阅读说明：本技术 一种非导电泥浆随钻电阻率成像测量装置 (Non-conductive mud is along with boring resistivity formation of image measuring device ) 是由 张卫 李新 倪卫宁 曾义金 米金泰 闫立鹏 于 2018-07-25 设计创作，主要内容包括：一种非导电泥浆随钻电阻率成像测量装置,包括：多个信号发射部,用于向地层输出测量电流信号；信号测量部,用于对地层回流的电流进行采集,得到电流检测数据；控制电路,其与信号测量部和各个信号发射部连接,用于控制信号发射部生成并输出相应的测量电流信号,还用于根据接收到的信号测量部所传输来的电流检测数据确定地层的地层电阻率；其中,多个信号发射部沿钻铤轴向对称分布在信号测量部的两侧。本装置将高频电磁波激励通过感应耦合方式穿过非导电泥浆传输到地层,将非导电泥浆与地层等效为一电容电阻形成的电路,本装置能够适用于采用油基泥浆等导电性较差的条件下的地层电阻率检测,其能够为地质导向和后期开发提供井筒高清图像。(A non-conductive mud resistivity imaging while drilling measuring device comprises: a plurality of signal emitting sections for outputting a measure current signal to the formation; the signal measuring part is used for collecting the current of the formation backflow to obtain current detection data; the control circuit is connected with the signal measuring part and each signal transmitting part, is used for controlling the signal transmitting part to generate and output a corresponding measuring current signal, and is also used for determining the formation resistivity of the formation according to the received current detection data transmitted by the signal measuring part; wherein, a plurality of signal transmitting parts are symmetrically distributed on two sides of the signal measuring part along the axial direction of the drill collar. The device excites high-frequency electromagnetic waves and penetrates non-conductive mud to be transmitted to the stratum in an inductive coupling mode, the non-conductive mud and the stratum are equivalent to a circuit formed by a capacitance resistor, the device can be suitable for formation resistivity detection under the condition of poor conductivity such as oil-based mud, and the like, and can provide shaft high-definition images for geological guidance and later development.)

1. A non-conductive mud resistivity imaging while drilling measuring device is characterized by comprising:

a plurality of signal emitting sections for outputting a measure current signal to the formation;

the signal measuring part is used for collecting current flowing through the signal measuring part to obtain current detection data;

the control circuit is connected with the signal measuring part and each signal transmitting part, is used for controlling the signal transmitting part to generate and output a corresponding measuring current signal, and is also used for determining the formation resistivity of the stratum according to the received current detection data transmitted by the signal measuring part;

the signal transmitting parts are symmetrically distributed on two sides of the signal measuring part along the axial direction of the drill collar.

2. The apparatus of claim 1, wherein the signal measurement section comprises:

the signal measuring electrode assembly is arranged in a first groove distributed on the outer wall of the drill collar, the first groove comprises a first groove component and a second groove component, the first groove component is closer to the outer wall of the drill collar than the second groove component, and the inner diameter of the first groove component is larger than that of the second groove component.

3. The apparatus as claimed in claim 2, wherein the outer wall of the drill collar has a plurality of first grooves uniformly distributed along a circumferential direction, and each first groove has a signal measuring electrode assembly disposed therein.

4. The apparatus of claim 2 or 3, wherein the signal measurement electrode assembly comprises: an electrode housing, a measuring electrode and an insulating tape, wherein,

the insulating tape is arranged between the electrode shell and the measuring electrode and used for electrically isolating the electrode shell from the measuring electrode;

the electrode housing is disposed within the first recess and has a lower end extending into the second recess component.

5. The apparatus of claim 2 or 3, wherein the signal receiving component comprises a measuring electrode and an insulating tape, wherein,

the insulating tape is disposed within the first groove and a lower end thereof extends into the second groove constituent part;

the measuring electrode is arranged in the insulating tape and is tightly attached to the insulating tape.

6. The apparatus according to any one of claims 2 to 5, wherein a measuring electrode holder for defining the signal measuring electrode assembly is provided in the first groove component, and a circular hole is formed in the measuring electrode holder so that the measuring electrode communicates with the outside.

7. The apparatus of claim 6, wherein the measurement electrode holder is formed with a radial protrusion extending toward a center of the measurement electrode assembly in a radial direction of the measurement electrode assembly.

8. An apparatus as claimed in any one of claims 2 to 7, wherein the apparatus includes a plurality of signal measurement electrode assemblies evenly distributed along the circumference of the drill collar.

9. The apparatus according to any one of claims 2 to 8, wherein the signal measuring section further comprises:

and the data acquisition circuit is electrically connected with the signal measurement electrode assembly and is used for processing and acquiring data of the electric signals transmitted by the signal measurement electrode assembly so as to obtain current detection data.

10. The apparatus of claim 9, wherein the apparatus further comprises:

the electronic circuit barrel is arranged in the inner cavity of the drill collar, a flow channel for conveying drilling fluid is arranged in the center of the electronic circuit barrel, a sealed electronic bin is formed by the outer wall of the electronic circuit barrel and the inner wall of the drill collar in a matched mode, and the data acquisition circuit is arranged in the electronic bin.

11. The apparatus according to any one of claims 1 to 10, wherein the signal transmitting section comprises:

the transmitting coil is arranged in a transmitting coil groove formed in the outer wall of the drill collar and used for outputting a measuring current signal to the stratum;

and the coil protection cover is used for covering the transmitting coil groove so as to protect the transmitting coil.

