阅读说明：本技术 一种基于时间域电磁法的储层监测方法、系统及计算机存储介质 (Reservoir monitoring method and system based on time domain electromagnetic method and computer storage medium ) 是由 党博 任志平 刘长赞 杨玲 王咪咪 于 2019-10-08 设计创作，主要内容包括：本发明实施例公开了一种基于时间域电磁法的储层监测方法、系统及计算机存储介质,该系统可以包括：永置式井下监测子系统、挂接于所述永置式井下监测子系统的瞬变电磁探测器,以及上位机；其中,所述永置式井下监测子系统通过电缆为所述瞬变电磁探测器供电；所述瞬变电磁探测器,配置为接收由瞬变电磁激励信号产生的响应信号,并将所述响应信号通过所述电缆传输至所述上位机；所述上位机,配置为根据所述响应信号监测储层电导率的变化状态。(The embodiment of the invention discloses a reservoir monitoring method, a system and a computer storage medium based on a time domain electromagnetic method, wherein the system comprises the following steps: the system comprises a permanent underground monitoring subsystem, a transient electromagnetic detector hung on the permanent underground monitoring subsystem and an upper computer; wherein the permanent downhole monitoring subsystem powers the transient electromagnetic detector via a cable; the transient electromagnetic detector is configured to receive a response signal generated by a transient electromagnetic excitation signal and transmit the response signal to the upper computer through the cable; and the upper computer is configured to monitor the change state of the reservoir conductivity according to the response signal.)

1. A reservoir monitoring system based on a time domain electromagnetic method, the system comprising: the system comprises a permanent underground monitoring subsystem, a transient electromagnetic detector hung on the permanent underground monitoring subsystem and an upper computer; wherein the content of the first and second substances,

the permanent underground monitoring subsystem supplies power to the transient electromagnetic detector through a cable;

the transient electromagnetic detector is configured to receive a response signal generated by a transient electromagnetic excitation signal and transmit the response signal to the upper computer through the cable;

and the upper computer is configured to monitor the change state of the reservoir conductivity according to the response signal.

2. The system of claim 1, wherein the permanent downhole monitoring subsystem comprises an electrical submersible pump operating condition monitoring subsystem or an intelligent well subsystem.

3. The system of claim 2, wherein the permanent downhole monitoring subsystem is an electric submersible pump working condition monitoring subsystem, the transient electromagnetic detector is hung at the lower part of an electric submersible motor in the electric submersible pump working condition monitoring subsystem, the transient electromagnetic detector is powered through a three-phase power cable and a cable sheath in the electric submersible pump working condition monitoring subsystem, and the cable sheath is used as a ground wire to transmit the response signal to the upper computer;

the permanent underground monitoring subsystem is an intelligent well subsystem, the transient electromagnetic detector is hung between a production allocation device and a cable-passing packer corresponding to each production zone in the intelligent well subsystem, the transient electromagnetic detector is powered by a single-core cable in the intelligent well subsystem, and the single-core cable is used as a ground wire to transmit the response signal to the upper computer.

4. The system of claim 1, wherein the transient electromagnetic detector comprises an electromagnetic probe, signal transmission and reception circuitry, signal processing and control circuitry, and signal encoding and transmission circuitry.

5. The system according to claim 1, further comprising a signal processing module between the transient electromagnetic detector and the upper computer, wherein the signal processing module is configured to perform filtering processing, amplification processing and comparison processing on the response signal transmitted in the cable in sequence, decode the response signal through a control chip, and send the decoded signal to the upper computer through a communication serial port.

6. The system of claim 1, wherein the upper computer comprises: a parameter input section, a data processing section, a storage section and a display section; wherein the content of the first and second substances,

the parameter input part is configured to input well condition information and preset display information;

the data processing part is configured to carry out the binary conversion and accumulation processing on the induced electromotive force responded by the receiving coil in the transient electromagnetic detector;

the storage part is configured to store the original response signal to a specified path;

the display part is configured to display the change relation of the response signals along with the monitoring time and the reservoir resistivity information obtained according to inversion of the response signals in a curve form.

