Tight reservoir gas-bearing characteristic simulation equipment and gas-bearing section evaluation method

Abstract

The invention discloses tight reservoir gas-bearing characteristic simulation equipment and a gas-bearing section evaluation method. The method comprises the steps that a nuclear magnetic imaging system in tight reservoir gas-bearing characteristic simulation equipment measures first nuclear magnetic imaging maps at different heights of a whole rock core, and the first nuclear magnetic imaging maps are inverted and superposed to form a first nuclear magnetic imaging inversion superposition map; a geothermal simulation system in tight reservoir gas-bearing characteristic simulation equipment controls a heating coil to heat a hydrocarbon generation section of a rock core, a water cooling system is started to keep the temperature of the heating coil constant, and a nuclear magnetic imaging system measures second nuclear magnetic imaging maps at different heights of a tight section of the rock core according to preset time intervals; carrying out inversion and superposition to form a second nuclear magnetic imaging inversion superposition graph; and performing comparative analysis on the first nuclear magnetic imaging inversion superimposed graph and the second nuclear magnetic imaging inversion superimposed graph at different time to obtain a gas-bearing characteristic change result of the core tight reservoir. The migration path and the enrichment rule of the hydrocarbon substances in the rock can be accurately depicted, and the method has important guiding significance on actual exploration.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration technology, and in particular to a device for simulating the gas-bearing characteristics of tight reservoirs and a method for evaluating gas-bearing sections. Background Technology

[0002] Tight sandstone gas, as an important natural gas resource, is one of the main sources of oil and gas extraction. Tight reservoirs are characterized by low porosity, low permeability, and strong heterogeneity. The logging response characteristics corresponding to gas layers are complex, making gas layer identification, prediction, and evaluation difficult and resulting in high extraction costs. Currently, the comprehensive prediction technology for gas-bearing properties of tight reservoirs in the oil and gas exploration field usually relies on the obvious characteristics of "low-frequency resonance and high-frequency attenuation" in gas-bearing sections of time-domain seismic data. It utilizes techniques such as sensitive attribute analysis, wavelet decomposition, and reconstruction to predict the gas-bearing range of multiple gas-bearing sections in the extraction area. Summary of the Invention

[0003] Existing comprehensive prediction technologies for gas-bearing properties in tight reservoirs require processing large amounts of seismic data. This complex data processing leads to a complicated and inaccurate overall prediction process, resulting in high costs and a lack of economic practicality. Therefore, accurately predicting the gas-bearing characteristics of tight reservoirs while reducing extraction costs has become a pressing issue.

[0004] In view of the above problems, the present invention is proposed to provide a tight reservoir gas-bearing characteristic simulation device and a gas-bearing section evaluation method to overcome or at least partially solve the above problems.

[0005] In a first aspect, embodiments of the present invention provide a tight reservoir gas-bearing characteristic simulation device, comprising: a gas-bearing characteristic simulation system, a core moving stage, a core containing device, a heating coil, a water circulation device, and a magnet coil;

[0006] The gas-bearing characteristic simulation system is used to control the moving height of the core moving stage to change the nuclear magnetic resonance imaging area of ​​the core sample, control the heating temperature of the core sample on the core moving stage and maintain the core sample temperature constant, and measure the nuclear magnetic resonance imaging spectrum of the core sample. The nuclear magnetic resonance imaging spectrum is inverted and superimposed into a nuclear magnetic resonance imaging inversion superimposed image to obtain the gas-bearing characteristic simulation results of the core sample.

[0007] The core moving stage is movably disposed within the core receiving device to change the height of the core sample placed on the core moving stage; the core receiving device is a hollow structure used to receive the core and to limit the position of the core.

[0008] Heating coils are evenly arranged at the lower end of the core container to provide a heat source to the core sample;

[0009] A water circulation device is installed above the heating coil to maintain a constant temperature for the core sample;

[0010] The magnet coil is positioned above the water circulation device to provide a magnetic field environment for the core sample.

[0011] In some optional embodiments, the above-mentioned tight reservoir gas-bearing characteristic simulation device further includes: a mobile stage base;

[0012] A heat insulation pad is provided on the base of the moving platform to isolate the temperature between the heating coil and the base of the moving platform;

[0013] When not in operation, the core moving stage is located on the moving stage base.

[0014] In some alternative embodiments, the gas-bearing feature simulation system includes: a power system, an nuclear magnetic resonance imaging system, a geothermal simulation system, and a water cooling system;

[0015] The power system is connected to the core moving stage and is used to control the core moving stage to move the core sample in the core container.

[0016] The nuclear magnetic resonance imaging system is connected to a magnet coil to control the magnetic field environment of the core sample and to measure the nuclear magnetic resonance imaging spectrum of the core sample. The nuclear magnetic resonance imaging spectrum is inverted and superimposed into a nuclear magnetic resonance imaging inversion superimposed image to obtain the simulation results of the gas-bearing characteristics of the core sample.

[0017] The geothermal simulation system is connected to a heating coil, which is used to control the heating coil to provide a heat source to the core sample placed on the core moving platform;

[0018] The water cooling system is connected to a water circulation device to control the water circulation system and maintain a constant temperature for the core sample.

[0019] In some optional embodiments, the above-mentioned tight reservoir gas-bearing characteristic simulation device further includes: a control device;

[0020] The control device controls the power system, nuclear magnetic resonance imaging system, geothermal simulation system and water cooling system in the gas-bearing characteristic simulation system to perform corresponding control actions;

[0021] The nuclear magnetic resonance imaging system also includes an imaging display for displaying nuclear magnetic resonance imaging spectra and nuclear magnetic resonance imaging inversion overlay maps of core samples.

