Online Nuclear Magnetic Resonance Evaluation Method and Device for Reservoir Physical Property Changes

Abstract

The present invention discloses an online nuclear magnetic reservoir physical property change evaluation method and device. The method includes: obtaining experimental data of an online nuclear magnetic physical simulation development experiment for a tight oil reservoir, where the experimental data includes the liquid permeability of the core before the displacement experiment, the liquid permeability of the core after the displacement experiment, the in-situ viscosity of the online nuclear magnetic in the oil-saturated state, and the in-situ viscosity of the online nuclear magnetic after the displacement experiment; establishing an evaluation index for comprehensively evaluating the dynamic changes of the physical properties of the tight oil reservoir according to the experimental data; and comprehensively evaluating the dynamic changes of the physical properties of the tight oil reservoir by using the evaluation index. The present invention can comprehensively evaluate the dynamic changes of the physical properties of the tight oil reservoir by using the evaluation index, and thus objectively reflect the changes and damages to the interior of the rock under conditions such as the selected development method and injection medium.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and particularly to an online nuclear magnetic resonance evaluation method and device for physical property changes of reservoir. Background Art

[0002] Before and after the online nuclear magnetic resonance physical simulation experiment of core, physical property parameters such as viscosity, wettability, pore structure, etc. will all change, and these changes will be reflected in the corresponding nuclear magnetic resonance T2 spectrum data. See Figure 5 . Figure 5 It is the T2 spectrum in different states during the online nuclear magnetic resonance experiment of tight core. During physical simulation experiments such as displacement and imbibition, the nuclear magnetic resonance T2 spectrum of the core often does not simply decrease downward by a certain amplitude, but often shifts left and right while decreasing. This phenomenon is mainly caused by the change of the boundary fluid adsorbed on the pore surface. When entering the production process, the fluid inside the core changes. Without considering adding wetting reversal components such as surfactants, the water-oil ratio in the pores becomes higher and higher. At this time, the proportion of crude oil in the boundary fluid continuously decreases, and the crude oil is continuously imbibed and displaced into the large pores and finally produced. Therefore, the T2 spectrum will shift to the right while continuously decreasing. According to the calculation formula of the mixed wettability of tight oil, the wettability at this time changes from neutral wetting to more hydrophilic. Therefore, the online nuclear magnetic resonance data during the physical simulation experiment fully reflects the changes in various physical properties such as the wettability of the core.

[0003] With the establishment of the online nuclear magnetic resonance evaluation method for the in-situ viscosity of tight oil and the establishment of the online nuclear magnetic resonance evaluation method for dynamic wettability, new understandings have been obtained on the changes of key physical property parameters inside the core based on the online nuclear magnetic resonance physical simulation experiment. The overall physical property change inside the core in the evaluation experiment can objectively reflect the changes and damages to the inside of the rock under conditions such as the selected development method and injection medium. However, there is currently no effective evaluation method for the overall dynamic physical property change inside the core in the online nuclear magnetic resonance physical simulation experiment in the prior art. Summary of the Invention

[0004] An embodiment of the present invention provides an online nuclear magnetic resonance evaluation method for physical property changes of reservoir, which is used to perform a composite evaluation on the dynamic physical property changes of the tight oil reservoir by using the evaluation index, and then objectively reflect the changes and damages to the inside of the rock under conditions such as the selected development method and injection medium. The method includes:

[0005] Obtain the experimental data of the online nuclear magnetic resonance physical simulation development experiment of the tight oil reservoir, where the experimental data includes the liquid permeability of the core before the displacement experiment, the liquid permeability of the core after the displacement experiment, the in-situ viscosity of the online nuclear magnetic resonance in the saturated oil state, and the in-situ viscosity of the online nuclear magnetic resonance after the displacement experiment;

[0006] Based on the experimental data, an evaluation index for comprehensively evaluating the dynamic changes in the physical properties of tight reservoir formations is established;

[0007] The dynamic changes in the physical properties of tight reservoir formations are comprehensively evaluated using the evaluation index.

[0008] Optionally, the method further includes:

[0009] Dividing the evaluation index into multiple levels;

[0010] The dynamic changes in the physical properties of tight reservoir formations are evaluated at different levels using the multiple levels.

