Evaluation Method for Dissolution and Cementation Rate of Calcite Minerals under Multi-Field Coupling

Abstract

This invention relates to the field of oil and gas reservoir geology and discloses a method for evaluating the dissolution and cementation rates of calcite minerals under multi-field coupling effects. The method includes: preparing standard artificial cores free from interference by impurities through constant-pressure cold pressing and high-temperature calcination; using a triaxial pressure chamber to achieve independent control and coupled loading of temperature, pore pressure, and confining pressure; conducting single-factor and orthogonal experiments in dissolution and cementation experimental groups; quantitatively calculating the reaction rate based on steady-state ion concentration data; and analyzing the multi-field coupling effect and the main controlling factors of diagenesis through a two-way grey relational analysis model. This invention solves the problems in existing technologies, such as systematic bias in evaluation results, inability to quantitatively analyze multi-field coupling effects, inability to clearly identify the main controlling factors of diagenesis, and poor repeatability due to low standardization of experimental procedures.

Description

Technical Field

[0001] This invention relates to the field of oil and gas reservoir geology, and in particular to a method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling. Background Technology

[0002] Calcite is a core diagenetic mineral that is widely developed in oil and gas reservoirs (including carbonate reservoirs, shale reservoirs, and tight sandstone reservoirs). Its dissolution can effectively improve reservoir properties and expand oil and gas storage space, which is a key mechanism for the formation of deep, high-quality reservoirs. Cementation, on the other hand, fills pore throats and reduces reservoir permeability, which is a core factor leading to reservoir compaction.

[0003] The dissolution and cementation diagenesis of calcite in oil and gas reservoirs is always occurring within a multi-field coupled environment formed by formation temperature, pore fluid pressure, and tectonic confining pressure. Temperature dominates the thermodynamic equilibrium and kinetic rate constant of the reaction, pore pressure controls the fluid phase and mineral solubility, and the triaxial stress field formed by the confining pressure, through a mechanochemical coupling effect, alters the lattice strain energy, defect concentration, and activation energy of dissolution / precipitation reactions on the calcite mineral surface, thus being the core factor regulating the direction and rate of diagenetic reactions. Especially in deep to ultra-deep oil and gas reservoirs, the superposition of stress redistribution and dissolution-cementation directly determines the preservation and directional expansion of secondary porosity.

[0004] Currently, experimental evaluation methods for calcite dissolution and cementation behavior mainly rely on high-pressure reactor intermittent experiments, thermogravimetric analysis, and in-situ spectroscopic characterization. These methods generally suffer from the following insurmountable technical shortcomings: First, they lack experimental variable dimensions, failing to recreate the true multi-field coupled environment of the formation. Existing methods can only achieve dual-factor coupling control of temperature and pore pressure, unable to independently and controllably apply triaxial mechanical stress to core samples, completely lacking the core stress field dimension of hydrocarbon formations. The experimental environment differs fundamentally from the actual diagenetic environment of the formation. Second, the evaluation results exhibit systematic bias and fail to reflect true diagenetic behavior. The mechanochemical coupling control effect of stress field on the calcite dissolution-cementation reaction has been confirmed by geological theory and field data. The lack of stress dimension design in existing methods leads to a significant systematic deviation between the experimentally measured reaction rate and the diagenetic behavior under actual formation stress conditions, failing to provide reliable experimental support for predicting reservoir porosity evolution. Third, they cannot quantitatively analyze multi-field coupling effects and cannot clearly identify the main controlling factors of diagenesis. Existing methods can only conduct simple single-factor or temperature-pressure dual-factor analyses, failing to systematically quantify the synergistic / antagonistic coupling effects among temperature, pore pressure, and confining pressure. They also cannot clearly define the influence weights and controlling order of each factor on the direction and rate of diagenetic reactions, making it difficult to establish quantitative prediction models for diagenesis. Furthermore, the experimental procedures suffer from low standardization and poor repeatability. Existing methods lack a systematic error control system and do not fully consider systematic errors caused by sample differences, variations in fluid ion concentration, and pipeline adsorption, resulting in poor repeatability and comparability of experimental results, and hindering the development of standardized industry evaluation methods.

[0005] Therefore, there is an urgent need to develop a standardized experimental method that can simultaneously achieve independent control and coupled loading of three fields: temperature, pore pressure, and confining pressure; can dynamically and quantitatively evaluate the dissolution and cementation rate of calcite; and can accurately analyze the multi-field coupling effect, so as to solve the core bottleneck of the existing technology. Summary of the Invention

[0006] The present invention aims to provide a method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling effects, in order to solve the problems in the existing technology, such as systematic bias in evaluation results, inability to quantitatively analyze multi-field coupling effects, inability to clearly identify the main controlling factors of diagenesis, and poor repeatability due to low standardization of experimental procedures.

[0007] To achieve the above objectives, the present invention provides the following method:

[0008] The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling provided by this invention is as follows:

[0009] S1. Preparation of standard rock cores: Pure calcite powder is subjected to constant pressure cold pressing and high temperature calcination to remove impurities, and standard artificial rock cores with uniform physical properties and no interference from impurities are prepared.

