Source rock hydrocarbon generation simulation experiment method

Abstract

The invention provides a hydrocarbon source rock hydrocarbon generation simulation experiment method. The method comprises the following steps: respectively testing the breakthrough pressure of a hydrocarbon source rock sample of a hydrocarbon fluid entering a target layer under the temperature and static rock pressure conditions corresponding to different thermal evolution stages, and respectively adding each measured breakthrough pressure with the static water pressure of the corresponding thermal evolution stage to obtain the hydrocarbon expulsion pressure of the different thermal evolution stages; based on a static rock pressure evolution history, a hydrostatic pressure evolution history and a formation temperature evolution history of a target layer and hydrocarbon expulsion pressures of different thermal evolution stages, determining a heating control parameter, a static rock pressure control parameter, a hydrocarbon expulsion pressure threshold and a hydrocarbon expulsion stop pressure threshold for continuous heating hydrocarbon generation simulation; and according to the determined temperature rise control parameter, static rock pressure control parameter, hydrocarbon expulsion pressure threshold and hydrocarbon expulsion stop pressure threshold, performing continuous temperature rise hydrocarbon generation simulation by using the hydrocarbon source rock sample of the target layer. The hydrocarbon source rock hydrocarbon generation simulation experiment method provided by the invention can accurately reflect the actual hydrocarbon generation condition.

Description

Technical Field

[0001] This invention relates to the field of hydrocarbon generation potential evaluation technology for source rocks, and in particular to a method for simulating hydrocarbon generation from source rocks. Background Technology

[0002] The hydrocarbon generation capacity and scale of source rocks are key to studying the resource potential of hydrocarbon-rich depressions. Some hydrocarbon-rich depressions are characterized by thick source rocks and deep burial in the core area. Research on the hydrocarbon generation capacity and scale of source rocks is inseparable from hydrocarbon generation simulation experiments.

[0003] Hydrocarbon generation simulation experiments under formation conditions are currently in their early stages. Classified by the heating process, they can be broadly categorized into stepwise heating hydrocarbon generation simulation experiments and single-sample continuous heating hydrocarbon generation simulation experiments. In stepwise heating hydrocarbon generation simulation experiments, each temperature point corresponds to one sample. Each sample is individually heated to its corresponding target temperature point in a single operation, and the product is collected. Stepwise heating hydrocarbon generation simulation experiments employ a heating method where multiple samples are heated to different temperature points separately, and a hydrocarbon expulsion pressure setting method that uses a fixed hydrocarbon expulsion pressure threshold or directly assigns a dynamic hydrocarbon expulsion pressure. Stepwise heating hydrocarbon generation simulation experiments are affected by the superposition of hydrocarbon generation processes. The products at high temperature points contain hydrocarbons that were not expelled during the oil generation stage, resulting in excessively high and distorted hydrocarbon production rates, making them unsuitable for direct production research. Therefore, at the current stage, single-sample continuous heating hydrocarbon generation simulation experiments are more commonly used. In a single-sample continuous-heat hydrocarbon generation simulation experiment, a single sample in the reactor is continuously heated to multiple (e.g., nine) temperature points, with a dynamic hydrocarbon expulsion pressure set at each stage of the heating process. During the sample heating process, hydrocarbon expulsion begins when the expulsion pressure is reached, and collection and analysis are performed at a constant temperature once the target temperature is reached. This single-sample continuous-heat hydrocarbon generation simulation experiment effectively solves the key problem of overlapping hydrocarbon generation processes. The experiment employs a single-sample continuous heating method and a fixed hydrocarbon expulsion pressure threshold or a fixed hydrocarbon expulsion pressure coefficient setting.

[0004] In hydrocarbon generation simulation experiments, hydrocarbon expulsion pressure is a crucial parameter. Existing single-sample continuous heating hydrocarbon generation simulation experiments often use a fixed hydrocarbon expulsion pressure or a fixed hydrocarbon expulsion pressure coefficient. However, the evolution of source rocks to the stage of high-volume gas generation is usually accompanied by a hydrocarbon generation and expulsion environment with great burial depth and high confining pressure. Using a fixed hydrocarbon expulsion pressure or a fixed hydrocarbon expulsion pressure coefficient will result in a higher hydrocarbon expulsion pressure than the actual natural gas expulsion pressure during the highly mature stage of the source rock (Ro>1.3%). This leads to ineffective hydrocarbon gas expulsion and a lower gas generation rate assessment, thus distorting the experimental results.

