A device and method for modeling diagenesis across tectonic periods

Abstract

The application discloses a kind of cross-tectonic period diagenesis simulation device and method.The device includes fluid driving system, reaction solution supply system and at least two groups of tectonic period reaction system connected in sequence, and different reaction systems are used to simulate the temperature and pressure conditions when geological fluid passes through each target layer during cross-tectonic period.The method first restores the geological conditions when geological fluid passes through each target layer during cross-tectonic period according to petrology and geochemistry analysis, combined with tectonic evolution history, burial history and fluid injection history, establishes cross-tectonic period diagenesis model, determines geological fluid type, and then determines the process of geological stress driving high-pressure layer fluid to migrate to low-pressure layer, restores the geological conditions when geological fluid passes through each target layer during cross-tectonic period;According to the restored geological process and geological conditions, the forward simulation of fluid dissolution, cementation, metasomatism and other diagenesis during cross-tectonic period is carried out by using cross-tectonic period diagenesis simulation device.Provide basis for judging the diagenetic mechanism of reservoir rock after high temperature and high pressure and multi-stage tectonic evolution.

Description

Technical Field

[0001] This invention relates to the field of geological experimental technology, and in particular to a device and method for simulating diagenesis across tectonic periods. Background Technology

[0002] In recent years, my country's oil and gas exploration targets have rapidly expanded from shallow to deep and ultra-deep layers, and resource types have shifted from conventional to unconventional. Adopting more efficient and economical methods to exploit these resources is an inevitable trend. Exploration practice shows that deep oil and gas reservoirs, due to the superimposed alteration of multiple diagenetic processes under deep burial, high temperature, and high pressure, present exceptionally difficult challenges in porosity analysis. Therefore, studying the mechanisms of diagenesis under high temperature and high pressure and the distribution patterns of burial dissolution remains a major challenge in deep oil and gas exploration. Traditional research methods primarily involve petrological and geochemical analysis of diagenetic products, followed by inferences about the process, mechanism, and scale of diagenesis. However, these methods have significant limitations. Geologists have long hoped to utilize water-rock forward modeling, which closely approximates geological conditions, to recreate the diagenetic process under burial conditions, thereby solving the problems of diagenetic mechanisms, controlling factors, and distribution scale.

[0003] Invention patent CN201510387709.6, "Experimental Device for Simulated Water-Rock Flow Test," includes a control unit; a reaction vessel with multiple sample tubes inside; and a constant flow pump, which includes multiple piston cylinders, multiple reversing units, and a drive mechanism. This device can simultaneously conduct multiple sets of comparative tests of simulated water-rock flow, ensuring that multiple rock samples react with the reaction liquid under the same test conditions. However, the device has shortcomings: the artificially prepared CO2 fluid, acetic acid fluid, and H2S solution react with the rock in the simulation experiment, failing to consider the need for underground fluids to cross different strata and the changes in fluid properties during transport; the fluid entering the reaction vessel to react with the rock is driven only by the constant flow pump, without distinguishing the type of fluid driving force, and cannot objectively simulate diagenetic processes such as dissolution, cementation, or replacement between the fluid and the reservoir under geological boundary conditions.

[0004] Utility model patent CN206573460U, "An experimental device for simulating the effect of dissolution on the diagenesis of tight sandstone reservoirs," relates to the field of petroleum geology. This device mainly consists of a water tank, a water pump, a liquid flow meter, a ball valve, a gas flow meter, an air compressor, a carbon dioxide storage tank, a mixture inlet, a connector, a particle baffle, feldspar particles, a transparent circular tube, a computer monitoring system, a velocity sensor, a mixture outlet, a high-speed camera, a circular tube mounting bracket, and a base. The carbon dioxide storage tank is connected sequentially to the air compressor, the gas flow meter, and the ball valve. The water tank is connected sequentially to the water pump, the liquid flow meter, and the ball valve. The transparent circular tube has a mixture inlet and connector on the left side, and a mixture outlet, velocity sensor, and computer monitoring system on the right side. The interior contains a particle baffle and feldspar particles. The limitations of this device are: first, the experimental device mainly provides a single tectonic-period water-rock reaction vessel and does not have the ability to simulate the diagenesis of formation fluids across different strata; second, the fluid type is limited, mainly using artificially prepared carbon dioxide fluid solution; and third, it only focuses on the dissolution and modification of rocks by acidic fluids, ignoring the precipitation or replacement processes that occur during the formation of reservoir rocks.

[0005] In summary, existing diagenetic simulation experimental devices and methods mainly suffer from three problems: First, the simulation conditions are not set according to the diagenetic patterns across tectonic periods in the study area, and the source of fluids and whether their properties change after long-distance transport are not considered. Most of them directly simulate the reaction between acidic fluids and rocks, resulting in experimental results that differ significantly from geological realities. Second, the experimental devices can only provide water-rock reaction vessels under a single stratum and a single temperature and pressure, and cannot simulate water-rock reactions of strata fluids across different tectonic periods or across strata with different properties. Third, the fluid driving method in the experimental devices is singular, mainly using liquid pumps to drive solution transport, while the geological stresses driving the transport of underground geological fluids include tectonic forces, hydrodynamic forces, geostatic pressure, and thermodynamic forces. Summary of the Invention

[0006] In view of the above problems, the present invention is proposed to provide a transtectonic diagenesis simulation device and method to overcome or at least partially solve the above problems, simulate the transtectonic diagenesis mode in the study area, and solve the problem of the porosity formation mechanism after reservoir rocks have undergone high temperature and high pressure and multiple tectonic evolution.