7. A reservoir monitoring method based on a time domain electromagnetic method, which is applied to the reservoir monitoring system based on the time domain electromagnetic method of any one of claims 1 to 6, and comprises the following steps:

determining a sampling time period according to the response characteristic of a receiving coil of the transient electromagnetic detector;

sampling the response signal received by the receiving coil according to the sampling time period;

comparing response signals of the same sampling time of a plurality of monitoring time periods to obtain a first comparison result;

and analyzing the first comparison result to obtain the change state of the resistivity of the reservoir.

8. The method of claim 7, wherein prior to comparing the response signals at the same sampling instant of the plurality of monitoring time periods, the method further comprises:

calculating by using the parameters of a transmitting coil and a receiving coil of the transient electromagnetic detector based on a preset reservoir detection model to obtain a simulated electromagnetic response signal;

comparing the simulated electromagnetic response signal with the received original response signal of the receiving coil to obtain a second comparison result;

and correcting and compensating the received original response signal of the receiving coil based on the second comparison result to obtain a corrected and compensated response signal.

9. The method of claim 8, further comprising:

and establishing a reservoir detection model of a time domain electromagnetic method, wherein the model comprises an iron core, air, an instrument outer protective pipe, well fluid, a casing, a cement sheath and a stratum.

10. A computer storage medium storing a time domain electromagnetic method based reservoir monitoring program, which when executed by at least one processor implements the time domain electromagnetic method based reservoir monitoring method steps of any one of claims 7 to 9.

Technical Field

The embodiment of the invention relates to the technical field of oil and gas downhole monitoring, in particular to a reservoir monitoring method and system based on a time domain electromagnetic method and a computer storage medium.

Background

At present, most oil fields mainly adopt water injection development, in the later stage of development, the heterogeneity of reservoirs is obvious, and in the geologic feature multidimensional land phase deposition multi-oil layer reservoirs, the permeability change between layers, in-layer and between planes is large, the difference of water absorption of each layer is obvious, and injected water always advances along a high permeability zone, so that the injected water in the longitudinal direction and the plane is not uniformly advanced. When the injected water of the high permeable stratum is pushed to the oil production well, the water injection is continued only through the high permeable stratum inefficiently and cannot expand the swept volume of the low permeable stratum, so that the water flooding range is limited or unpredictable. Based on the complexity of the oil displacement and water replacement process and the unpredictability of the effect of the oil displacement and water replacement process on the reservoir, higher requirements are provided for the accuracy of dynamic reservoir monitoring.

Under the influence of a metal casing, a system and a method capable of permanently monitoring the resistivity of a cased stratum do not exist at present, and the resistivity is related to lithology, physical properties, oil-bearing property and formation water property and is one of important indexes for evaluating the oil-bearing and gas-bearing property of a reservoir. Therefore, how to monitor the resistivity of the reservoir after the casing in real time provides guidance for fine water drive adjustment and optimized exploitation of the oil field, and is a great difficulty in the research process of improving the oil field recovery efficiency.

Disclosure of Invention

In view of this, embodiments of the present invention are intended to provide a reservoir monitoring method, system and computer storage medium based on a time domain electromagnetic method; the real-time online monitoring of the reservoir after the casing can be realized.

The technical scheme of the embodiment of the invention is realized as follows:

in a first aspect, an embodiment of the present invention provides a reservoir monitoring system based on a time domain electromagnetic method, where the system includes: the system comprises a permanent underground monitoring subsystem, a transient electromagnetic detector hung on the permanent underground monitoring subsystem and an upper computer; wherein the content of the first and second substances,

the permanent underground monitoring subsystem supplies power to the transient electromagnetic detector through a cable;

the transient electromagnetic detector is configured to receive a response signal generated by a transient electromagnetic excitation signal and transmit the response signal to the upper computer through the cable;

and the upper computer is configured to monitor the change state of the reservoir conductivity according to the response signal.

In a second aspect, an embodiment of the present invention provides a reservoir monitoring method based on a time domain electromagnetic method, where the method is applied to the reservoir monitoring system based on the time domain electromagnetic method in the first aspect, and the method includes:

determining a sampling time period according to the response characteristic of a receiving coil of the transient electromagnetic detector;

sampling the response signal received by the receiving coil according to the sampling time period;

comparing response signals of the same sampling time of a plurality of monitoring time periods to obtain a first comparison result;

and analyzing the first comparison result to obtain the change state of the resistivity of the reservoir.