[0005] With the deepening of exploration and development and the advancement of hydrocarbon generation simulation technology, traditional step-by-step heating hydrocarbon generation simulation experiments and single-sample continuous heating hydrocarbon generation simulation experiments can no longer meet the needs of resource evaluation in oil and gas basins. Therefore, it is necessary to study hydrocarbon generation simulation experiments that can more accurately reflect actual hydrocarbon generation conditions, providing effective support for determining the true hydrocarbon generation capacity of source rocks and guiding resource evaluation in hydrocarbon-rich depressions. Summary of the Invention

[0006] The purpose of this invention is to provide a hydrocarbon generation simulation experiment technical solution that can accurately reflect actual hydrocarbon generation conditions.

[0007] To achieve the above objectives, the present invention provides a method for simulating hydrocarbon generation from source rocks, the method comprising:

[0008] Obtain source rock samples of the target layer and the evolution history of static rock pressure, hydrostatic pressure, and formation temperature (i.e., static rock pressure, hydrostatic pressure, and formation temperature of the target layer at different thermal evolution stages).

[0009] Using source rock samples from the target layer, the breakthrough pressure of hydrocarbon fluids entering the source rock samples of the target layer was tested under temperature and static pressure (i.e., confining pressure) corresponding to different thermal evolution stages. The measured breakthrough pressures were added to the hydrostatic pressure of the corresponding thermal evolution stage to obtain the hydrocarbon expulsion pressure of different thermal evolution stages. The type of hydrocarbon fluid was determined according to whether the corresponding thermal evolution stage was in the oil generation stage or the gas generation stage. If the corresponding thermal evolution stage was in the oil generation stage, the type of hydrocarbon fluid was liquid-phase hydrocarbon fluid; if the corresponding thermal evolution stage was in the gas generation stage, the type of hydrocarbon fluid was gas-phase hydrocarbon fluid.

[0010] Based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, the heating control parameters, static rock pressure (i.e., confining pressure) control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion cessation pressure threshold for continuous heating hydrocarbon generation simulation of source rock samples from the target layer are determined. Then, according to the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion cessation pressure threshold, continuous heating hydrocarbon generation simulation is performed using source rock samples from the target layer.

[0011] According to the preferred implementation of the simulation experiment method for hydrocarbon generation from source rocks, the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer can be determined, but is not limited to, by the Eton method in basin simulation technology.

[0012] According to a preferred embodiment of the hydrocarbon generation simulation experiment method for source rocks, the breakthrough pressure for testing hydrocarbon fluids entering the target layer of the source rock sample includes:

[0013] Hydrocarbon source rock samples from the target layer were processed into plunger samples;

[0014] The plunger sample was subjected to simulated formation water saturation in the target layer under the conditions of target temperature and static rock pressure (i.e. confining pressure). Then, hydrocarbon fluid was used as the displacement medium to displace the plunger sample. The inlet pressure when the hydrocarbon fluid invaded the source rock sample of the target layer and reached a stable state was determined as the breakthrough pressure of the hydrocarbon fluid entering the source rock sample of the target layer.

[0015] More preferably, the diameter of the plunger sample is 1-2 inches, for example 1.5 inches;

[0016] More preferably, the plunger sample is subjected to salt washing treatment before the target layer is simulated to be saturated with formation water;

[0017] More preferably, the ingress pressure of the hydrocarbon source rock sample when the hydrocarbon fluid invades the target layer and reaches a stable state is determined by the resistance method.

[0018] According to the preferred embodiment of the hydrocarbon generation simulation experiment method of source rock, if the corresponding thermal evolution stage is in the oil generation stage, the type of hydrocarbon fluid is liquid phase hydrocarbon fluid, and the hydrocarbon fluid is selected as oil produced from the target layer or simulated oil produced from the target layer.

[0019] According to the preferred embodiment of the hydrocarbon generation simulation experiment method of source rock, if the corresponding thermal evolution stage is in the gas generation stage, the type of hydrocarbon fluid is gaseous hydrocarbon fluid, and the hydrocarbon fluid is the gas produced from the target layer or the simulated gas produced from the target layer.

