Rock core gas drive front edge determination method and device, electronic equipment and storage medium

Abstract

The embodiment of the invention discloses a rock core gas drive front edge determination method and device, electronic equipment and a storage medium. The method comprises the following steps: acquiring a first nuclear magnetic resonance spectrum and a first layered nuclear magnetic resonance spectrum when a target rock core is not displaced; performing gas displacement on the target rock core to obtain a second nuclear magnetic resonance spectrum and nuclear magnetic signal variation of the target rock core in the displacement process; when it is detected that the nuclear magnetic signal variable quantity of the target rock core is larger than a preset nuclear magnetic signal variable quantity threshold value, a second layered nuclear magnetic resonance spectrum of the target rock core is obtained; and according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target rock core, determining the gas drive front of the target rock core. By adopting the scheme, the one-dimensional rock core of different gases under the formation condition is dynamically monitored in real time through the online nuclear magnetic resonance layering technology, and the dynamic fine representation of the gas drive front is realized.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of oil extraction, and in particular to a method, device, electronic equipment and storage medium for determining a core gas drive front. Background Art

[0002] As a common means of energy supplementation and development, gas drive has obvious advantages over water drive in terms of replenishing formation energy and injection capacity.

[0003] For the same reservoir, changes in key injection and production parameters during gas drive development will affect the dynamic changes of the gas drive front. For different reservoirs, the gas drive front will also change due to the influence of factors such as different reservoir physical properties and reservoir heterogeneity. Analyzing the gas drive process using a single nuclear magnetic resonance technique cannot quantitatively and finely characterize the microscopic changes of the gas drive front during the gas drive process, nor can it dynamically and finely characterize the key physical property parameters of the gas drive front. Summary of the invention

[0004] The embodiments of the present invention provide a method, device, electronic device and storage medium for determining a core gas drive front, so as to achieve refined determination of key physical property parameters of a gas drive front and their changing rules.

[0005] In a first aspect, an embodiment of the present invention provides a method for determining a core gas drive front, comprising:

[0006] Obtaining a first nuclear magnetic resonance spectrum and a first layered nuclear magnetic resonance spectrum of the target core before displacement; wherein the layered nuclear magnetic resonance spectrum is obtained by layering the target core and obtaining nuclear magnetic resonance spectra of each core slice;

[0007] Performing gas displacement on the target core, and obtaining a second nuclear magnetic resonance spectrum and a change in nuclear magnetic resonance signal of the target core during the displacement process;

[0008] When it is detected that the change amount of the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change amount threshold, a second layer nuclear magnetic resonance spectrum of the target core is obtained;

[0009] The gas drive front of the target core is determined according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core.

[0010] In a second aspect, an embodiment of the present invention further provides a core gas drive front determination device, comprising:

[0011] A first spectrum acquisition module is used to acquire a first nuclear magnetic resonance spectrum and a first layered nuclear magnetic resonance spectrum of the target core before displacement; wherein the layered nuclear magnetic resonance spectrum is obtained by layering the target core and acquiring the nuclear magnetic resonance spectrum of each core slice;

[0012] A gas displacement module, used for performing gas displacement on the target core and obtaining a second nuclear magnetic resonance spectrum and a change amount of nuclear magnetic resonance signal of the target core during the displacement process;

[0013] A second layered nuclear magnetic resonance spectrum acquisition module is used to acquire a second layered nuclear magnetic resonance spectrum of the target core when it is detected that the change amount of the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change amount threshold;

[0014] The gas drive front determination module is used to determine the gas drive front of the target core according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core.

[0015] In a third aspect, an embodiment of the present invention further provides an electronic device, the electronic device comprising:

[0016] one or more processors;

[0017] A storage device for storing one or more programs;

[0018] When the one or more programs are executed by the one or more processors, the one or more processors implement the core gas drive front determination method described in any embodiment of the present invention.

[0019] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for determining the core gas drive front described in any embodiment of the present invention.

[0020] The embodiment of the present invention provides a method, device, electronic device and storage medium for determining a gas drive front of a core, wherein a first nuclear magnetic resonance spectrum and a first layered nuclear magnetic resonance spectrum of a target core before being driven are obtained; wherein the layered nuclear magnetic resonance spectrum is obtained by obtaining the nuclear magnetic resonance spectrum of each core slice after the target core is layered; the target core is gas-driven to obtain a second nuclear magnetic resonance spectrum and a change in nuclear magnetic signal of the target core during the driving process; when it is detected that the change in the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change threshold, a second layered nuclear magnetic resonance spectrum of the target core is obtained; and the gas drive front of the target core is determined based on the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core. The technical solution of the embodiment of the present invention is adopted to dynamically monitor the miscible / immiscible displacement process of one-dimensional cores with different injected gas media under formation conditions in real time through low-field online nuclear magnetic resonance stratification technology. The dynamic and fine characterization of the gas drive front under microscopic conditions is achieved through the nuclear magnetic resonance spectrum obtained during the gas drive process; and the dynamic change law and seepage law of the gas drive front and its key physical parameters are analyzed in combination with the key injection and production parameters. It provides a basis for the design, optimization, dynamic tracking and adjustment of key parameters of the development plan, so as to achieve stable control of the oil and gas interface, slow down gas channeling, expand the injection swept volume and reduce the distribution of residual oil, further improve the crude oil recovery rate, and achieve the purpose of maximizing the development benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings. The drawings are only for the purpose of illustrating preferred embodiments and are not to be considered as limiting the present invention. Also, the same reference symbols are used throughout the drawings to represent the same parts. In the drawings:

[0022] Figure 1 is a flow chart of a method for determining a core gas drive front provided in an embodiment of the present invention;

[0023] Figure 2 It is a structural schematic diagram of an online nuclear magnetic gas drive front dynamic characterization device provided in an embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of a core slice and a layered nuclear magnetic resonance spectrum provided in an embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of a curve of the relationship between relaxation time and amplitude of a target core provided in an embodiment of the present invention;

[0026] Figure 5AIt is a schematic diagram of a 0-8 mm core slice nuclear magnetic resonance spectrum provided in an embodiment of the present invention;

[0027] Figure 5B This is a schematic diagram of a nuclear magnetic resonance spectrum of a 8-16 mm core slice provided in an embodiment of the present invention;

[0028] Figure 5C It is a schematic diagram of a 16-24 mm core slice nuclear magnetic resonance spectrum provided in an embodiment of the present invention;

[0029] Figure 5D This is a schematic diagram of a 24-32 mm core slice nuclear magnetic resonance spectrum provided in an embodiment of the present invention;

[0030] Figure 5E This is a schematic diagram of a 32-40 mm core slice nuclear magnetic resonance spectrum provided in an embodiment of the present invention;

[0031] Fig. 5F It is a schematic diagram of a 40-48 mm core slice nuclear magnetic resonance spectrum provided in an embodiment of the present invention;

[0032] Fig. 6A is a schematic diagram of a layered nuclear magnetic resonance spectrum of a 0PV gas displacement provided in an embodiment of the present invention;

[0033] Figure 6B It is a schematic diagram of a layered nuclear magnetic resonance spectrum of 0.03PV gas displacement provided in an embodiment of the present invention;

[0034] Figure 6C It is a schematic diagram of a layered nuclear magnetic resonance spectrum of 0.05PV gas displacement provided in an embodiment of the present invention;

[0035] Fig.6D It is a schematic diagram of a layered nuclear magnetic resonance spectrum of 0.3PV gas displacement provided in an embodiment of the present invention;

[0036] Fig. 6E It is a schematic diagram of a layered nuclear magnetic resonance spectrum of a 1.5PV gas displacement provided in an embodiment of the present invention;

[0037] Figure 7 is a structural schematic diagram of a core gas drive front determination device provided in an embodiment of the present invention;

[0038] Figure 8 It is a structural schematic diagram of an electronic device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0040] Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the operations (or steps) as sequential processes, many of the operations (or steps) therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0041] Among them, the acquisition, storage, use and processing of data in the technical solution of this application are in compliance with the relevant provisions of national laws and regulations.

[0042] Figure 1 This is a flow chart of a method for determining a core gas drive front provided in an embodiment of the present invention. This embodiment is applicable to the case of determining a core gas drive front. The method of this embodiment can be executed by a core gas drive front determination device, which can be implemented in hardware and / or software. The device can be configured in a server for determining a core gas drive front. The method specifically includes the following steps:

[0043] S110, obtaining a first nuclear magnetic resonance spectrum and a first layered nuclear magnetic resonance spectrum of the target core before displacement.

[0044] Before the target core is displaced, the target core needs to be pre-treated, and the pre-treatment includes but is not limited to drying treatment, vacuum treatment, saturated water treatment and saturated oil treatment. Before the target core is pre-treated, the target core needs to be marked, and the injection end and the production end of the target core during gas displacement are marked, so that the direction of gas displacement is consistent, ensuring that the layered nuclear magnetic resonance spectrum can correspond one-to-one with the core slice.

[0045] As an optional but non-limiting implementation, before obtaining the first nuclear magnetic resonance spectrum and the first layered nuclear magnetic resonance spectrum of the target core before displacement, the steps include but are not limited to steps A1-A3:

[0046] Step A1: drying, vacuuming and saturating the first core with first simulated formation water to obtain a second core, and obtaining a third nuclear magnetic resonance spectrum and a third layered nuclear magnetic resonance spectrum of the second core; wherein the first simulated formation water is prepared by distilled water.

[0047] Among them, see Figure 2 , connect the gas displacement device with the online nuclear magnetic resonance device so that when the target core is gas-displaced, the nuclear magnetic resonance spectrum of the target core can be obtained. Connect the experimental pipeline according to the specific experimental requirements, and wrap a layer of foam insulation on the outside of the exposed pipeline to prevent heat loss and ensure the phase stability of the fluid.