[0007] In a first aspect, embodiments of the present invention provide a method for simulating diagenesis across tectonic periods, comprising:

[0008] Based on the petrological parameters of the core, the chronological order of mineral infilling and dissolution was determined. Based on the chronological order and the reconstructed tectonic evolution history, burial history and fluid infusion history of the study area, the transtectonic diagenetic model and geological fluid type were determined.

[0009] Based on the diagenetic patterns and fluid types across tectonic periods, the corresponding geological stress types driving geological fluid migration are determined;

[0010] Based on the fluid inclusions and cluster isotope thermometry of the core, the formation temperature of the geological fluid as it passed through each target layer during the tectonic period was determined.

[0011] Based on the burial history and formation pressure gradient, the axial pressure, confining pressure and fluid pressure of the formation on each target layer when the geological fluid passes through each target layer across tectonic periods are determined;

[0012] Core samples from each target layer across tectonic periods are selected based on the geological stress type. The fluid driving force implementation method is selected, and corresponding rock samples are prepared using the selected core samples. Each rock sample is placed into the corresponding tectonic period reaction system of the diagenetic simulation device across tectonic periods. The reaction solution configured according to the fluid type is injected into the reaction solution supply system of the device. Diagenetic simulation across tectonic periods is performed based on the fluid driving force implementation method, the formation temperature of each target layer, and the formation axial pressure, confining pressure, and fluid pressure.

[0013] Secondly, embodiments of the present invention provide a simulation device for diagenesis across tectonic periods, comprising a fluid drive system, a reaction solution supply system and at least two sets of tectonic reaction systems connected in sequence.

[0014] The fluid drive system is used to provide power for the flow of the reaction solution inside the reaction solution supply system into the construction reaction system that is directly connected to the reaction solution supply system;

[0015] The tectonic reaction system includes: a water-rock reactor, a reactor fluid pressure control system, a reactor axial pressure control system, and a reactor confining pressure control system connected to the water-rock reactor, and a pressure linkage control system. The pressure linkage control system is used to control the fluid pressure in the water-rock reactor to be lower than the axial pressure and confining pressure. The water-rock reactor is equipped with a temperature control device.

[0016] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0017] (1) The transtectonic diagenesis simulation method provided in this embodiment of the invention establishes a transtectonic diagenesis model and determines the type of geological fluid based on petrological and geochemical analysis, combined with the reconstruction technology of tectonic evolution history, burial history and fluid charging history. Then, it determines the process of high-pressure fluid migration to low-pressure strata driven by geological stress, and restores the geological conditions when the geological fluid passes through each target layer during the transtectonic period, including formation temperature, formation axial pressure, confining pressure and fluid pressure. Based on the restored geological process and geological conditions, the forward modeling simulation of diagenesis such as dissolution, cementation and replacement of fluids during the transtectonic period is carried out using the transtectonic diagenesis simulation device. This provides a basis for judging the mechanism and conditions of formation, maintenance and reduction of reservoir karst pores during the burial stage.

[0018] (2) The transtectonic diagenesis simulation device provided in this embodiment of the invention includes a fluid drive system, a reaction solution supply system and at least two sets of tectonic reaction systems connected in sequence; the fluid drive system is used to provide power for the reaction solution inside the reaction solution supply system to flow into the tectonic reaction system directly connected to the reaction solution supply system; the tectonic reaction system includes: a water-rock reactor, a reactor fluid pressure control system, a reactor axial pressure control system and a reactor confining pressure control system respectively connected to the water-rock reactor, and a pressure linkage control system, the pressure linkage control system is used to control the fluid pressure in the water-rock reactor to be lower than the axial pressure and confining pressure, and a temperature control device is provided in the water-rock reactor. It can simulate the diagenetic patterns across tectonic periods in the study area, and simulate the migration process of high-pressure fluids to low-pressure strata driven by geological stress (including tectonic forces, hydrodynamics, geostatic pressure, and thermodynamics). This allows for forward modeling of diagenetic processes such as dissolution, cementation, and replacement of fluids across rock strata, thereby determining the mechanisms and conditions for the formation, maintenance, and reduction of pores in reservoir rocks during the burial stage. Ultimately, it can solve the problem of pore formation mechanisms in reservoir rocks after experiencing high temperature, high pressure, and multiple tectonic evolutions.

[0019] (3) The transtectonic diagenesis simulation device provided in this embodiment of the invention simulates the transtectonic diagenesis mode through multiple sets of tectonic reaction systems connected in sequence. The tectonic reaction system includes a reactor fluid pressure control system, a reactor axial pressure control system, and a reactor confining pressure control system, which are respectively connected to the water-rock reactor, as well as a pressure linkage control system. The water-rock reactor is also equipped with a temperature control device, so that each reactor can simulate the fluid pressure, temperature, and stratum axial pressure and confining pressure of the corresponding tectonic period. It reasonably simulates the geological stress that drives the underground geological fluid migration, including tectonic movement force, hydrodynamic force, geostatic pressure and thermodynamic force, thereby restoring the real diagenetic conditions.

[0020] 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

[0021] 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:

[0022] Figure 1 This is a flowchart of the method for simulating diagenesis across tectonic periods in Embodiment 1 of the present invention;

[0023] Figure 2 This is an example diagram illustrating the burial history of strata and the thermal evolution of organic matter in an embodiment of the present invention;

[0024] Figure 3 For this Figure 1 The detailed implementation flowchart of step S16 is shown below;

[0025] Figure 4 This is a schematic diagram of the diagenesis simulation device spanning tectonic periods in Embodiment 2 of the present invention;

[0026] Figure 5 for Figure 4 Schematic diagram of the structure of the Zhongshui rock reactor 31;

[0027] Figure 6 for Figure 4 Schematic diagram of the structure of the water-rock reaction system 3;

[0028] Figure 7 This is a flowchart illustrating the specific implementation of the tectonic diagenesis simulation method in this embodiment of the invention. Detailed Implementation

[0029] 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.