[0020] According to the preferred implementation method of the hydrocarbon generation simulation experiment method for source rocks, the heating control parameters, static pressure (i.e., confining pressure) control parameters, hydrocarbon generation pressure threshold, and hydrocarbon expulsion pressure at different thermal evolution stages of the target layer are determined based on the evolution history of static rock pressure, static water pressure, formation temperature, and hydrocarbon generation pressure of the source rock sample in the target layer for continuous heating hydrocarbon generation simulation. These parameters include:

[0021] Based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, the static rock pressure, hydrostatic pressure, and hydrocarbon expulsion pressure corresponding to different formation temperatures of the target layer are determined.

[0022] Based on the formation temperature evolution history of the target layer, the heating control parameters for continuous heating hydrocarbon generation simulation of source rock samples from the target layer were determined.

[0023] The static rock pressure corresponding to different formation temperatures in the target layer is used as the static rock pressure (i.e., confining pressure) at each temperature during the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer, thereby determining the control parameters of static rock pressure (i.e., confining pressure) for the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer.

[0024] The hydrocarbon expulsion pressure corresponding to different formation temperatures in the target layer is used as the hydrocarbon expulsion pressure threshold for each temperature during the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer, thereby determining the hydrocarbon expulsion pressure threshold for the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer.

[0025] The hydrostatic pressure corresponding to different formation temperatures in the target layer is used as the hydrocarbon expulsion stop pressure threshold for each temperature during the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer, thereby determining the hydrocarbon expulsion stop pressure threshold for the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer.

[0026] More preferably, the heating control parameters include the heating rate at different stages, the target temperature, and the isothermal time at the target temperature.

[0027] According to a preferred embodiment of the hydrocarbon generation simulation experiment method using source rock, the continuous heating hydrocarbon generation simulation using source rock samples from the target layer, based on the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, includes:

[0028] The source rock sample was placed in the source rock hydrocarbon generation simulation experimental device, and then the source rock sample of the target layer was heated according to the determined heating control parameters. During the heating process, static rock pressure (containment pressure) was applied to the source rock sample of the target layer according to the static rock pressure control parameters.

[0029] During the heating process, the pore pressure of the source rock sample of the target layer at each temperature is monitored in real time. When the pore pressure of the source rock sample of the target layer reaches the corresponding hydrocarbon discharge pressure threshold at that temperature, the source rock sample of the target layer is kept constant at the current temperature and static rock pressure (containment pressure) and the hydrocarbon discharge valve is opened to discharge hydrocarbons from the source rock sample of the target layer. The hydrocarbon discharge valve is closed to stop the hydrocarbon discharge when the pore pressure of the source rock sample of the target layer drops to the hydrocarbon discharge stop pressure threshold, and the subsequent heating process is continued according to the determined heating control parameters.

[0030] More preferably, according to the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, the continuous heating hydrocarbon generation simulation using source rock samples from the target layer further includes: in the hydrocarbon expulsion step of the source rock samples from the target layer, collecting and measuring the oil and gas expelled from the source rock samples from the target layer; more preferably, the gas expelled from the source rock samples from the target layer is collected using the saturated brine method.

[0031] More preferably, according to the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, the continuous heating hydrocarbon generation simulation using source rock samples from the target layer also includes: performing a sealing test and gas washing on the source rock hydrocarbon generation simulation experimental device before placing the source rock samples in the source rock hydrocarbon generation simulation experimental device.

[0032] The technical solution provided by this invention better restores the actual hydrocarbon-generating strata conditions of source rocks, accurately reflects the actual hydrocarbon generation situation, and provides effective support for determining the true hydrocarbon generation capacity of source rocks and guiding resource evaluation in hydrocarbon-rich depression areas.

