating magnetic field corresponding to each first oil well.
Further, the magnetic sensor is located in a probe tube, wherein the probe tube is located between a drill bit of the second oil well and a non-magnetic drill collar.
Further, the surface instrument is electrically connected with the current source;
the surface instrument is also used for sending a first control signal to the current source so as to control the current source not to supply power to the casing of the first oil well, and is also used for sending a second control signal to the current source so as to control the current source to supply power to the casing of the first oil well.
Further, the magnetic sensor is in threaded connection with the probe tube; or the probe tube is fixedly connected with a closed box, and the magnetic sensor is fixedly arranged in the closed box.
Further, a sealing ring is arranged on the edge of the closed box,
further, the closed box is square, cuboid or cylinder.
Further, a drilling device is arranged in the second oil well.
Further, one end of the current source is electrically connected with the top end of the sleeve of the first oil well through a first wire; the other end of the current source is electrically connected with the ground through a second wire, or the other end of the current source is electrically connected with the top end of the sleeve of the third oil well through the second wire.
According to the method and the device for determining the distance between the drilling well, provided by the invention, the alternating current is input into the sleeve in the drilling well, so that the sleeve in the drilling well is magnetized, then the magnetic sensor in the drilling well acquires the amplitude information of the alternating magnetic field generated by the sleeve in the drilling well, the ground instrument can calculate the distance between the drilling well and the drilling well according to the amplitude information, the amplitude information can better represent the information of the drilling well, the distance between two adjacent oil wells can be accurately determined, and the measurement accuracy is higher; the distance between the other end of the current source and the ground is greater than or equal to 50 meters, or the distance between the first oil well and the third oil well is greater than or equal to 50 meters, so that the phenomenon that current cannot flow downwards along the drilled casing due to the formation of a close-range loop is avoided; the scheme provided by the embodiment can detect the distance between the device and the adjacent oil well in real time in the drilling process of the drilling well, namely, the device and the scheme for measuring the distance between the device and the adjacent oil well while drilling are provided. In the embodiment, only one end of the current source is required to be connected with the top end of the well casing, no tool is required to be put into the well, normal production of the well is not affected, and the distance detection scheme provided by the embodiment is safe and convenient to operate; and the high-power current is adopted to demagnetize the sleeve, so that the magnetization field intensity can be effectively enhanced, the distance measurement distance and the distance measurement precision are improved, and an effective technical means is provided for the distance detection of the adjacent well and the collision prevention of the cluster well.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description, serve to explain the principles of the disclosure.
FIG. 1 is a schematic flow chart of a method for determining a distance between oil wells according to an embodiment of the present invention;
FIG. 2 is a flow chart of another method for determining a distance between wells according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an alternating magnetic field on a casing of a first well in another method for determining a well distance according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a derived model of an alternating magnetic field of a casing of a first well in another method for determining a distance between wells according to an embodiment of the present invention;
FIG. 5 is a schematic flow chart of another method for determining a distance between wells according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of an apparatus for determining a distance between oil wells according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a measurement principle of an apparatus for determining a distance between oil wells according to an embodiment of the present invention;
FIG. 8 is a schematic structural diagram of another device for determining the distance between wells according to an embodiment of the present invention;
fig. 9 is a schematic measurement diagram of another device for determining a distance between oil wells according to an embodiment of the present invention.
Reference numerals:
61: a ground instrument; 62: a magnetic sensor; 63: a current source;
64: a first well; 65: a sleeve; 66: a second well;
71: a probe tube; 72: a drill rod; 73: drill collar
74: a measurement while drilling system; 75: a power drill; 76: a drill bit.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present disclosure as detailed in the accompanying claims.
First, the terms involved in the present invention will be explained:
drilling: the well is being drilled. Drilling: the well has completed the drilling process.
The specific application scenario of the invention is as follows. Oil wells such as cluster wells are widely used in offshore and land oil fields due to their advantages such as economy, high efficiency, convenience in management, etc. Along with the development of large-scale oil fields, the directional drilling technology of cluster wells is greatly developed and improved, but along with the smaller well spacing between oil wells and the complex well body structure of the oil wells, the accident that the well bores of adjacent oil wells collide with each other is very easy to occur in the drilling process. The well collision accident can bring serious consequences, the well casing is deformed if the well casing is light, the well casing is penetrated if the well casing is heavy, and then the normal production of an oil well is affected, so that huge economic loss is caused. Therefore, the method solves the problem of well collision of the cluster well and has great significance for ensuring the safety of drilling operation of the cluster well. So that a measurement of the distance between adjacent wells, i.e. the distance between the well being drilled and the well being drilled, can be made.
Currently, a passive magnetic detection method is adopted by us Scientific Drilling International, which is based on the principle that a magnetic field sensor is provided in the well being drilled, and the magnetic field sensor is used to detect the magnetic abnormal field information generated by the adjacent well being drilled magnetized by the geomagnetic field, and then determine the distance between the well being drilled and the well being drilled according to the magnetic abnormal field information. However, since the magnetic field strength of the geomagnetic field is relatively weak, the magnetic abnormal field strength generated after magnetizing the well casing by the geomagnetic field is also weak, so that a high-precision magnetic sensor is required to detect a weak magnetic field signal, thereby increasing the cost of measurement; and, also because the magnetic abnormal field intensity generated after the geomagnetic field magnetizes the well casing is weaker, the method can only detect the oil well with a shorter distance, and the detection accuracy is lower.
In addition, wu Zhiyong et al of China university propose another active magnetic detection method, which uses two electromagnets with equal magnetic moment and opposite directions to magnetize the casings of adjacent oil wells in the well drilling process, and installs a magnetic field sensor at the center of the two electromagnets, and uses the magnetic sensor to detect the magnetic field intensity information of the casing magnetization, so as to determine the distance between the two oil wells according to the magnetic field intensity information. However, in this method, the length of the probe to be used for the detection is long and needs to be 1.2 meters or more, which adversely affects the guiding function of the well being drilled. Moreover, because of the limitation of underground power supply and space, the magnetizing magnetic fields generated by the two electromagnets are weak, so that the effective detection distance can only reach a few meters.