[0010] S2. Sample loading and system construction: The standard artificial core is loaded into a triaxial pressure chamber in which the temperature, pore pressure and confining pressure can be independently and closed-loop controlled. Controllable triaxial mechanical stress is applied to the standard artificial core through the confining pressure to build a multi-field coupled reaction system that matches the diagenetic environment of oil and gas reservoirs.

[0011] S3. Two-way reaction group design: Set up a dissolution experimental group, a cementation experimental group and a blank control group, and inject matching reaction liquids into the triaxial pressure chamber to clarify the boundary conditions for diagenetic reaction simulation.

[0012] S4. Multi-field coupled gradient experiment: For each group of experiments, the sensitive range of variables is first locked through single-factor experiments. Then, with temperature, pore pressure and confining pressure as three experimental factors, a three-factor, five-level standard orthogonal experimental scheme is adopted to carry out continuous flow dynamic diagenetic reaction experiments under the set working conditions.

[0013] S5. Dynamic sampling and steady-state determination: Based on the reaction process, the effluent is collected at regular intervals to detect the Ca²⁺ ion concentration in the effluent. The steady-state of the reaction is determined by continuous sampling data, and the corrected effective ion concentration data is obtained.

[0014] S6. Quantitative calculation of reaction rate: Based on the effective ion concentration data, combined with the inlet and outlet ion concentration difference, fluid flow rate, and effective contact surface area between calcite and fluid in the core, the dissolution rate or cementation rate of calcite under the corresponding working conditions is quantitatively calculated.

[0015] S7. Evaluation of multi-field coupling effect: For the two-way reaction of dissolution and cementation, a grey relational analysis model containing single-field variables and two-field interaction terms is constructed respectively. The grey relational degree of each factor and the multi-field coupling contribution rate of each reaction direction are calculated to clarify the influence weight and coupling law of each factor on the reaction direction and rate.

[0016] Furthermore, the preparation process of the standard artificial rock core in step S1 is as follows: pure calcite powder is placed in a cylindrical rock core mold, and then cold-pressed on a press at a constant pressure of 200MPa to obtain a molded sample. Subsequently, the molded sample is placed in a temperature-controlled furnace and calcined at a constant temperature of 450℃ for 10 hours to obtain a standard artificial rock core with consistent geometric dimensions, porosity, and permeability parameters.

[0017] Furthermore, the specific settings for the grouped experiments in step S3 are as follows: the dissolution experimental group is injected with deionized water as the reaction solution to simulate the acidic fluid dissolution scenario of the formation; the cementation experimental group is injected with a simulated formation aqueous solution with a Ca²⁺ concentration of 100 mmol / L as the reaction solution to simulate the mineral cementation scenario of the formation; the blank control group uses an equal volume of inert quartz sand column to replace the standard artificial core, and conducts experiments synchronously with the dissolution experimental group and the cementation experimental group to deduct systematic errors caused by factors such as changes in the ion concentration of the fluid itself and adsorption in the pipeline.

[0018] Furthermore, the gradients and rules for the single-factor experiments described in step S4 are as follows: Temperature single-factor experiment: Temperature gradients are set to 30℃, 80℃, 120℃, 160℃, and 200℃. During the experiment, the confining pressure is fixed at 10MPa and the pore pressure is fixed at 10MPa. The dissolution experiment group and the cementation experiment group are carried out simultaneously. Confining pressure single-factor experiment: Confining pressure gradients are set to 10MPa, 20MPa, 30MPa, 40MPa, and 50MPa. During the experiment, the temperature is fixed at 100℃ and the pore pressure is fixed at 10MPa. The dissolution and cementation experimental groups used identical fixed parameters. For the single-factor pore pressure experiment, pore pressure gradients of 5 MPa, 10 MPa, 15 MPa, 20 MPa, and 25 MPa were set. During the experiment, the confining pressure was fixed at 10 MPa and the temperature was 100℃. Effluent data from the corresponding experimental group and the blank control group were collected simultaneously. For each single-factor operating condition and each level combination of the orthogonal experiment, at least 3 parallel repeated experiments were set for both the dissolution and cementation groups. Data with a relative deviation of less than 3% in parallel experiments were considered valid.

[0019] Furthermore, the dynamic sampling and steady-state determination rules in step S5 are as follows: after each working condition has been continuously and stably reacted for 15 minutes, at least 3 groups of 1 mL effluent samples are continuously collected at 30-minute intervals; when the relative deviation of the Ca²⁺ concentration detection values ​​of the adjacent 3 groups of samples is less than 2%, the reaction is determined to have reached dynamic steady state, and the average value of the 3 groups of detection values ​​is taken and the correction value of the blank control group is subtracted as the effective ion concentration data of the working condition.

[0020] Furthermore, the calculation formulas for the dissolution rate and cementation rate in step S6 are as follows:

[0021]

[0022] In the formula, The value represents the calcite reaction rate, expressed in mol / (m²·s). Positive values ​​correspond to the dissolution rate, while negative values ​​correspond to the cementation rate. The molar concentration of Ca²⁺ at the inlet of the reaction solution is expressed in mol / m³. The corrected Ca²⁺ molar concentration of the outlet liquid obtained in step S5 is expressed in mol / m³. The steady-state volumetric velocity of the fluid is expressed in m³ / s. This represents the effective contact surface area between calcite and fluid within the core, expressed in m².