[0011] Optionally, the calculation formula for the evaluation index DCI is:

[0012]

[0013] where CI W is the wettability change index, k is the liquid permeability of the core measured in the laboratory, μ i is the in-situ viscosity measured by on-line nuclear magnetic resonance, and δ is the lower calibration value of the change degree of in-situ viscosity before and after development.

[0014] Optionally, after comprehensively evaluating the dynamic changes in the physical properties of tight reservoir formations using the evaluation index, the method further includes:

[0015] Displaying the results of the comprehensive evaluation.

[0016] An embodiment of the present invention further provides an on-line nuclear magnetic resonance device for evaluating the changes in the physical properties of reservoir formations, which is used to comprehensively evaluate the dynamic changes in the physical properties of tight reservoir formations using the evaluation index, and then objectively reflect the changes and damages to the interior of the rock caused by the selected development method, injection medium, and other conditions. The device includes:

[0017] An experimental data acquisition module for acquiring the experimental data of the on-line nuclear magnetic resonance physical simulation development experiment of the tight reservoir formation. The experimental data includes the liquid permeability of the core measured in the laboratory before the displacement experiment, the liquid permeability of the core measured in the laboratory after the displacement experiment, the in-situ viscosity measured by on-line nuclear magnetic resonance in the saturated oil state, and the in-situ viscosity measured by on-line nuclear magnetic resonance after the displacement experiment;

[0018] An evaluation index establishment module for establishing an evaluation index for comprehensively evaluating the dynamic changes in the physical properties of tight reservoir formations according to the experimental data;

[0019] A comprehensive evaluation module for comprehensively evaluating the dynamic changes in the physical properties of tight reservoir formations using the evaluation index.

[0020] Optionally, the device further includes:

[0021] A level division module for dividing the evaluation index into multiple levels;

[0022] A grading evaluation module for performing a grading composite evaluation on the dynamic changes of the physical properties of a tight oil reservoir according to multiple levels.

[0023] Optionally, the calculation formula of the evaluation index DCI is:

[0024]

[0025] Wherein, CI W is the wettability change index, k is the liquid permeability of the core measured, μ i is the in-situ viscosity of the online nuclear magnetic resonance, and δ is the lower limit calibration value of the change degree of the in-situ viscosity before and after development.

[0026] Optionally, the device further includes:

[0027] A display module for displaying the results of the composite evaluation.

[0028] An embodiment of the present invention further provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the above method is implemented.

[0029] An embodiment of the present invention further provides a computer-readable storage medium, and the computer-readable storage medium stores a computer program for executing the above method.

[0030] In the embodiment of the present invention, by obtaining the experimental data of the online nuclear magnetic resonance physical simulation development experiment of the tight oil reservoir, according to the experimental data, an evaluation index for performing a composite evaluation on the dynamic changes of the physical properties of the tight oil reservoir is established, and the evaluation index can be used to perform a composite evaluation on the dynamic changes of the physical properties of the tight oil reservoir, so as to objectively reflect the changes and damages to the inside of the rock under conditions such as the selected development method and injection medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings. In the drawings:

[0032] Figure 1 is the flowchart of the online nuclear magnetic resonance reservoir physical property change evaluation method in the embodiment of the present invention;

[0033] Figure 2 is the flowchart of performing a grading composite evaluation in the embodiment of the present invention;

[0034] Figure 3 Schematic structural diagram of the on-line nuclear magnetic reservoir physical property change evaluation device in the embodiment of the present invention;

[0035] Figure 4 Schematic structural diagram of the hierarchical composite evaluation in the embodiment of the present invention;

[0036] Figure 5 Schematic diagram of T2 spectra in different states during the on-line nuclear magnetic experiment of tight cores in the embodiment of the present invention;

[0037] Figure 6 Schematic diagram of the comparison of DCI index changes during the core development process in the embodiment of the present invention;

[0038] Figure 7 Schematic diagram of the comparison of the final DCI indexes of the development of three typical tight oil areas in the embodiment of the present invention. Detailed implementation manners

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer and more understandable, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Herein, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but not to limit the present invention.