In a third aspect, embodiments of the present invention provide a computer storage medium storing a time domain electromagnetic method-based reservoir monitoring program, which when executed by at least one processor implements the steps of the time domain electromagnetic method-based reservoir monitoring method of the second aspect.

The embodiment of the invention provides a reservoir monitoring method and system based on a time domain electromagnetic method and a computer storage medium; the position of the transient electromagnetic detector is kept fixed and unchanged by means of the existing cables and power supply of the conventional permanent underground monitoring subsystem, so that the reservoir monitoring system is still influenced by the metal casing in the process of monitoring the conductivity change of the reservoir, but the influence of the metal casing and the cement bond quality on the monitoring performance does not need to be compensated repeatedly; in addition, the corrosion speed of the metal casing in the underground is far slower than the change speed of the reservoir, so that the corrosion change of the metal casing can be ignored within a certain time period, and the influence on the metal casing in the monitoring result can be regarded as fixed background noise, so that the on-line monitoring of the resistivity change of the reservoir after the casing is realized, and the timeliness and the precision of the reservoir monitoring are improved.

Drawings

Fig. 1 is a schematic composition diagram of a reservoir monitoring system based on a time domain electromagnetic method according to an embodiment of the present invention;

fig. 2 is a schematic diagram illustrating a sub-system for monitoring the operating condition of the electrical submersible pump according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of an intelligent well subsystem assembly provided by an embodiment of the present invention;

FIG. 4 is a schematic diagram of a transient electromagnetic detector according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of another reservoir monitoring system based on a time domain electromagnetic method according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a host computer according to an embodiment of the present invention;

fig. 7 is a schematic diagram of a specific hardware structure of the upper computer according to the embodiment of the present invention;

fig. 8 is a schematic flow chart of a reservoir monitoring method based on a time domain electromagnetic method according to an embodiment of the present invention;

FIG. 9 is a schematic flow chart of modifying and compensating an original response signal according to an embodiment of the present invention;

fig. 10 is a schematic diagram of a reservoir exploration model according to an embodiment of the present invention.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

At present, a conventional reservoir monitoring system after sleeving is characterized in that a reservoir real-time monitoring system is configured for each well by means of the convenient conditions of cables arranged in an oil submersible electric pump well and an intelligent well, and the current monitoring parameters mainly comprise indirect parameters such as pressure, temperature, flow, water content and the like, can be used for analyzing reservoir characteristics, and can adjust the capacity according to the test results of the flow and the pressure; however, under the influence of the metal casing, the reservoir online monitoring system cannot directly measure resistivity information, and if the resistivity after the casing needs to be monitored in real time, a scheme capable of penetrating through the casing to detect the resistivity needs to be found.

In view of the above situation, the time domain electromagnetic method is also applied to reservoir monitoring after casing due to the advantages of a non-contact measurement mode, sensitivity to resistivity, inclusion of various frequency components, absence of direct coupling and the like. The specific process is as follows: although the existing scheme for detecting the outer storage layer by using the time domain electromagnetic method can realize the detection of the formation resistivity by penetrating through the casing, the scheme is influenced by the metal casing, and needs to continuously compensate and correct the heterogeneity of the casing, the cement sheath and the formation, so that the signal processing difficulty is high, and the data interpretation precision is low.

In view of the above problems, embodiments of the present invention are expected to provide a reservoir monitoring system 1 based on a time domain electromagnetic method, and referring to fig. 1, the system 1 may include: the system comprises a permanent underground monitoring subsystem 11, a transient electromagnetic detector 12 hung on the permanent underground monitoring subsystem 11 and an upper computer 13; wherein the content of the first and second substances,

the permanent underground monitoring subsystem 11 supplies power to the transient electromagnetic detector 12 through a cable;

the transient electromagnetic detector 12 is configured to receive a response signal generated by a transient electromagnetic excitation signal and transmit the response signal to the upper computer 13 through the cable;

and the upper computer 13 is configured to monitor the change state of the reservoir conductivity according to the response signal.