[0048] After the target core is packaged, it is placed in a special core holder (made of glass fiber and polyetheretherketone material, resistant to high temperature and high pressure and without nuclear magnetic signal), evacuated and saturated with formation water prepared with distilled water, and the internal pressure of the core is increased to the experimental condition by using the formation water prepared with distilled water, and the clamp ring pressure liquid (such as fluorine oil, without nuclear magnetic signal) is heated to the experimental temperature, and stabilized for a period of time to ensure that the test is carried out under experimental conditions without affecting the nuclear magnetic signal. After the temperature and pressure are stabilized, the third nuclear magnetic resonance spectrum and the third layered nuclear magnetic resonance spectrum of the second core are tested at the experimental temperature and pressure, and the third nuclear magnetic resonance spectrum and the third layered nuclear magnetic resonance spectrum are used as the base nuclear magnetic signal of the target core. The base nuclear magnetic signal is compared with the nuclear magnetic signal obtained during gas displacement to determine the change characteristics of the gas drive front of the core.

[0049] Step A2: drying, vacuumizing and saturating the second core with second simulated formation water to obtain a third core; wherein the second simulated formation water is prepared by heavy water.

[0050] After the target core is saturated with the first simulated formation water, the target core is taken out from the holder and the wet weight of the core is tested, and the target core is dried again. The target core is packaged again and loaded into the holder, and the formation water prepared with saturated heavy water is dried and vacuumed to eliminate the water phase signal inside the target core. The internal pressure of the target core is increased to the experimental pressure by using the formation water prepared with heavy water, and the ring pressure liquid (fluorine oil, no nuclear magnetic signal) of the holder is heated to the experimental temperature, and the temperature and pressure are stabilized to ensure that the process of generating bound water is carried out under experimental conditions.

[0051] Step A3: Inject the formation crude oil into the third core to obtain the target core.

[0052] Among them, after increasing the crude oil pressure in the intermediate container to the experimental pressure, the injection fluid is switched to saturate the real crude oil in the formation at an appropriate speed. The displacement volume is 10PV, and a saturated core with bound water is created. It is aged for a period of time to effectively simulate the original state of the formation.

[0053] By adopting the technical solution of the embodiment of the present invention and combining the characteristics of the nuclear magnetic resonance instrument, fluid saturation is directly performed on the online nuclear magnetic resonance instrument through an improved fluid heating and pressurization method and a core saturation method. While ensuring that the test is carried out under high temperature and high pressure experimental conditions, the experimental preparation steps are simplified, mistakes are avoided, and the experimental efficiency and accuracy are improved.

[0054] The target core obtained after pretreatment is obtained, and the first nuclear magnetic resonance spectrum and the first layered nuclear magnetic resonance spectrum of the target core before displacement are obtained. The layered nuclear magnetic resonance spectrum is obtained by layering the target core and obtaining the nuclear magnetic resonance spectrum of each core slice.

[0055] As an optional but non-limiting implementation, the step of obtaining the first layer NMR spectrum of the target core before displacement includes but is not limited to steps B1-B2:

[0056] Step B1: Divide the target core into at least two core slices.

[0057] Step B2: respectively obtaining layered nuclear magnetic resonance spectra of the at least two core slices to determine a first layered nuclear magnetic resonance spectrum of the target core.

[0058] Among them, see Figure 3 , dividing the target core marked with the injection end and the production end into 6 core slices, obtaining the nuclear magnetic resonance spectra of the 6 core slices; combining the nuclear magnetic resonance spectra of the 6 core slices to obtain the first layered nuclear magnetic resonance spectrum of the target core. In the embodiment of the present invention, the layered nuclear magnetic resonance spectrum obtained when no displacement is performed is referred to as the first layered nuclear magnetic resonance spectrum.

[0059] It can be understood that the first layered nuclear magnetic resonance spectrum can be a reference to distinguish the different layered nuclear magnetic resonance spectra that appear before and after in the embodiment to execute the corresponding logic. Any layered nuclear magnetic resonance spectrum is selected from the layered nuclear magnetic resonance spectrum so that the execution logic can be explained from the selected layered nuclear magnetic resonance spectrum. Therefore, the layered nuclear magnetic resonance spectrum that appears for the first time in this article is called the first layered nuclear magnetic resonance spectrum, and the other layered nuclear magnetic resonance spectra that appear subsequently and are different from the first layered nuclear magnetic resonance spectrum are called second layered nuclear magnetic resonance spectra, which will not be repeated later.

[0060] S120, performing gas displacement on the target core, and obtaining a second nuclear magnetic resonance spectrum and a change in nuclear magnetic resonance signal of the target core during the displacement process.