[0022] Secondly, embodiments of the present invention provide a method for evaluating the gas-bearing section of a tight reservoir, the method being implemented based on a tight reservoir gas-bearing characteristic simulation device, including:

[0023] The nuclear magnetic resonance imaging system in the tight reservoir gas-bearing characteristics simulation equipment measures the first nuclear magnetic resonance imaging spectrum at different heights of the whole core, inverts the first nuclear magnetic resonance imaging spectrum at different heights and superimposes it into the first nuclear magnetic resonance imaging inversion superimposed image.

[0024] The geothermal simulation system in the tight reservoir gas-bearing characteristic simulation equipment controls the heating coil to heat to a preset temperature and heats the hydrocarbon-generating section of the core. The water cooling system is turned on to keep the core temperature constant. The nuclear magnetic resonance imaging system measures the second nuclear magnetic resonance imaging spectrum at different heights of the tight section of the core multiple times at preset time intervals. The second nuclear magnetic resonance imaging spectrum at different heights is inverted and superimposed to form a second nuclear magnetic resonance imaging inversion superimposed image, thus obtaining second nuclear magnetic resonance imaging inversion superimposed images at different times.

[0025] By comparing and analyzing the first NMR imaging inversion overlay image with the second NMR imaging inversion overlay images at different times, the results of changes in gas-bearing characteristics of tight reservoirs in the core were obtained.

[0026] In some optional embodiments, determining the first nuclear magnetic resonance imaging (NMR) spectrum at different heights of the whole core includes:

[0027] The control device in the tight reservoir gas-bearing characteristics simulation equipment controls the power system to move the core moving platform from the bottom to the top.

[0028] During the movement of the core station, the nuclear magnetic resonance imaging system is controlled to determine the first nuclear magnetic resonance imaging spectrum of the core at a specified measurement height, and the measurement height of the dense section is recorded to obtain the first nuclear magnetic resonance imaging spectrum at different heights.

[0029] In some optional embodiments, controlling the heating coil to heat to a preset temperature and heating the hydrocarbon generation section of the core includes:

[0030] The geothermal simulation system controls the heating coils to heat to a preset temperature;

[0031] The power system controls the core moving platform to move until it is level with the upper end of the hydrocarbon generation section of the core and the upper end of the heating coil, and the current position of the core moving platform is recorded as the heating position;

[0032] The heating coil heats the hydrocarbon generation section of the core according to the preset heating time.

[0033] In some optional embodiments, second nuclear magnetic resonance imaging (NMR) spectra at different heights of the compact section of the core are measured at preset time intervals, including:

[0034] The control device in the tight reservoir gas-bearing characteristics simulation equipment controls the power system to move the core moving platform from the heating position to the top.

[0035] During the movement, the second nuclear magnetic resonance imaging (NMR) spectra of the compact section of the core were measured at different measurement heights to obtain the second NMR spectra of the compact section at different heights, and the core moving stage was lowered to the heating position.

[0036] After waiting for the preset time interval, the step of controlling the power system to move the core moving stage from the heating position to the top is executed again until the second nuclear magnetic resonance imaging spectrum at different heights of the measured compact section no longer changes.

[0037] In some optional embodiments, the superposition of a first MRI inversion overlay image includes:

[0038] According to the measured height order, the first nuclear magnetic resonance imaging spectra at different heights after inversion are stitched together to obtain the first nuclear magnetic resonance imaging inversion superimposed image;

[0039] The superimposed image of the second nuclear magnetic resonance imaging inversion includes:

[0040] According to the measured height sequence, the second nuclear magnetic resonance imaging spectra at different heights after inversion are stitched together to obtain the second nuclear magnetic resonance imaging inversion superimposed image.

[0041] In some optional embodiments, the first NMR imaging inversion overlay image and the second NMR imaging inversion overlay images measured at different time intervals are compared and analyzed to obtain the results of changes in the gas-bearing characteristics of the core tight reservoir, including:

[0042] By comparing and analyzing the first NMR imaging inversion overlay map and the second NMR imaging inversion overlay map measured at different times according to the lateral relaxation time, the results of the changes in the enrichment area of ​​hydrocarbons in the dense section of the core were obtained.

[0043] By comparing and analyzing the first NMR imaging inversion overlay image with the second NMR imaging inversion overlay image measured at different times according to the longitudinal relaxation time, the migration path of hydrocarbons in the dense section of the core was obtained.

[0044] In some optional embodiments, the above-described method for evaluating gas-bearing sections of tight reservoirs further includes:

[0045] Based on the results of changes in gas-bearing characteristics of tight reservoirs from core samples and actual geological data, combined with the influence range of fracturing, the optimal exploitation location for tight reservoirs was determined.

[0046] This invention provides a computer storage medium storing computer-executable instructions, which, when executed by a processor, implement a method for evaluating gas-bearing sections of tight reservoirs.

[0047] This invention provides a terminal device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements a method for evaluating gas-bearing sections of tight reservoirs.