Therefore, in conclusion, the currently used measurement while drilling method cannot simultaneously meet the requirements of high accuracy, long distance measurement, simple operation and the like. In addition, current measurement while drilling methods fail to determine the distance between the wellbore being drilled and the multiple drilled wells, respectively, when there are multiple drilled wells around the perimeter of the wellbore being drilled. The invention provides a method and a device for determining the distance of an oil well, and aims to solve the technical problems in the prior art.
The following describes the technical scheme of the present invention and how the technical scheme of the present invention solves the above technical problems in detail with specific embodiments. The following embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. Embodiments of the present invention will be described below with reference to the accompanying drawings.
Fig. 1 is a flow chart of a method for determining a distance between oil wells according to an embodiment of the present invention. As shown in fig. 1, the method includes:
step 101, after a current source supplies power to a casing of a first oil well so that the casing of the first oil well forms an alternating magnetic field, acquiring the amplitude of the alternating magnetic field detected by a magnetic sensor, wherein the first oil well is an oil well with a drilling process, the magnetic sensor is fixedly arranged in a second oil well, the second oil well is an oil well with the drilling process, and one end of the current source is electrically connected with the top end of the casing of the first oil well; the other end of the current source is electrically connected with the earth, or the other end of the current source is electrically connected with the top end of a sleeve of a third oil well, and the third oil well is another oil well with the well drilling process completed; wherein, the distance between the other end of the current source and the ground and the current source is more than or equal to 50 meters; the distance between the first oil well and the third oil well is greater than or equal to 50 meters.
In this embodiment, specifically, the execution body of this embodiment may be a ground instrument, or other apparatus or device. The embodiment is described with the execution body as a ground instrument.
The first well is a well in which the drilling process has been completed, and the second well is a well in which the drilling process is being performed. During the drilling of the second well, the distance between the first well and the second well needs to be measured in real time to avoid the well bores from colliding with each other.
First, a magnetic sensor is fixedly arranged in a second oil well, and the magnetic sensor is electrically connected with a surface instrument. A high power current source is provided with one end of the current source electrically connected to the top end of the casing of the first well. The other end of the current source is electrically connected with the ground, wherein the distance between the connecting point of the other end of the current source and the ground and the current source is required to be more than or equal to 50 meters; or, the other end of the current source is electrically connected with the top end of the sleeve of a third oil well, wherein the third oil well is another oil well with the drilling process completed, and the distance between the first oil well and the third oil well is more than or equal to 50 meters. And, this high-power current source is disposed on the ground.
Specifically, the first well is a drilled well and the second well is a drilling well; placing a high power current source on the surface near the well site, the current source having one end connected to the well casing; the other end of the current source is connected to another drilled well outside 50 meters, or the other end of the current source is connected to a copper electrode well contacted with the ground outside 50 meters, so that the current can not flow downwards along the drilled sleeve due to the formation of a close-range loop. Wherein, the copper electrode is a connection point between the other end of the current source and the ground.
Then, injecting an alternating current into the first oil well by using a high-power current source, wherein the alternating current is low-frequency and high-power current, the frequency of the alternating current is generally less than 30 hertz (Hz), and the magnitude of the alternating current is I 0 The casing of the first well may thus be magnetized, the casing of the first well forming an alternating magnetic field.
Because the second oil well is provided with a magnetic sensor, the magnetic sensor is electrically connected with the surface instrument. The magnetic sensor can receive magnetic field intensity information of an alternating magnetic field formed by the casing of the first oil well, the magnetic field intensity information is the amplitude of the alternating magnetic field, and then the ground instrument can acquire the amplitude of the alternating magnetic field detected by the magnetic sensor.
Step 102, determining the distance between the second oil well and the first oil well according to the amplitude value.
In this embodiment, specifically, according to the obtained amplitude of the alternating magnetic field, the surface instrument may calculate the distance between the second oil well and the first oil well according to the oil well distance calculating method provided in the prior art, where the distance is a vector distance.
According to the embodiment, through inputting current into the well-drilled casing, the well-drilled casing is magnetized, then the magnetic sensor in the well-drilled casing obtains amplitude information of an alternating magnetic field generated by the well-drilled casing, the ground instrument can calculate the distance between the well-drilled casing and the well-drilled casing according to the amplitude information, the well-drilled information can be well represented by the amplitude information, the distance between two adjacent oil wells can be accurately determined, and the measurement accuracy is high; the distance between the other end of the current source and the ground is greater than or equal to 50 meters, or the distance between the first oil well and the third oil well is greater than or equal to 50 meters, so that the phenomenon that current cannot flow downwards along the drilled casing due to the formation of a close-range loop is avoided; the scheme provided by the embodiment can detect the distance between the device and the adjacent oil well in real time in the drilling process of the drilling well, namely, a measurement while drilling device and a scheme for the distance between the device and the adjacent oil well are provided; in addition, in the embodiment, only one end of the current source is required to be connected with the top end of the well casing, no tool is required to be put into the well, normal production of the well is not affected, and the distance detection scheme provided by the embodiment is safe and convenient to operate; and the high-power current is adopted to demagnetize the sleeve, so that the magnetization field intensity can be effectively enhanced, the distance measurement distance and the distance measurement precision are improved, and an effective technical means is provided for the distance detection of the adjacent well and the collision prevention of the cluster well.
Fig. 2 is a flow chart of another method for determining a distance between oil wells according to an embodiment of the present invention. As shown in fig. 2, the method includes:
step 201, when the current source does not supply power to the casing of the first oil well, acquiring first magnetic field intensity information of the static magnetic field detected by the magnetic sensor, and performing fourier transform on the first magnetic field intensity information to obtain a first amplitude of the static magnetic field.
In an alternative embodiment, step 201 specifically includes: and sending a first control signal to the current source, wherein the first control signal characterizes that the current source is not used for supplying power to the casing of the first oil well, acquiring first magnetic field intensity information, and carrying out Fourier transform on the first magnetic field intensity information to obtain a first amplitude value of the static magnetic field.
The first oil well is an oil well with a drilling process completed, the magnetic sensor is fixedly arranged in the second oil well, the second oil well is an oil well with the drilling process being performed, and one end of the current source is electrically connected with the top end of the casing pipe of the first oil well; the other end of the current source is electrically connected with the earth, or the other end of the current source is electrically connected with the top end of a sleeve of a third oil well, and the third oil well is another oil well with the well drilling process completed.