[0030] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0031] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0032] In the description of this invention, it should be noted that the terms "comprising," "including," "having," "containing," etc., are all open-ended terms, meaning that they include but are not limited to. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] To address the problem that existing technologies cannot simulate the diagenetic process under real burial environments, this invention provides a transtectonic diagenetic simulation device and method to simulate the transtectonic diagenetic pattern in the study area and solve the problem of pore formation mechanism after reservoir rocks experience high temperature and high pressure and multiple tectonic evolution.

[0034] Example 1

[0035] Embodiment 1 of the present invention provides a method for simulating diagenesis across tectonic periods, the process of which is as follows: Figure 1 As shown, it includes the following steps:

[0036] First, the geological processes and conditions of geological fluids passing through each target layer during the tectonic period are reconstructed. This includes delineating the porosity evolution stage of the study area based on the petrological and geochemical analysis results of rock samples from the study area, and delineating the diagenetic mode of fluids during the tectonic period and the rock samples, fluid types, temperature and pressure conditions corresponding to the simulation experiment by combining the reconstruction techniques of tectonic evolution history, burial history and fluid charging history. Specifically, this includes the following steps S11 to S14.

[0037] Step S11: Based on the petrological parameters of the core, determine the chronological order of mineral infilling and dissolution. Based on the chronological order of mineral infilling and dissolution and the restored tectonic evolution history, burial history and fluid infusion history of the study area, determine the transtectonic diagenetic model and geological fluid type.

[0038] (1) Based on the petrological parameters of the rock thin sections of the core, identify the original rock minerals, filling minerals and dissolution minerals in the rock thin sections. The filling minerals include cement and bitumen. Micro-area elemental and isotopic analyses are performed on the original rock minerals and cement to determine the rock type, the type of dissolution during the burial diagenesis stage and the type of precipitation diagenesis.

[0039] Types of dissolution or precipitation-induced diagenesis, such as organic acid dissolution, hydrothermal dissolution, hydrothermal infilling, and TSR.

[0040] (2) Determine the order of mineral filling and dissolution based on the contact relationship between the original rock minerals and the filling minerals.

[0041] (3) Based on the restored tectonic evolution history, burial history and fluid filling history of the study area, the chronological order of mineral filling and dissolution is projected onto the burial history map based on tectonic evolution, the pore evolution stage of the study area is delineated, the fluid transtectonic diagenesis model is established, and the transtectonic fluid type is determined.

[0042] Fluid type, such as organic acids, hydrothermal fluids, TSR, and freshwater from the atmosphere, is the fluid property condition for the simulation experiment.

[0043] Taking the Gaoshi 17 well in a certain area as an example, its stratigraphic burial and organic matter thermal evolution history, i.e., the burial history diagram based on tectonic evolution, is shown below. Figure 2 As shown, Figure 2 The curves with temperature labels are temperature change curves, and the other curves are depth curves, showing that the pore evolution stage is divided into 7 stages.

[0044] Step S12: Based on the diagenetic mode and fluid type across tectonic periods, determine the corresponding geological stress type that drives the migration of geological fluids.

[0045] Geological stresses that drive the movement of geological fluids may include tectonic forces, hydrodynamic forces, geostatic pressure, and thermodynamic forces.

[0046] Step S13: Determine the formation temperature of geological fluids as they pass through each target layer across tectonic periods based on fluid inclusions and cluster isotope thermometry of the core.

[0047] Step S14: Based on the burial history and formation pressure gradient, determine the axial pressure, confining pressure and fluid pressure of the formation when the geological fluid passes through each target layer across the tectonic period.

[0048] Based on the burial evolution history of the target layer, the stratum depth when the geological fluid passes through multiple target layers across tectonic periods is determined. Then, the static rock pressure and fluid pressure at each target layer are calculated by combining the stratum pressure gradient, which are the stratum pressure and fluid pressure conditions for the simulation experiment.

[0049] The above steps reconstruct the geological processes and conditions of the geological fluid as it passed through each target layer during the transtectonic period, and determine the experimental scheme for simulating transtectonic diagenesis. Specifically, this includes: dividing the transtectonic diagenesis of the study area into various stages based on the transtectonic diagenesis model established in step S11; determining the experimental fluid based on the geological fluid type determined in step S11; selecting rock samples from each layer of the transtectonic period in the simulation experiment based on the geological stress type determined in step S12; selecting the fluid driving force implementation method based on the geological stress type determined in step S12; and determining the experimental temperature and pressure corresponding to each layer of the transtectonic period in the simulation experiment based on steps S13 and S14.

[0050] The following steps are a simulation of the experimental process.

[0051] Step S15: Select rock cores from each target layer across tectonic periods according to the geological stress type, select the fluid driving force implementation method, prepare corresponding rock samples using the selected rock cores, put each rock sample into the corresponding tectonic period reaction system of the cross-tectonic diagenesis simulation device, and inject the reaction solution configured according to the fluid type into the reaction solution supply system of the device.

[0052] First, whole-rock mineral composition and content analysis was performed on core samples from each target layer in the study area. Then, rock samples for simulation experiments were prepared. The rock samples can be plunger samples or particle samples. The plunger samples have a diameter of about 2.5 cm and a length of no more than 3 cm. Porosity, permeability and CT analysis were performed before the experiment. The particle samples have a particle size of 16-20 mesh.