[0048] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0049] The tight reservoir gas-bearing characteristic simulation device in this embodiment of the invention includes a gas-bearing characteristic simulation system, a core moving stage, a core containing device, a heating coil, a water circulation device, and a magnetic coil. The core moving stage, core containing device, heating coil, water circulation device, and magnetic coil provide the necessary conditions for the simulation experiment, supporting the smooth conduct of the tight reservoir gas-bearing characteristic simulation experiment. Under the control of the control device, the gas-bearing characteristic simulation system can measure the nuclear magnetic resonance (NMR) spectra at different heights of the core. Based on these NMR spectra, the gas-bearing characteristics of the tight reservoir in the core can be further analyzed and studied. Compared with existing sensitive attribute analysis, wavelet decomposition, and reconstruction techniques, this device significantly reduces the measurement process, enabling the prediction of gas-bearing sections in tight reservoirs using a single device. This reduces prediction costs and provides accurate measurement results, providing data support for the optimal development layers of deep tight reservoirs and has practical guiding significance.

[0050] The method for evaluating gas-bearing sections of tight reservoirs provided in this invention is based on a tight reservoir gas-bearing characteristic simulation device. The device uses a nuclear magnetic resonance (NMR) imaging system to measure first NMR images at different heights of the entire core sample. These first NMR images at different heights are then inverted and superimposed to form a first NMR inversion overlay image. This overlay image serves as a reference, laying the foundation for subsequent research on the enrichment and migration patterns of hydrocarbons in tight reservoirs. The geothermal simulation system within the tight reservoir gas-bearing characteristic simulation device controls the heating coils to a preset temperature. As the burial depth increases, the temperature and pressure of the rock rise. To ensure that the rock temperature is consistent with the underground burial depth, the heating coils are used to heat the hydrocarbon-generating section of the rock. After heating for a period of time, a water-cooling system is activated to maintain a constant temperature in the core sample above the heating coils. If the temperature is not kept constant, the rock temperature will gradually decrease, which is inconsistent with the underground burial depth, thus making the measurement results inaccurate.

[0051] Heating coils heat the hydrocarbon-generating sections of the core. The hydrocarbon-generating potential of these sections represents the rock's hydrocarbon expulsion capacity. Heating the hydrocarbon-generating sections causes the generated gas to continuously migrate towards the tight sections as the temperature changes. Studying the trend of hydrocarbon content changes during this migration provides data support for determining the optimal layer. The nuclear magnetic resonance (NMR) imaging system repeatedly measures the second NMR spectra at different heights within the tight sections of the core at preset time intervals. The NMR spectra at different heights are then inverted and superimposed to form a second NMR inversion overlay, resulting in inversion overlays at different times. Since the rock undergoes a heat transfer process during heating, measuring the second NMR spectra at regular intervals allows for the analysis and evaluation of the degree of hydrocarbon accumulation in the actual tight reservoir as the depth of the hydrocarbon-generating site increases and the geothermal temperature rises. This provides guidance for establishing a parameter conversion model of "thermal evolution-hydrocarbon migration path," inferring the hydrocarbon content of the tight reservoir, and identifying effective extraction locations.

[0052] Finally, by comparing and analyzing the first NMR imaging inversion overlay map with the second NMR imaging inversion overlay maps at different times, the changes in gas-bearing characteristics of the core tight reservoir were obtained. By comparing and analyzing the first NMR imaging inversion overlay map obtained without heating and the second NMR imaging inversion overlay map obtained after heating, the migration path and enrichment area of ​​hydrocarbon gases emitted from the hydrocarbon generation furnace in the tight reservoir can be accurately depicted. The simulation results are accurate and can play a guiding role in actual exploration work, thereby improving the exploitation efficiency of tight reservoir gas reservoirs.

[0053] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0054] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0055] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0056] Figure 1 This is a structural diagram of the tight reservoir gas-bearing characteristic simulation device in Embodiment 1 of the present invention;

[0057] Figure 2 This is a detailed structural diagram of the tight reservoir gas-bearing characteristic simulation device in Embodiment 1 of the present invention;

[0058] Figure 3This is a flowchart of the gas-bearing section evaluation method for tight reservoirs in Embodiment 2 of the present invention;

[0059] Figure 4 This is a schematic diagram of the core sample in Embodiment 2 of the present invention;

[0060] Figure 5 This is an example diagram of the first nuclear magnetic resonance imaging spectrum in Embodiment 2 of the present invention. Detailed Implementation

[0061] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0062] To address the problems of complex and inaccurate prediction of gas-bearing properties in tight reservoirs in existing technologies, embodiments of the present invention provide a device for simulating the gas-bearing characteristics of tight reservoirs and a method for evaluating gas-bearing sections.

[0063] Example 1

[0064] Embodiment 1 of the present invention provides a device for simulating the gas-bearing characteristics of tight reservoirs, the schematic diagram of which is shown below. Figure 1 As shown, it includes: a gas-bearing characteristic simulation system 1, a core moving platform 2, a core containing device 3, a heating coil 4, a water circulation device 5, and a magnet coil 6;

[0065] The gas-bearing characteristic simulation system is used to control the moving height of the core moving stage to change the nuclear magnetic resonance imaging area of ​​the core sample, control the heating temperature of the core sample on the core moving stage and maintain the core sample temperature constant, and measure the nuclear magnetic resonance imaging spectrum of the core sample. The nuclear magnetic resonance imaging spectrum is inverted and superimposed into a nuclear magnetic resonance imaging inversion superimposed image to obtain the gas-bearing characteristic simulation results of the core sample.

[0066] The core moving stage is movably installed inside the core receiving device to change the height of the core sample placed on the core moving stage; the core receiving device has a hollow structure to hold the core and limit its position.

[0067] Heating coils are evenly arranged at the lower end of the core container to provide a heat source to the core sample;

[0068] A water circulation device is installed above the heating coil to maintain a constant temperature for the core sample;

[0069] The magnet coil is positioned above the water circulation device to provide a magnetic field environment for the core sample.