12. The apparatus of claim 11, wherein the coil shield comprises a structural strength shield and an insulating protective band disposed in close axial proximity along the drill collar, wherein the insulating protective band is disposed on a side remote from the signal measurement portion.

Technical Field

The invention relates to the technical field of petroleum exploration and development, in particular to a resistivity measurement while drilling device, and particularly relates to a non-conductive mud resistivity imaging measurement while drilling device.

Background

Modern oil drilling and production operations require a great deal of information about the underground well conditions and the stratum, and the detection of shaft information mainly comprises two modes of a cable mode and a drilling mode.

Wireline logging may involve lowering a sonde into the borehole after some or all of the drilling tasks have been completed to determine the formation properties traversed by the borehole. The logging cable not only provides power for the detector, but also is a channel for transmitting data and control signals between the detector and the ground. During operation, the logging cable can lift the detector and measure various properties of the stratum according to the depth position by using the detector. The cable logging instrument can only work in a vertical well or an approximately vertical well because the cable logging instrument needs to be put into the well by the gravity of the cable logging instrument, so that the cable logging instrument has higher requirement on the dog-leg degree of a well hole. Once the inclination of the borehole is larger, the wireline logging instrument cannot be lowered continuously, so that the working range of wireline logging is limited.

Disclosure of Invention

In order to solve the problems, the invention provides a non-conductive mud resistivity imaging while drilling measuring device, which comprises:

a plurality of signal emitting sections for outputting a measure current signal to the formation;

the signal measuring part is used for collecting the current of the formation backflow to obtain current detection data;

the control circuit is connected with the signal measuring part and each signal transmitting part, is used for controlling the signal transmitting part to generate and output a corresponding measuring current signal, and is also used for determining the formation resistivity of the stratum according to the received current detection data transmitted by the signal measuring part;

the signal transmitting parts are symmetrically distributed on two sides of the signal measuring part along the axial direction of the drill collar.

According to an embodiment of the present invention, the signal measuring section includes:

the signal measuring electrode assembly is arranged in a first groove distributed on the outer wall of the drill collar, the first groove comprises a first groove component and a second groove component, the first groove component is closer to the outer wall of the drill collar than the second groove component, and the inner diameter of the first groove component is larger than that of the second groove component.

According to one embodiment of the invention, a plurality of first grooves are uniformly distributed on the outer wall of the drill collar along the circumferential direction, and a signal measuring electrode assembly is arranged in each first groove.

According to one embodiment of the present invention, the signal measuring electrode assembly includes: an electrode housing, a measuring electrode and an insulating tape, wherein,

the insulating tape is arranged between the electrode shell and the measuring electrode and used for electrically isolating the electrode shell from the measuring electrode;

the electrode housing is disposed within the first recess and has a lower end extending into the second recess component.

According to one embodiment of the invention, the signal receiving assembly comprises a measuring electrode and an insulating tape, wherein,

the insulating tape is disposed within the first groove and a lower end thereof extends into the second groove constituent part;

the measuring electrode is arranged in the insulating tape and is tightly attached to the insulating tape.

According to one embodiment of the present invention, a measuring electrode holder for defining the signal measuring electrode assembly is provided in the first groove component, and a circular hole is formed in the measuring electrode holder so that the measuring electrode communicates with the outside.

According to an embodiment of the present invention, the measurement electrode holder is formed with a radial protrusion extending toward a center of the measurement electrode assembly in a radial direction of the measurement electrode assembly.

According to one embodiment of the invention, the device comprises a plurality of signal measurement electrode assemblies which are evenly distributed along the circumference of the drill collar.

According to an embodiment of the present invention, the signal measuring section further includes:

and the data acquisition circuit is electrically connected with the signal measurement electrode assembly and is used for processing and acquiring data of the electric signals transmitted by the signal measurement electrode assembly so as to obtain current detection data.

According to an embodiment of the invention, the apparatus further comprises:

the electronic circuit barrel is arranged in the inner cavity of the drill collar, a flow channel for conveying drilling fluid is arranged in the center of the electronic circuit barrel, a sealed electronic bin is formed by the outer wall of the electronic circuit barrel and the inner wall of the drill collar in a matched mode, and the data acquisition circuit is arranged in the electronic bin.

According to an embodiment of the present invention, the signal transmitting part includes:

the transmitting coil is arranged in a transmitting coil groove formed in the outer wall of the drill collar and used for outputting a measuring current signal to the stratum;

and the coil protection cover is used for covering the transmitting coil groove so as to protect the transmitting coil.

According to one embodiment of the invention, the coil protection cover comprises a structural strength protection cover and an insulation protection belt which are arranged in the drill collar in the axial direction, wherein the insulation protection belt is arranged on the side far away from the signal measuring part.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required in the description of the embodiments or the prior art:

FIG. 1 is a schematic structural diagram of a non-conductive mud resistivity imaging while drilling measurement device according to one embodiment of the invention;

FIG. 2 is a schematic circuit diagram of a non-conductive mud resistivity imaging while drilling measurement device according to one embodiment of the invention;

FIG. 3 is a schematic diagram of an integrated circuit model of a non-conductive mud and formation, according to one embodiment of the invention;

FIG. 4 is a schematic diagram of a non-conductive mud and formation integrated circuit model according to another embodiment of the invention

FIG. 5 is a total impedance equivalence plot of a measurement loop according to one embodiment of the invention;

FIG. 6 is a schematic mechanical diagram of a non-conductive mud resistivity imaging while drilling measurement device according to one embodiment of the invention;

FIG. 7 is a schematic structural view of a measurement electrode assembly according to one embodiment of the present invention;

FIG. 8 is a schematic structural view of a measurement electrode assembly according to another embodiment of the present invention;

fig. 9 is a schematic view of the structure of a measurement electrode assembly according to still another embodiment of the present invention.