[0061] Before gas displacement of the target core, a booster is used to inject the gas used in the experiment into the intermediate container (the pressure after boosting needs to be lower than the experimental pressure to leave room for pressure changes caused by heating); a displacement pump is used to stabilize the gas pressure inside the intermediate container to the displacement pressure; and an insulating heating jacket / oven is used to heat the intermediate container and the internal fluid to the experimental temperature until stable (the heating stabilization time is determined by the power of the insulating heating jacket / oven and the size of the intermediate container, for example, the heating stabilization time is at least 4 hours). Since the pressure of the gas increases due to thermal expansion, a displacement pump is required to track the fluid pressure in the container in real time during the entire heating process to stabilize the gas pressure at the experimental displacement pressure in time.

[0062] As an optional but non-limiting implementation, the gas displacement of the target core and obtaining the second nuclear magnetic resonance spectrum and nuclear magnetic signal change of the target core during the displacement process include but are not limited to steps C1-C2:

[0063] Step C1: obtaining a preset gas for gas displacement of the target core; the preset gas includes carbon dioxide and nitrogen that do not contain nuclear magnetic resonance signals.

[0064] Step C2: displacing the formation crude oil in the target core with a preset gas, and acquiring in real time the second nuclear magnetic resonance spectrum, nuclear magnetic signal change, and injection and production parameters of the target core during the displacement process; wherein the injection and production parameters include injection and production pressure, injection and production gas and liquid volume, and injection and production speed.

[0065] Among them, except for hydrocarbon gas and other gases with nuclear magnetic resonance signals, different injected gas media such as carbon dioxide, nitrogen and oxygen-reduced air have no nuclear magnetic resonance signals. Therefore, in the process of saturated core gas drive after establishing bound water with deuterium water, its nuclear magnetic resonance spectrum will only reflect the changes in oil phase signals. Since gas is easier to flow, gas channeling is more likely to occur in the gas drive process than water drive and other methods, resulting in the failure to effectively capture the changes in the gas drive front in time. Nuclear magnetic resonance has a faster test speed for core nuclear magnetic resonance spectrum. Therefore, it is necessary to continuously test the nuclear magnetic resonance spectrum of the core during the entire displacement process, monitor the signal change amount and percentage of the fluid in the core in real time, and preliminarily judge the current degree of utilization of pores of different sizes, the degree of gas drive and the effect of gas drive, and then decide whether to adjust the injection and production parameters and whether to use the test method of layered nuclear magnetic resonance spectrum to capture the changes in the gas drive front and improve the experimental efficiency.

[0066] The injection and production parameters may refer to the injection parameters and production parameters when gas displacement is performed on the target core. The injection and production parameters include but are not limited to injection and production pressure, injection and production gas and liquid volume, and injection and production speed. For example, the injection and production pressure may refer to the pressure input at the injection end and the pressure output at the production end when gas displacement is performed on the target core.

[0067] S130. When it is detected that the change amount of the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change amount threshold, a second layered nuclear magnetic resonance spectrum of the target core is obtained.

[0068] When displacing the target core, gas is used to displace the crude oil in the target core, so that the crude oil content in the target core is reduced, and the nuclear magnetic resonance signal will also be reduced accordingly, which will affect the acquisition of the gas drive front of the core. The use of layered nuclear magnetic resonance spectrum can accurately obtain the gas drive front of each core slice.

[0069] As an optional but non-limiting implementation, when it is detected that the change in the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change threshold, obtaining a second layered nuclear magnetic resonance spectrum of the target core includes but is not limited to steps D1-D2:

[0070] Step D1: Detect the change in the nuclear magnetic signal of the target core to determine whether the change in the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change threshold.

[0071] Step D2: If the change in the nuclear magnetic resonance signal of the target core is greater than a preset nuclear magnetic resonance signal change threshold, a second layer nuclear magnetic resonance spectrum of the target core is obtained.

[0072] Among them, since the test speed of the nuclear magnetic resonance spectrum is relatively fast, it is necessary to continuously test the second nuclear magnetic resonance spectrum of the target core during the entire displacement process, and monitor the signal change of the fluid in the target core in real time. When the change of the nuclear magnetic signal is greater than the preset nuclear magnetic signal change threshold, the layered nuclear magnetic resonance will be used to obtain the second layered nuclear magnetic resonance spectrum of the target core. The preset nuclear magnetic signal change threshold can be 3%.

[0073] S140, determining the gas drive front of the target core according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum, and the second layered nuclear magnetic resonance spectrum of the target core.

[0074] Among them, relaxation is an important phenomenon in nuclear magnetic resonance testing. Relaxation is the process in which the magnetization vector deviates from the equilibrium state and then returns to the equilibrium state when nuclear magnetic resonance occurs under the excitation of the radio frequency field. The relaxation time is divided into longitudinal relaxation time T1 and transverse relaxation time T2, but the longitudinal relaxation time test time is relatively long. Considering the test efficiency and the rapid change of the gas drive front, the transverse relaxation time T2 is selected to be measured during the dynamic monitoring of the gas drive front. The transverse relaxation time of rock consists of three parts, and the expression is as follows:

[0075]

[0076] Where T2 is the transverse relaxation time, ms; T2B is the bulk relaxation time, ms; T 2S is the surface relaxation time, ms; T D2 is the diffusion relaxation time, ms. When conducting nuclear magnetic resonance testing on cores, T2 is mainly related to the surface relaxation T 2B Therefore, the relaxation time of the nuclei in a single channel can be expressed as:

[0077]

[0078] Where ρ2 is the rock surface relaxation strength parameter, μm·ms -1 , depends on the pore surface properties and mineral composition; is the specific surface area of ​​a single pore, μm -1 , is inversely proportional to the pore radius, S is the rock surface area, and V is the rock volume.