[0070] The temperature of rocks increases with increasing underground burial depth. The gas-bearing characteristic simulation system in the tight reservoir gas-bearing characteristic simulation equipment of this invention can perform thermal evolution on core samples, simulating the underground burial temperature of rock strata, making the rock strata in the core samples closer to the actual formation, thus simulating more accurate results. This simulation equipment can study the degree of hydrocarbon accumulation in tight rock reservoirs as the formation depth increases and the formation temperature rises, analyze and evaluate the enrichment patterns of hydrocarbons in actual tight reservoirs, and provide data support for the optimal development layers of deep tight reservoirs.

[0071] Optionally, the above-mentioned tight reservoir gas-bearing characteristic simulation equipment also includes: a mobile stage base 7;

[0072] A heat insulation pad 8 is provided on the base of the moving platform to isolate the temperature between the heating coil and the base of the moving platform;

[0073] When not in operation, the core moving stage is located on the moving stage base.

[0074] The heating coil is located at the lower end of the core container. When the heating coil is used to heat the core sample, excessive heating temperature may damage the moving stage base. Therefore, a heat insulation pad is installed on the core moving stage to prevent excessive temperature from damaging the moving stage base.

[0075] Optionally, the gas-bearing characteristic simulation system in the above-mentioned tight reservoir gas-bearing characteristic simulation equipment includes: a power system 11, a nuclear magnetic resonance imaging system 14, a geothermal simulation system 12, and a water cooling system 13;

[0076] The power system is connected to the core moving stage and is used to control the core moving stage to move the core sample in the core container.

[0077] The nuclear magnetic resonance imaging system is connected to a magnet coil to control the magnetic field environment of the core sample and to measure the nuclear magnetic resonance imaging spectrum of the core sample. The nuclear magnetic resonance imaging spectrum is inverted and superimposed into a nuclear magnetic resonance imaging inversion superimposed image to obtain the simulation results of the gas-bearing characteristics of the core sample.

[0078] The geothermal simulation system is connected to a heating coil, which is used to control the heating coil to provide a heat source to the core sample placed on the core moving stage;

[0079] The water cooling system is connected to a water circulation device to control the water circulation system and maintain a constant temperature for the core sample.

[0080] The power system in the gas-bearing characteristic simulation system provides power to the core moving stage, enabling the stage to move the core. The power system can be an electric motor or a mechanical motor; no specific limitation is made in this embodiment. The nuclear magnetic resonance (NMR) imaging system controls the magnet coil to provide a stable and uniform magnetic field environment for the core and measures the NMR spectrum during core movement, ensuring the accuracy of the measured NMR signals of hydrocarbons in the core. From the measured NMR spectrum, the simulated gas-bearing characteristics of the core can be accurately observed. These gas-bearing characteristics are essentially the hydrocarbons in the rock. The nuclear magnetic resonance (NMR) signal response characteristics of hydrogen ions during transport; the geothermal system provides a heat source for the thermal evolution of the core sample, keeping the core sample at the formation temperature at the underground burial depth, making the rock strata closer to the real rock strata, and ensuring the accuracy of the measurement results; the water cooling system can maintain a constant temperature of the core sample. When the rock is buried underground, the temperature change of the formation is not too large. Therefore, after heating the core sample, it is necessary to control the water cooling system to maintain a constant temperature of the rock in order to conduct accurate simulation and obtain the hydrogen ion NMR signal response characteristics that change with the transport of hydrocarbons in the dense strata.

[0081] Optionally, the above-mentioned gas-containing characteristic simulation system further includes: a control device 9;

[0082] The control device controls the power system, nuclear magnetic resonance imaging system, geothermal simulation system and water cooling system in the gas-bearing characteristic simulation system to perform corresponding control actions;

[0083] The nuclear magnetic resonance imaging system also includes an imaging display for displaying nuclear magnetic resonance imaging spectra and nuclear magnetic resonance imaging inversion overlay maps of core samples.

[0084] The control device can control the operation of the tight reservoir gas-bearing characteristic simulation equipment to successfully complete the determination of the nuclear magnetic resonance imaging spectrum of the core sample, obtain the gas-bearing characteristic simulation results of the tight reservoir, and determine the trend of hydrocarbon content in the tight reservoir based on the gas-bearing characteristic simulation results. Thus, based on the actual geological conditions, the enrichment characteristics of hydrocarbons in the tight reservoir can be analyzed, and finally, a data foundation is laid for determining the effective exploitable strata of the tight reservoir.

[0085] The imaging display in the nuclear magnetic resonance imaging system can show the nuclear magnetic resonance imaging spectrum, which shows the enrichment and migration path of hydrocarbons in the sample.

[0086] For a detailed structural diagram of the tight reservoir gas-bearing characteristic simulation device in this embodiment, please refer to [link / reference]. Figure 2As shown, the control device controls the nuclear magnetic resonance imaging system, the water cooling system, the geothermal simulation system, and the power system. The nuclear magnetic resonance imaging system is connected to the magnet coil and controls the magnet coil to provide a stable and uniform magnetic field environment for the rock core. The water cooling system is connected to the water circulation device to maintain the temperature of the rock core in the rock core container. The geothermal simulation system is connected to the heating coil and controls the heating coil to provide a heat source for the rock core. The power system is connected to the moving platform base and controls the rock core moving platform to move the rock core.