[0023] Furthermore, the method for constructing the grey relational analysis model in step S7 is as follows: for the dissolution reaction, the dissolution rate calculated in step S6 is used as the reference sequence. For the cementation reaction, the cementation rate calculated in step S6 is used as the reference sequence. ; by temperature Confining pressure pore pressure The effective confining pressure obtained The pore pressure This is a single-factor comparison sequence, corresponding sequentially. , , ;, with the interaction term of temperature and confining pressure Temperature and pore pressure interaction term Interaction term between confining pressure and pore pressure For the two-field interaction term comparison sequence, corresponding sequentially , , Based on the above sequences, the original data matrices for dissolution and cementation reactions were constructed respectively. After dimensionless normalization, difference sequence and two-level extreme value calculations, and correlation coefficient calculations, the grey relational degree corresponding to the dissolution reaction was finally obtained. Grey relational degree corresponding to cementation reaction ,in =1,2,3,4,5,6 with sequence One-to-one correspondence.

[0024] Furthermore, the multi-field coupling contribution rate mentioned in step S7 is calculated independently for dissolution and cementation reactions, and the specific formula and judgment rules are as follows:

[0025] Formula for calculating the contribution rate of dissolution reaction coupling:

[0026]

[0027] Formula for calculating the contribution rate of cementation reaction coupling:

[0028]

[0029] In the formula, Single-factor comparison sequence corresponding to temperature in the dissolution reaction. Grey relational degree;

[0030] Single-factor comparison sequence corresponding to effective confining pressure in the dissolution reaction. Grey relational degree;

[0031] Single-factor comparison sequence of pore pressure in dissolution reaction Grey relational degree;

[0032] In the dissolution reaction, the two-field comparison sequence corresponding to the interaction term of temperature and confining pressure. Grey relational degree;

[0033] Two-field comparison sequences corresponding to the temperature-pore pressure interaction term in the dissolution reaction. Grey relational degree;

[0034] : The two-field comparison sequence corresponding to the interaction term of confining pressure and pore pressure in the dissolution reaction Grey relational degree;

[0035] Single-factor comparison sequence corresponding to temperature in the cementation reaction. Grey relational degree;

[0036] In the cementation reaction, the single-factor comparison sequence corresponding to the effective confining pressure. Grey relational degree;

[0037] Single-factor comparison sequence of pore pressure in cementation reaction Grey relational degree;

[0038] In the cementation reaction, the two-field comparison sequence corresponding to the interaction term between temperature and confining pressure. Grey relational degree;

[0039] Two-field comparison sequence corresponding to the interaction term of temperature and pore pressure in the cementation reaction. Grey relational degree;

[0040] In the cementation reaction, the two-field comparison sequence corresponding to the interaction term of confining pressure and pore pressure. Grey relational degree;

[0041] When the contribution rate of dissolution reaction coupling is greater than 25%, it is determined that the influence of multi-field coupling on the formation of reservoir dissolution pores is not negligible; when the contribution rate of cementation reaction coupling is greater than 20%, it is determined that the influence of multi-field coupling on the destruction of reservoir pore cementation is not negligible; when the difference between the contribution rates of dissolution and cementation reaction coupling is greater than 15%, it is determined that multi-field coupling has a directional regulating effect on the direction of diagenetic reaction.

[0042] Furthermore, for both dissolution and cementation reactions, the influence weights and controlling order are determined according to the following steps: based on the grey relational analysis of the corresponding single-factor sequences. and The independent influence weights of each factor are calculated using the normalization method. The calculation formula is as follows:

[0043] ;

[0044] In the formula: For the first The influence weight of each single factor The grey relational degree corresponds to the single-factor sequence, and the relational degree value is positively correlated with the influence weight; an effective stress coefficient is introduced. The combined influence weight of confining pressure and pore pressure is adjusted using the following formula:

[0045] ;

[0046] Among them, the effective stress coefficient The value ranges from 0.5 to 1.0, and is determined based on the measured porosity of the standard artificial rock core. When the measured porosity of the rock core is ≤5%, Take 0.5; when the porosity is 5%~10%, Take 0.7; when porosity > 10%, Set the value to 1.0; according to the revised influence weights from high to low, establish the order of factors controlling the dissolution reaction and cementation reaction respectively, and determine the factors with a weight ratio of ≥40% as the first controlling factor of the corresponding reaction.

[0047] Furthermore, a reservoir evaluation and prediction method is established according to the following steps: combining the independent influence weights, main control order, and corresponding coupling contribution rates of dissolution and cementation reactions, using the measured geothermal gradient, geostress profile, and formation pore pressure parameters of the target oil and gas reservoir as input items, and the dissolution rate and cementation rate as output indicators, a dynamic evolution model of calcite diagenesis is established; taking the dissolution rate being greater than the cementation rate as the core judgment condition, and combining the critical threshold of reservoir porosity of 2%, favorable dissolution reservoir zones are divided to complete the quantitative evaluation and prediction of favorable dissolution reservoir zones in deep oil and gas reservoirs.