Through the reservoir monitoring system 1 shown in fig. 1, the position of the transient electromagnetic detector is kept fixed by means of the existing cables and power supplies of the conventional permanent underground monitoring subsystem, so that although the reservoir monitoring system 1 is still influenced by the metal casing in the process of monitoring the conductivity change of the reservoir, the influence of the metal casing and the cement bond quality on the monitoring performance does not need to be compensated repeatedly; in addition, the corrosion speed of the metal casing in the underground is far slower than the change speed of the reservoir, so that the corrosion change of the metal casing can be ignored within a certain time period, and the influence on the metal casing in the monitoring result can be regarded as fixed background noise, so that the on-line monitoring of the resistivity change of the reservoir after the casing is realized, and the timeliness and the precision of the reservoir monitoring are improved.

For the reservoir monitoring system 1 shown in fig. 1, the permanent downhole monitoring subsystem 11 may preferably include an electrical submersible pump operating condition monitoring subsystem or an intelligent well subsystem, as an example. Therefore, an intelligent well subsystem can be used for connecting an oil pipe and a steel pipe cable, or the existing three-phase power cable in the submersible electric pump working condition monitoring subsystem is used for supplying power to the transient electromagnetic detector 12 and providing a transmission channel for transmitting a response signal to the upper computer 13.

For the above example, in one possible implementation, referring to the exemplary submersible electric pump condition monitoring subsystem shown in fig. 2, it may include a multistage centrifugal pump for lifting well fluid to the surface by high speed rotation of an impeller on a pump shaft, a gas separator, a protector, a submersible motor, and an electrical cable, among others; the gas separator is used for separating oil and gas before the oil-submersible pump is surprisingly entered into the oil-submersible pump so as to reduce the influence of the gas on the working performance of the oil-submersible pump; the protector is mainly used for preventing well fluid from entering the submersible motor, so that the submersible motor is prevented from being burnt; the submersible motor can be immersed in an oil well with a specified depth to work, and underground crude oil or well fluid can be continuously and reliably extracted; the main function of the cable is to transmit surface electrical energy to the submersible downhole motor and to complete the communication between the downhole and the surface system. Based on the above description about the working condition monitoring subsystem of the electrical submersible pump, referring to fig. 2, the permanent downhole monitoring subsystem 11 is a working condition monitoring subsystem of the electrical submersible pump, the transient electromagnetic detector 12 is hung on the lower portion of the electrical submersible motor in the working condition monitoring subsystem 11 of the electrical submersible pump, the transient electromagnetic detector is powered by a three-phase power cable and a cable sheath in the working condition monitoring subsystem of the electrical submersible pump, and the cable sheath is used as a ground wire to transmit the response signal to the upper computer. For the specific implementation process, a three-phase power cable and a cable sheath can be used as a transmission channel to supply power to the underground monitoring system by a star point equipotential method, the sheath is used as a ground wire to transmit a response signal to an upper computer 13 positioned on the ground, and the upper computer 13 on the ground displays and transmits the resistivity information of the current reservoir in real time, so that the online monitoring of the reservoir is realized.

For the above example, in another possible implementation, referring to the exemplary intelligent well subsystem shown in fig. 3, the subsystem is provided with a single core cable, a flow testing device and a regulating device underground, the production capacity is regulated according to parameters such as pressure, temperature, oil, gas and water content of each production zone, and the optimized combined production of multiple reservoirs is realized through layered testing, layered control and layered mining. Based on the above description about the intelligent well subsystem, referring to fig. 3, the permanent downhole monitoring subsystem 11 is an intelligent well subsystem, the transient electromagnetic detector 12 is hung between a production allocation device and a cable-passing packer corresponding to each production zone in the intelligent well subsystem, the transient electromagnetic detector 12 is powered by a single-core cable in the intelligent well subsystem, and the single-core cable is used as a ground wire to transmit the response signal to the upper computer. The production allocator is used for controlling different production pressure differences to obtain different yields; the cable-passing packer is a mechanical device for packing an oil sleeve annulus; the single-core cable is used for realizing power supply of the underground instrument and transmission of data signals.