[0087] Example 2

[0088] This invention provides a method for evaluating the gas-bearing section of a tight reservoir. This method is implemented based on the tight reservoir gas-bearing characteristic simulation equipment described in Embodiment 1. The flowchart is shown below. Figure 3 As shown, it includes the following steps:

[0089] Step S201: The nuclear magnetic resonance imaging system in the tight reservoir gas-bearing characteristic simulation equipment measures the first nuclear magnetic resonance imaging spectrum at different heights of the whole core, inverts the first nuclear magnetic resonance imaging spectrum at different heights and superimposes it into the first nuclear magnetic resonance imaging inversion superimposed image;

[0090] Step S202: The geothermal simulation system in the tight reservoir gas-bearing characteristic simulation equipment controls the heating coil to heat to the preset temperature and heats the hydrocarbon generation section of the core. The water cooling system is turned on to keep the core temperature constant. The nuclear magnetic resonance imaging system measures the second nuclear magnetic resonance imaging spectrum at different heights of the tight section of the core multiple times at preset time intervals. The second nuclear magnetic resonance imaging spectrum at different heights is inverted and superimposed to form the second nuclear magnetic resonance imaging inversion superimposed image, thus obtaining the second nuclear magnetic resonance imaging inversion superimposed image at different times.

[0091] Step S203: Compare and analyze the first NMR imaging inversion overlay image and the second NMR imaging inversion overlay images at different times to obtain the results of changes in gas-bearing characteristics of the core tight reservoir.

[0092] The tight reservoir gas-bearing characteristic simulation equipment provided in this embodiment can simulate the environment of a core buried underground. Using this equipment, the tight reservoir gas-bearing section evaluation method in embodiment two can be implemented. It can simulate the gas-bearing characteristics of the tight reservoir core, measure the hydrogen ion nuclear magnetic resonance signal response characteristics of the tight strata as hydrocarbons migrate, determine the trend of hydrocarbon content change in the tight reservoir, analyze and infer the hydrocarbon enrichment characteristics based on the actual geological conditions, and clarify the effective exploitation location of the tight reservoir, providing strong technical support for the comprehensive prediction of gas content in tight reservoirs.

[0093] When taking core samples using this method, the sampling area needs to be selected based on the stratigraphic distribution, hydrocarbon generation site distribution, and tight reservoir thickness in the development area. Continuous columnar core samples can be taken, and the length and cross-sectional diameter of the samples need to be selected according to requirements, such as a cross-section of 25mm-26mm and a length of 100mm-105mm. The size of the core samples also needs to match the core container to ensure that the core samples can move smoothly within the core container under the movement of the core moving platform. However, when the core sampling size cannot meet the length requirements, multiple discontinuous columnar samples can be taken and arranged in the stratigraphic distribution order, then placed sequentially in the core container.

[0094] Optionally, in step S101 above, determining the first nuclear magnetic resonance imaging (NMR) spectrum at different heights of the entire core includes:

[0095] The control device in the tight reservoir gas-bearing characteristics simulation equipment controls the power system to move the core moving platform from the bottom to the top.

[0096] During the movement of the core station, the nuclear magnetic resonance imaging system is controlled to determine the first nuclear magnetic resonance imaging spectrum of the core at a specified measurement height, and the measurement height of the dense section is recorded to obtain the first nuclear magnetic resonance imaging spectrum at different heights.

[0097] See the schematic diagram of the core sample. Figure 4 As shown, the hydrocarbon-generating section of the core is located at the lower end of the tight section. Under the influence of geothermal temperature, hydrocarbons in the hydrocarbon-generating section will migrate to the tight reservoir under the expansion force of hydrocarbon generation. The tight section will be enriched with the gas generated by the hydrocarbon-generating section. Only by identifying the high-quality gas-bearing section in the tight section can the optimal mining location of the rock strata be determined and the resource extraction rate of the source rock be improved.

[0098] Before determining the first NMR image, the core sample needs to be processed. This may include drying the sample to remove internal moisture. The drying temperature can be 100℃, and the drying time can be 48 hours. Depending on the specific core sample, the processing should be carried out according to the actual situation until the internal moisture of the rock is removed. During the determination of the first NMR image, the control device controls the power system to provide power to the core moving stage, moving the core sample from the bottom to the top. During the movement, the first NMR image of the core at a specified height is measured. At this time, the entire core needs to be measured. After the measurement is completed, the first NMR images of the core at different heights are obtained. The gas-bearing characteristics at each specified height can be determined based on the color differences on the NMR images.

[0099] Figure 5 This is an example of the first NMR image without heating the core. Figure 5The image shows the first nuclear magnetic resonance (NMR) images at three different altitudes, from top to bottom. Based on the color changes in the images, the distribution of pores and fluids within the rock can be determined. Figure 5 The distribution of nanopores and macropores in the core, as well as the distribution of hydrocarbons in kerogen and nanopores, are shown. Fluid flows out through the pores in the core. Different fluid components are distributed in different areas on the first NMR imaging spectrum. A larger distribution area and higher signal intensity indicate a higher proportion of the fluid component in the pores, corresponding to higher saturation. In the first NMR imaging spectrum, the NMR curve can characterize the distribution of hydrocarbons expelled from the hydrocarbon-generating section. (See [reference needed]). Figure 5 As shown in the cumulative curve, the curve under the horizontal relaxation time can clearly identify the enrichment region of hydrocarbons in the horizontal direction, and the curve under the vertical relaxation time can clearly identify the enrichment region of hydrocarbons in the vertical direction. The change of the curve can indicate the change of hydrocarbon content.