Detailed Description

The following detailed description of the embodiments of the present invention will be provided with reference to the drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. It should be noted that, as long as there is no conflict, the embodiments and the features of the embodiments of the present invention may be combined with each other, and the technical solutions formed are within the scope of the present invention.

In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details or with other methods described herein.

The logging-while-drilling can acquire stratum information, process data and transmit the data to the ground in real time or approximately real time while drilling operation is performed, so that underground stratum conditions are analyzed in time, drilling parameters are adjusted, drilling operation is optimized, the maximum reservoir drilling rate of geosteering drilling is realized, and yield is improved by greatly increasing the base area of a well hole and the stratum. Because the data acquisition and measurement of the logging while drilling are carried out while drilling, the invasion of the stratum is not obvious, and the accuracy of the data can be increased. Logging while drilling can be used for highly deviated wells and horizontal wells, and the time of a drilling machine can be greatly saved.

In logging while drilling, a method of identifying a formation or an oil reservoir by using a difference in formation resistivity is called a resistivity logging method. The high-resolution resistivity logging while drilling can obtain the microstructure information of a shaft while drilling, not only can help to optimally drill a well, but also can identify a formation dip angle and a crack through an image, so that the lost circulation is identified and beneficial guidance is provided for later fracturing. Conventional high resolution resistivity while drilling is measured by a lateral method, i.e., a low frequency or direct current electric field is used to establish a current channel between the formation and the instrument, so as to detect the formation resistivity.

During drilling, a drilling fluid (mud) is adopted, and the functions of the drilling fluid (mud) mainly comprise: (1) cooling the drill bit; (2) keeping the pressure in the well slightly larger than the formation pressure to prevent blowout; (3) the rock debris broken by the drill bit is brought back to the surface, etc., through the space between the drill tool and the ground.

The slurry can be classified into two types according to conductivity: water-based mud and oil-based mud. Under certain conditions, especially in the emerging unconventional shale gas reservoir, the shale gas reservoir must be drilled with oil-based mud because the main formation of the shale gas layer is mudstone, and the clay material in the mudstone is sensitive to water (swells when it encounters water), so that the size of the wellbore will change if water-based mud is used, which threatens the safety of drilling.

However, water-based muds are electrically conductive, and oil-based muds are poorly or even non-conductive. Existing formation resistivity imaging while drilling techniques are designed primarily to accommodate water-based mud types (e.g., patents US6359438B1, US5339037, CN 201410759458.5). The existing oil-based mud imaging technology is mainly a wireline logging mode (for example, US6714014B2), and the existing oil-based mud imaging technology cannot be directly applied to logging-while-drilling operation.

The invention provides a novel device for measuring resistivity imaging of non-conductive mud while drilling, which is used for detecting the resistivity of a stratum to be analyzed based on the capacitive coupling principle and aims to solve the problem that the prior art cannot meet the problem that the formation imaging while drilling is difficult under the conditions of non-conductive mud, oil-based mud and the like.

Fig. 1 shows a schematic structural diagram of a non-conductive mud resistivity imaging while drilling measurement device provided by the embodiment.

As shown in fig. 1, the non-conductive mud resistivity imaging while drilling measurement device provided by the present embodiment preferably includes: a signal measuring part 101, a first signal transmitting part 102a, a second signal transmitting part 102b, and a control circuit 103. Wherein, the first signal transmitting part 102a and the second signal transmitting part 102b are both connected with the control circuit 103, and the first signal transmitting part 102a and the second signal transmitting part 102b can generate and output corresponding measuring current signals under the control of the control circuit 103 and transmit the measuring current signals to the stratum.

The signal measuring part 101 is connected with the control circuit 103, and is used for collecting the current of the formation backflow to obtain current detection data, and transmitting the current detection data to the control circuit 103 electrically connected with the signal measuring part, so that the control circuit 103 determines the formation resistivity of the formation according to the current detection data transmitted by the signal measuring part 101, and the resistivity imaging measurement while drilling is realized.

In this embodiment, the first signal transmitting portion 102a and the second signal transmitting portion 102b are preferably symmetrically distributed on both sides of the signal measuring portion 101 along the axial direction of the drill collar. It should be noted that in other embodiments of the present invention, the number of signal emitting portions included in the non-conductive mud resistivity imaging while drilling measurement apparatus may also be more than two (e.g., 4 or 6, etc.), wherein the signal emitting portions preferably appear in pairs and are symmetrically distributed on two sides of the signal measuring portion.

FIG. 2 shows a schematic circuit structure diagram of the non-conductive mud resistivity imaging while drilling measurement device.