In this embodiment, specifically, the execution body of this embodiment may be a ground instrument, or other apparatus or device. The embodiment is described with the execution body as a ground instrument.
The first well is a well in which the drilling process has been completed, and the second well is a well in which the drilling process is being performed. During the drilling of the second well, the distance between the first well and the second well needs to be measured in real time to avoid the well bores from colliding with each other.
Firstly, fixedly arranging a magnetic sensor in a second oil well, and electrically connecting the magnetic sensor with a ground instrument; specifically, a probe is arranged between a drill bit of the second oil well and the non-magnetic drill collar, a magnetic sensor is arranged in the probe, and the magnetic sensor is used for receiving magnetic field information generated after the casing is magnetized; and, the circuit in the probe can upload the acquired magnetic field data to the surface instrument through a measurement while drilling (Measurement While Drilling, abbreviated as MWD). Providing a high-power current source, and electrically connecting one end of the current source with the top end of the sleeve of the first oil well; and the other end of the current source is electrically connected with the ground, or the other end of the current source is electrically connected with the top end of a sleeve of a third oil well, wherein the third oil well is another oil well with the drilling process completed. And, this high-power current source is disposed on the ground. The current source is electrically connected with the ground instrument.
Specifically, the first well is a drilled well and the second well is a drilling well; placing a high power current source on the surface near the well site, the current source having one end connected to the well casing; the other end of the current source is connected to another drilled well outside 50 meters, or the other end of the current source is connected to a copper electrode well contacted with the ground outside 50 meters, so that the current can not flow downwards along the drilled sleeve due to the formation of a close-range loop. Wherein, the copper electrode is a connection point between the other end of the current source and the ground.
Then, the surface instrument sends a first control signal to the current source, wherein the first control signal characterizes that the current source is not used for supplying power to the casing of the first oil well, and at the moment, the current source is not used for supplying power to the casing of the first oil well, namely, the current source is not used for inputting alternating current to the casing of the first oil well; so that at this time, no ac current is injected into the casing of the first well, and the casing of the first well is not magnetized; at this time, the magnetic sensor in the second oil well receives the first magnetic field intensity information of the static magnetic field of the earth; then the ground instrument acquires the first magnetic field intensity information, and the ground instrument carries out Fourier transform on the first magnetic field intensity information, so that the amplitude H of the static magnetic field can be obtained. The magnitude H of the static magnetic field of the earth. Is the first amplitude. Wherein the first well is a drilled well and the second well is a drilling well. And, when the distance between the drilled well and the drilling well is long, for example, the distance is more than 20 meters, the magnetized magnetic field is too small to be received by the magnetic sensor, so that the surface instrument can only calculate the amplitude H of the static magnetic field of the earth. .
And 202, when the current source supplies power to the casing of the first oil well, acquiring second magnetic field intensity information detected by the magnetic sensor, and performing Fourier transform on the second magnetic field intensity information to obtain a second amplitude value.
In an alternative embodiment, step 202 specifically includes: and sending a second control signal to the current source, wherein the second control signal characterizes the control current source to supply power to the casing of the first oil well, acquires second magnetic field intensity information, and performs Fourier transform on the second magnetic field intensity information to obtain a second amplitude.
In this embodiment, specifically, the surface instrument sends a second control signal to the current source, where the second control signal characterizes that the current source is controlled to supply power to the casing of the first oil well, and at this time, the current source supplies power to the casing of the first oil well, that is, the current source inputs an alternating current to the casing of the first oil well; so that at this time, alternating current is injected into the casing of the first well, and the casing of the first well is magnetized; at this time, the magnetic sensor in the second well receives the second magnetic field strength information; the ground instrument acquires second magnetic field intensity information, and then the ground instrument performs Fourier transform on the second magnetic field intensity information to obtain a second amplitude H ', and at this time, the second amplitude H' is the amplitude H of the static magnetic field of the earth. Plus the amplitude H of the alternating magnetic field.
And 203, subtracting the first amplitude from the second amplitude to obtain the amplitude of the alternating magnetic field.
In this embodiment, specifically, the ground level instrument subtracts the first amplitude from the second amplitude to obtain the amplitude H of the alternating magnetic field.
Step 204, determining the distance between the second oil well and the first oil well asWherein H is the amplitude of the alternating magnetic field, pi is the circumference ratio, mu 0 For vacuum permeability, μ is the permeability of the surrounding formation of the casing of the first well, α is the central axis of the second well and the firstAn included angle between central axes of casings of the oil well, θ being an included angle between a first straight line which is a connecting straight line between a micro ring on the casing of the first oil well and a position point of the magnetic sensor, and a second straight line which is a straight line passing through the micro ring on the casing of the first oil well and parallel to the central axes of the second oil well, I l The current intensity at depth l for the casing of the first well, and I l ＝I 0 e -l/k K is a preset coefficient, I 0 For the current intensity value input by the current source into the casing of the first oil well, the depth l is the distance between the micro-ring on the casing of the first oil well and the top end of the casing of the first oil well.
In this embodiment, fig. 3 is a schematic diagram of an alternating magnetic field on a casing of a first well in another method for determining a distance between wells according to an embodiment of the present invention, as shown in fig. 3, after an alternating current is supplied to the casing of the first well by a current source, there is a continuous leakage current I flowing into a surrounding formation during a process that the current flows down the casing of the first well d I.e. the current is lost, but since the casing of the first well is ferromagnetic, the resistivity of the casing is very small and the resistivity of the casing differs from that of the stratum by 6-7 orders of magnitude, thus the current I is leaked d Is very small.
In fig. 3, the length of the sleeve is far greater than the diameter and thickness of the sleeve, so that the sleeve after being electrified can be equivalent to an electrified straight wire, and the sleeve can be decomposed into a plurality of microcircles dl'. The point where the casing of the first oil well is connected with the current source is an injection point, and the current intensity value of the current input by the current source to the casing of the first oil well is I 0 Assuming that the distance between a certain micro-ring P on the casing of the first well and the injection point is the depth l, the current I at P l Exponentially decaying according to the following formula, I l ＝I 0 e -l/k K is a preset coefficient, and the coefficient k can be determined by the diameter phi of the casing, the resistance R of the unit length of the casing, the conductivity sigma of the stratum around the casing and the like. Specifically, the depth l is the distance between the center of a micro-ring on the casing of the first well and the injection pointAlternatively, where the micro-ring is considered as a point, the depth l is the distance between a micro-ring on the casing of the first well and the injection point.