[0100] Optionally, in step S102 above, controlling the heating coil to heat to a preset temperature and heating the hydrocarbon-generating section of the core includes:

[0101] The geothermal simulation system controls the heating coils to heat to a preset temperature;

[0102] The power system controls the core moving platform to move until it is level with the upper end of the hydrocarbon generation section of the core and the upper end of the heating coil, and the current position of the core moving platform is recorded as the heating position;

[0103] The heating coil heats the hydrocarbon generation section of the core according to the preset heating time.

[0104] The preset heating temperature of the heating coil is set according to the pyrolysis temperature of the rock, for example, 220-240℃. The preset heating temperature varies depending on the region of the rock sample. The core moving stage is moved until the upper end of the hydrocarbon-generating section of the core is level with the upper end of the heating coil, heating the entire hydrocarbon-generating section. The height of the moving stage at this point is recorded as the heating position. When measuring the second NMR image, the core height needs to be moved from this heating position. After the preset heating time, the internal temperature of the core will change and undergo thermal evolution, at which point hydrocarbons will begin to migrate. The preset heating time needs to be adjusted according to the specific rock sample. In short, the preset temperature and preset heating time need to be set according to actual needs to ensure the conditions for NMR imaging of the rock. When measuring the second NMR image of the heated core, the water cooling system needs to be turned on. The water cooling system controls the water circulation device to keep the core warm, maintaining a constant temperature above the heating coil and improving measurement accuracy.

[0105] Optionally, in step S102 above, measuring the second nuclear magnetic resonance imaging spectrum at different heights of the compact section of the core at preset time intervals includes:

[0106] The control device in the tight reservoir gas-bearing characteristics simulation equipment controls the power system to move the core moving platform from the heating position to the top.

[0107] During the movement, the second nuclear magnetic resonance imaging (NMR) spectra of the compact section of the core were measured at different measurement heights to obtain the second NMR spectra of the compact section at different heights, and the core moving stage was lowered to the heating position.

[0108] After waiting for the preset time interval, the step of controlling the power system to move the core moving stage from the heating position to the top is executed again until the second nuclear magnetic resonance imaging spectrum at different heights of the measured compact section no longer changes.

[0109] After heating the core, the height of the core moving stage is adjusted from the heating position, and the second NMR spectrum of the compact section is measured at different heights. These different heights need to be consistent with the measurement height of the compact section of the core when it is not heated. After completing the measurement of the entire compact section, the second NMR spectrum of the compact section at different heights is obtained. The purpose of this is to compare it with the first NMR spectrum of the core when it is not heated, so as to more accurately analyze the changes in the content of hydrocarbons in the compact section of the core under the influence of temperature.

[0110] When determining the second NMR spectrum, multiple measurements are required at preset intervals. This is because the internal temperature of the core does not reach the heating temperature immediately upon heating; it is actually a thermal evolution process, thus requiring measurements at intervals. The underground temperature varies depending on the sampling point and depth of the core sample, so the preset interval can be adjusted as needed. For example, the preset interval could be 60-70 minutes. After each measurement, the moving stage is lowered to the heating position to continue heating, awaiting the next measurement. This process is repeated multiple times until the second NMR spectrum at different heights in the dense section no longer changes, indicating that the internal temperature of the core has reached the actual underground temperature at the burial depth and has fully reacted. Each measurement yields a second NMR spectrum at a different height; multiple measurements at preset time intervals produce second NMR spectra at different time points.

[0111] Optionally, in step S101 above, the process of superimposing the first nuclear magnetic resonance imaging inversion overlay image includes:

[0112] According to the measured height order, the first nuclear magnetic resonance imaging spectra at different heights after inversion are stitched together to obtain the first nuclear magnetic resonance imaging inversion superimposed image;

[0113] Optionally, in step S102 above, the superimposed second MRI inversion overlay image includes:

[0114] According to the measured height sequence, the second nuclear magnetic resonance imaging spectra at different heights after inversion are stitched together to obtain the second nuclear magnetic resonance imaging inversion superimposed image.

[0115] After measuring the first and second NMR images, they were inverted. Inverting the NMR images enhances image resolution, resulting in high-quality NMR images. After inverting the first NMR image, the images at different heights were stitched together in the order of measurement height to obtain a first NMR inversion overlay. This directly reflects the pore distribution at different heights in the unheated core state, thus allowing analysis of hydrocarbon content distribution. Similarly, after inverting the second NMR image for each measurement, the images at different heights were stitched together in the order of measurement height to obtain second NMR inversion overlays at different times. These second NMR inversion overlays at different times reflect the hydrocarbon migration changes in the core under heating conditions, manifested on the image as the NMR signal response characteristics of hydrogen ions, thereby clarifying the trend of hydrocarbon content changes in tight reservoirs.

[0116] Optionally, in step S103 above, the first NMR imaging inversion overlay image and the second NMR imaging inversion overlay images measured at different time intervals are compared and analyzed to obtain the results of changes in the gas-bearing characteristics of the core tight reservoir, including:

[0117] By comparing and analyzing the first NMR imaging inversion overlay map and the second NMR imaging inversion overlay map measured at different times according to the lateral relaxation time, the results of the changes in the enrichment area of ​​hydrocarbons in the dense section of the core were obtained.

[0118] By comparing and analyzing the first NMR imaging inversion overlay image with the second NMR imaging inversion overlay image measured at different times according to the longitudinal relaxation time, the migration path of hydrocarbons in the dense section of the core was obtained.