[0033] Compared with the prior art, the technical solution provided by the present invention has the following superior effects:

[0034] 1. The technical solution provided by this invention utilizes the breakthrough pressure of hydrocarbon fluids entering the source rock sample of the target layer under different temperature and static pressure conditions corresponding to different thermal evolution stages, and the hydrostatic pressure at different thermal evolution stages, to determine the hydrocarbon expulsion pressure at different thermal evolution stages. This determination guides the continuous heating hydrocarbon generation simulation process, achieving dynamic control of the hydrocarbon expulsion pressure throughout the entire continuous heating hydrocarbon generation simulation. The technical solution provided by this invention establishes hydrocarbon expulsion pressures under different temperature and pressure environments and uses these to guide the hydrocarbon generation simulation process. Compared to traditional hydrocarbon generation simulation experiments with fixed hydrocarbon expulsion pressures or fixed hydrocarbon expulsion pressure coefficients, this approach more closely approximates real formation conditions. Combined with the continuous heating experimental process, it effectively solves the problem of ineffective expulsion of highly flammable gas under fixed hydrocarbon expulsion pressures or fixed hydrocarbon expulsion pressure coefficients in hydrocarbon generation simulation experiments.

[0035] 2. The technical solution provided by this invention is a single-sample continuous heating hydrocarbon generation simulation experiment based on breakthrough pressure detection and basin evolution history simulation constraints. It can effectively solve the defects of traditional hydrocarbon generation simulation experiments, such as overlapping hydrocarbon generation processes and single pressure settings, and can effectively solve the problems of gas emission distortion and inconsistency with actual formation conditions. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating the determination of hydrocarbon discharge pressure in Embodiment 1 of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below. Here, the illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0038] This invention provides a method for simulating hydrocarbon generation from source rocks, the method comprising:

[0039] Step S101: Obtain source rock samples of the target layer and the evolution history of static rock pressure, hydrostatic pressure, and formation temperature (i.e., static rock pressure, hydrostatic pressure, and formation temperature of the target layer at different thermal evolution stages).

[0040] Step S102: Using source rock samples from the target layer, test the breakthrough pressure of hydrocarbon fluids entering the source rock samples of the target layer under temperature and static pressure (i.e., confining pressure) corresponding to different thermal evolution stages. Add the measured breakthrough pressures to the hydrostatic pressure of the corresponding thermal evolution stage to obtain the hydrocarbon expulsion pressure of different thermal evolution stages. The type of hydrocarbon fluid is determined according to whether the corresponding thermal evolution stage is in the oil generation stage or the gas generation stage. If the corresponding thermal evolution stage is in the oil generation stage, the type of hydrocarbon fluid is liquid-phase hydrocarbon fluid; if the corresponding thermal evolution stage is in the gas generation stage, the type of hydrocarbon fluid is gas-phase hydrocarbon fluid.

[0041] Step S1013: Based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, determine the heating control parameters, static rock pressure (i.e., confining pressure) control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold for continuous heating hydrocarbon generation simulation of source rock samples from the target layer; and use source rock samples from the target layer to perform continuous heating hydrocarbon generation simulation according to the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold.

[0042] Furthermore, the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer can be determined, but is not limited to, using the Eton method in basin simulation technology.

[0043] Furthermore, the breakthrough pressure for testing hydrocarbon fluids entering source rock samples from the target layer includes:

[0044] Hydrocarbon source rock samples from the target layer were processed into plunger samples;

[0045] The plunger sample was subjected to simulated formation water saturation in the target layer under target temperature and static rock pressure (i.e., confining pressure). Then, hydrocarbon fluid was used as the displacement medium to displace the plunger sample. The inlet pressure at which the hydrocarbon fluid invaded the source rock sample in the target layer and reached a stable state was determined as the breakthrough pressure of the hydrocarbon fluid entering the source rock sample in the target layer.

[0046] Furthermore, the diameter of the plunger is 1-2 inches, for example, 1.5 inches.

[0047] Furthermore, the plunger samples were subjected to salt washing treatment before the target layer was simulated to be saturated with formation water.

[0048] Furthermore, the ingress pressure of the hydrocarbon source rock sample when the hydrocarbon fluid invades into the target layer and reaches a stable state was determined by the resistance method.

[0049] Furthermore, if the corresponding thermal evolution stage is in the oil generation stage, the hydrocarbon fluid type is liquid-phase hydrocarbon fluid, and the hydrocarbon fluid selected is the oil produced from the target layer or a simulated oil produced from the target layer.

[0050] Furthermore, if the corresponding thermal evolution stage is in the gas generation stage, the hydrocarbon fluid type is gaseous hydrocarbon fluid, and the hydrocarbon fluid selected is the target layer produced gas or a simulated gas of the target layer produced gas.