The sleeve after being electrified is equivalent to an electrified straight wire, a micro-ring with the width dl' at any point P on the sleeve is taken, and the magnetic field intensity generated by the micro-ring at the position point Q of the magnetic field sensor is calculated according to the Piaor-savart law; integrating all the microcircles dl' on the whole sleeve to obtain a functional relation which is satisfied by the intensity of the magnetic field generated by the whole sleeve at the Q positionWherein pi is the circumference ratio, d is the preset distance, mu 0 For vacuum permeability, μ is the permeability of the surrounding formation of the casing of the first well, α is the angle between the central axis of the second well and the central axis of the casing of the first well, θ is the angle between a first line, which is the line connecting the micro-ring on the casing of the first well to the location point of the magnetic sensor, and a second line, which is the line passing through the micro-ring on the casing of the first well and parallel to the central axis of the second well, I l The current intensity at depth l for the casing of the first well, and I l ＝I 0 e -l/k K is a preset coefficient, I 0 For the current intensity value input by the current source into the casing of the first oil well, the depth l is the distance between the micro-ring on the casing of the first oil well and the top end of the casing of the first oil well. Wherein μ is measurable prior to ranging; i l The measurement while drilling can be obtained by calculating the parameters of the casing and the stratum before the measurement while drilling; alpha can be measured in real time while ranging.
Specifically, fig. 4 is a schematic diagram of a derivation model of an alternating magnetic field of a casing of a first oil well in another method for determining an oil well distance according to an embodiment of the present invention, as shown in fig. 4, a three-dimensional rectangular coordinate system is established, a point where a magnetic sensor is located on a second oil well is a location point Q, the second oil well has a central axis, the central axis of the second oil well may also be referred to as a central axis of a probe of the second oil well, and a straight line passing through the location point Q and being perpendicular to the central axis of the second oil well is taken as a Y axis of the three-dimensional rectangular coordinate system; the first oil well has a central axis, which may also be referred to as the central axis of the casing of the first oil well, and an intersection point is formed between the Y axis and the central axis of the casing of the first oil well, and the intersection point is taken as an origin point O of a three-dimensional rectangular coordinate system; taking a straight line passing through the origin O and being parallel to the central axis of the second oil well as a Z axis of a three-dimensional rectangular coordinate system; a straight line perpendicular to both the Y axis and the Z axis and passing through the origin O is taken as the X axis of the three-dimensional rectangular coordinate system. The distance d between the Z axis and the central axis of the second well may be taken as the distance d between the first well and the second well.
The angle between the central axis of the second well and the central axis of the casing of the first well is alpha. Because the length of the sleeve is far greater than the diameter and thickness of the sleeve, the sleeve after being electrified can be equivalent to an electrified straight wire, the sleeve is decomposed into a plurality of micro-rings dl ', an included angle formed by each micro-ring dl' and a position point Q of a magnetic field sensor in a probe tube is theta, specifically, theta is an included angle between a first straight line and a second straight line, the first straight line is a connecting straight line between a micro-ring P on the sleeve of a first oil well and the position point Q of a magnetic sensor, the second straight line is a straight line which passes through the micro-ring on the sleeve of the first oil well and is parallel to the central axis of the second oil well, wherein P can be the center point of the micro-ring, and the micro-ring can be regarded as a point P; the distance between the micro-ring P on the casing of the first well and the location point Q of the magnetic sensor is r. The distance l' is the distance between the micro-ring P and the origin O.
First, as known from the law of biot-savart, a micro-ring of width dl' at a certain point P on the sleeve generates a magnetic induction of the order ofWherein, preferably, mu 0 ＝4π×10 -7 Tm/A。
Then, deducing the relation between l' and theta, and between r and theta; from the following componentsCan get->Then pair->And (2) differentiating θ simultaneously on both sides of the equation, there is +.>Then, by->Obtain->
Then, willAnd->Substituted intoIn (3) after finishing->
Then, according to the relation dH=dB/mu of the magnetic field strength dH and the magnetic induction dB, the magnetic field strength generated by a micro-ring with the width dl' at the P point of the sleeve after being electrified is obtained
Then, integrating all the microcircles dl' on the whole casing to obtain the magnetic field intensity of the whole casing generated at the position of the magnetic field sensor in the well
Thus, a formula can be obtained
Thereby substituting the amplitude H calculated in step 203 intoThe distance d between the second oil well and the first oil well can be calculated; as seen in fig. 4, the distance d between the second well and the first well is the distance between the Z axis and the central axis of the second well.
According to the embodiment, through inputting alternating current into the well-drilled casing, the well-drilled casing is magnetized, then the magnetic sensor in the well-drilled casing obtains amplitude information of an alternating magnetic field generated by the well-drilled casing, the ground instrument can calculate the distance between the well-drilled casing and the well-drilled casing according to the amplitude information, the well-drilled information can be well represented by the amplitude information, the distance between two adjacent oil wells can be accurately determined, and the measurement accuracy is high; the scheme provided by the embodiment can detect the distance between the device and the adjacent oil well in real time in the drilling process of the drilling well, namely, a measurement while drilling device and a scheme for the distance between the device and the adjacent oil well are provided; in addition, in the embodiment, only one end of the current source is required to be connected with the top end of the well casing, no tool is required to be put into the well, normal production of the well is not affected, and the distance detection scheme provided by the embodiment is safe and convenient to operate; and the high-power current is adopted to demagnetize the sleeve, so that the magnetization field intensity can be effectively enhanced, the distance measurement distance and the distance measurement precision are improved, and an effective technical means is provided for the distance detection of the adjacent well and the collision prevention of the cluster well. In addition, the embodiment provides a specific calculation formula and a specific calculation method for calculating the distance.