[0053] Each rock sample is placed into the corresponding tectonic reaction system of the transtectonic diagenesis simulation device. Specifically, this can be done by placing the corresponding rock samples into the water-rock reaction vessel of the corresponding tectonic reaction system in order of the earliest to the latest tectonic period, starting with the tectonic reaction system closest to the reaction solution supply system of the transtectonic diagenesis simulation device. The reaction systems of each tectonic period are connected sequentially.

[0054] The transtectonic diagenesis simulation device is specifically the transtectonic diagenesis simulation device in Example 2.

[0055] The number of structuring phases is consistent with the number of groups in the structuring phase reaction system.

[0056] It should be noted that the number of groups in the tectonic reaction system of the cross-tectonic diagenesis simulation device can be flexibly set. Based on the number of tectonic periods in the study area or the number of rock samples corresponding to the tectonic period, select a cross-tectonic diagenesis simulation device with a number of groups of tectonic reaction systems that is not less than the number of periods or samples, and only connect the tectonic reaction system in the device with the same number of groups as the number of periods or samples.

[0057] After placing the rock samples into the water-rock reaction vessel corresponding to the reaction system of each tectonic period, seal the reaction vessel, connect the pipeline, and open the corresponding valve.

[0058] Step S16: Simulate diagenesis across tectonic periods based on the fluid driving force realization method, the formation temperature of each target layer, and the formation axial pressure, confining pressure, and fluid pressure.

[0059] For details, see Figure 3 As shown, the following steps may be included:

[0060] Step S161: The reaction solution in the reaction solution supply system is driven into the water-rock reactor of the nearest tectonic reaction system through the fluid drive system of the device. The pressure linkage control system of the tectonic reaction system controls the reactor fluid pressure control system, reactor axial pressure control system and reactor confining pressure control system connected to the water-rock reactor respectively, so that the fluid pressure value in the water-rock reactor is the corresponding fluid pressure, the axial pressure value is the corresponding formation axial pressure, and the confining pressure value is the corresponding formation confining pressure.

[0061] Step S162: Sequentially set the fluid pressure, axial pressure, and confining pressure values ​​in the water-rock reactor of the next tectonic reaction system into which the reaction solution flows.

[0062] Specifically, the pressure linkage control system of the next tectonic reaction system through the flow of the reaction solution controls the reactor fluid pressure control system, reactor axial pressure control system and reactor confining pressure control system connected to the water-rock reactor of the reaction system, so that the fluid pressure value in the water-rock reactor is the corresponding fluid pressure, the axial pressure value is the corresponding formation axial pressure, and the confining pressure value is the corresponding formation confining pressure.

[0063] Step S163: The fluid temperature inside the water-rock reactor is controlled to the corresponding fluid temperature using the temperature control equipment of the water-rock reactor in each tectonic reaction system.

[0064] Once the static rock pressure and fluid pressure in each water-rock reactor reach the set values, the temperature in the water-rock reactor corresponding to each tectonic period is set according to the geological background of each tectonic period through which the fluid passes.

[0065] Step S164: Maintain constant temperature and pressure in the water-rock reactor of each tectonic phase reaction system for the set time.

[0066] Step S165: Obtain the corresponding post-reaction solutions through the sampling system of each structural stage reaction system.

[0067] After the simulation experiment, the diagenetic evolution process was determined by comparing the composition of the pre-reaction solution with the post-reaction solutions, and by comparing the post-reaction rock samples with the corresponding pre-reaction rock samples. Elemental composition and content analysis were performed on the solutions, and whole-rock mineral composition and content analysis were performed on the rock samples. If the rock sample was a plunger sample, porosity, permeability, and CT analysis were also conducted.

[0068] By comparing the data collected from samples before and after the experiment, and the data of the reaction solution before the experiment and the generated solution after the experiment, the diagenetic mechanism of the target layer is analyzed, such as one or more of the following transtectonic diagenetic processes: organic acid dissolution, hydrothermal dissolution, hydrothermal infilling, TSR, and regression dissolution caused by tectonic uplift.

[0069] The transtectonic diagenesis simulation method provided in Embodiment 1 of this invention, based on petrological and geochemical analysis, combined with techniques for reconstructing tectonic evolution history, burial history, and fluid charging history, establishes a transtectonic diagenesis model, determines the type of geological fluid, and then determines the process of fluid migration from high-pressure to low-pressure strata driven by geological stress. It reconstructs the geological conditions when the geological fluid passes through each target layer during the transtectonic period, including formation temperature, formation axial pressure, confining pressure, and fluid pressure. Based on the reconstructed geological processes and conditions, a forward modeling simulation of diagenesis, such as dissolution, cementation, and metasomatism, is conducted using a transtectonic diagenesis simulation device. This provides a basis for determining the mechanisms and conditions under which reservoir karst pores are formed, maintained, and reduced during the burial stage.

[0070] Example 2

[0071] Embodiment 2 of the present invention provides a simulation device for diagenesis across tectonic periods, the structure of which is as follows: Figure 4 As shown, it includes a fluid drive system 1, a reaction solution supply system 2, and at least two sets of construction phase reaction systems 3 connected in sequence.

[0072] The fluid drive system 1 provides power for the flow of the reaction solution inside the reaction solution supply system 2 into the construction reaction system 3, which is directly connected to the reaction solution supply system 2.

[0073] Each group of tectonic reaction systems 3 includes: a water-rock reactor 31, a reactor fluid pressure control system 32, a reactor axial pressure control system 33, and a reactor confining pressure control system 34, all connected to the water-rock reactor 31, and a pressure linkage control system 35. The pressure linkage control system 35 is used to control the fluid pressure inside the water-rock reactor 31 to be lower than the axial pressure and confining pressure. A temperature control device (not shown in the figure) is installed inside the water-rock reactor 31.