[0048] The beneficial effects of this invention are reflected in:

[0049] Recreating the real diagenetic environment: Achieving independent control and coupled loading of three fields: temperature, pore pressure, and confining pressure, filling the gap in the stress field dimension of existing technologies, and accurately matching the real diagenetic scenario of oil and gas reservoirs.

[0050] Precise quantification of bidirectional rates: By eliminating system interference through full-process error control, the rate of calcite dissolution and cementation reaction can be precisely and repeatedly quantified, solving the core problem of large evaluation deviations in existing technologies.

[0051] Analysis of multi-field coupling effects: A dedicated grey relational model is constructed for bidirectional diagenetic reactions, which can quantify the coupling contribution rate, the influence weight of factors and the order of control, breaking through the limitation of existing technologies that cannot analyze the multi-field coupling laws.

[0052] Adaptable to field exploration needs: The method has a high degree of standardization and can be directly connected to the measured parameters of the reservoir to establish a diagenetic evolution model, realize the quantitative evaluation and prediction of favorable dissolution reservoir zones, and has both scientific research and engineering application value. Attached Figure Description

[0053] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0054] Figure 1 A schematic diagram of the process for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling provided in an embodiment of the present invention;

[0055] Figure 2 An experimental trend diagram showing the change of calcite dissolution rate with temperature, provided for an embodiment of the present invention;

[0056] Figure 3 A graph showing the relationship between the calcite dissolution rate and saturation state and pressure level provided in an embodiment of the present invention;

[0057] Figure 4 The graph showing the relationship between calcite dissolution volume and strain rate is provided for an embodiment of the present invention. Detailed Implementation

[0058] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or end that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or ends.

[0060] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0061] Currently, experimental evaluation methods for calcite dissolution and cementation behavior mainly rely on high-pressure reactor intermittent experiments, thermogravimetric analysis, and in-situ spectroscopic characterization. These methods generally suffer from the following insurmountable technical shortcomings: First, they lack experimental variable dimensions, failing to recreate the true multi-field coupled environment of the formation. Existing methods can only achieve dual-factor coupling control of temperature and pore pressure, unable to independently and controllably apply triaxial mechanical stress to core samples, completely lacking the core stress field dimension of hydrocarbon formations. The experimental environment differs fundamentally from the actual diagenetic environment of the formation. Second, the evaluation results exhibit systematic bias and fail to reflect true diagenetic behavior. The mechanochemical coupling control effect of stress field on the calcite dissolution-cementation reaction has been confirmed by geological theory and field data. The lack of stress dimension design in existing methods leads to a significant systematic deviation between the experimentally measured reaction rate and the diagenetic behavior under actual formation stress conditions, failing to provide reliable experimental support for predicting reservoir porosity evolution. Third, they cannot quantitatively analyze multi-field coupling effects and cannot clearly identify the main controlling factors of diagenesis. Existing methods can only conduct simple single-factor or temperature-pressure dual-factor analyses, failing to systematically quantify the synergistic / antagonistic coupling effects among temperature, pore pressure, and confining pressure. They also cannot clearly define the influence weights and controlling order of each factor on the direction and rate of diagenetic reactions, making it difficult to establish quantitative prediction models for diagenesis. Furthermore, the experimental procedures suffer from low standardization and poor repeatability. Existing methods lack a systematic error control system and do not fully consider systematic errors caused by sample differences, variations in fluid ion concentration, and pipeline adsorption, resulting in poor repeatability and comparability of experimental results, and hindering the development of standardized industry evaluation methods.

[0062] Therefore, there is an urgent need to develop a standardized experimental method that can simultaneously achieve independent control and coupled loading of three fields: temperature, pore pressure, and confining pressure; can dynamically and quantitatively evaluate the dissolution and cementation rate of calcite; and can accurately analyze the multi-field coupling effect, so as to solve the core bottleneck of the existing technology.

[0063] The present invention aims to provide a method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling effects, in order to solve the problems in the existing technology, such as systematic bias in evaluation results, inability to quantitatively analyze multi-field coupling effects, inability to clearly identify the main controlling factors of diagenesis, and poor repeatability due to low standardization of experimental procedures.

[0064] This invention provides a method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling, comprising the following steps:

[0065] S1. Preparation of standard rock cores: Pure calcite powder is subjected to constant pressure cold pressing and high temperature calcination to remove impurities, thus preparing standard artificial rock cores with uniform physical properties and free from interference from impurities.

[0066] In this embodiment of the invention, the preparation process of the standard artificial rock core is as follows: pure calcite powder is placed in a cylindrical rock core mold, and then cold-pressed on a press at a constant pressure of 200MPa to obtain a molded sample. Subsequently, the molded sample is placed in a temperature-controlled furnace and calcined at a constant temperature of 450℃ for 10 hours to obtain a standard artificial rock core with consistent geometric dimensions, porosity, and permeability parameters.