[0051] Furthermore, based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, the following parameters are determined for continuous heating and hydrocarbon generation simulation of source rock samples from the target layer: heating control parameters, static rock pressure (i.e., confining pressure) control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion cessation pressure threshold.

[0052] Based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, the static rock pressure, hydrostatic pressure, and hydrocarbon expulsion pressure corresponding to different formation temperatures of the target layer are determined.

[0053] Based on the formation temperature evolution history of the target layer, the heating control parameters for continuous heating hydrocarbon generation simulation of source rock samples from the target layer were determined.

[0054] The static rock pressure corresponding to different formation temperatures in the target layer is used as the static rock pressure (i.e., confining pressure) at each temperature during the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer, thereby determining the control parameters of static rock pressure (i.e., confining pressure) for the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer.

[0055] The hydrocarbon expulsion pressure corresponding to different formation temperatures in the target layer is used as the hydrocarbon expulsion pressure threshold for each temperature during the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer, thereby determining the hydrocarbon expulsion pressure threshold for the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer.

[0056] The hydrostatic pressure corresponding to different formation temperatures in the target layer is used as the hydrocarbon expulsion stop pressure threshold for each temperature during the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer, thereby determining the hydrocarbon expulsion stop pressure threshold for the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer.

[0057] Furthermore, the heating control parameters include the heating rate at different stages, the target temperature, and the isothermal time at the target temperature.

[0058] Furthermore, based on the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, continuous heating hydrocarbon generation simulations were performed using source rock samples from the target layer, including:

[0059] The source rock sample was placed in the source rock hydrocarbon generation simulation experimental device, and then the source rock sample of the target layer was heated according to the determined heating control parameters. During the heating process, static rock pressure (containment pressure) was applied to the source rock sample of the target layer according to the static rock pressure control parameters.

[0060] During the heating process, the pore pressure of the source rock sample of the target layer at each temperature is monitored in real time. When the pore pressure of the source rock sample of the target layer reaches the corresponding hydrocarbon discharge pressure threshold at that temperature, the source rock sample of the target layer is kept constant at the current temperature and static rock pressure (containment pressure) and the hydrocarbon discharge valve is opened to discharge hydrocarbons from the source rock sample of the target layer. The hydrocarbon discharge valve is closed to stop the hydrocarbon discharge when the pore pressure of the source rock sample of the target layer drops to the hydrocarbon discharge stop pressure threshold, and the subsequent heating process is continued according to the determined heating control parameters.

[0061] Furthermore, according to the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, the continuous heating hydrocarbon generation simulation using source rock samples from the target layer also includes: in the hydrocarbon expulsion step of the source rock samples from the target layer, collecting and measuring the oil and gas expelled from the source rock samples from the target layer.

[0062] Furthermore, the gas emitted from the source rock sample of the target layer was collected using the saturated brine discharge method;

[0063] Furthermore, based on the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, the continuous heating hydrocarbon generation simulation using source rock samples from the target layer also includes: analyzing the oil and gas expelled from the source rock samples of the target layer.

[0064] Furthermore, according to the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure, and hydrocarbon expulsion stop pressure, the continuous heating hydrocarbon generation simulation using source rock samples from the target layer also includes: performing a sealing test and gas washing on the source rock hydrocarbon generation simulation experimental device before placing the source rock samples in the source rock hydrocarbon generation simulation experimental device.

[0065] Example 1

[0066] A method for simulating hydrocarbon generation from source rocks, the method comprising:

[0067] 1. Obtain source rock samples from the target layer.

[0068] 2. A small number of source rock samples from the target layer were taken, and rock pyrolysis was performed to determine the vitrinite reflectance (Ro) and total organic carbon (TOC) content of the source rock samples from the target layer. Organic petrological observations were also conducted. The source rock samples from the target layer were grayish-black mudstone and shale, with the organic microstructure mainly consisting of layered algae. The vitrinite reflectance (Ro) was 0.54%, indicating a low-maturity thermal evolution stage, and the organic matter type was type II1.

[0069] 3. The evolution history of static rock pressure, hydrostatic pressure, and formation temperature was determined using the Eton method in basin simulation technology.