As can be seen from the above example of the permanent downhole monitoring subsystem 11, the transient electromagnetic detector 12 is combined with the permanent downhole monitoring subsystem 11, and the existing cable and power supply system of the intelligent well subsystem or the submersible electric pump working condition monitoring subsystem is used to enable the transient electromagnetic detector 12 to stay in the wellbore for a long time, although the response signal is also influenced by the metal casing, the corrosion speed of the metal casing in the downhole is far slower than the change speed of the reservoir, and the reservoir resistivity information can be analyzed in real time by using the response signal in a period of time, so as to monitor the dynamic change of the reservoir resistivity on line.

For the reservoir monitoring system 1 shown in fig. 1, illustratively, as shown in fig. 4, the transient electromagnetic detector 12 may include an electromagnetic probe 121, signal transmission and reception circuitry 122, signal processing and control circuitry 123, and signal encoding and transmission circuitry 124; wherein, the electromagnetic probe 121 is wound with a transmitting coil and a receiving coil, and by applying a transient electromagnetic excitation signal to the transmitting coil, in the signal turn-off interval, the resistivity information of the reservoir can be inverted by using a response signal received by the receiving coil. Finally, the response signal measured by the transient electromagnetic detector 12 can be transmitted to the ground upper computer 13 through a cable, and is displayed on the upper computer 13 in real time.

As for the reservoir monitoring system 1 shown in fig. 1, as shown in fig. 5, in the reservoir monitoring system 1, a signal processing module 14 may be further included between the transient electromagnetic detector 12 and the upper computer 13, and may be configured to perform filtering processing, amplification processing, and comparison processing on the response signal transmitted in the cable in sequence, decode the response signal through a control chip, and send the decoded signal to the upper computer 13 through a communication serial port. Particularly, the communication serial port can be preferably an RS232 serial port.

For the reservoir monitoring system 1 shown in fig. 1, for example, as shown in fig. 6, the upper computer 13 may include: a parameter input section 131, a data processing section 132, a storage section 133, and a display section 134; the parameter input part 131 is configured to input well condition information and preset display information, and specifically may include a well number, a depth where an instrument is located, and the like; a data processing section 132 configured to perform a binary conversion and accumulation process on the induced electromotive force in response to the receiving coil in the transient electromagnetic probe 12; a storage section 133 configured to store the original response signal to the specified path; the display part 134 is configured to display the variation relationship of the response signal along with the monitoring time and the reservoir resistivity information obtained by inverting the response signal in a curve form, so as to improve the intuitiveness of real-time monitoring, and it should be noted that the curve playback can be performed on the original test signal according to the requirement.

It is understood that in this embodiment, "part" may be part of a circuit, part of a processor, part of a program or software, etc., and may also be a unit, and may also be a module or a non-modular.

In addition, each component in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit. The integrated unit can be realized in a form of hardware or a form of a software functional module.

Based on the understanding that the technical solution of the present embodiment essentially or a part contributing to the prior art, or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium, and include several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to execute all or part of the steps of the method of the present embodiment. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

For the above upper computer 13, a specific hardware structure thereof may be as shown in fig. 7, including: a communication interface 701, a memory 702, and a processor 703; the various components are coupled together by a bus system 704. It is understood that the bus system 704 is used to enable communications among the components. The bus system 704 includes a power bus, a control bus, and a status signal bus in addition to a data bus. For clarity of illustration, however, the various buses are labeled in fig. 7 as the bus system 704. Wherein the content of the first and second substances,

the communication interface 701 is configured to receive and transmit signals in a process of receiving and transmitting information with other external network elements;

the memory 702 is used for storing a computer program capable of running on the processor 703;

the processor 703 is configured to execute the functions and steps configured by each component in the upper computer 13 when the computer program is run.

It is to be understood that the memory 702 in embodiments of the present invention may be either volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The non-volatile Memory may be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable PROM (EEPROM), or a flash Memory. Volatile Memory can be Random Access Memory (RAM), which acts as external cache Memory. By way of example, but not limitation, many forms of RAM are available, such as Static random access memory (Static RAM, SRAM), Dynamic Random Access Memory (DRAM), synchronous Dynamic random access memory (syncronous DRAM, SDRAM), Double Data Rate synchronous Dynamic random access memory (ddr Data Rate SDRAM, ddr SDRAM), Enhanced synchronous SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct memory bus RAM (DRRAM). The memory 702 of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

The processor 703 may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the method may be implemented by hardware integrated logic circuits in the processor 703 or by instructions in the form of software. The Processor 703 may be a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, or discrete hardware components. The various methods, steps and logic blocks disclosed in the embodiments of the present invention may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in the memory 702, and the processor 703 reads the information in the memory 702 and performs the steps of the above method in combination with the hardware thereof.