[0074] The water-rock reactor is used to simulate the water-rock reaction between fluid and rock samples under set experimental temperature, fluid pressure, and formation pressure conditions. The reactor fluid pressure control system is used to control the fluid pressure in the water-rock reactor to simulate formation fluid pressure. The reactor axial hydraulic control system is used to control the axial pressure of the rock sample in the water-rock reactor. The reactor confining pressure control system is used to control the confining pressure of the rock sample in the water-rock reactor to simulate the static rock pressure. The pressure linkage control system is used to set the pressure difference between formation fluid pressure, axial hydraulic pressure, and reactor confining pressure to ensure that the formation fluid pressure is always lower than the axial hydraulic pressure and reactor confining pressure.

[0075] The fluid drive system 1 can be used to set the flow rate required for the experiment. In some embodiments, the reaction solution supply system includes a hollow cylinder and a piston. The piston divides the receiving cavity formed by the hollow cylinder into an independent upper chamber and a lower chamber. The upper chamber is used to hold the reaction solution. The fluid drive system is used to draw fluid from the outside, causing the fluid to flow into the lower chamber. The force generated by the fluid flow pushes the piston away from the lower chamber, thereby pushing the reaction solution in the upper chamber into the water-rock reactor of the tectonic reaction system.

[0076] Preferably, a removable pressure cap is installed at the top of the empty column in the reaction solution supply system. The pressure cap prevents fluid from spraying out due to excessive fluid pressure during the experiment, ensuring the safety of the apparatus during the experiment.

[0077] The hollow cylinder and piston mentioned above can be made of high-pressure resistant metal materials.

[0078] The water-rock reactor 31 can specifically be a high-temperature, high-pressure triaxial stress water-rock reactor. See some embodiments for details. Figure 5 As shown, the water-rock reactor 31 includes, from the inside out, a sample chamber 311, a screw fixing frame 312, and a reactor shell 313.

[0079] The sample chamber 311 is provided with a filter 314 and a hollow hydraulic push rod 315 at its two ends respectively. The hollow hydraulic push rods 315 at both ends are connected to the reaction solution inlet and the reaction solution outlet respectively. The reaction vessel shell 313 is open at one end, and a sealing cap 316 is provided at the open end. One end of the screw fixing frame 312 is connected to the sealing cap 316, and the other end is connected to the sample chamber 311 by screws.

[0080] The sample chamber 311 can be a hollow copper cylindrical sample tube. The copper material gives the sample tube a certain degree of softness, which can ensure close contact between the sample and the inner wall of the sample tube under external pressure, preventing fluid from leaking out from the gap between the sample and the inner wall of the sample tube. At the same time, the copper material also ensures the high temperature resistance of the sample tube.

[0081] Furthermore, the screw holder 312 can be a three-hole screw holder to ensure the position of the sample chamber and the sealing cap is fixed under high temperature and high pressure conditions. The sealing cap is used to seal the sample chamber.

[0082] The aforementioned screw fixing bracket 312, reactor shell 313, and sealing cap 316 are all made of metal materials resistant to high temperature and high pressure.

[0083] The filter element 314 can be made of Hastelloy alloy; the mesh of the filter element has circular holes with a diameter of 100 mesh. Hastelloy alloy has the properties of high temperature resistance and corrosion resistance.

[0084] The hollow hydraulic push rod 315 is controlled by the reactor axial hydraulic control system 33, which axially compresses the rock sample in the sample chamber 311, thereby providing axial pressure.

[0085] Furthermore, a support sleeve 317 is provided around the sample chamber 311; the support sleeve 317 can be composed of two pieces, each of which has at least two through holes.

[0086] The support sleeve 317 is mainly used to protect the sample chamber 311. When the sample chamber is a hollow copper cylindrical sample tube, the support sleeve can be an alloy cylinder, consisting of two pieces, which wrap around the outside of the hollow copper cylindrical sample tube. Each support sleeve contains two round holes so that the confining pressure fluid can pass through the support sleeve to wrap around the hollow copper cylindrical sample tube and apply confining pressure.

[0087] Furthermore, each end of the sample chamber 311 is provided with a latch 318; the latch 318 is used to fix the support sleeve 317 to the periphery of the sample chamber 311.

[0088] The reactor shell 313 is hollow and can hold the confining pressure fluid, and a temperature control device (not shown in the figure) is installed therein. In some embodiments, the temperature control device includes a heater and a temperature thermocouple. The temperature control device heats the confining pressure fluid to maintain the temperature of the water-rock reaction in the sample chamber.

[0089] Graphite pads 319 are provided at both ends of the screw fixing bracket 312 where they contact the sealing cap 316 and the bottom of the reactor shell 313, respectively.

[0090] Further, see Figure 6 ( Figure 6 As shown in the example of the three tectonic reaction systems, the tectonic reaction system 3 also includes a preheating device 36; the preheating device 36 is located between the reaction solution inlet (not shown in the figure) and the water-rock reactor 31, and is used to preheat the fluid flowing into the water-rock reactor 31.

[0091] Furthermore, the reactor fluid pressure control system 32 is connected to the reaction solution outlet of the water-rock reactor 31; the reactor fluid pressure control system 32 includes a back pressure valve 321 and a pressure tracking pump 322, the back pressure valve 321 is used to control the fluid pressure inside the water-rock reactor 31. The back pressure valve 321 is connected to the outlet end of the water-rock reactor 31 through a multi-channel combination valve to control the fluid pressure inside the upstream reactor.