[0040] Figure 1 Flow chart of an on-line nuclear magnetic reservoir physical property change evaluation method provided by an embodiment of the present invention, as Figure 1 shown, the method includes:

[0041] Step 101, obtaining experimental data of an on-line nuclear magnetic physical simulation development experiment of a tight oil reservoir, where the experimental data includes the liquid permeability of the core before the displacement experiment, the liquid permeability of the core after the displacement experiment, the on-line nuclear magnetic in-situ viscosity in the oil-saturated state, and the on-line nuclear magnetic in-situ viscosity after the displacement experiment.

[0042] Step 102, establishing an evaluation index for comprehensively evaluating the dynamic changes of the physical properties of the tight oil reservoir according to the experimental data.

[0043] In this embodiment, the calculation formula of the evaluation index DCI is:

[0044]

[0045] where DCI is the comprehensive evaluation index of the dynamic changes of the reservoir physical properties, dimensionless; CI W is the wettability change index, dimensionless; k is the liquid permeability of the core, ×10 -3 μm2; μ i is the on-line nuclear magnetic in-situ viscosity, mPa·s; δ is the lower limit calibration value of the change degree of the in-situ viscosity before and after development, dimensionless.

[0046] The larger the value of the composite evaluation index DCI for the dynamic changes in reservoir physical properties by online nuclear magnetic resonance, the more obvious the change in the internal physical properties of the reservoir during the development process. DCI comprehensively considers the changes in three key parameters, namely in-situ viscosity, dynamic wettability, and liquid-phase permeability, during the development process. It can be seen that the DCI index includes factors such as the viscosity of the bulk fluid, the viscosity and wettability of the boundary fluid, and the increase in pore size and permeability caused by factors such as long-term flushing of clay, dissolution of salt, and generation of microfractures during the development process. In the expression of the DCI index, it is considered that the more hydrophilic the change in reservoir wettability during the development process, the more obvious the transformation effect; as the physical model experiment progresses, the greater the change in liquid-phase permeability indicates the greater the change in the internal pore structure of the core, that is, the more obvious the change in the reservoir; the greater the decrease in the last item of in-situ viscosity, the more obvious the change in the internal fluid distribution of the reservoir during the development process. δ is used to calibrate the lower limit of the change amplitude of in-situ viscosity, and a value less than that of the rock sample with the worst development effect is taken as the calibration value. Combining multiple groups of data, taking δ as 50% as the calibration value can ensure that the internal value of the third item is greater than 1.

[0047] Step 103: Use the evaluation index to conduct a composite evaluation of the dynamic changes in the physical properties of the tight oil reservoir.

[0048] The method for evaluating the changes in the physical properties of the reservoir by online nuclear magnetic resonance provided by the embodiments of the present invention obtains the experimental data of the online nuclear magnetic physical simulation development experiment of the tight oil reservoir, and according to the experimental data, establishes an evaluation index for the composite evaluation of the dynamic changes in the physical properties of the tight oil reservoir, that is, the evaluation index can be used to conduct a composite evaluation of the dynamic changes in the physical properties of the tight oil reservoir, and further objectively reflect the changes and damages to the interior of the rock by the selected development method, injection medium, and other conditions.

[0049] Figure 2 This is the flowchart for the hierarchical composite evaluation in the embodiments of the present invention. As Figure 2 shown, the method further includes:

[0050] Step 201: Divide the evaluation index into multiple levels;

[0051] Step 202: Conduct a hierarchical composite evaluation of the dynamic changes in the physical properties of the tight oil reservoir according to multiple levels.

[0052] During specific implementation, the change situation of the internal physical properties of the core can be understood by referring to Table 1 below, so as to guide the actual production and development.

[0053] Table 1

[0054]

[0055] In the embodiment of the present invention, in order to facilitate the staff to intuitively understand the results of the composite evaluation, after using the evaluation index to perform a composite evaluation on the dynamic changes of the physical properties of the tight reservoir, the method further includes:

[0056] Display the results of the composite evaluation.

[0057] Specifically, the results of the composite evaluation can be displayed in the form of a table.