[0067] S2. Sample loading and system construction: Standard artificial cores are loaded into a triaxial pressure chamber that can independently control the temperature, pore pressure, and confining pressure in a closed loop. Controllable triaxial mechanical stress is applied to the standard artificial cores through confining pressure to build a multi-field coupled reaction system that matches the diagenetic environment of oil and gas reservoirs.

[0068] In this embodiment of the invention, ...

[0069] S3. Two-way reaction group design: Set up a dissolution experimental group, a cementation experimental group and a blank control group, and inject the corresponding matching reaction liquid into the triaxial pressure chamber to clarify the boundary conditions for diagenetic reaction simulation.

[0070] In this embodiment of the invention, the specific setup for the grouped experiments is as follows: the dissolution experimental group is injected with deionized water as the reaction solution to simulate the acidic fluid dissolution scenario of the formation; the cementation experimental group is injected with a simulated formation aqueous solution with a Ca²⁺ concentration of 100 mmol / L as the reaction solution to simulate the mineral cementation scenario of the formation; the blank control group uses an equal volume of inert quartz sand column to replace the standard artificial rock core, and conducts experiments simultaneously with the dissolution experimental group and the cementation experimental group to deduct systematic errors caused by factors such as changes in the fluid's own ion concentration and pipeline adsorption.

[0071] S4. Multi-field coupled gradient experiment: For each group of experiments, the sensitive range of variables is first locked through single-factor experiments. Then, with temperature, pore pressure and confining pressure as three experimental factors, a three-factor, five-level standard orthogonal experimental scheme is adopted to carry out continuous flow dynamic diagenetic reaction experiments under the set working conditions.

[0072] In this embodiment of the invention, the gradients and rules for the single-factor experiments are as follows: Temperature single-factor experiment: The temperature gradients are set to 30℃, 80℃, 120℃, 160℃, and 200℃. During the experiment, the confining pressure and pore pressure are fixed at 10MPa, and the dissolution experiment group and the cementation experiment group are carried out simultaneously; Confining pressure single-factor experiment: The confining pressure gradients are set to 10MPa, 20MPa, 30MPa, 40MPa, and 50MPa. During the experiment, the temperature is fixed at 100℃ and the pore pressure is fixed at 10MPa, and the dissolution experiment group and the cementation experiment group are carried out simultaneously; The corrosion and cementation experimental groups used identical fixed parameters. For the single-factor pore pressure experiment, pore pressure gradients of 5 MPa, 10 MPa, 15 MPa, 20 MPa, and 25 MPa were set. During the experiment, the confining pressure was fixed at 10 MPa and the temperature was 100℃. Effluent data from the corresponding experimental group and the blank control group were collected simultaneously. For each single-factor working condition and each level combination of the orthogonal experiment, at least 3 parallel repeated experiments were set for both the corrosion and cementation groups. The relative deviation of the parallel experimental data was less than 3% to be considered valid data.

[0073] S5. Dynamic Sampling and Steady-State Determination: Based on the reaction process, the effluent is sampled at regular intervals to detect the Ca²⁺ ion concentration in the effluent. The steady-state of the reaction is determined by continuous sampling data, and the corrected effective ion concentration data is obtained.

[0074] In this embodiment of the invention, the dynamic sampling and steady-state determination rules are as follows: after each working condition has been continuously stable for 15 minutes, at least 3 groups of 1 mL effluent samples are continuously collected at 30-minute intervals; when the relative deviation of the Ca²⁺ concentration detection values ​​of the three adjacent groups of samples is less than 2%, the reaction is determined to have reached dynamic steady state, and the average value of the three groups of detection values ​​is taken and the blank control group correction value is subtracted as the effective ion concentration data of the working condition.

[0075] S6. Quantitative calculation of reaction rate: Based on the effective ion concentration data, combined with the inlet and outlet ion concentration difference, fluid flow rate, and the effective contact surface area between calcite and fluid in the core, the dissolution rate or cementation rate of calcite under the corresponding working conditions is quantitatively calculated.

[0076] In this embodiment of the invention, the formulas for calculating the dissolution rate and the cementation rate are as follows:

[0077]

[0078] In the formula, The value represents the calcite reaction rate, expressed in mol / (m²·s). Positive values ​​correspond to the dissolution rate, while negative values ​​correspond to the cementation rate. The molar concentration of Ca²⁺ at the inlet of the reaction solution is expressed in mol / m³. The corrected Ca²⁺ molar concentration of the outlet liquid obtained in step S5 is expressed in mol / m³. The steady-state volumetric velocity of the fluid is expressed in m³ / s. This represents the effective contact surface area between calcite and fluid within the core, expressed in m².

[0079] S7. Evaluation of multi-field coupling effect: For the two-way reaction of dissolution and cementation, a grey relational analysis model containing single-field variables and two-field interaction terms is constructed respectively. The grey relational degree of each factor and the multi-field coupling contribution rate of each reaction direction are calculated to clarify the influence weight and coupling law of each factor on the reaction direction and rate.