As shown in fig. 2, in the present embodiment, the control circuit 103 of the apparatus preferably includes a transmission control unit 201 and a resistivity measurement unit 202. Wherein the transmission control unit 201 is connected to the transmission drive circuit 203, while the transmission drive circuit 203 is also connected to the respective signal transmission sections (e.g., the first signal transmission section 102a and the second signal transmission section 102b) through the respective modulators (e.g., the first modulator 204a and the second modulator 204 b). The emission driving circuit 203 and the modulator can process the signal transmitted by the emission control unit 201 and transmit the processed signal to each signal emission part, so as to control each signal emission part to output a corresponding measured current signal.

Specifically, in the present embodiment, the transmission drive circuit 203 preferably includes a band-pass filter and a power amplifier. The band-pass filter is connected to the transmission control unit 201, and is configured to perform band-pass filtering on a signal (i.e., a transmission control signal) transmitted by the transmission control unit 201 and transmit the filtered signal to a power amplifier connected thereto, so that the power amplifier performs power amplification on the signal. The modulator can modulate the signal transmitted by the transmission driving circuit 203 (for example, adjust the operating frequency and bandwidth, increase the transmission power, and the like), and transmit the modulated signal to the corresponding signal transmitting portion.

The signal emitting parts are respectively correspondingly connected with the modulators and can generate measuring current according to the signals transmitted by the modulators and transmit the measuring current to the stratum. Specifically, in the present embodiment, the signal transmitting section preferably includes a transmitting coil. In the working process, the transmitting coil is used as a primary coil, the stratum and the drill collar form a secondary coil, and based on the transformer principle, the transmitting coil can load current on the secondary coil, so that a measuring current signal enters the stratum.

As shown in fig. 2, in the present embodiment, the signal measuring part 101 preferably includes a plurality of measuring electrode assemblies (e.g., a first measuring electrode assembly 205a, a second measuring electrode assembly 205b, and a third measuring electrode assembly 205c) and a data acquisition circuit 206. The measurement electrode assemblies are preferably each disposed on a stabilizer protruding from the outer wall of the borehole and capable of sensing current flowing through itself (e.g., sensing current flowing into the formation through itself or from the formation into itself).

The plurality of measurement electrode assemblies included in the signal measurement portion 101 are preferably uniformly distributed along the circumferential direction of the borehole, that is, for the present embodiment, the included angles between the first measurement electrode assembly 205a, the second measurement electrode assembly 205b, and the third measurement electrode assembly 205c and the adjacent measurement electrode assemblies are all 120 degrees.

Of course, in other embodiments of the present invention, the number of the measurement electrode assemblies included in the signal measurement portion 101 may also be other reasonable values (for example, 1, 2, or more than 3, etc.) according to actual needs, and meanwhile, the distribution manner of the measurement electrode assemblies may also adopt other reasonable manners, which is not limited to this.

It should be noted that if the non-conductive mud resistivity imaging while drilling measurement device only contains 1 measurement electrode assembly, the instrument is required to rotate to different angles of the borehole under the condition of rotary drilling during the operation process, so as to measure 1 or more times at different angles, and finally obtain the whole borehole information of the whole borehole 360-degree range. The higher the angular resolution of the detection, the shorter the single measurement time is required, and the higher the requirements on the acquisition measurement system are.

If the non-conductive mud resistivity imaging while drilling measuring device comprises a plurality of measuring electrode assemblies, the device can perform superposition of data measured by different measuring electrode assemblies at the same angle, so that the signal to noise ratio is improved, and the circumferential resolution effect is increased. In addition, when the non-conductive mud resistivity imaging while drilling measuring device comprises a plurality of measuring electrode assemblies, even when the instrument does not rotate, the device can obtain formation information in a plurality of directions, and further helps to measure formation resistivity at different angles, and the device is more adaptive.

In the present embodiment, the data acquisition circuit 206 preferably includes a plurality of pre-amplification filter circuits (the data acquisition circuit 206 includes a first pre-amplification filter circuit 207a, a second pre-amplification filter circuit 207b, and a third pre-amplification filter circuit 207c corresponding to the number of measurement electrode assemblies), an analog signal multiplexer 208, and a detection acquisition circuit 209.

The first pre-amplification filter circuit 207a, the second pre-amplification filter circuit 207b and the third pre-amplification filter circuit 207c are respectively connected to the first measurement electrode assembly 205a, the second measurement electrode assembly 205b and the third measurement electrode assembly 205 c. The analog signal multiplexer 208 includes three signal input terminals and one signal output terminal, wherein the three signal input terminals are respectively connected to the output ports of the first pre-amplification filter circuit 207a, the second pre-amplification filter circuit 207b and the third pre-amplification filter circuit 207c, and the output terminal of the analog signal multiplexer 208 is connected to the detection acquisition circuit 209. The detector acquisition circuit 209 is capable of acquiring data of the analog signal transmitted from the analog signal multiplexer 208 and transmitting the obtained current detection data to the resistivity measurement unit 202 connected thereto, so that the resistivity measurement unit 202 can determine the formation resistivity of the formation from the current detection data.

FIG. 3 shows a circuit model of non-conductive mud integrated with the formation. Capacitive coupling is a coupling mode generated due to the existence of distributed capacitance, and is also called electrostatic coupling or electric field coupling. The two non-contact front and back stage circuits (or two unit circuits) can be regarded as a coupling capacitor connected in series, and because the capacitor has the functions of conducting alternating current and blocking direct current, alternating current signals can be transmitted from the front stage circuit to the back stage circuit in a non-contact way in a capacitive coupling mode, and the capacitive coupling principle can be applied to the non-contact conductance measurement technology.