[0058] The following uses a specific embodiment to illustrate the present invention:

[0059] Six cores from three typical tight oil areas in Changqing, Daqing, and Jilin, China, are selected for online nuclear magnetic water flooding experiments. During the experiment, the nuclear magnetic data of the cores and the changes in liquid permeability are measured. The in-situ viscosity and dynamic wetting index are calculated through the nuclear magnetic data. The changes in the DCI index during the water flooding process of the six cores are calculated using the above data, and the results are as Figure 6 shown. Taking the displacement volume of 1PV as the boundary, the overall physical property changes during the core development process are divided into two obvious stages. Before 1PV, significant changes have occurred in the in-situ viscosity, wettability, seepage resistance, etc. within the core. This stage is the stage of expanding the swept area after the injection medium is injected. Wherever the injection medium reaches, it can push and displace the easily mobilized crude oil in the bulk fluid forward in a piston-like manner, and the corresponding in-situ viscosity will also be significantly reduced. At the same time, due to the mixed wettability of the tight core, the injected water adsorbs on the surface of some water-wet pores, and the change in fluid distribution also leads to a relatively large change in the wettability in the early stage. After 1PV, the overall physical property changes within the core are relatively small and basically tend to be stable. After water flooding development in the three typical tight reservoirs, the physical property changes in the Jilin tight reservoir are the most obvious, followed by Changqing, and the physical property changes in the Daqing tight reservoir are relatively small.

[0060] The final DCI index is as Figure 7 shown. According to the evaluation criteria in Table 1, it can be concluded that the physical properties of the tight cores in Daqing are partially changed after water flooding, the physical properties of Changqing are changed to a greater extent, and the physical properties of the tight cores in Jilin are strongly changed after water flooding.

[0061] Based on the same inventive concept, an on-line nuclear magnetic reservoir physical property change evaluation device is also provided in the embodiments of the present invention, as described in the following embodiments. Since the principle of solving problems by the on-line nuclear magnetic reservoir physical property change evaluation device is similar to that of the on-line nuclear magnetic reservoir physical property change evaluation method, therefore, for the implementation of the on-line nuclear magnetic reservoir physical property change evaluation device, reference can be made to the implementation of the on-line nuclear magnetic reservoir physical property change evaluation method, and the repeated parts will not be elaborated. As used hereinafter, the term "unit" or "module" may be a combination of software and / or hardware that can achieve a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0062] Figure 3 FIG. is a schematic structural diagram of the on-line nuclear magnetic reservoir physical property change evaluation device provided by the embodiment of the present invention, as Figure 3 shown, the device includes:

[0063] An experimental data acquisition module 301, configured to acquire experimental data of an on-line nuclear magnetic physical simulation development experiment of a tight oil reservoir, where the experimental data includes the liquid permeability of the core before the displacement experiment, the liquid permeability of the core after the displacement experiment, the on-line nuclear magnetic in-situ viscosity in the saturated oil state, and the on-line nuclear magnetic in-situ viscosity after the displacement experiment;

[0064] An evaluation index establishment module 302, configured to establish an evaluation index for comprehensively evaluating the dynamic change of the physical properties of the tight oil reservoir according to the experimental data;

[0065] A comprehensive evaluation module 303, configured to comprehensively evaluate the dynamic change of the physical properties of the tight oil reservoir by using the evaluation index.

[0066] Figure 4 FIG. is a schematic structural diagram of the hierarchical comprehensive evaluation provided by the embodiment of the present invention, as Figure 4 shown, the device further includes:

[0067] A level division module 401, configured to divide the evaluation index into multiple levels;

[0068] A hierarchical evaluation module 402, configured to perform hierarchical comprehensive evaluation on the dynamic change of the physical properties of the tight oil reservoir according to multiple levels.

[0069] In the embodiment of the present invention, the calculation formula of the evaluation index DCI is:

[0070]

[0071] where CI W is the wettability change index, k is the liquid permeability of the core, μ i is the on-line nuclear magnetic in-situ viscosity, and δ is the lower limit calibration value of the in-situ viscosity change degree before and after development.

[0072] In an embodiment of the present invention, the apparatus further includes:

[0073] A display module, configured to display the result of the composite evaluation.

[0074] To achieve the above object, according to another aspect of the present application, there is also provided a computer device. The computer device includes a memory, a processor, a communication interface, and a communication bus. A computer program that can run on the processor is stored on the memory. When the processor executes the computer program, the steps in the method of the above embodiment are implemented.

[0075] The processor may be a central processing unit (CPU). The processor may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. chips, or a combination of the above types of chips.