[0079] The distribution of T2 relaxation time reflects the distribution of specific surface area inside the porous medium. The larger the specific surface area, the smaller the corresponding pores and the shorter the T2 relaxation time. Since both oil and water have nuclear magnetic resonance signals, the oil signal and the water signal will overlap on the nuclear magnetic resonance spectrum, making it impossible to distinguish between oil and water. Therefore, fluorinated oil or deuterated water without nuclear magnetic resonance signals is usually used to hide one of the phase signals. The nuclear magnetic resonance echo train signal can be detected by the receiving coil. By inverting the echo train, the T2 relaxation time distribution can be obtained, and the nuclear magnetic resonance signal intensity is proportional to the number of hydrogen nuclei contained in the sample being tested.

[0080] In an optional scheme of an embodiment of the present invention, the gas drive front is characterized based on the layered NMR spectrum of the CPMG sequence. Compared with the traditional SESPI sequence layered NMR, it can solve the problem of missing low-frequency signals and peak offset of the measured layered NMR signals, which is the core characterization method of the embodiment of the present invention. The NMR spectrum can reflect the NMR signal of the whole core, and the layered NMR spectrum test can divide the core into several core slices according to the experimental test requirements to reflect the NMR signals of different slice positions, and the slice thickness is usually in the millimeter level. By testing the NMR spectrum of each slice separately, the changes in the NMR signals of various parts of the rock are monitored. The analysis principle and method adopted by the NMR spectrum of each slice are the same as the above-mentioned NMR spectrum. It can simultaneously reflect the use of pores of different sizes at different slice positions, making up for the shortcomings of the NMR spectrum that can only test the whole core, and by analyzing the NMR spectrum of slices at different positions of the rock, the dynamic and fine characterization of the gas drive front is realized.

[0081] As an optional but non-limiting implementation, the gas drive front of the target core is determined based on the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core, including but not limited to steps E1-E2:

[0082] Step E1: Analyze the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum, and the second layered nuclear magnetic resonance spectrum of the target core to determine the spectrum analysis results.

[0083] Step E2: Determine the gas drive front of the target core according to the spectrum analysis result.

[0084] Among them, the sandstone core of the H79 block and the laboratory compounded crude oil were used to carry out the carbon dioxide immiscible gas drive experiment. During the experiment, the core was sliced ​​into 8 mm sections and tested for nuclear magnetic resonance spectrum and layered nuclear magnetic resonance spectrum.

[0085] See also Figure 4 Through the analysis of the nuclear magnetic resonance spectrum, it can be seen that the target core nuclear magnetic resonance spectrum after oil saturation presents a bimodal morphology, in which the peak with a shorter relaxation time represents the capillary bound crude oil in the smaller pores, and the peak with a longer relaxation time represents the movable crude oil in the larger pores. In the process of carbon dioxide immiscible displacement, with the increase of injection volume, the overall signal of the nuclear magnetic resonance spectrum gradually decreases, but it is mainly caused by the decrease of the right peak signal, and the change of the left peak signal is small. Therefore, it can be judged that carbon dioxide immiscible displacement can mainly mobilize crude oil in large pores, but has poor ability to mobilize crude oil in small pores. At the same time, according to the changes in the signal of the overall nuclear magnetic resonance spectrum of the core at different times, the displacement efficiency of carbon dioxide immiscible displacement at different stages can be calculated. By calculating the changes in oil displacement efficiency in real time, the utilization of pores of different sizes at different stages of the experiment can be accurately obtained, and the displacement progress of the experiment can be monitored in real time. When the oil displacement efficiency changes by more than 3%, it should be selected to measure its layered nuclear magnetic resonance spectrum at this time to conduct in-depth research on its front changes.

[0086] See also Figures 5A-5FThrough the analysis of the layered NMR spectra, it can be seen that for the NMR signals at the same core slice position, as the carbon dioxide immiscible displacement proceeds, the layered NMR signals at different positions change successively. Taking the core slice position of 0-8mm as an example, when the injection volume reaches 0.03PV, the layered NMR spectra at this slice position begin to change significantly, and the NMR signal with short relaxation time decreases significantly, while the NMR signal does not change much during the subsequent injection process. This shows that the gas drive front has affected the core 0-8mm position when the injection volume reaches 0.03PV. For other slice positions, as the displacement continues, the NMR signals from the injection end to the production end also change successively. The closer the slice signal is to the production end, the later it changes, which reflects the migration speed and dynamic migration process of the gas drive front moving forward.