In logging models with oil-based drilling fluids, formation conductivity is very low (e.g., 10)^-6～10^-5S/m), the formation equivalent capacitive reactance cannot be ignored in practice, so the present invention provides a more accurate equivalent logging model, i.e., the parallel model as shown in fig. 3.

As shown in FIG. 3, in the equivalent logging parallel model, the formation is represented by an equivalent resistance R and a capacitance Xc, which are connected in parallel. While the oil-based drilling fluid acts primarily as a capacitor, represented by the capacitance Xc' that is in series with the circuit model representing the formation. Direct current is difficult to pass through the oil-based drilling fluid, and alternating current can enter a stratum to generate an electric field under certain frequency (for example, 4 KHz-100 KHz) by utilizing a circuit network model shown in figure 3. Therefore, in this embodiment, the resistivity measurement unit 202 preferably controls the signal transmitting part to output alternating current, and the resistivity measurement unit 202 may determine the formation equivalent resistance by jointly measuring and solving three parameters by using a logging model under an oil-based drilling fluid as shown in fig. 3. After the formation equivalent resistance is obtained, the resistivity measurement unit 202 may obtain the formation resistivity of the formation to be analyzed through scale conversion.

The inventor verifies the principle and researches and tests results to show that the stratum conductivity is between 10^-4～10^{- 2}When the drilling fluid is in the S/m range, the equivalent capacitance of the drilling fluid is almost unchanged, the deviation of the formation resistance and the result obtained by independent calculation is not large, and the logging result is ideal.

Of course, in other embodiments of the invention, the resistivity measurement unit 202 may also determine the formation resistivity of the formation to be analyzed in other reasonable ways according to actual needs, and the invention is not limited thereto.

For example, in one embodiment of the invention, the resistivity measurement unit 202 may also employ a model such as that shown in FIG. 4 to determine the formation resistivity of the formation to be analyzed. For the model shown in fig. 4, the current lines between the signal measuring assembly 101 and the formation are pie-shaped along the radial direction of the well axis because the first signal transmitting part 102a and the second signal transmitting part 102b are symmetrically distributed on both sides of the signal measuring assembly 101.

Stray capacitance of the formation (including stray capacitance C corresponding to first signal transmitting portion 102 a)₁Stray capacitance C corresponding to the signal measuring unit 101₂And a stray capacitance C corresponding to the second signal transmitting section 102b₃) The total impedance of the measurement loop may be equivalent to the circuit form shown in fig. 5.

As can be seen from fig. 5, for the total impedance Z of the measurement loop there are:

wherein R represents the formation resistivity.

Expression (1) can be simplified as:

wherein the content of the first and second substances,

thus, the formation resistivity R can be calculated according to the following expression:

where U denotes a voltage at the signal transmitting part, i denotes an amplitude of the current measured by the signal measuring part, and Φ denotes a phase of the current measured by the signal measuring part.

As shown in fig. 2 again, in this embodiment, the apparatus for measuring resistivity imaging while drilling with non-conductive mud further includes a tool face sensor 210 and a tool face detection unit 211. Wherein, optionally, the tool face detection unit 211 may be integrated in the control circuit 103. The tool face sensor 210 is preferably implemented as an orthogonal fluxgate sensor, and the tool face detection unit 211 is capable of determining the corresponding orientation of the signal measurement electrode assembly according to the signal transmitted by the tool face sensor 210.

Specifically, in this embodiment, if the signal measuring part includes a plurality of signal measuring electrode assemblies, the tool face detection unit 211 may determine the orientation of one of the signal measuring electrode assemblies, and then determine the orientations of the other signal measuring electrode assemblies according to the relative angles between the signal measuring electrode assemblies.

In this embodiment, the non-conductive mud resistivity imaging while drilling measurement device preferably further comprises a data storage circuit 212, and the data storage circuit 212 is connected with the control circuit 103. Since the data amount of the data generated by the control circuit 103 is large, in consideration of the data transmission efficiency between the downhole and the surface, in the present embodiment, the control circuit 103 transmits the resistivity data generated by itself to the data storage circuit 212 to be stored by the data storage circuit 212.

According to actual needs, in this embodiment, the apparatus for measuring resistivity imaging while drilling of non-conductive mud may further include a communication circuit 213. The communication circuit 213 is connected to the control circuit 103, and enables data communication between the control circuit 103 and other external devices (e.g., ground devices).

The signal measuring unit and the resistivity measuring unit are used for measuring resistivity data, and the tool face sensor and the tool face detecting unit are used for obtaining angle coordinates, and the resistivity data is mapped according to the angle coordinates to obtain image spreading.

High resolution image sensing places high demands on the measurement speed of both the data acquisition circuitry (which actually acquires current or voltage) connected to the signal measurement electrode assembly and the tool face detection module (which includes the tool face sensor and the tool face detection unit).

The faster the instrument is rotated, the shorter the data acquisition time is given to the data acquisition circuitry and the tool face detection module. For example, if a 128 sector resolution is to be achieved when the instrument is rotating at 120 revolutions per minute (rpm), the sum of the resistivity acquisition and tool face detection times will need to be no greater than 0.0039 seconds.

Fig. 6 shows a schematic mechanical structure diagram of the non-conductive mud resistivity imaging while drilling measurement device provided by the embodiment.