[0076] The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and units, such as the corresponding program units in the method embodiment of the present invention above. The processor executes various functional applications and data processing of the work by running the non-transitory software programs, instructions, and modules stored in the memory, that is, the method in the above method embodiment is implemented.

[0077] The memory may include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created by the processor, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory may optionally include a memory remotely set relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0078] The one or more units are stored in the memory and, when executed by the processor, execute the method in the above embodiment.

[0079] An embodiment of the present invention further provides a computer-readable storage medium, which stores a computer program for executing the above method.

[0080] In summary, the physical property dynamic change composite evaluation index DCI established by the present invention can comprehensively reflect the changes in wettability, viscosity, and permeability of the core during the physical simulation experiment. During the experiment, by calculating the DCI index of each core, the overall physical property change magnitude and damage degree of each core under this development method and injection medium can be understood. And the classification evaluation boundary of the physical property dynamic change composite evaluation index DCI is proposed, which can effectively predict the actual development process of the reservoir and propose targeted development countermeasures.

[0081] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0082] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the specified function in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0083] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device realizes the specified function in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0084] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions for implementing the steps specified in one process or a plurality of processes and / or blocks Figure 1 one process or a plurality of processes and / or blocks Figure 1 steps for the functions specified in one block or a plurality of blocks.

[0085] In the above-described specific embodiments, the objects, technical solutions, and beneficial effects of the present invention have been further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An online nuclear magnetic reservoir physical property change evaluation method, characterized in that Including: Obtaining experimental data of an online nuclear magnetic physical simulation development experiment for a tight reservoir, where the experimental data includes the core liquid permeability before the displacement experiment, the core liquid permeability after the displacement experiment, the online nuclear magnetic in-situ viscosity in the oil-saturated state, and the online nuclear magnetic in-situ viscosity after the displacement experiment; Based on the experimental data, establishing an evaluation index for comprehensively evaluating the dynamic changes in the physical properties of the tight reservoir; Using the evaluation index to comprehensively evaluate the dynamic changes in the physical properties of the tight reservoir; Wherein, the calculation formula of the evaluation index DCI is: Among them, CI W is the wettability change index, k is the liquid permeability of the core measured, μ i is the in-situ viscosity of the online nuclear magnetic resonance, and δ is the lower calibration value of the change degree of the in-situ viscosity before and after development.

2. The method according to claim 1, characterized in that, Also including: Dividing the evaluation index into multiple levels; Conducting a hierarchical comprehensive evaluation of the dynamic changes in the physical properties of the tight reservoir according to multiple levels.

3. The method according to claim 1, wherein After using the evaluation index to comprehensively evaluate the dynamic changes in the physical properties of the tight reservoir, the method further includes: Displaying the results of the comprehensive evaluation.

4. An on-line nuclear magnetic reservoir physical property change evaluation device, characterized in that, Including: An experimental data acquisition module for obtaining experimental data of an online nuclear magnetic physical simulation development experiment for a tight reservoir, where the experimental data includes the core liquid permeability before the displacement experiment, the core liquid permeability after the displacement experiment, the online nuclear magnetic in-situ viscosity in the oil-saturated state, and the online nuclear magnetic in-situ viscosity after the displacement experiment; An evaluation index establishment module for establishing an evaluation index for comprehensively evaluating the dynamic changes in the physical properties of the tight reservoir based on the experimental data; A comprehensive evaluation module for using the evaluation index to comprehensively evaluate the dynamic changes in the physical properties of the tight reservoir; Wherein, the calculation formula of the evaluation index DCI is: Among them, CI W is the wettability change index, k is the liquid permeability of the core measured, μ i is the in-situ viscosity of on-line nuclear magnetic resonance, and δ is the lower calibration value of the change degree of in-situ viscosity before and after development.

5. The device according to claim 4, characterized in that, Also including: A level division module for dividing the evaluation index into multiple levels; A hierarchical evaluation module for conducting a hierarchical comprehensive evaluation of the dynamic changes in the physical properties of the tight reservoir according to multiple levels.

6. The device according to claim 4, wherein The device further includes: A display module for displaying the results of the comprehensive evaluation.

7. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1 to 3.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and when the computer program is executed by the processor, it implements the method according to any one of claims 1 to 3.

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