[0087] See also Figures 6A-6E When the layered NMR spectra are plotted according to the displacement stage, the dynamic migration process of the displacement front will be more intuitive and obvious. At the same time, by calculating the change in the layered NMR signal at each slice position and each injection stage, the gas drive oil displacement efficiency at each slice position and each injection stage can be obtained. By comparing the oil displacement efficiency of different front migration characteristics, we can have a deeper understanding of the properties of the gas drive front, and then provide a certain reference for the formulation of the gas drive plan.

[0088] This is an optional but non-limiting implementation method, wherein the gas drive front of the target core is determined based on the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum, and the second layered nuclear magnetic resonance spectrum of the target core, and further includes but is not limited to steps F1-F3:

[0089] Step F1: Acquire a third nuclear magnetic resonance spectrum and a third layered nuclear magnetic resonance spectrum; wherein the third nuclear magnetic resonance spectrum and the third layered nuclear magnetic resonance spectrum are used to characterize the basement nuclear magnetic signal of the target core.

[0090] Step F2: determining the gas drive front physical property parameters of the target core according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum, the second layered nuclear magnetic resonance spectrum, the third nuclear magnetic resonance spectrum and the third layered nuclear magnetic resonance spectrum; the gas drive front physical property parameters include oil saturation, in-situ viscosity and reservoir wettability.

[0091] Step F3: Determine the gas drive front of the target core according to the gas drive front physical property parameters of the target core.

[0092] Among them, since the key physical parameters of the core can be obtained by using the traditional layered NMR spectrum based on the SE-SPI sequence, the layered NMR spectrum based on the CMPG sequence can also obtain the key physical parameters of the core, and the data obtained due to the difference in the sequence is more accurate. The physical parameters of the gas drive front include but are not limited to oil saturation, recovery degree, in-situ viscosity and reservoir wettability. The key physical parameters and recovery rate changes at the corresponding position of each core slice are obtained, and the key physical parameters at different positions of the core are accurately characterized, and the gas drive front can be dynamically and finely characterized indirectly through their changes.

[0093] In an optional scheme of an embodiment of the present invention, the in-situ viscosity of the target core is obtained through the first layer nuclear magnetic resonance spectrum, the second layer nuclear magnetic resonance spectrum and the third layer nuclear magnetic resonance spectrum of the target core. The viscosity of the crude oil in the target core is relatively large. During the gas displacement process, the gas will dissolve in the crude oil, and the crude oil will also be extracted by the gas. When the viscosity in the target core is reduced, it indicates that the gas and the crude oil are miscible, and the gas drive front of the target core can be determined when the viscosity in the target core is reduced.

[0094] Layered NMR spectra are used to obtain the key physical parameters and recovery rate changes at the corresponding positions of each core slice at different displacement stages. By accurately characterizing the key physical parameters at different positions of the core, the gas drive front can be dynamically and finely characterized indirectly through their changes.

[0095] In summary, both NMR spectra and layered NMR spectra have their own advantages. In actual production experimental applications, the gas drive front can be dynamically characterized quantitatively and qualitatively from multiple aspects through comprehensive analysis of NMR spectra and layered NMR spectra. By comparing the change patterns of the gas drive front and its key physical parameters under different injected gas media (except for gases with NMR signals such as hydrocarbon gases), injection and production methods, displacement pressures and injection rates, the corresponding gas drive front seepage mechanism can be obtained, which provides a reference for the formulation of later gas drive development plans for oil reservoirs and the selection of measures to enhance oil recovery.

[0096] An embodiment of the present invention provides a method for determining a core gas drive front, by obtaining a first nuclear magnetic resonance spectrum and a first layered nuclear magnetic resonance spectrum of a target core before being driven; wherein the layered nuclear magnetic resonance spectrum is obtained by obtaining nuclear magnetic resonance spectra of each core slice after the target core is layered; gas is driven on the target core to obtain a second nuclear magnetic resonance spectrum and a change in nuclear magnetic signal of the target core during the drive process; when it is detected that the change in the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change threshold, a second layered nuclear magnetic resonance spectrum of the target core is obtained; and the gas drive front of the target core is determined based on the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core. The technical solution of the embodiment of the present invention is adopted to dynamically monitor the miscible / immiscible displacement process of one-dimensional cores with different injected gas media under formation conditions in real time through low-field online nuclear magnetic resonance stratification technology. The dynamic and fine characterization of the gas drive front under microscopic conditions is achieved through the nuclear magnetic resonance spectrum obtained during the gas drive process; and the dynamic change law and seepage law of the gas drive front and its key physical parameters are analyzed in combination with the key injection and production parameters. It provides a basis for the design, optimization, dynamic tracking and adjustment of key parameters of the development plan, so as to achieve stable control of the oil and gas interface, slow down gas channeling, expand the injection swept volume and reduce the distribution of residual oil, further improve the crude oil recovery rate, and achieve the purpose of maximizing the development benefits.