Fig. 5 is a flow chart of another method for determining a distance between oil wells according to an embodiment of the present invention. As shown in fig. 5, the method includes:
step 301, when the number of the first oil wells is N, the number of the current sources is N, N is a positive integer greater than or equal to 2, the first oil wells are connected with the current sources in a one-to-one correspondence manner, after each of the N current sources inputs current into the casing of the first oil well corresponding to the current source so that the casing of each first oil well forms an alternating magnetic field, the amplitude of the alternating magnetic field formed by the casing of each first oil well detected by the magnetic sensor is obtained, wherein the frequencies of the currents input into the casings of different first oil wells by different current sources are different; wherein each first oil well is an oil well which has completed the drilling process, the magnetic sensor is fixedly arranged in the second oil well, the second oil well is an oil well which is being subjected to the drilling process, and one end of each current source is electrically connected with the top end of the casing of the first oil well corresponding to the current source; the other end of each current source is electrically connected with the earth, or the other end of each current source is electrically connected with the top end of a sleeve of a third oil well corresponding to the current source, and the third oil well is another oil well with the drilling process completed; wherein, the distance between the other end of each current source and the ground is greater than or equal to 50 meters; the distance between each first oil well and the third oil well is greater than or equal to 50 meters.
In this embodiment, specifically, the execution body of this embodiment may be a ground instrument, or other apparatus or device. The embodiment is described with the execution body as a ground instrument.
And when N drilled wells are arranged around the second oil well, wherein N is more than or equal to 2, namely when the number of the first oil wells is at least two. First, a magnetic sensor is fixedly arranged in a second oil well, and the magnetic sensor is electrically connected with a surface instrument. And providing a current source for each first well in one-to-one correspondence with each first well,
one end of each current source is electrically connected with the top end of the casing of the first oil well corresponding to the current source, and the frequency of the current input into the casing of the different first oil wells by different current sources is different. The other end of each current source is electrically connected with the ground, wherein the distance between the connecting point of the other end of each current source and the ground and the current source is greater than or equal to 50 meters; or the other end of each current source is electrically connected with the top end of the sleeve of the third oil well corresponding to the current source, and the third oil well is another oil well with the drilling process completed, wherein the distance between each first oil well and the third oil well is greater than or equal to 50 meters respectively.
For each first well, the principle of magnetic field generation is the same as step 101 in fig. 1, and steps 201 to 203 in fig. 2 are not repeated.
And 302, carrying out Fourier transform on the alternating magnetic field signals to obtain the corresponding amplitude value of each first oil well.
In this embodiment, specifically, in this embodiment, the surface instrument needs to perform fourier transform on the alternating magnetic field signal in step 301, and after performing fourier transform, the amplitude H' of each first oil well can be obtained. The surface instrument then needs to subtract the amplitude H' of each first well first from the amplitude H of the static magnetic field corresponding to that first well. The final amplitude H "for each first well is obtained. And then the amplitude H' of the alternating magnetic field of each well can be solved.
For example, three drilled wells A, B, C are provided around the well being drilled, three high-power current sources can be used to simultaneously feed f into the casing of A, B, C wells A 、f B 、f C The magnetic field sensor in the well can detect magnetic induction intensity signals with three different frequencies, namely the amplitude represented by the information of the magnetic field intensity received by the magnetic field sensor is the amplitude of the static magnetic field of the earth superimposed with the amplitude of the alternating magnetic field magnetized by the A, B, C three well casing, namely H 0 +H(f A )+H(f B )+H(f C ) Wherein H (f A ) The amplitude of the alternating magnetic field generated after magnetizing the casing of the well A, H (f B ) The amplitude of the alternating magnetic field, H (f), generated after magnetizing the casing of the borehole B C ) Is the amplitude of the alternating magnetic field generated after magnetizing the casing of the well C. Surface instrument pair magnetic transmissionThe signals transmitted by the sensor are subjected to Fourier transformation, so that the amplitude of the alternating magnetic field with three frequencies can be obtained respectively.
In this embodiment, a high-power source may be used to time-share inject the same low-frequency ac current into the casings of the plurality of first oil wells through the ground power supply switching system, so as to simplify the ground system.
Step 303, determining the distance between the second oil well and each first oil well according to the amplitude value corresponding to each first oil well.
In this embodiment, specifically, for each first well, the calculation may be performed by using the method in step 101 in fig. 1 or steps 204-207 in fig. 2 when calculating the distance between the second well and each first well.
For example, when there are three drilled wells A, B, C around the well being drilled, the distance d between the three drilled wells and the well being drilled can be determined by using the distance calculation method of FIG. 1 or FIG. 2, respectively, for each well A 、d B And d C 。
The amplitude value of the alternating magnetic field detected by the magnetic sensor is obtained after a current source supplies power to the casing of each first oil well so that the casing of each first oil well forms the alternating magnetic field; performing Fourier transform on the amplitude of the alternating magnetic field to obtain the corresponding amplitude of each first oil well; and determining the distance between the second oil well and each first oil well according to the amplitude value corresponding to each first oil well. So that the distances between the drilling well being drilled and the plurality of drilled wells, respectively, can be measured.
Fig. 6 is a schematic structural diagram of an apparatus for determining a distance between oil wells according to an embodiment of the present invention, and fig. 7 is a schematic measuring principle diagram of an apparatus for determining a distance between oil wells according to an embodiment of the present invention, where, as shown in fig. 6 and fig. 7, the apparatus of this embodiment may include:
a surface instrument 61, a magnetic sensor 62, and a current source 63;
one end of the current source 63 is electrically connected to the top end of a casing 65 of a first well 64, the first well 64 being a well that has completed a drilling process; the surface instrument 61 is electrically connected with the magnetic sensor 62, the magnetic sensor 62 is fixedly arranged in a second oil well 66, and the second oil well 66 is an oil well which is subjected to a drilling process; the other end of the current source 63 is electrically connected to the earth, or the other end of the current source 63 is electrically connected to the top end of the casing of the third oil well, which is another oil well that has completed the drilling process; wherein, the distance between the other end of the current source 63 and the ground and the current source 63 is greater than or equal to 50 meters; the distance between the first well 64 and the third well is 50 meters or more.
A current source 63 for supplying power to the casing 65 of the first well 64 so that the casing 65 of the first well 64 forms an alternating magnetic field;
the surface instrument 61 is configured to acquire the amplitude of the alternating magnetic field detected by the magnetic sensor 62, and determine the distance between the second oil well 66 and the first oil well 64 according to the amplitude.