[0119] The first NMR inversion overlay image was measured from the core without heating, while the second NMR inversion overlay image was measured during the heating process. Comparing the first NMR inversion overlay image with the second NMR inversion overlay images measured at different times allows for accurate analysis of the trend of hydrocarbon content changes with temperature within the core. Specifically, by comparing the lateral relaxation time, the changes in hydrocarbon enrichment areas in the dense section of the core at different relaxation times can be analyzed. These enrichment areas also reflect changes in hydrocarbon content; areas with higher hydrocarbon content exhibit stronger hydrogen ion NMR response signals, indicating greater porosity on the spectrum. As heating time progresses, the trend of hydrocarbon content changes becomes increasingly clear. By comparing the longitudinal relaxation time, the migration paths of hydrocarbons in the dense section of the core can be analyzed. After heating the hydrocarbon-generating section... The generated gas migrates into the tight reservoir under the expansion force of hydrocarbon generation. As the longitudinal relaxation time changes, the migration path of hydrocarbons changes. Therefore, by comparing and analyzing the first NMR imaging inversion overlay and the second NMR imaging inversion overlay at different times, a parameter conversion model of "thermal evolution-hydrocarbon migration path" can be established. The simulation results of this model are accurate and can clearly define the migration law of hydrocarbons, providing data support for the optimal development layer of deep tight reservoirs and improving the accuracy of gas content prediction in tight reservoirs.

[0120] Optionally, the above-mentioned evaluation method for gas-bearing sections of tight reservoirs also includes:

[0121] Based on the results of changes in gas-bearing characteristics of tight reservoirs from core samples and actual geological data, combined with the influence range of fracturing, the optimal exploitation location for tight reservoirs was determined.

[0122] By comparing and analyzing the inversion overlay images from two types of nuclear magnetic resonance imaging, the changes in gas-bearing characteristics of tight reservoirs in the core were obtained. Based on this, and taking into account local conditions, actual geological data, and the impact range of fracturing, the most exploitable location of the tight reservoir can be identified. Through actual exploration verification, the gas-bearing section evaluation method of tight reservoirs in this embodiment was used to predict the gas content of tight reservoirs and determine the optimal exploitation location. The experimental results are accurate, and the effective exploitation location of tight reservoirs in the target exploration area can be quickly and effectively determined. The exploitation efficiency is high, and it has strong guiding significance for actual production.

[0123] This invention also provides a computer storage medium storing computer-executable instructions, which, when executed by a processor, provide the aforementioned method for evaluating gas-bearing sections of tight reservoirs.

[0124] This invention also provides a terminal device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-described method for evaluating gas-bearing sections of tight reservoirs.

[0125] Unless otherwise specifically stated, terms such as processing, calculation, operation, determination, display, etc., may refer to the actions and / or processes of one or more processing or computing systems or similar devices that represent the manipulation and conversion of data representing physical (e.g., electronic) quantities within the registers or memory of the processing system into other data similarly representing physical quantities within the memory, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0126] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0127] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0128] Those skilled in the art will also understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments herein can be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in alternative ways for each specific application; however, such implementation decisions should not be construed as departing from the scope of this disclosure.

[0129] The steps of the methods or algorithms described in conjunction with the embodiments herein can be directly embodied in hardware, software modules executed by a processor, or a combination thereof. The software modules can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can exist as discrete components in the user terminal.

[0130] For software implementation, the techniques described in this application can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. This software code can be stored in memory units and executed by a processor. The memory units can be implemented within the processor or outside the processor; in the latter case, they are communicatively coupled to the processor via various means, as is well known in the art.

[0131] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

Claims

1. A device for simulating the gas-bearing characteristics of tight reservoirs, characterized in that, include: Gas-bearing characteristic simulation system, core moving platform, core containing device, heating coil, water circulation device and magnet coil; The gas-bearing characteristic simulation system is used to control the moving height of the core moving stage to change the nuclear magnetic resonance imaging area of ​​the core sample, control the heating temperature of the core sample on the core moving stage and maintain the core sample temperature constant, and measure the nuclear magnetic resonance imaging spectrum of the core sample. The nuclear magnetic resonance imaging spectrum is inverted and superimposed into a nuclear magnetic resonance imaging inversion superimposed image to obtain the gas-bearing characteristic simulation results of the core sample. The core moving stage is movably disposed within the core receiving device to change the height of the core sample placed on the core moving stage; the core receiving device is a hollow structure used to receive the core and to limit the position of the core. The heating coils are evenly arranged at the lower end of the core receiving device to provide a heat source to the core sample; The water circulation device is located above the heating coil to maintain a constant temperature for the core sample. The magnet coil is positioned above the water circulation device to provide a magnetic field environment for the core sample.

2. The tight reservoir gas-bearing characteristic simulation device as described in claim 1, characterized in that, Also includes: Mobile platform base; A heat insulation pad is provided on the base of the moving platform to isolate the temperature between the heating coil and the base of the moving platform; When not in operation, the core moving stage is located on the moving stage base.

3. The tight reservoir gas-bearing characteristic simulation device as described in claim 1, characterized in that, The gas-bearing characteristic simulation system includes: a power system, a nuclear magnetic resonance imaging system, a geothermal simulation system, and a water cooling system; The power system is connected to the core moving stage and is used to control the core moving stage to move the core sample in the core containing device; The nuclear magnetic resonance imaging system is connected to a magnet coil to control the magnetic field environment of the core sample and to measure the nuclear magnetic resonance imaging spectrum of the core sample. The nuclear magnetic resonance imaging spectrum is inverted and superimposed into a nuclear magnetic resonance imaging inversion superimposed image to obtain the simulation results of the gas-bearing characteristics of the core sample. The geothermal simulation system is connected to a heating coil, which is used to control the heating coil to provide a heat source to the core sample placed on the core moving platform; The water cooling system is connected to a water circulation device and is used to control the water circulation system to maintain a constant temperature for the core sample.