[0097] Figure 7 is a schematic diagram of the structure of a core gas drive front determination device provided in an embodiment of the present invention, the device comprising: a first spectrum acquisition module 710, a gas displacement module 720, a second layered nuclear magnetic resonance spectrum acquisition module 730 and a core gas drive front determination module 740; wherein,

[0098] The first spectrum acquisition module 710 is used to acquire a first nuclear magnetic resonance spectrum of the target core before displacement and a first layered nuclear magnetic resonance spectrum; wherein the layered nuclear magnetic resonance spectrum is obtained by layering the target core and acquiring the nuclear magnetic resonance spectrum of each core slice;

[0099] A gas displacement module 720 is used to perform gas displacement on the target core and obtain a second nuclear magnetic resonance spectrum and a change amount of nuclear magnetic resonance signal of the target core during the displacement process;

[0100] The second layered nuclear magnetic resonance spectrum acquisition module 730 is used to acquire the second layered nuclear magnetic resonance spectrum of the target core when it is detected that the change amount of the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change amount threshold;

[0101] The core gas drive front determination module 740 is used to determine the gas drive front of the target core according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core.

[0102] Based on the above embodiment, optionally, the first atlas acquisition module includes:

[0103] The first core is dried, vacuumed and saturated with first simulated formation water to obtain a second core, and a third nuclear magnetic resonance spectrum and a third layered nuclear magnetic resonance spectrum of the second core are obtained; wherein the first simulated formation water is prepared by distilled water;

[0104] The second core is dried, vacuumed and saturated with second simulated formation water to obtain a third core; wherein the second simulated formation water is prepared by heavy water;

[0105] The formation crude oil is injected into the third core to obtain the target core.

[0106] Based on the above embodiment, optionally, the first atlas acquisition module includes:

[0107] Dividing the target core into at least two core slices;

[0108] The layered nuclear magnetic resonance spectra of the at least two core slices are respectively obtained to determine the first layered nuclear magnetic resonance spectrum of the target core before displacement.

[0109] Based on the above embodiment, optionally, the gas displacement module includes:

[0110] Obtaining a preset gas for gas displacement of the target core; the preset gas includes carbon dioxide and nitrogen that do not contain nuclear magnetic resonance signals;

[0111] The formation crude oil in the target core is displaced by a preset gas, and the second nuclear magnetic resonance spectrum, nuclear magnetic signal change and injection and production parameters of the target core during the displacement process are obtained in real time; wherein the injection and production parameters include injection and production pressure, injection and production gas and liquid volume and injection and production speed.

[0112] Based on the above embodiment, optionally, the second layered NMR spectrum acquisition module includes:

[0113] Detecting the change in the nuclear magnetic signal of the target rock core to determine whether the change in the nuclear magnetic signal of the target rock core is greater than a preset nuclear magnetic signal change threshold;

[0114] If the change in the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change threshold, a second layer nuclear magnetic resonance spectrum of the target core is obtained.

[0115] Based on the above embodiment, optionally, the core gas drive front determination module includes:

[0116] Analyze the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum, and the second layered nuclear magnetic resonance spectrum of the target core to determine spectrum analysis results;

[0117] The gas drive front of the target core is determined based on the spectrum analysis results.

[0118] Based on the above embodiment, optionally, the core gas drive front determination module further includes:

[0119] Obtaining a third nuclear magnetic resonance spectrum and a third layered nuclear magnetic resonance spectrum of the second core; wherein the third nuclear magnetic resonance spectrum and the third layered nuclear magnetic resonance spectrum are used to characterize the basement signal of the target core;

[0120] Determining the gas drive front physical property parameters of the target core according to the first nuclear magnetic resonance spectrum, the first layer nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum, the second layer nuclear magnetic resonance spectrum, the third nuclear magnetic resonance spectrum and the third layer nuclear magnetic resonance spectrum; the gas drive front physical property parameters include oil saturation, in-situ viscosity and reservoir wettability;

[0121] The gas drive front of the target core is determined according to the physical property parameters of the gas drive front of the target core.

[0122] The core gas drive front determination device provided in the embodiment of the present invention can execute the core gas drive front determination method provided in any embodiment of the present invention, and has the corresponding functions and beneficial effects of executing the core gas drive front determination method. For detailed process, please refer to the relevant operations of the core gas drive front determination method in the aforementioned embodiment.

[0123] Figure 8 1 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. The electronic device 10 is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0124] like Figure 8 As shown, the electronic device 10 includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0125] A number of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0126] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as a core gas drive front determination method.

[0127] In some embodiments, the core gas drive front determination method may be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the core gas drive front determination method described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to execute the core gas drive front determination method in any other appropriate manner (e.g., by means of firmware).