[0070] 4. Take one sample of source rock from the target layer and process it into a 1.5-inch diameter plunger sample by wire cutting. The plunger sample is then subjected to salt washing treatment. Using the plunger sample after salt washing treatment, the breakthrough pressure of hydrocarbon fluid entering the source rock sample of the target layer is tested under the temperature and static rock pressure (i.e., confining pressure) corresponding to different thermal evolution stages. The measured breakthrough pressures are added to the hydrostatic pressure of the corresponding thermal evolution stage to obtain the hydrocarbon expulsion pressure of different thermal evolution stages.

[0071] The type of hydrocarbon fluid is determined based on whether the corresponding thermal evolution stage is in the oil generation stage or the gas generation stage: if the corresponding thermal evolution stage is in the oil generation stage, the type of hydrocarbon fluid is liquid-phase hydrocarbon fluid, and the hydrocarbon fluid is selected from the target layer to produce oil; if the corresponding thermal evolution stage is in the gas generation stage, the type of hydrocarbon fluid is gas-phase hydrocarbon fluid, and the hydrocarbon fluid is selected from the target layer to produce gas.

[0072] The breakthrough pressure test for hydrocarbon fluid entering the source rock sample of the target layer includes: saturating the plunger sample with simulated formation water (mineralization of 20,000 ppm) in the target layer under target temperature and static rock pressure (i.e., confining pressure), then using hydrocarbon fluid as the displacement medium to displace the plunger sample, and determining the ingress pressure when the hydrocarbon fluid enters the source rock sample of the target layer and reaches a stable state using the resistance method as the breakthrough pressure for hydrocarbon fluid entering the source rock sample of the target layer.

[0073] Among them, the determination of hydrocarbon expulsion pressure is as follows: Figure 1 As shown; Figure 1 In the diagram, curve A represents the static rock pressure evolution history curve of the target layer, serving as the static rock pressure (i.e., confining pressure) during the breakthrough pressure test; curve B represents the hydrostatic pressure evolution history curve of the target layer; curve C represents the breakthrough pressure curves obtained from different thermal evolution stages; and calibration point D represents the hydrocarbon expulsion pressure at a certain thermal evolution stage, which is equal to the hydrostatic pressure of the thermal evolution stage plus the breakthrough pressure. The thermal evolution stage corresponding to calibration point D is in the oil generation stage, with a formation depth of approximately 3000m, a static rock pressure of 60MPa, and a breakthrough pressure of 7MPa.

[0074] 5. Based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, determine the heating control parameters, static rock pressure (i.e., confining pressure) control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion cessation pressure threshold for continuous heating hydrocarbon generation simulation of source rock samples from the target layer. Specifically, this includes:

[0075] Based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, the static rock pressure, hydrostatic pressure, and hydrocarbon expulsion pressure corresponding to different formation temperatures of the target layer are determined.

[0076] Based on the formation temperature evolution history of the target layer, the heating control parameters for continuous heating hydrocarbon generation simulation of source rock samples of the target layer were determined. The heating control parameters include the heating rate, target temperature and isothermal time at the target temperature point at different stages. Taking the first stage as an example, the heating rate is 1℃ / min, the temperature is increased from room temperature of 20℃ to the target temperature of 40℃, and the isothermal time at the target temperature point is 48h.

[0077] The static rock pressure corresponding to different formation temperatures in the target layer is used as the static rock pressure (i.e., confining pressure) at each temperature during the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer, thereby determining the control parameters of static rock pressure (i.e., confining pressure) for the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer.

[0078] The hydrocarbon expulsion pressure corresponding to different formation temperatures in the target layer is used as the hydrocarbon expulsion pressure threshold for each temperature during the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer, thereby determining the hydrocarbon expulsion pressure threshold for the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer.

[0079] The hydrostatic pressure corresponding to different formation temperatures in the target layer is used as the hydrocarbon expulsion stop pressure threshold for each temperature during the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer, thereby determining the hydrocarbon expulsion stop pressure threshold for the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer.

[0080] 6. Based on the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, conduct continuous heating hydrocarbon generation simulation using source rock samples from the target layer. This specifically includes:

[0081] The remaining sample after wire cutting in step 4 is coarsely crushed into small pieces with a diameter of 0.5cm-1cm to obtain coarsely crushed samples. The coarsely crushed samples are placed in a hydrocarbon source rock generation simulation experimental device, and nitrogen gas is introduced into the device to a pressure of not less than 10 MPa. Then, deionized water is injected to a pressure of not less than 50 MPa. The device is then tested for sealing. If the pressure in the device remains unchanged for 30 minutes, the device is considered to have passed the sealing test. Otherwise, the device is reset and the sealing test is repeated. After the device has passed the sealing test, the coarsely crushed samples are removed from the device. The device is then evacuated to a pressure below 0.05 MPa and then filled with nitrogen for gas washing.