As shown in fig. 6, in the present embodiment, the first signal emitting portion 102a and the second signal emitting portion 102b of the non-conductive mud resistivity imaging while drilling measuring device are preferably disposed at positions close to both ends of the whole measurement while drilling measuring device, specifically, the first signal emitting portion 102a and the second signal emitting portion 102b are symmetrically distributed on both sides of the signal measuring portion 101, and the first signal emitting portion 102a and the second signal emitting portion 102b are distributed in such a manner that a good current focusing effect can be formed, so that a current line between the signal measuring portion 101 and the formation is pie-shaped along a well axis radial direction, thereby contributing to improving a detection depth and a detection accuracy.

The symmetrical distribution of the first signal transmitting part 102a and the second signal transmitting part 102b enables the two transmitting electrodes in the two signal transmitting parts to simultaneously and reversely transmit signals, the current on the drill collar will radiate from the positive center of the two transmitting electrodes and the vicinity thereof to the outer side stratum, the outer wall of the whole drill collar becomes equal potential, and thus the natural focusing effect is achieved. When encountering a high-resistance or low-resistance interlayer, the control circuit can judge the abnormal position of the resistance by detecting the transmitting power on a single transmitting electrode, and then automatically adjust and balance the transmitting power, so that the power is radiated to the stratum better, the measuring current can enter the high-resistance or low-resistance interlayer more deeply, and the detection depth and the detection resolution are improved.

It should be noted that, in this embodiment, according to actual needs, one of the first signal transmitting portion 102a and the second signal transmitting portion 102b may also serve as a transmitting end and the other as a receiving end, so as to form a pair of lateral measurement electrodes, and the two lateral measurement electrodes can cooperatively measure lateral formation resistivity without orientation. The roles of the two signal emitting parts can be interchanged during the measurement, which is equivalent to the focus compensation, and thus contributes to the improvement of the signal-to-noise ratio. Although the measuring mode has no azimuth resolution, the current on the whole drill collar is measured, so that the signal intensity and the signal-to-noise ratio are higher.

Of course, in other embodiments of the invention, according to actual needs, the non-conductive mud resistivity imaging while drilling measuring device includes a plurality of pairs of signal transmitting portions, and through the signal transmitting portions which are arranged at different axial positions of the drill collar and symmetrically distributed relative to the signal measuring portions, the non-conductive mud resistivity imaging while drilling measuring device can obtain detection results of a plurality of different depths, so that convenience is provided for exploring the influence of formations of different depths on the measurement results, and the acquisition of formation information of different depths can also provide a basis for judging the structure or properties of the formation.

In this embodiment, the first signal transmitting portion 102a and the second signal transmitting portion 102b have the same structure, and in order to more clearly illustrate the working principle and advantages of the non-conductive mud resistivity imaging while drilling measuring device provided by this embodiment, the first signal transmitting portion 102a is taken as an example to be further described below.

Specifically, in the present embodiment, the first signal transmitting portion 102a preferably includes a transmitting coil 401 and a coil protecting cover. Wherein the transmitter coil 401 is preferably disposed in a transmitter coil recess formed in the outer wall of the drill collar for outputting a measurement current signal to the formation. The coil shield is used to cover the transmitter coil recess, thus protecting the transmitter coil 401.

Specifically, the coil shield preferably includes a structural strength shield 402 and an insulating protective tape 403 disposed axially adjacent along the drill collar, with the insulating protective tape being disposed on a side away from the signal measurement portion. The structural strength boot 402 is preferably a metal boot that primarily protects the internal transmitting coil 401 and its corresponding accessories, while also providing wear protection. In this embodiment, the coil protecting cover 402 is preferably made of nonmagnetic steel P550.

It should be noted that in other embodiments of the present invention, the coil protection cover 402 may be implemented by using other reasonable materials according to practical needs, and the present invention is not limited thereto.

In this embodiment, as shown in fig. 6, an insulating protection tape 403 is disposed adjacent to the structural strength protection cover 402 and on the side away from the signal measuring part 101, which can electrically isolate the signal transmitting part and the drill collar on both sides thereof.

In particular, insulating guard band 403 helps to couple current into the formation. In the embodiment, because the device is a measurement-while-drilling instrument, the whole detector is preferably designed based on a metal drill collar, the typical outer diameter of the drill collar is 4.5-8.5in, and the typical material is a non-magnetic drill collar material P550 and the like. Without the insulating protective tape 403, the outer wall of the drill collar 404 outside the transmitter coil 401 would form a secondary loop, thereby conducting the current short circuit, and thus preventing the measurement current from entering the formation. In various embodiments of the present invention, the insulation protection tape 403 may be made of PEEK, glass fiber reinforced plastic, or industrial ceramic, which have insulation properties.

In this embodiment, as shown in fig. 6, the non-conductive mud resistivity imaging while drilling measurement device optionally further comprises two wear strips (i.e., a first wear strip 405 and a second wear strip 406). Wherein the first wearstrips 405 and the second wearstrips 406 are respectively disposed on a side of the first signal transmitting portion 102a away from the signal measuring portion 101 and a side of the second signal transmitting portion 102b away from the signal measuring portion 101, which can reduce wear of the signal measuring portion and each signal transmitting portion, thereby improving durability of the apparatus.

In this embodiment, the flow channel 407 is formed inside each of the signal emitting portion, the signal measuring portion, and the wear-resistant band, so that the drilling fluid can flow through the flow channel 407.