[0080] In this embodiment of the invention, the method for constructing the grey relational analysis model is as follows: for the dissolution reaction, the dissolution rate calculated in step S6 is used as the reference sequence. For the cementation reaction, the cementation rate calculated in step S6 is used as the reference sequence. ; by temperature Confining pressure pore pressure The effective confining pressure obtained pore pressure This is a single-factor comparison sequence, corresponding sequentially. , , ;, with the interaction term of temperature and confining pressure Temperature and pore pressure interaction term Interaction term between confining pressure and pore pressure For the two-field interaction term comparison sequence, corresponding sequentially , , Based on the above sequences, the original data matrices for dissolution and cementation reactions were constructed respectively. After dimensionless normalization, difference sequence and two-level extreme value calculations, and correlation coefficient calculations, the grey relational degree corresponding to the dissolution reaction was finally obtained. Grey relational degree corresponding to cementation reaction ,in =1,2,3,4,5,6 with sequence One-to-one correspondence; the contribution rate of multi-field coupling is calculated independently for dissolution and cementation reactions, and the specific formulas and judgment rules are as follows:

[0081] Formula for calculating the contribution rate of dissolution reaction coupling:

[0082]

[0083] Formula for calculating the contribution rate of cementation reaction coupling:

[0084]

[0085] In the formula, Single-factor comparison sequence corresponding to temperature in the dissolution reaction. Grey relational degree;

[0086] Single-factor comparison sequence corresponding to effective confining pressure in the dissolution reaction. Grey relational degree;

[0087] Single-factor comparison sequence of pore pressure in dissolution reaction Grey relational degree;

[0088] In the dissolution reaction, the two-field comparison sequence corresponding to the interaction term of temperature and confining pressure. Grey relational degree;

[0089] Two-field comparison sequences corresponding to the temperature-pore pressure interaction term in the dissolution reaction. Grey relational degree;

[0090] : The two-field comparison sequence corresponding to the interaction term of confining pressure and pore pressure in the dissolution reaction Grey relational degree;

[0091] Single-factor comparison sequence corresponding to temperature in the cementation reaction. Grey relational degree;

[0092] In the cementation reaction, the single-factor comparison sequence corresponding to the effective confining pressure. Grey relational degree;

[0093] Single-factor comparison sequence of pore pressure in cementation reaction Grey relational degree;

[0094] In the cementation reaction, the two-field comparison sequence corresponding to the interaction term between temperature and confining pressure. Grey relational degree;

[0095] Two-field comparison sequence corresponding to the interaction term of temperature and pore pressure in the cementation reaction. Grey relational degree;

[0096] In the cementation reaction, the two-field comparison sequence corresponding to the interaction term of confining pressure and pore pressure. Grey relational degree;

[0097] When the contribution rate of dissolution reaction coupling is >25%, the influence of multi-field coupling on the formation of reservoir-derived dissolution porosity is considered non-negligible; when the contribution rate of cementation reaction coupling is >20%, the influence of multi-field coupling on the destruction of reservoir porosity cementation is considered non-negligible; when the difference between the contribution rates of dissolution and cementation reaction coupling is >15%, multi-field coupling is considered to have a directional regulatory effect on the direction of diagenetic reaction; for dissolution reaction and cementation reaction respectively, the influence weights and the order of control are determined according to the following steps: based on the grey relational degree of the corresponding single-factor sequence. and The independent influence weights of each factor are calculated using the normalization method. The calculation formula is as follows:

[0098] ;

[0099] In the formula: For the first The influence weight of each single factor The grey relational degree corresponds to the single-factor sequence, and the relational degree value is positively correlated with the influence weight; an effective stress coefficient is introduced. The combined influence weight of confining pressure and pore pressure is adjusted using the following formula:

[0100] ;

[0101] Among them, the effective stress coefficient The value ranges from 0.5 to 1.0, and is determined based on the measured porosity of standard artificial rock cores. When the measured porosity of the rock core is ≤5%, Take 0.5; when the porosity is 5%~10%, Take 0.7; when porosity > 10%, Take 1.0; according to the corrected influence weights from high to low, establish the main control order of factors for dissolution reaction and cementation reaction respectively, and determine the factors with a weight ratio of ≥40% as the first main control factor of the corresponding reaction; establish a reservoir evaluation and prediction method according to the following steps: combining the independent influence weights, main control order and corresponding coupling contribution rates of dissolution and cementation reactions, using the measured geothermal gradient, geostress profile and formation pore pressure parameters of the target oil and gas reservoir as input items, and the dissolution rate and cementation rate as output indicators, establish a dynamic evolution model of calcite diagenesis; taking the dissolution rate being greater than the cementation rate as the core judgment condition, and combining the critical threshold of reservoir porosity of 2%, divide favorable dissolution reservoir zones, and complete the quantitative evaluation and prediction of favorable dissolution reservoir zones of deep oil and gas reservoirs.

[0102] Figure 2The figure shows the experimental trend of calcite dissolution rate as a function of temperature, provided for embodiments of the present invention. The figure illustrates the change in the percentage of calcite ore dissolved over time at different temperatures under the same saturated solution conditions. As the temperature increases, the dissolution rate accelerates significantly, exhibiting typical temperature-dependent kinetic characteristics, indicating that temperature is a key controlling factor affecting the dissolution efficiency of calcite.