[0092] Furthermore, the tectonic reaction system 3 also includes a product solution sampling system 37; a reactor fluid pressure control system 32 is connected between the reaction solution outlet of the water-rock reactor and the product solution sampling system 37. The product solution sampling system 37 is used to collect the reaction product solution flowing out of the front-end reactor.

[0093] A diagenetic simulation device contains two or more tectonic reaction systems 3, which are connected by multi-channel valves to ultimately realize the simulation of diagenesis across different strata and tectonic periods.

[0094] The diagenesis simulation device provided in Embodiment 2 of the present invention includes a fluid drive system, a reaction solution supply system, and at least two sets of tectonic reaction systems connected in sequence. The fluid drive system is used to provide power for the reaction solution inside the reaction solution supply system to flow into the tectonic reaction system directly connected to the reaction solution supply system. The tectonic reaction system includes a water-rock reactor, a reactor fluid pressure control system, a reactor axial pressure control system, and a reactor confining pressure control system connected to the water-rock reactor, and a pressure linkage control system. The pressure linkage control system is used to control the fluid pressure inside the water-rock reactor to be lower than the axial pressure and confining pressure. A temperature control device is installed inside the water-rock reactor. It can simulate the diagenetic patterns across tectonic periods in the study area, and simulate the migration process of high-pressure fluids to low-pressure strata driven by geological stress (including tectonic forces, hydrodynamics, geostatic pressure, and thermodynamics). This allows for forward modeling of diagenetic processes such as dissolution, cementation, and replacement of fluids across rock strata, thereby determining the mechanisms and conditions for the formation, maintenance, and reduction of pores in reservoir rocks during the burial stage. Ultimately, it can solve the problem of pore formation mechanisms in reservoir rocks after experiencing high temperature, high pressure, and multiple tectonic evolutions.

[0095] The tectonic reaction system simulates the diagenetic process across tectonic periods by using multiple sets of sequentially connected tectonic reaction systems. The tectonic reaction system includes a reactor fluid pressure control system, a reactor axial pressure control system, and a reactor confining pressure control system, all connected to the water-rock reactor, as well as a pressure linkage control system. The water-rock reactor is also equipped with a temperature control device, which enables each reactor to simulate the fluid pressure, temperature, axial pressure, and confining pressure of the corresponding tectonic period. This reasonably simulates the geological stress that drives the migration of underground geological fluids, including tectonic forces, hydrodynamic forces, geostatic pressure, and thermodynamic forces, thereby restoring the real diagenetic conditions.

[0096] The following section uses a dolomite reservoir in a target layer of a certain study area as an example to further illustrate the above-mentioned diagenetic simulation method.

[0097] See the experimental procedure. Figure 7 As shown, rock types were analyzed by petrological analysis, experimental fluid types by fluid charging history analysis, formation temperature, static rock pressure, and fluid pressure by burial history analysis, and diagenetic types during the burial tectonic period were analyzed by tectonic-burial evolution history analysis, thereby determining the experimental conditions for fluid crossing the tectonic period. After collecting dolomite from the target layer in the study area, the samples were crushed, finely washed, and dried for whole-rock mineral and CT analysis. Cross-domain tectonic period experiments were conducted using the obtained rock samples and diagenetic simulation devices. Through whole-rock mineral and CT analysis of the samples after the experiment and ion analysis of the reaction-generated solution, the identification and evaluation of dissolution, precipitation, or replacement were carried out.

[0098] Firstly, the porosity evolution stages are divided using petrological and geochemical methods. The porosity evolution of the target layer can be divided into seven stages: ① the critical development period of original porosity during the syn- and quasi-syn-sedimentary period; ② the critical porosity maintenance period during the early burial (early diagenetic) acidic diagenetic environment; ③ the porosity improvement and stabilization period during the late Atlas-early Hercynian uplift and exposure; ④ the porosity filling period during the middle burial and hydrothermal activity; ⑤ the large-scale burial and dissolution period during the large-scale intrusion of exogenous organic acids; ⑥ the oil intrusion evolution period; and ⑦ the hydrocarbon adjustment and minor silica intrusion during the late uplift.

[0099] The following petrological evidence (thin sections of rock castings) indicates that burial dissolution played a significant role in the formation of dissolution cavities in the target layer:

[0100] ① Obvious dissolution and modification features are visible at the edges of some enlarged intergranular pores, which obviously occurred after dolomitization. Moreover, the lack of common seepage silt suggests that dissolution and modification during the burial period is highly likely.

[0101] ② The dissolution cavities are commonly filled with medium-coarse crystal dolomite and saddle-shaped dolomite, which are products of fluid activity during the burial period;

[0102] ③ It can be seen that some of the dolomite in the dissolution cavities has been dissolved into harbor shapes, while some of the entire dolomite has been dissolved to form dolomite casting holes.

[0103] The above evidence reveals that the target reservoir underwent multiple phases and a relatively long period of dissolution during its burial period, playing a significant role in improving the dissolution and connectivity of the reservoir space. Extensive review of thin rock sections showed that in some sections, the contribution rate of burial-genetic dissolution cavities to the reservoir space reached over 50%, with an average contribution rate of 20%–30%. Using tectonic-burial history reconstruction techniques, a transtectonic diagenetic model corresponding to the study area was established. Specifically, in this embodiment, the Weiyuan-Anyue-Suining-Nanchong-Yanting area in the study area is a hydrocarbon and acid generation center with the highest organic acid concentration. Furthermore, the well-developed fault system provides a pathway for the migration of organic acids along faults towards the paleo-uplift. Therefore, a transtectonic diagenetic model of organic acid burial and dissolution is proposed, and a corresponding burial and organic matter thermal evolution history is established. Figure 2 As shown.