[0082] Take an appropriate amount of source rock sample and place it in the source rock hydrocarbon generation simulation experimental device after gas washing. Then, heat the source rock sample of the target layer according to the determined heating control parameters. During the heating process, apply static rock pressure (containment pressure) to the source rock sample of the target layer according to the static rock pressure control parameters.

[0083] During the heating process, the pore pressure of the source rock sample in the target layer is monitored in real time at each temperature. When the pore pressure of the source rock sample in the target layer reaches the corresponding hydrocarbon expulsion pressure threshold at that temperature, the source rock sample in the target layer is kept constant at the current temperature and static rock pressure (containment pressure), and the hydrocarbon expulsion valve is opened to expel hydrocarbons from the source rock sample in the target layer. The oil and gas expelled from the source rock sample in the target layer are collected and measured until the pore pressure of the source rock sample in the target layer decreases to the hydrocarbon expulsion stop pressure threshold. At this point, the hydrocarbon expulsion valve is closed to stop hydrocarbon expulsion, and the subsequent heating process continues according to the determined heating control parameters. Among these processes, the gas expelled from the source rock sample in the target layer is collected using the saturated brine method.

[0084] The oil and gas collected from each hydrocarbon expulsion were subjected to chromatographic analysis, and the organic carbon (TOC) and vitrinite reflectance (Ro) of the solid residue of the final source rock sample were determined by rock pyrolysis.

[0085] Experimental results show that the source rock samples of the target layer are mainly oil-generating with weak gas generation potential, and the gas is mostly concentrated in the range of hydrocarbons retained within the source layer, which is consistent with the actual oil and gas exploration status of the target layer. The method provided in this embodiment improves the retained hydrocarbon yield by 24% compared to traditional single-sample source rock continuous heating hydrocarbon generation simulation experiments, with a maximum gas production rate of 220 mg / g TOC. Compared to traditional single-sample source rock continuous heating hydrocarbon generation simulation experiments with a fixed hydrocarbon expulsion pressure coefficient, the peak gas production rate is increased by 175%. Compared to traditional single-sample source rock continuous heating hydrocarbon generation simulation experiments with a fixed hydrocarbon expulsion pressure, the total gas production rate is increased by 12%. The experimental results are consistent with the discovery of tight gas in the target layer, effectively confirming the scientific validity of the technical solution provided by this invention.

[0086] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for simulating hydrocarbon generation from source rocks, the method comprising: Obtain source rock samples and hydrostatic pressure evolution history, hydrostatic pressure evolution history, and formation temperature evolution history of the target layer; Using source rock samples from the target layer, the breakthrough pressure of hydrocarbon fluids entering the source rock samples of the target layer was tested under temperature and hydrostatic pressure conditions corresponding to different thermal evolution stages. The measured breakthrough pressures were added to the hydrostatic pressure of the corresponding thermal evolution stage to obtain the hydrocarbon expulsion pressure of different thermal evolution stages. The type of hydrocarbon fluid was determined according to whether the corresponding thermal evolution stage was in the oil generation stage or the gas generation stage. If the corresponding thermal evolution stage was in the oil generation stage, the type of hydrocarbon fluid was liquid-phase hydrocarbon fluid; if the corresponding thermal evolution stage was in the gas generation stage, the type of hydrocarbon fluid was gas-phase hydrocarbon fluid. Based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, the heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold for continuous heating hydrocarbon generation simulation of source rock samples from the target layer are determined. Then, according to the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, continuous heating hydrocarbon generation simulation is performed using source rock samples from the target layer.

2. The method according to claim 1, wherein, The breakthrough pressures for testing hydrocarbon fluids entering source rock samples from the target layer include: Hydrocarbon source rock samples from the target layer were processed into plunger samples; The plunger sample was subjected to simulated formation water saturation in the target layer under target temperature and static rock pressure conditions. Then, hydrocarbon fluid was used as the displacement medium to displace the plunger sample. The inlet pressure at which the hydrocarbon fluid invaded the source rock sample in the target layer and reached a stable state was determined as the breakthrough pressure of the hydrocarbon fluid entering the source rock sample in the target layer.