[0103] Figure 3 This diagram illustrates the relationship between the calcite dissolution rate and saturation state and pressure level, as provided in an embodiment of the invention. The data points in the diagram represent experimental measurements under different saturation conditions. The dissolution rate under different pressure conditions shows a significant upward trend, indicating that under the same unsaturated state, the higher the pressure, the greater the calcite dissolution rate. This trend demonstrates that pressure promotes the dissolution kinetics of calcite, an effect that exceeds the scope of explanation for purely thermodynamic differences in saturation, reflecting the substantial impact of pressure as a multi-field coupled variable on dissolution efficiency.

[0104] Figure 4 This diagram illustrates the relationship between calcite dissolution volume and strain rate, as provided in an embodiment of the present invention. The strain rate is primarily controlled by the effective stress, which is determined by both the confining pressure and the pore pressure. Therefore, this diagram reflects the intrinsic connection between calcite dissolution behavior and mechanical deformation under multi-field coupling.

[0105] Example 1

[0106] This invention provides a method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling, comprising the following steps:

[0107] Standard core preparation

[0108] Pure calcite powder with a purity ≥ 99.9% was passed through a 200-mesh standard sieve and placed into a cylindrical core mold with a diameter of 25 mm. The mold was then cold-pressed at a constant pressure of 200 MPa for 10 minutes to obtain the molded sample. Subsequently, the molded sample was placed in a muffle furnace and calcined at a constant temperature of 450℃ for 10 hours to remove residual organic matter and stress. After natural cooling to room temperature, a standard artificial core with a diameter of 25 mm, a length of 50 mm, a porosity of 8.2%, and a permeability of 0.12 mD was obtained. A total of 6 parallel samples were prepared to ensure that the deviation of the core's geometric dimensions and physical properties was less than 2%.

[0109] Sample preparation and system setup

[0110] The prepared standard artificial core was placed into a triaxial pressure chamber that allows for independent closed-loop control of temperature, pore pressure, and confining pressure. Controllable triaxial mechanical stress was applied to the core through a confining pressure loading system to build a multi-field coupled reaction system that matches the diagenetic environment of deep oil and gas reservoirs. The system's sealing was checked to ensure there was no fluid leakage.

[0111] Two-way reaction grouping design

[0112] Three parallel dissolution experimental groups, two parallel cementation experimental groups, and one blank control group were set up, as follows:

[0113] Dissolution Experiment Group: Deionized water was injected as the reaction solution to simulate the acidic fluid dissolution scenario of the formation;

[0114] Cementation Experiment Group: A simulated formation aqueous solution with a Ca²⁺ concentration of 100 mmol / L was injected as the reaction solution to simulate the cementation scenario of calcite in the formation;

[0115] Blank control group: Inert quartz sand columns of equal volume and size were used to replace standard artificial rock cores and were used to conduct experiments simultaneously with the dissolution and cementation experimental groups to deduct systematic errors.

[0116] Multi-field coupled gradient experiment

[0117] First, single-factor experiments were used to determine the sensitive range of variables related to the dissolution and cementation reactions of calcite. Then, a standard orthogonal experimental design with 3 factors and 5 levels was used to conduct orthogonal experiments. The gradient and rules for the single-factor experiments were as follows:

[0118] Temperature single-factor experiment: The temperature gradient was set to 30℃, 80℃, 120℃, 160℃ and 200℃. During the experiment, the confining pressure was fixed at 10MPa and the pore pressure was fixed at 10MPa. The dissolution experiment group and the cementation experiment group were carried out simultaneously.

[0119] Single-factor confining pressure experiment: The confining pressure gradient was set to 10MPa, 20MPa, 30MPa, 40MPa and 50MPa. The temperature was fixed at 100℃ and the pore pressure was fixed at 10MPa during the experiment. The parameters of the dissolution experiment group and the cementation experiment group were completely consistent.

[0120] Pore ​​pressure single-factor experiment: The pore pressure gradient was set to 5MPa, 10MPa, 15MPa, 20MPa and 25MPa. During the experiment, the confining pressure was fixed at 10MPa and the temperature was fixed at 100℃. Data of the experimental group and the blank control group were collected simultaneously. Each single-factor working condition and each level combination of the orthogonal experiment were set up with 3 parallel repeated experiments. The relative deviation of the parallel experimental data was less than 3% and was regarded as valid data.

[0121] Dynamic sampling and steady-state determination

[0122] After each set of operating conditions has been continuously and stably reacted for 15 minutes, three sets of 1 mL effluent samples were continuously collected at 30-minute intervals. The Ca²⁺ ion concentration in the samples was detected using inductively coupled plasma optical emission spectrometry (ICP-OES). When the relative deviation of the Ca²⁺ concentration detection values ​​of the three adjacent sets of samples is less than 2%, the reaction is determined to have reached a dynamic steady state. The average value of the three sets of detection values ​​is taken and the correction value of the blank control group is subtracted to obtain the effective ion concentration data for that operating condition.