As shown in fig. 6, in the present embodiment, the signal measuring portion 101 preferably includes a plurality of signal measuring electrode assemblies, and the signal measuring electrode assemblies are respectively disposed on stabilizers protruding from the outer wall of the drill collar. Specifically, the measurement electrode assembly preferably includes a measurement electrode 409 and an insulating tape 410. Wherein the measuring electrode 409 is nested in the insulating tape 410, the insulating tape 401 can realize the electric isolation between the measuring electrode 409 and the drill collar 404.

It should be noted that the stabilizer is preferably made of the same material as the drill collar, and in various embodiments of the invention, the stabilizer may be either integrally formed with the drill collar or a separate component. The outer surface of the stabilizer may preferably be laser coated, inlaid with alloy blocks, or the like to improve wear resistance. Of course, in other embodiments of the present invention, the stabilizer may not be disposed on the outer wall of the drill collar, and the signal measurement electrode assembly may be disposed directly on the outer wall of the drill collar.

In this embodiment, the structures of the signal measurement electrode assemblies are the same, so for convenience of description, a further description will be given below by taking one of the measurement electrode assemblies as an example. Fig. 7 shows a schematic mechanism of the measurement electrode assembly in the present embodiment.

As shown in FIG. 7, in the present embodiment, the signal measuring electrode assemblies are disposed in the first grooves distributed on the outer wall of the drill collar. Wherein, the first groove preferably comprises a first groove component 501 and a second groove component 502, the first groove component 501 is closer to the outer wall of the drill collar than the second groove component 502 and the inner diameter of the first groove component 501 is larger than that of the second groove component 502.

In this embodiment, the signal measuring electrode preferably includes: a measurement electrode 409, an insulating tape 410 and an electrode housing 503. Wherein the electrode housing 503 is disposed in the first groove and the lower end thereof extends into the second groove component 502. Specifically, a plurality of sealing grooves are formed in the outer wall of the electrode housing 503 along the circumferential direction, the electrode housing 503 can be tightly attached to the inside of the second groove forming portion 502 by the first sealing ring 504 disposed in the sealing grooves, and the sealing ring can play a role in protecting the pressure isolation.

The magnitude of the diameter of the measurement electrode 409 determines the magnitude of the detectable current due to the equipotential surface on the drill collar. In this embodiment, the measuring electrode 409 is preferably implemented by a button package. Wherein, the smaller the button is, the higher the resolution ratio of the device is, and the detection difficulty is also bigger. In the present embodiment, the button diameter of the measuring electrode 409 is preferably 5mm to 50 mm. Of course, in other embodiments of the invention, the measuring electrode 409 may have other reasonable geometric dimensions, and the invention is not limited thereto.

As shown in fig. 7, the insulating tape 410 is embedded in the electrode housing 503, and the measuring electrode 409 is embedded in the insulating tape 410, so that the insulating tape 410 can electrically isolate the electrode housing 503 from the measuring electrode 409.

In this embodiment, the insulating tape 410 is preferably made of a high temperature resistant composite insulating material, such as ceramic or PEEK material. The electrode housing 503 is preferably of a cylindrical configuration and is preferably made of a non-magnetic steel alloy material. The measuring electrode 409 is preferably made of a metal alloy material (e.g., beryllium copper, nickel copper, etc.) which is good in electric conduction and wear-resistant.

The measuring electrode and the insulating tape and the electrode shell are bonded by a special process, and in the embodiment, a low-temperature glass sealing process is preferably adopted. In the low-temperature glass sealing process, the expansion coefficient deviation of the low-temperature glass powder, the measuring electrode and the insulating tape can be less than 10%, so that the close connection under the high-temperature condition in a well can be ensured.

Of course, in other embodiments of the present invention, other reasonable processes may be used to effectively bond the measuring electrode and the insulating tape, and the insulating tape and the electrode housing according to actual conditions. For example, in one embodiment of the invention, the measuring electrode and the insulating tape and the electrode shell are bonded by using epoxy glue.

As shown in fig. 7, in the present embodiment, the measuring electrode 409 is preferably a T-shaped structure with a large outer diameter (preferably 5mm to 50mm) and a small inner diameter (preferably 3mm to 25mm), which can effectively improve the pressure resistance of the measuring electrode 409. Meanwhile, the outer side of the insulating tape 410 is preferably also in a T-shaped structure.

In this embodiment, the first groove component 501 is provided with a measuring electrode fixing member 505 for defining a signal measuring electrode assembly, and a circular hole is formed on the measuring electrode fixing member 505 to communicate the measuring electrode 409 with the outside.

Wherein the measuring electrode fixing member 505 fixes the measuring electrode fixing member 505 on the surface of the first groove component part 501 preferably by means of bolts 506. In addition, the diameter of the circular hole formed in the central position of the measuring electrode fixing member 505 is preferably larger than the diameter of the measuring electrode 409, so that the circular hole can not only prevent the measuring electrode fixing member 505 from contacting the measuring electrode 409, but also enable the measuring electrode 409 to communicate with the outside through the circular hole.

In this embodiment, the measuring electrode fixing member 505 is formed with a radial protrusion extending toward the center of the measuring electrode assembly in the radial direction of the measuring electrode assembly, thereby realizing the position limitation of the measuring electrode assembly. It should be noted that, according to actual needs, an adjusting member may be further disposed between the radial protrusion of the measurement electrode fixing member 505 and the measurement electrode assembly, and the adjusting member is capable of adjusting the height matching degree between the measurement electrode fixing member 505 and the measurement electrode assembly, so that the measurement electrode fixing member 505 can effectively and reliably limit the measurement electrode assembly.