In the present embodiment, specifically, the surface instrument 61, the magnetic sensor 62, and the current source 63 in the dashed box in fig. 6 constitute a well distance determining means.
The first well 64 is a well that has completed the drilling process and the second well 66 is a well that is undergoing the drilling process. During the drilling of the second well 66, the distance between the first well 64 and the second well 66 needs to be measured in real time to avoid the wellbores from colliding with each other.
First, one magnetic sensor 62 is fixedly installed in the second oil well 66, and the magnetic sensor 62 is electrically connected to the surface instrument 61. Providing a high power current source 63, electrically connecting one end of the current source 63 to the top end of a casing 65 of a first well 64; and the other end of the current source 63 is electrically connected to the earth or the other end of the current source 63 is electrically connected to the top end of a casing of a third well, which is another well in which the drilling process has been completed. The high-power current source 63 is provided on the ground.
Specifically, the first well 64 is a drilled well and the second well 66 is a drilling well; placing a high power current source 63 at the surface near the well site, the current source 63 having one end connected to a well casing 65; the other end of the current source 63 is connected to another drilled well outside 50 meters, or the other end of the current source 63 is connected to a copper electrode well in contact with the earth outside 50 meters, thereby avoiding the formation of a close-range loop that would prevent current from flowing down the drilled casing 65. The copper electrode is a connection point between the other end of the current source 63 and the ground.
Then, an AC current is injected into the first oil well 64 by using a high-power current source 63, wherein the AC current is low-frequency and high-power, the frequency of the AC current is generally less than 30 hertz (Hz), and the magnitude of the AC current is I 0 The casing 65 of the first well 64 may thus be magnetized, the casing 65 of the first well 64 forming an alternating magnetic field.
Since a magnetic sensor 62 is provided in the second borehole, the magnetic sensor 62 is electrically connected to the surface unit 61. The magnetic sensor 62 can thus receive the magnetic field strength information of the alternating magnetic field formed by the casing 65 of the first oil well 64, which is the amplitude of the alternating magnetic field, and the surface instrument 61 can thus acquire the amplitude of the alternating magnetic field detected by the magnetic sensor 62.
The surface instrument 61 can calculate the distance between the second well 66 and the first well 64, which is a vector distance, according to the well distance calculation method provided in the related art based on the obtained amplitude of the alternating magnetic field.
The present embodiment provides a device composed of a surface instrument 61, a magnetic sensor 62 and a current source 63, wherein one end of the current source 63 is electrically connected with the top end of a casing 65 of a first oil well 64, and the first oil well 64 is an oil well which has completed a drilling process; the surface instrument 61 is electrically connected with the magnetic sensor 62, the magnetic sensor 62 is fixedly arranged in a second oil well 66, and the second oil well 66 is an oil well which is subjected to a drilling process; the other end of the current source 63 is electrically connected to the earth, or the other end of the current source 63 is electrically connected to the top end of the casing of the third oil well, which is another oil well that has completed the drilling process; a current source 63 for supplying power to the casing 65 of the first well 64 so that the casing 65 of the first well 64 forms an alternating magnetic field; the surface instrument 61 is configured to acquire the amplitude of the alternating magnetic field detected by the magnetic sensor 62, and determine the distance between the second oil well 66 and the first oil well 64 according to the amplitude. In this embodiment, by inputting current into the casing 65 in the well drilling process, the casing 65 in the well drilling process is magnetized, then the magnetic sensor 62 in the well drilling process obtains the amplitude information of the alternating magnetic field generated by the casing 65 in the well drilling process, the surface instrument 61 can calculate the distance between the well drilling process and the well drilling process according to the amplitude information, the amplitude information can better represent the well drilling process information, and further the distance between two adjacent oil wells can be accurately determined, and the measurement accuracy is high; the scheme provided by the embodiment can detect the distance between the device and the adjacent oil well in real time in the drilling process of the drilling well, namely, a measurement while drilling device and a scheme for the distance between the device and the adjacent oil well are provided; in addition, in the embodiment, only one end of the current source 63 is required to be connected with the top end of the drilled casing 65, no tool is required to be put into the drilled casing, normal production of the drilled casing is not affected, and the distance detection scheme provided by the embodiment is safe and convenient to operate; and the high-power alternating current is adopted to demagnetize the sleeve 65, so that the magnetization field intensity can be effectively enhanced, the distance measurement distance and the distance measurement precision are improved, and an effective technical means is provided for the distance detection of the adjacent well and the collision prevention of the cluster well.
Fig. 8 is a schematic structural diagram of another device for determining a distance between oil wells according to an embodiment of the present invention, and fig. 9 is a schematic measuring principle diagram of another device for determining a distance between oil wells according to an embodiment of the present invention, where, based on the embodiment shown in fig. 6 and fig. 7, as shown in fig. 8 and fig. 9, the magnetic sensor 62 is located in the probe 71, and where the probe 71 is located between the drill 76 of the second oil well 66 and the non-magnetic drill collar 73.
The magnetic sensor 62 is screwed with the probe 71. Alternatively, the probe 71 is fixedly connected with a closed box, and the magnetic sensor 62 is fixedly arranged in the closed box; the edge of the closed box is provided with a sealing ring; the closed box is square, cuboid or cylindrical.
A drilling apparatus is disposed in the second well 66.
One end of the current source 63 is electrically connected to the top end of the casing 65 of the first well 64 by a first wire; the other end of the current source 63 is electrically connected to the earth through a second wire, or the other end of the current source 63 is electrically connected to the top end of the casing of the third well through a second wire.
In this embodiment, in particular, the magnetic sensor 62 is located in a probe 71, wherein the probe 71 is located between a drill bit 76 of the second well 66 and a non-magnetic drill collar.
The magnetic sensor 62 may be connected to the probe 71 in any of the following ways: the outer surface of the magnetic sensor 62 is screwed with the inner surface of the probe 71 by a screw; alternatively, a closed box is fixedly connected to the probe 71, the magnetic sensor 62 is fixedly disposed in the closed box, and the closed box is square or rectangular, and a sealing ring is required to be disposed on the edge of the closed box.