It is to be understood that the embodiments described herein may be implemented in hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the Processing units may be implemented within one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), general purpose processors, controllers, micro-controllers, microprocessors, other electronic units configured to perform the functions described herein, or a combination thereof.

For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory and executed by a processor. The memory may be implemented within the processor or external to the processor.

For the reservoir monitoring system 1, the implementation and application process for monitoring the reservoir conductivity is as follows:

firstly, hanging a transient electromagnetic detector 12 according to whether a current well is an oil-submersible electric pump well or an intelligent well; then, the transient electromagnetic detector 12 is powered by an electric submersible pump or an intelligent well system; then, the transient electromagnetic detector 12 starts to work and monitors; then, the electric submersible pump or the cable of the intelligent well system is used for transmitting the response signal received by the transient electromagnetic detector 12; then, the signal processing module 14 positioned on the ground collects the response signal, processes the response signal and sends the processed response signal to the upper computer 13; finally, the upper computer 13 stores and analyzes the response signal, and displays the resistivity information of the reservoir.

Through the scheme, the response signal is transmitted in real time by means of the conventional underground monitoring subsystem 11, the sleeve is not required to be magnetized, the structure of a shaft is not required to be changed, and a special cable and a power supply are not required to be equipped.

The reservoir monitoring system 1 described based on the foregoing technical solution, referring to fig. 8, illustrates a reservoir monitoring method based on a time domain electromagnetic method according to an embodiment of the present invention, where the method is applied to the reservoir monitoring system 1 based on the time domain electromagnetic method described in the foregoing technical solution, and the method includes:

s810: determining a sampling time period according to the response characteristic of a receiving coil of the transient electromagnetic detector;

s820: sampling the response signal received by the receiving coil according to the sampling time period;

s830: comparing response signals of the same sampling time of a plurality of monitoring time periods to obtain a first comparison result;

s840: and analyzing the first comparison result to obtain the change state of the resistivity of the reservoir.

It can be understood that the technical solution shown in fig. 8 needs to be implemented by the reservoir monitoring system 1 based on the time domain electromagnetic method described in the foregoing technical solution, and therefore, the technical solution shown in fig. 8 also transmits a response signal in real time by means of a conventional downhole monitoring subsystem, does not need to magnetize a casing, does not need to change a wellbore structure, and further does not need to be equipped with a special cable and a power supply, and on the premise of not affecting the working states of the existing intelligent well and the submersible electric pump well and the normal operation of the existing monitoring system, there is no direct coupling caused by an emission signal, and there is no artificial seismic source and high-power excitation source which may damage a reservoir, a cement sheath, and the like, so that development cost is saved, and online monitoring of the downhole permanent reservoir is implemented.

For the technical solution shown in fig. 8, in a possible implementation manner, as shown in fig. 9, before comparing the response signals at the same sampling time of the multiple monitoring time periods in S803, the method further includes:

s801: calculating by using the parameters of a transmitting coil and a receiving coil of the transient electromagnetic detector based on a preset reservoir detection model to obtain a simulated electromagnetic response signal;

s802: comparing the simulated electromagnetic response signal with the received original response signal of the receiving coil to obtain a second comparison result;

s803: and correcting and compensating the received original response signal of the receiving coil based on the second comparison result to obtain a corrected and compensated response signal.

For the above implementation, preferably, the method further includes:

and establishing a reservoir detection model of a time domain electromagnetic method, wherein the model comprises an iron core, air, an instrument outer protective pipe, well fluid, a casing, a cement sheath and a stratum. Specifically, the reservoir exploration model described in the preferred example is shown in fig. 10, and the media in the model are iron core, air, outer casing of the instrument, well fluid, casing, cement sheath and formation respectively from inside to outside. The permeability, the dielectric constant and the conductivity of the innermost layer medium are respectively (mu)₁,ε₁,σ₁) The permeability, permittivity and conductivity of the second layer medium from inside to outside are respectively (mu)₂,ε₂,σ₂) The third layer to the outermost layer (J-th layer) are analogized in sequence, and the radius of each layer of medium is r₁,r₂,…,r_J. It is understood that in the active region, there is both a primary field and a secondary field; in the passive region, there is only a secondary field.