In the embodiment, as shown in fig. 7, the non-conductive mud resistivity imaging while drilling measurement device further comprises an electronic circuit barrel 507, wherein the electronic circuit barrel 507 is arranged in the inner cavity of the drill collar. In order to ensure that the drilling fluid has a backflow path, a flow channel 407 for conveying the drilling fluid is arranged at the central position of the electronic circuit barrel 507 along the axial direction of the electronic circuit barrel.

In this embodiment, the outer wall of the electronic cartridge 507 and the inner wall of the drill collar cooperatively form a sealed electronic chamber. Specifically, the outer wall of the electronics cartridge 507 is preferably formed with a second groove 508, the second groove 508 cooperating with the inner wall of the drill collar to form an electronics compartment for providing associated circuitry 509, such as data acquisition circuitry, control circuitry, data storage circuitry, and communication circuitry. Wherein, the lower tail part of the measuring electrode 409 extends downwards but does not exceed the inner diameter of the drill collar, so as to be convenient for connecting with an electronic circuit on the inner electronic framework.

In order to protect the electronic devices in the electronic cabin, in this embodiment, a plurality of sealing grooves are further formed on the outer wall of the electronic circuit drum 507 along the circumferential direction at the positions on both sides of the electronic cabin. The electronics cartridge 507 provides isolation protection for the electronics compartment by means of a second seal 510 mounted in these seal grooves.

Of course, in other embodiments of the present invention, the measurement electrode assembly may be implemented in other reasonable structures. For example, in one embodiment of the present invention, the measurement electrode assembly may also be implemented using a structure as shown in fig. 8 or 9.

As shown in fig. 8, in this embodiment, the measurement electrode assembly no longer includes the electrode case 503, and the insulating tape 410 is closely attached to the inside of the second groove component 502, compared to the structure shown in fig. 7. Further, the outer wall of the insulating tape 410 is optionally formed with a plurality of sealing grooves in the circumferential direction, which may be pressure-isolated by a third sealing ring 511 disposed in the sealing grooves. Meanwhile, optionally, the outer wall of the measuring electrode 409 may also be formed with a plurality of sealing grooves along the circumferential direction, and the measuring electrode 409 may be pressure-isolated by a fourth sealing ring 512 disposed in the sealing grooves.

As shown in fig. 9, in this embodiment, the measurement electrode assembly also no longer includes the electrode case 503, and the insulating tape 410 is closely attached to the inner wall of the second groove component 502, compared to the structure shown in fig. 7. The outer wall of the insulating strip 410 is preferably cylindrical in shape. Meanwhile, in order to achieve pressure isolation, a third sealing ring 511 is disposed in a sealing groove circumferentially distributed on the outer wall of the insulating tape 410.

In this embodiment, the device can utilize the measurement electrode assembly and the signal transmitting part to scan the formation along with the rotation of the drill collar. Meanwhile, when the drill collar does not rotate, the device can obtain formation resistivity information at multiple angles through measuring electrode assemblies distributed at different angles. In addition, according to actual needs, the device can combine the detection data of a plurality of measuring electrode assemblies, so that the lateral resistivity data with no azimuth and high signal intensity can be obtained.

In addition, it should be noted that in other embodiments of the present invention, according to actual needs, the non-conductive mud resistivity imaging while drilling measuring device may further include a plurality of signal measuring portions arranged along the axial direction of the drill collar, so that formation information at different depths may be obtained in one measuring process.

From the above description, it can be seen that the prior art can not satisfy the requirement of formation imaging while drilling (for example, measurement of formation resistivity) under the condition of non-conductive mud and oil-based mud, and the non-conductive mud resistivity imaging while drilling measurement device provided by the invention is based on the capacitive coupling principle to measure the formation resistivity. The device transmits the high-frequency electromagnetic wave excitation to the stratum through the non-conductive slurry in an inductive coupling mode, the non-conductive slurry and the stratum are equivalent to a circuit formed by a capacitance resistor, and meanwhile, the resistivity of the stratum is obtained by separation after the result is obtained by detection and calculation, so that the accurate measurement of the resistivity is realized. Compared with the prior art, the device for measuring the resistivity of the non-conductive mud while drilling by the invention can be suitable for formation resistivity detection under the condition of poor conductivity such as oil-based mud, and can provide high-definition images of a shaft for geosteering and later development.

Meanwhile, the packaging mode of the measuring electrode in the non-conductive mud resistivity imaging while drilling measuring device can further improve the reliability of the device, and meanwhile, the signal transmitting part utilizes the coil protective cover to improve the stress characteristic of the packaging outer layer, which is also beneficial to improving the reliability of the instrument.

It is to be understood that the disclosed embodiments of the invention are not limited to the particular structures or process steps disclosed herein, but extend to equivalents thereof as would be understood by those skilled in the relevant art. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

Reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase "one embodiment" or "an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

While the above examples are illustrative of the principles of the present invention in one or more applications, it will be apparent to those of ordinary skill in the art that various changes in form, usage and details of implementation can be made without departing from the principles and concepts of the invention. Accordingly, the invention is defined by the appended claims.