A drilling apparatus is disposed in the second well 66. As can be seen in fig. 9, during the drilling process for the second well 66, drill pipe 72, drill collar 73, measurement while drilling system 74, probe 71, magnetic sensor 62, power drill 75, drill bit 76, etc. are provided in the second well 66 in that order from the surface in a downward direction.
One end of the current source 63 is electrically connected to the tip of the casing 65 of the first well 64 via a first wire; the other end of the current source 63 is electrically connected to the ground through a second wire, or the other end of the current source 63 is electrically connected to the top end of the casing of the third well through a second wire.
In this embodiment, by inputting an ac current into the casing 65 in the well, so as to magnetize the casing 65 in the well, then the magnetic sensor 62 in the well obtains the amplitude information of the alternating magnetic field generated by the casing 65 in the well, the ground instrument 61 can calculate the distance between the well and the well according to the amplitude information, the amplitude information can better represent the well information, and further the distance between two adjacent oil wells can be accurately determined, and the measurement accuracy is higher; the scheme provided by the embodiment can detect the distance between the device and the adjacent oil well in real time in the drilling process of the drilling well, namely, a measurement while drilling device and a scheme for the distance between the device and the adjacent oil well are provided; in addition, in the embodiment, only one end of the current source 63 is required to be connected with the top end of the drilled casing 65, no tool is required to be put into the drilled casing, normal production of the drilled casing is not affected, and the distance detection scheme provided by the embodiment is safe and convenient to operate; and the high-power alternating current is adopted to demagnetize the sleeve 65, so that the magnetization field intensity can be effectively enhanced, the distance measurement distance and the distance measurement precision are improved, and an effective technical means is provided for the distance detection of the adjacent well and the collision prevention of the cluster well.
Further, based on the embodiment shown in fig. 8 and 9, the distance between the second well and the first well isWherein H is the amplitude of the alternating magnetic field, pi is the circumference ratio, d is the preset distance, mu 0 Mu is the magnetic permeability of the surrounding stratum of the casing 65 of the first oil well 64, alpha is the angle between the central axis of the second oil well 66 and the central axis of the casing 65 of the first oil well 64, theta is the angle between a first straight line, which is the connecting straight line between the micro-ring on the casing 65 of the first oil well 64 and the position point of the magnetic sensor 62, and a second straight line, which is the straight line passing through the micro-ring on the casing 65 of the first oil well 64 and being parallel to the central axis of the second oil well 66, I l The current intensity at depth l for casing 65 of first well 64, and I l ＝I 0 e -l/k K is a preset coefficient, I 0 The depth l is the distance between the micro-ring on the casing 65 of the first well 64 and the tip of the casing 65 of the first well 64, for the current intensity value input by the current source 63 into the casing 65 of the first well 64.
The ground instrument 61 is specifically configured to: when the current source 63 does not supply power to the casing 65 of the first oil well 64, acquiring first magnetic field intensity information of the static magnetic field detected by the magnetic sensor 62, and performing fourier transform on the first magnetic field intensity information to obtain a first amplitude of the static magnetic field; when the current source 63 supplies power to the casing 65 of the first oil well 64, acquiring second magnetic field intensity information detected by the magnetic sensor 62, and performing Fourier transform on the second magnetic field intensity information to obtain a second amplitude; subtracting the first amplitude from the second amplitude to obtain the amplitude of the alternating magnetic field.
In this embodiment, the above process may refer to steps 204-207 of fig. 2, and will not be described again.
Further, on the basis of the embodiment shown in fig. 8 and 9, the floor gauge 61 is further configured to: after each current source 63 of the N current sources 63 inputs a current into the casing of the first oil well 64 corresponding to the current source 63 so that the casing of each first oil well 64 forms an alternating magnetic field, acquiring alternating magnetic field signals detected by the magnetic sensor 62, wherein the frequencies of the currents input by different current sources 63 into the casings of different first oil wells 64 are different, the number of the first oil wells 64 is N, N is a positive integer greater than or equal to 2, and the first oil wells 64 are connected with the current sources 63 in a one-to-one correspondence manner; performing Fourier transform on the alternating magnetic field signals to obtain the amplitude value corresponding to each first oil well 64; the distance between the second well 66 and each of the first wells 64, respectively, is determined based on the corresponding amplitude of each of the first wells 64.
In this embodiment, the above process may refer to each step of fig. 3, and will not be described again.
Further, on the basis of the embodiment shown in fig. 8 and 9, the floor gauge 61 is electrically connected to a current source 63; the surface instrument 61 is further adapted to send a first control signal to the current source 63 to control the current source 63 not to supply power to the casing 65 of the first well 64, and to send a second control signal to the current source 63 to control the current source 63 to supply power to the casing 65 of the first well 64.
In this embodiment, the above process may refer to steps 201-202 in fig. 2, and will not be described again.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any adaptations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
It is to be understood that the present disclosure is not limited to the precise arrangements and instrumentalities shown in the drawings, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims (8)

1. A method for determining a distance from an oil well, comprising:
acquiring the amplitude of the alternating magnetic field detected by a magnetic sensor after a current source supplies power to a casing of a first oil well to enable the casing of the first oil well to form the alternating magnetic field, wherein the first oil well is an oil well with a drilling process, the magnetic sensor is fixedly arranged in a second oil well, the second oil well is an oil well with a drilling process, and one end of the current source is electrically connected with the top end of the casing of the first oil well; the other end of the current source is electrically connected with the ground, or the other end of the current source is electrically connected with the top end of a sleeve of a third oil well, wherein the third oil well is another oil well with a drilling process; the distance between the other end of the current source and the ground is greater than or equal to 50 meters; the distance between the first oil well and the third oil well is greater than or equal to 50 meters;
Determining a distance between the second well and the first well according to the amplitude value;
the distance between the second oil well and the first oil well isWherein H is the amplitude of the alternating magnetic field, pi is the circumference ratio, mu 0 Is vacuum magnetic permeability, mu is magnetic permeability of surrounding stratum of the sleeve of the first oil well, alpha is an included angle between the central axis of the second oil well and the central axis of the sleeve of the first oil well, and theta is a first straight line and a second straight lineAn included angle between two straight lines, wherein the first straight line is a connecting straight line between a micro ring on the casing of the first oil well and the position point of the magnetic sensor, the second straight line is a straight line passing through the micro ring on the casing of the first oil well and parallel to the central axis of the second oil well, I l A current intensity at a depth l for a casing of the first well, and I l ＝I 0 e -l/k K is a preset coefficient, I 0 The depth l is the distance between the micro-ring on the casing of the first oil well and the top end of the casing of the first oil well, and is the current intensity value input into the casing of the first oil well by the current source.