It should be noted that, based on the model shown in fig. 10, for the method shown in fig. 8 or fig. 9, the deduction process is as follows:

firstly, a magnetic vector A is introduced, and considering the symmetry of the cylindrical coordinates, the magnetic vector A has_r＝A_z0, orderThe homogeneous helmholtz equation satisfied by the secondary field is expressed as formula 1:

wherein k is_jIs the wave number. Solving the formula 1, the magnitude of the secondary field vector potential in the j-th layer medium can be obtained as shown in the formula 2:

wherein N is the number of turns of the transmitting coil, I is the transmitting current, A_jAnd B_jAre respectively a undetermined coefficient, I₁(x_jr)、K₁(x_jr) are first and second class 1-order complex Bessel functions, and z is the distance between the transmit and receive coils.

Then, combining the vector magnetic potential and field magnitude relation, the value of the z-direction magnetic field component can be obtained as shown in formula 3:

then, by substituting equation 2 into equation 3, the magnetic field strength in the z direction of the receiving coil can be obtained.

Then, according to the boundary conditions of each layer of medium, the induced electromotive force in the frequency domain of the receiving coil in the medium 1 can be derived as shown in formula 4:

where ω is the angular frequency, N_RThe number of turns of the receiving coil is S, and the effective area of the receiving coil of the induction field is S.

Finally, the Gaver-stohfest inverse Laplace transform method (G-S inverse transform) is adopted to convert the formula 4 from the frequency domain to the time domain, and the induced electromotive force of the time domain of the receiving coil can be obtained as shown in the formula 5:

wherein, K_pFor the filter coefficients of the G-S method, the more the number of inverse G-S transform points, the more accurate the result is, and the smaller the error with the analytic solution.

Through the above process, it can be known that: compared with the oil-water displacement process of the reservoir, the corrosion change of the metal sleeve is extremely weak within a quite long monitoring time, and the influence of the corrosion change of the metal sleeve can be completely ignored within a short time, so that the proportion of the change of the resistivity of the reservoir in a multiple transient electromagnetic response differential mode can be greatly improved. Setting the measurement period to M, the received response can be expressed as shown in equation 6:

U_1-M＝[U₁ U₂ … U_M]^T (6)

wherein, U_m＝[U_m(t₁) U_m(t₂) … U_m(t_L)]^TAnd L is the total number of sampling points.

Based on equation 6, it can be known that, by monitoring the reservoir resistivity for a long time, since the position of the system 1 is fixed, the influence of the metal casing and the cement bond quality on the monitoring performance does not need to be compensated repeatedly. Therefore, the resistivity change condition of the reservoir can be analyzed according to the long-time monitoring result, and the permanent monitoring of the resistivity of the reservoir after the casing is realized.

In the reservoir monitoring method and system based on the time domain electromagnetic method, provided by the embodiment of the invention, in the process of measuring the resistivity change in the field actually, as the response signal received by the probe contains comprehensive data such as liquid in the casing, the casing body, the cement sheath, the stratum and the like, and the really required information is only the change condition of the resistivity of the rock stratum and the oil-water layer, in order to remove the interference influence of other media on the received information processing, after the field test is finished, the data collected by the reservoir detector after the casing needs to be corrected and compensated, the purest stratum resistivity change data is obtained, and the real-time online monitoring of the reservoir is realized.

In addition, an embodiment of the present invention provides a computer storage medium, where a reservoir monitoring program based on a time domain electromagnetic method is stored, and when being executed by at least one processor, the reservoir monitoring program based on the time domain electromagnetic method implements the steps of the reservoir monitoring method based on the time domain electromagnetic method in the foregoing technical solution.

It should be noted that: the technical schemes described in the embodiments of the present invention can be combined arbitrarily without conflict.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.