3. The method according to claim 2, wherein, The plunger sample was subjected to salt washing treatment before the formation water saturation of the target layer was simulated.

4. The method according to claim 2, wherein, The ingress pressure of a hydrocarbon fluid entering a source rock sample in the target layer and reaching a stable state was determined using the resistance method.

5. The method according to claim 1 or 2, wherein, If the corresponding thermal evolution stage is in the oil generation stage, the hydrocarbon fluid type is liquid-phase hydrocarbon fluid, and the hydrocarbon fluid is selected from the target layer produced oil or simulated oil produced from the target layer. If the corresponding thermal evolution stage is in the gas generation stage, the hydrocarbon fluid type is gaseous hydrocarbon fluid, and the hydrocarbon fluid selected is the produced gas from the target layer or the simulated gas produced from the target layer.

6. The method according to claim 1, wherein, Based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, the following parameters are determined for continuous heating and hydrocarbon generation simulation of source rock samples from the target layer: heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion cessation pressure threshold. Based on the evolution history of static rock pressure, hydrostatic pressure, and formation temperature of the target layer, as well as the hydrocarbon expulsion pressure at different thermal evolution stages, the static rock pressure, hydrostatic pressure, and hydrocarbon expulsion pressure corresponding to different formation temperatures of the target layer are determined. Based on the formation temperature evolution history of the target layer, the heating control parameters for continuous heating hydrocarbon generation simulation of source rock samples from the target layer were determined. The static rock pressure corresponding to different formation temperatures in the target layer is used as the static rock pressure corresponding to each temperature during the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer, so as to determine the static rock pressure control parameter for the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer. The hydrocarbon expulsion pressure corresponding to different formation temperatures in the target layer is used as the hydrocarbon expulsion pressure threshold for each temperature during the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer, thereby determining the hydrocarbon expulsion pressure threshold for the continuous heating hydrocarbon generation simulation of the source rock sample in the target layer. The hydrostatic pressure corresponding to different formation temperatures in the target layer is used as the hydrocarbon expulsion stop pressure threshold for each temperature during the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer, thereby determining the hydrocarbon expulsion stop pressure threshold for the continuous heating hydrocarbon generation simulation of the source rock samples in the target layer.

7. The method according to claim 6, wherein, The heating control parameters include the heating rate at different stages, the target temperature, and the isothermal time at the target temperature.

8. The method according to claim 1 or 6, wherein, Based on the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, continuous heating hydrocarbon generation simulation was performed using source rock samples from the target layer, including: The source rock sample was placed in the source rock hydrocarbon generation simulation experimental device, and then the source rock sample of the target layer was heated according to the determined heating control parameters. During the heating process, static rock pressure was applied to the source rock sample of the target layer according to the static rock pressure control parameters. During the heating process, the pore pressure of the source rock sample of the target layer at each temperature is monitored in real time. When the pore pressure of the source rock sample of the target layer reaches the corresponding hydrocarbon discharge pressure threshold at that temperature, the source rock sample of the target layer is kept constant at the current temperature and static rock pressure conditions, and the hydrocarbon discharge valve is opened to discharge hydrocarbons from the source rock sample of the target layer. The hydrocarbon discharge valve is closed to stop the hydrocarbon discharge when the pore pressure of the source rock sample of the target layer drops to the hydrocarbon discharge stop pressure threshold, and the subsequent heating process is continued according to the determined heating control parameters.

9. The method according to claim 8, wherein, According to the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, the continuous heating hydrocarbon generation simulation using source rock samples from the target layer also includes: in the hydrocarbon expulsion step of the source rock samples from the target layer, collecting and measuring the oil and gas expelled from the source rock samples from the target layer.

10. The method according to claim 8, wherein, According to the determined heating control parameters, static rock pressure control parameters, hydrocarbon expulsion pressure threshold, and hydrocarbon expulsion stop pressure threshold, the continuous heating hydrocarbon generation simulation using source rock samples from the target layer also includes: performing a sealing test and gas washing on the source rock hydrocarbon generation simulation experimental device before placing the source rock samples in the source rock hydrocarbon generation simulation experimental device.

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