2. The method of claim 1, wherein the obtaining the amplitude of the alternating magnetic field detected by the magnetic sensor after the current source supplies power to the casing of the first well to cause the casing of the first well to form the alternating magnetic field comprises:
When the current source does not supply power to the casing of the first oil well, acquiring first magnetic field intensity information of a static magnetic field detected by the magnetic sensor, and performing Fourier transform on the first magnetic field intensity information to obtain a first amplitude of the static magnetic field;
when the current source supplies power to the casing of the first oil well, acquiring second magnetic field intensity information detected by the magnetic sensor, and carrying out Fourier transform on the second magnetic field intensity information to obtain a second amplitude;
subtracting the first amplitude from the second amplitude to obtain the amplitude of the alternating magnetic field.
3. The method of claim 2, wherein obtaining first magnetic field strength information detected by the magnetic sensor when the current source is not supplying power to the casing of the first well comprises:
transmitting a first control signal to the current source, wherein the first control signal characterizes and controls the current source not to supply power to the casing of the first oil well, and acquires the first magnetic field intensity information;
when the current source supplies power to the casing of the first oil well, acquiring second magnetic field intensity information detected by the magnetic sensor, wherein the second magnetic field intensity information comprises:
And sending a second control signal to the current source, wherein the second control signal characterizes and controls the current source to supply power to the casing of the first oil well, and the second amplitude value is obtained.
4. A method according to any one of claims 1-3, wherein when the number of first oil wells is N, the number of current sources is N, N is a positive integer greater than or equal to 2, the first oil wells are connected to the current sources in a one-to-one correspondence, and the obtaining the amplitude of the alternating magnetic field detected by the magnetic sensor after the current sources supply power to the casing of the first oil well to form the alternating magnetic field to the casing of the first oil well includes:
after each of the N current sources inputs current into the casing of the first oil well corresponding to the current source so that the casing of each first oil well forms an alternating magnetic field, acquiring an alternating magnetic field signal detected by the magnetic sensor, wherein the frequencies of the currents input into the casings of different first oil wells by different current sources are different;
performing Fourier transformation on the alternating magnetic field signals to obtain amplitude values corresponding to each first oil well;
accordingly, determining the distance between the second well and the first well according to the amplitude value comprises:
And determining the distance between the second oil well and each first oil well according to the amplitude corresponding to each first oil well.
5. An apparatus for determining a distance between wells, comprising:
a floor level, a magnetic sensor, and a current source;
one end of the current source is electrically connected with the top end of a sleeve of a first oil well, and the first oil well is an oil well with a drilling process completed; the surface instrument is electrically connected with the magnetic sensor, the magnetic sensor is fixedly arranged in a second oil well, and the second oil well is an oil well which is subjected to a drilling process; the other end of the current source is electrically connected with the ground, or the other end of the current source is electrically connected with the top end of a sleeve of a third oil well, wherein the third oil well is another oil well with a drilling process; the distance between the other end of the current source and the ground is greater than or equal to 50 meters; the distance between the first oil well and the third oil well is greater than or equal to 50 meters;
the current source is used for supplying power to the casing of the first oil well so that the casing of the first oil well forms an alternating magnetic field;
The surface instrument is used for acquiring the amplitude of the alternating magnetic field detected by the magnetic sensor and determining the distance between the second oil well and the first oil well according to the amplitude;
the distance between the second oil well and the first oil well isWherein H is the amplitude of the alternating magnetic field, pi is the circumference ratio, mu 0 Is vacuum permeability, μ is permeability of surrounding stratum of the casing of the first well, α is an angle between the central axis of the second well and the central axis of the casing of the first well, θ is an angle between a first straight line which is a connecting line between a micro ring on the casing of the first well and a position point of the magnetic sensor, and a second straight line which is a straight line passing through the micro ring on the casing of the first well and parallel to the central axis of the second well, I l A current intensity at a depth l for a casing of the first well, and I l ＝I 0 e -l/k K is a preset coefficient, I 0 A current intensity value input into the casing of the first oil well for the current source, wherein the depth l is the distance between a micro-ring on the casing of the first oil well and the top end of the casing of the first oil well;
The ground instrument is specifically used for:
when the current source does not supply power to the casing of the first oil well, acquiring first magnetic field intensity information of a static magnetic field detected by the magnetic sensor, and performing Fourier transform on the first magnetic field intensity information to obtain a first amplitude of the static magnetic field;
when the current source supplies power to the casing of the first oil well, acquiring second magnetic field intensity information detected by the magnetic sensor, and carrying out Fourier transform on the second magnetic field intensity information to obtain a second amplitude;
subtracting the first amplitude from the second amplitude to obtain the amplitude of the alternating magnetic field.
6. The apparatus of claim 5, wherein the surface instrument is further configured to:
after each of N current sources inputs current into the casing of the first oil well corresponding to the current source so that the casing of each first oil well forms an alternating magnetic field, acquiring alternating magnetic field signals detected by a magnetic sensor, wherein the frequencies of the currents input into the casings of different first oil wells by different current sources are different, the number of the first oil wells is N, N is a positive integer greater than or equal to 2, and the first oil wells are connected with the current sources in a one-to-one correspondence manner;
Performing Fourier transformation on the alternating magnetic field signals to obtain amplitude values corresponding to each first oil well;
and determining the distance between the second oil well and each first oil well according to the amplitude corresponding to each first oil well.
7. The apparatus of claim 5, wherein the magnetic sensor is located in a probe, wherein the probe is located between a drill bit of the second well and a non-magnetic drill collar.
8. The apparatus of any one of claims 5-7, wherein the surface instrument is electrically connected to the current source;
the surface instrument is also used for sending a first control signal to the current source so as to control the current
The source is not supplying power to the casing of said first well, and is also used to send a second control signal to said current source,
to control the current source to supply power to the casing of the first well.
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