[0128] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0129] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0130] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0131] To provide interaction with a user, the systems and techniques described herein may be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0132] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0133] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0134] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0135] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining a core gas flooding front, characterized in that: The method comprises: Obtaining a first nuclear magnetic resonance spectrum and a first layered nuclear magnetic resonance spectrum of the target core before displacement; wherein the layered nuclear magnetic resonance spectrum is obtained by layering the target core and obtaining nuclear magnetic resonance spectra of each core slice; Performing gas displacement on the target core, and obtaining a second nuclear magnetic resonance spectrum and a change in nuclear magnetic resonance signal of the target core during the displacement process; When it is detected that the change amount of the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change amount threshold, a second layer nuclear magnetic resonance spectrum of the target core is obtained; The gas drive front of the target core is determined according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core.

2. The method according to claim 1, characterized in that Before obtaining the first nuclear magnetic resonance spectrum and the first layered nuclear magnetic resonance spectrum of the target core before displacement, the method includes: The first core is dried, vacuumed and saturated with first simulated formation water to obtain a second core, and a third nuclear magnetic resonance spectrum and a third layered nuclear magnetic resonance spectrum of the second core are obtained; wherein the first simulated formation water is prepared by distilled water; The second core is dried, vacuumed and saturated with second simulated formation water to obtain a third core; wherein the second simulated formation water is prepared by heavy water; The formation crude oil is injected into the third core to obtain the target core.

3. The method according to claim 1, characterized in that: The method of obtaining the first layer nuclear magnetic resonance spectrum of the target core before displacement includes: Dividing the target core into at least two core slices; The layered nuclear magnetic resonance spectra of the at least two core slices are respectively obtained to determine the first layered nuclear magnetic resonance spectrum of the target core before displacement.

4. The method according to claim 1, characterized in that The gas displacement of the target core and obtaining a second nuclear magnetic resonance spectrum and a change in nuclear magnetic signal of the target core during the displacement process include: Obtaining a preset gas for gas displacement of the target core; the preset gas includes carbon dioxide and nitrogen that do not contain nuclear magnetic resonance signals; The formation crude oil in the target core is displaced by a preset gas, and the second nuclear magnetic resonance spectrum, nuclear magnetic signal change and injection and production parameters of the target core during the displacement process are obtained in real time; wherein the injection and production parameters include injection and production pressure, injection and production gas and liquid volume and injection and production speed.

5. The method according to claim 1, characterized in that When it is detected that the change amount of the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change amount threshold, obtaining a second layered nuclear magnetic resonance spectrum of the target core includes: Detecting the change in the nuclear magnetic signal of the target rock core to determine whether the change in the nuclear magnetic signal of the target rock core is greater than a preset nuclear magnetic signal change threshold; If the change in the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change threshold, a second layer nuclear magnetic resonance spectrum of the target core is obtained.

6. The method according to claim 1, characterized in that The method of determining the gas drive front of the target core according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core comprises: Analyze the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum, and the second layered nuclear magnetic resonance spectrum of the target core to determine spectrum analysis results; The gas drive front of the target core is determined based on the spectrum analysis results.

7. The method according to claim 2, characterized in that The method of determining the gas drive front of the target core according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core further includes: Obtaining a third nuclear magnetic resonance spectrum and a third layered nuclear magnetic resonance spectrum; wherein the third nuclear magnetic resonance spectrum and the third layered nuclear magnetic resonance spectrum are used to characterize the basement nuclear magnetic signal of the target core; Determining the gas drive front physical property parameters of the target core according to the first nuclear magnetic resonance spectrum, the first layer nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum, the second layer nuclear magnetic resonance spectrum, the third nuclear magnetic resonance spectrum and the third layer nuclear magnetic resonance spectrum; the gas drive front physical property parameters include oil saturation, in-situ viscosity and reservoir wettability; The gas drive front of the target core is determined according to the physical property parameters of the gas drive front of the target core.

8. A core gas drive front determination device, characterized in that: The device comprises: A first spectrum acquisition module is used to acquire a first nuclear magnetic resonance spectrum and a first layered nuclear magnetic resonance spectrum of the target core before displacement; wherein the layered nuclear magnetic resonance spectrum is obtained by layering the target core and acquiring the nuclear magnetic resonance spectrum of each core slice; A gas displacement module, used for performing gas displacement on the target core and obtaining a second nuclear magnetic resonance spectrum and a change amount of nuclear magnetic resonance signal of the target core during the displacement process; A second layered nuclear magnetic resonance spectrum acquisition module is used to acquire a second layered nuclear magnetic resonance spectrum of the target core when it is detected that the change amount of the nuclear magnetic signal of the target core is greater than a preset nuclear magnetic signal change amount threshold; The core gas drive front determination module is used to determine the gas drive front of the target core according to the first nuclear magnetic resonance spectrum, the first layered nuclear magnetic resonance spectrum, the second nuclear magnetic resonance spectrum and the second layered nuclear magnetic resonance spectrum of the target core.

9. An electronic device, characterized in that: include: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the core gas drive front determination method as described in any one of claims 1-7.

10. A storage medium containing computer executable instructions, characterized in that: The computer executable instructions are used to execute the core gas drive front determination method as claimed in any one of claims 1 to 7 when executed by a computer processor.

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