4. The gas-bearing characteristic simulation system as described in claim 3, further comprising: Control device; The control device controls the power system, nuclear magnetic resonance imaging system, geothermal simulation system and water cooling system in the gas-bearing characteristic simulation system to perform corresponding control actions; The nuclear magnetic resonance imaging system further includes an imaging display for displaying nuclear magnetic resonance imaging spectra and nuclear magnetic resonance imaging inversion overlay images of the core sample.

5. A method for evaluating gas-bearing sections of tight reservoirs, characterized in that, Based on the tight reservoir gas-bearing characteristic simulation device according to any one of claims 1-4, including: The nuclear magnetic resonance imaging system in the tight reservoir gas-bearing characteristic simulation equipment measures the first nuclear magnetic resonance imaging spectrum at different heights of the whole core, inverts the first nuclear magnetic resonance imaging spectrum at different heights and superimposes it into a first nuclear magnetic resonance imaging inversion superimposed image. The geothermal simulation system in the tight reservoir gas-bearing characteristic simulation equipment controls the heating coil to heat the hydrocarbon generation section of the core to a preset temperature, and turns on the water cooling system to keep the core temperature constant. The nuclear magnetic resonance imaging system measures the second nuclear magnetic resonance imaging spectrum at different heights of the tight section of the core at preset time intervals, inverts the second nuclear magnetic resonance imaging spectrum at different heights and superimposes it into a second nuclear magnetic resonance imaging inversion superimposed image to obtain the second nuclear magnetic resonance imaging inversion superimposed image at different times. By comparing and analyzing the first NMR imaging inversion overlay image with the second NMR imaging inversion overlay images at different times, the results of changes in gas-bearing characteristics of tight reservoirs in the core were obtained.

6. The method as described in claim 5, characterized in that, The determination of the first nuclear magnetic resonance imaging spectrum at different heights of the whole core includes: The control device in the tight reservoir gas-bearing characteristics simulation equipment controls the power system to move the core moving platform from the bottom to the top. During the movement of the core station, the nuclear magnetic resonance imaging system is controlled to determine the first nuclear magnetic resonance imaging spectrum of the core at a specified measurement height, and the measurement height of the dense section is recorded to obtain the first nuclear magnetic resonance imaging spectrum at different heights.

7. The method as described in claim 5, characterized in that, Controlling the heating coil to heat to a preset temperature and heating the hydrocarbon generation section of the core includes: The geothermal simulation system controls the heating coil to heat to a preset temperature; The power system controls the core moving platform to move until it is level with the upper end of the hydrocarbon generation section of the core and the upper end of the heating coil, and records the current position of the core moving platform as the heating position; The heating coil heats the hydrocarbon generation section of the core according to a preset heating time.

8. The method as described in claim 6, characterized in that, The second nuclear magnetic resonance imaging (NMR) spectra at different heights in the compact section of the core were measured at preset time intervals, including: The control device in the tight reservoir gas-bearing characteristics simulation equipment controls the power system to move the core moving platform from the heating position to the top. During the movement, the second nuclear magnetic resonance imaging (NMR) spectra of the compact section of the core were measured at different measurement heights to obtain the second NMR spectra of the compact section at different heights, and the core moving stage was lowered to the heating position. After waiting for the preset time interval, the step of controlling the power system to move the core moving stage from the heating position to the top is executed again until the second nuclear magnetic resonance imaging spectrum at different heights of the measured compact section no longer changes.

9. The method as described in claim 5, characterized in that, The superimposed image is the first nuclear magnetic resonance imaging inversion superimposed image, including: According to the measured height order, the first nuclear magnetic resonance imaging spectra at different heights after inversion are stitched together to obtain the first nuclear magnetic resonance imaging inversion superimposed image; The superimposed image of the second nuclear magnetic resonance imaging inversion includes: According to the measured height sequence, the second nuclear magnetic resonance imaging spectra at different heights after inversion are stitched together to obtain the second nuclear magnetic resonance imaging inversion superimposed image.

10. The method as described in claim 5, characterized in that, By comparing and analyzing the first NMR imaging inversion overlay image with the second NMR imaging inversion overlay images measured at different time intervals, the changes in gas-bearing characteristics of the core tight reservoir were obtained, including: By comparing and analyzing the first NMR imaging inversion overlay map and the second NMR imaging inversion overlay map measured at different times according to the lateral relaxation time, the results of the changes in the enrichment area of ​​hydrocarbons in the dense section of the core were obtained. By comparing and analyzing the first NMR imaging inversion overlay image with the second NMR imaging inversion overlay image measured at different times according to the longitudinal relaxation time, the migration path of hydrocarbons in the dense section of the core was obtained.

11. The method as described in claim 5, characterized in that, Also includes: Based on the results of changes in gas-bearing characteristics of tight reservoirs from core samples and actual geological data, combined with the influence range of fracturing, the optimal exploitation location for tight reservoirs was determined.

12. A computer storage medium, characterized in that, The computer storage medium stores computer-executable instructions, which, when executed by a processor, implement the tight reservoir gas-bearing section evaluation method according to any one of claims 5-11.

13. A terminal device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method for evaluating gas-bearing sections of tight reservoirs as described in any one of claims 5-11.

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