[0104] For trans-tectonic diagenesis, it is generally accepted that source rocks or deep hydrothermal fluids can generate large-scale acidic fluids. The key question is whether the fluids will fully react with the surrounding rocks during migration, and whether large-scale dissolution can still occur when they actually enter the target layer. Considering that the actual underground migration of acidic fluids from source rocks or deep hydrothermal fluids to carbonate reservoirs is a trans-tectonic dissolution process, this experiment subdivides the underground buried dissolution process into two diagenetic stages: the near-acid source stage and the reservoir stage. Furthermore, the buried dissolution occurs in an open environment, with the acidic fluids migrating and reacting within the pores of the rock. Using a trans-tectonic diagenetic simulation device, a dissolution experiment was conducted on the acidic fluids sequentially passing through the near-acid source stage and the reservoir stage. Specifically, the fluid was first injected into the rock in the near-acid source stage, reacted within the rock's pores, and then migrated to the rock sample in the reservoir stage for dissolution. In the experiment, the acidic fluid was prepared by adding 7.16 g / L acetic acid to oilfield water, and the solution pH was 2.5. The formation temperature near the acid source was 120℃, the fluid pressure was 40MPa, and the static rock pressure was 85MPa. The formation temperature near the target layer was 90℃, the fluid pressure was 25MPa, and the static rock pressure was 70MPa. Both stages used porous dolomite plunger samples. Prior to the experiment, the samples underwent physical property analysis and CT scanning of the rock's internal pore characteristics. The flow rate was 0.2 ml / min, and the total reaction solution volume was 1.6 L. After the dissolution experiment, the reaction solutions generated in the near-acid source and reservoir stages were collected and their pH values ​​analyzed. The pH value of the reaction solution generated in the near-acid source stage was 3.6, while the pH value of the reaction solution generated in the reservoir stage was 6.1. This experiment confirms that acidic fluids can retain their acidity during the channeling process and undergo sufficient reaction in the reservoir stage. By comparing the porosity characteristics of samples after dissolution in the two stages, it was found that in the dolomite near the acid source, straight fractures formed, and the fluid mainly traveled along the dominant migration channels, reducing the contact area with the rock pores and thus ensuring that the acidic fluid retained its acidity during long-distance migration. In the reservoir stage, porosity dissolution in the dolomite increased, forming solution pores and caves. Based on the simulation results, the key issue of the scale of burial dissolution was well explained, and a mechanism for the retention of acidic fluid in burial dissolution was proposed. That is, near the acid source, the fluid migrates laterally. Due to the high temperature and high flow rate, the dissolution pore type is mainly solution fractures, forming channels for the acidic fluid to travel, thus ensuring that the acidic fluid is transported to the target layer to improve the reservoir space. The specific model of the established mechanism for the retention of acidic fluid in burial dissolution is shown in [link to specific diagram]. Figure 2 .

[0105] Figure 2 Specifically, the stratigraphic burial and organic matter thermal evolution history of well Gaoshi 17 was established, showing a total of 7 evolutionary stages. The stratigraphic temperature changes in each stage are as follows: Figure 2 As shown.

[0106] 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 specific order or hierarchy described.

[0107] 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.

[0108] 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 method of modeling diagenesis across tectonic periods, characterized by, include: Based on the petrological parameters of the core, the chronological order of mineral infilling and dissolution was determined. Based on the chronological order and the reconstructed tectonic evolution history, burial history and fluid infusion history of the study area, the transtectonic diagenetic model and geological fluid type were determined. Based on the diagenetic patterns and fluid types across tectonic periods, the corresponding geological stress types driving geological fluid migration are determined; Based on the fluid inclusions and cluster isotope thermometry of the core, the formation temperature of the geological fluid as it passed through each target layer during the tectonic period was determined. Based on the burial history and formation pressure gradient, the axial pressure, confining pressure and fluid pressure of the formation on each target layer when the geological fluid passes through each target layer across tectonic periods are determined; Core samples from each target layer across tectonic periods are selected based on the geological stress type. The fluid driving force implementation method is selected, and corresponding rock samples are prepared using the selected core samples. Each rock sample is placed into the corresponding tectonic period reaction system of the diagenetic simulation device across tectonic periods. The reaction solution configured according to the fluid type is injected into the reaction solution supply system of the device. Diagenetic simulation across tectonic periods is performed based on the fluid driving force implementation method, the formation temperature of each target layer, and the formation axial pressure, confining pressure, and fluid pressure.

2. The method of claim 1, wherein, Also includes: The diagenetic evolution process was determined by comparing the composition of the pre-reaction solution with the post-reaction solutions obtained from the reaction systems of each tectonic period, and by comparing the post-reaction rock samples with the corresponding pre-reaction rock samples.

3. The method of claim 1, wherein, The determination of the chronological order of mineral infilling and dissolution based on the petrological parameters of the core includes: Based on the petrological parameters of the thin sections of the core, the original minerals, filling minerals, and dissolved minerals in the thin sections are identified, including cement and bitumen. Micro-area elemental and isotopic analyses were performed on the protolith minerals and cements to determine the rock type, the type of dissolution during the burial diagenesis stage, and the type of precipitation diagenesis. Based on the contact relationship between the original rock minerals and the filling minerals, the chronological order of mineral filling and dissolution is determined.

4. The method of claim 1, wherein, Based on the chronological order and the restored tectonic evolution history, burial history, and fluid infusion history of the study area, the transtectonic diagenetic model and geological fluid type are determined, specifically including: Based on the restored tectonic evolution history, burial history, and fluid infusion history of the study area, the chronological order is projected onto a burial history map based on tectonic evolution to delineate the porosity evolution stages that occurred in the study area, establish a fluid transtectonic diagenetic model, and then determine the transtectonic fluid type.

5. The method of claim 1, wherein, The process of placing each rock sample into the corresponding tectonic reaction system of the transtectonic diagenesis simulation device specifically includes: Following the order of the corresponding tectonic periods from earliest to latest, starting with the tectonic period reaction system closest to the reaction solution supply system in the cross-tectonic diagenesis simulation device, the corresponding rock samples were sequentially placed into the water-rock reaction vessel of the corresponding tectonic period reaction system.

6. The method of claim 5, wherein, The simulation of transtectonic diagenesis based on the fluid driving force realization method, the formation temperature of each target layer, and the axial pressure, confining pressure, and fluid pressure of the formation specifically includes: Through the pressure linkage control system of the tectonic reaction system closest to the reaction solution supply system, the fluid pressure control system, axial pressure control system, and confining pressure control system of the reactor connected to the water-rock reactor of the tectonic reaction system are controlled respectively, so that the fluid pressure value in the water-rock reactor is the corresponding fluid pressure, the axial pressure value is the corresponding formation axial pressure, and the confining pressure value is the corresponding formation confining pressure; the fluid pressure value, axial pressure value, and confining pressure value in the water-rock reactor of the next tectonic reaction system into which the reaction solution flows are set sequentially. The fluid temperature inside the water-rock reactor is controlled to the corresponding fluid temperature using the temperature control equipment of the water-rock reactor in each tectonic stage reaction system. Maintain constant temperature and pressure inside the water-rock reactor for the set time in each tectonic phase reaction system; The corresponding post-reaction solutions were obtained through the sampling system of each tectonic phase reaction system.

7. The method according to any one of claims 1 to 6, characterized in that, The preparation of corresponding rock samples using selected rock cores specifically includes: Using the selected core samples, corresponding plunger samples or particle samples are prepared. The diameter of the plunger sample is 2.5 cm and the length is no more than 3 cm. The particle sample has a particle size of 16-20 mesh.

8. A cross-structural period diagenesis modeling apparatus, characterized by, The apparatus for implementing the cross-tectonic diagenesis simulation method of claim 1 includes a fluid drive system, a reaction solution supply system and at least two sets of tectonic reaction systems connected in sequence. The fluid drive system is used to provide power for the flow of the reaction solution inside the reaction solution supply system into the construction reaction system that is directly connected to the reaction solution supply system; The tectonic reaction system includes: a water-rock reactor, a reactor fluid pressure control system, a reactor axial pressure control system, and a reactor confining pressure control system connected to the water-rock reactor, and a pressure linkage control system. The pressure linkage control system is used to control the fluid pressure in the water-rock reactor to be lower than the axial pressure and confining pressure. The water-rock reactor is equipped with a temperature control device.

9. The apparatus of claim 8, wherein, The water-rock reactor, from the inside out, includes a sample chamber, a screw fixing frame, and a reactor shell; The sample chamber is provided with a filter and a hollow hydraulic push rod at each end, and the hollow hydraulic push rods at both ends are connected to the reaction solution inlet and the reaction solution outlet, respectively. The reactor shell is open at one end, and a sealing cap is provided at the open end; One end of the screw fixing bracket is connected to the sealing cap, and the other end is connected to the sample chamber by screws.

10. The apparatus of claim 9, wherein, The filter element is made of Hastelloy alloy; the mesh of the filter element is a circular hole with a diameter of 100 mesh.

11. The apparatus of claim 9, wherein, A support sleeve is also provided around the sample chamber; The support sleeve consists of two pieces, each of which has at least two through holes.

12. The apparatus of claim 11, wherein, The sample chamber is provided with latches at both ends; the latches are used to fix the support sleeve to the periphery of the sample chamber.

13. The apparatus as claimed in claim 9, characterized in that, The sample chamber is a hollow copper cylindrical sample tube.

14. The apparatus of claim 9, wherein, The temperature control device includes a heater and a temperature thermocouple; The temperature control device is located inside the reactor shell.

15. The apparatus of claim 9, wherein, The fluid pressure control system of the reactor is connected to the reaction solution outlet of the water-rock reactor; The reactor fluid pressure control system includes a back pressure valve and a pressure tracking pump. The back pressure valve is used to control the fluid pressure inside the water-rock reactor.

16. The apparatus of claim 15, wherein, The construction phase reaction system also includes a generated solution sampling system; The reactor fluid pressure control system is connected between the reaction solution outlet of the water-rock reactor and the generated solution sampling system.

17. The apparatus of any one of claims 9 to 16, wherein The construction phase reaction system also includes preheating equipment; The preheating equipment is located between the reaction solution inlet and the water-rock reactor.

18. The device of any one of claims 9 to 16, wherein, Graphite pads are provided at both ends of the screw fixing bracket where they contact the sealing cap and the bottom of the reactor shell, respectively.

19. The apparatus of claim 8, wherein, The reaction solution supply system includes a hollow cylinder and a piston. The piston divides the cavity formed by the hollow cylinder into an independent upper chamber and a lower chamber. The upper chamber is used to hold the reaction solution. The fluid drive system is used to make the fluid flow into the lower chamber and make the power generated by the fluid flow drive the piston to move and flow the reaction solution in the upper chamber into the water-rock reactor of the tectonic reaction system. The top of the hollow column is fitted with a removable pressure cap.

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