[0123] Quantitative calculation of reaction rate

[0124] Based on the effective ion concentration data, the dissolution rate or cementation rate of calcite under the corresponding working conditions is calculated using the following formula:

[0125]

[0126] In this embodiment, the inlet liquid of the dissolution experimental group =0 mol / m³, fluid velocity =1.67×10−9m³ / s, effective contact surface area of ​​core S=0.0039m²; calculated, under the conditions of 100℃, confining pressure 10MPa, and pore pressure 10MPa, the calcite dissolution rate is 8.72×10−7mol / (m²・s).

[0127] The core results of the single-factor experiment in this embodiment are as follows:

[0128] Effect of temperature on the dissolution rate: The dissolution rate is 1.05×10−7 mol / (m²・s) at 30℃, 3.26×10−7 mol / (m²・s) at 80℃, 1.25×10−6 mol / (m²・s) at 120℃, 2.84×10−6 mol / (m²・s) at 160℃, and 4.17×10−6 mol / (m²・s) at 200℃. The dissolution rate increases exponentially with increasing temperature, which is consistent with the Arrhenius kinetics.

[0129] Effect of confining pressure on dissolution rate: The dissolution rate is 8.72×10−7 mol / (m²・s) at 10 MPa, 9.45×10−7 mol / (m²・s) at 20 MPa, 9.87×10−7 mol / (m²・s) at 30 MPa, 1.02×10−6 mol / (m²・s) at 40 MPa, and 1.05×10−6 mol / (m²・s) at 50 MPa. Increasing confining pressure has a weak promoting effect on the dissolution rate, and the increase gradually saturates with increasing confining pressure.

[0130] Effect of pore pressure on dissolution rate: The dissolution rate is 9.03×10−7 mol / (m²・s) at 5 MPa, 8.72×10−7 mol / (m²・s) at 10 MPa, 8.41×10−7 mol / (m²・s) at 15 MPa, 8.15×10−7 mol / (m²・s) at 20 MPa, and 7.92×10−7 mol / (m²・s) at 25 MPa. Increased pore pressure has a slight inhibitory effect on the dissolution rate.

[0131] Evaluation of multi-field coupling effects and analysis of controlling factors

[0132] For the dissolution reaction, using the measured dissolution rate as the reference sequence, a grey relational analysis model was constructed, and the grey relational degree of each sequence was calculated as: dissolution, dissolution, dissolution, dissolution, dissolution. The coupling contribution rate of the dissolution reaction was calculated as: Dissolution reaction coupling contribution rate = 0.924 + 0.587 + 0.312 + 0.763 + 0.425 + 0.208 × 100% = 46.8%. The coupling contribution rate is greater than 25%, indicating that the influence of multi-field coupling on the formation of reservoir-derived dissolution porosity is not negligible, and there is a significant synergistic coupling effect among the three fields. The influence weights of each factor were calculated using the normalization method: temperature weight 50.7%, effective confining pressure weight 32.2%, and pore pressure weight 17.1%, introducing the effective stress coefficient. After correction to 0.7 (matching core porosity of 8.2%), temperature was determined to be the primary controlling factor of the dissolution reaction, effective confining pressure was the secondary controlling factor, and pore pressure was the secondary influencing factor.

[0133] Evaluation of favorable zones of reservoir

[0134] Based on the aforementioned main control sequence and coupling contribution rate, a dynamic evolution model of calcite diagenesis was established using the measured geothermal gradient of 3.2℃ / 100m, geostress gradient of 2.3MPa / 100m, and formation pore pressure gradient of 1.1MPa / 100m in the target deep oil and gas reservoir as input terms. With the dissolution rate being greater than the cementation rate as the core criterion, and combined with the critical threshold of reservoir porosity of 2%, favorable dissolution reservoir zones at burial depths of 4500~5800m were delineated as the target reservoir, providing direct experimental support for field exploration.

[0135] Comparative Example 1

[0136] This comparative example uses the conventional high-pressure reactor intermittent experimental method to evaluate the dissolution rate of calcite powder samples identical to those in Example 1. It can only couple the two variables of temperature and pore pressure, and cannot apply controllable confining pressure (triaxial stress). The experimental temperature was 100℃, and the pore pressure was 10MPa. All other reaction solutions, detection methods, and experimental durations were identical to those in Example 1. The test results show that the calcite dissolution rate measured in this comparative example is 1.24×10−6 mol / (m²・s), which is significantly different from the measured dissolution rate of 8.72×10−7 mol / (m²・s) under the same conditions in Example 1, with a relative deviation of 42.2%. The comparison results demonstrate that existing technologies lack the stress field dimension and cannot recreate the true diagenetic environment of the formation. The evaluation results show a serious systematic deviation from the actual calcite diagenetic behavior under real conditions. In contrast, this invention, by introducing controllable stress loading, can accurately recreate the true multi-field coupled environment of the formation, and the evaluation results are more consistent with actual geological conditions, with significantly better accuracy than existing technologies.

[0137] The above descriptions are merely embodiments of the present invention. Commonly known technical solutions or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling, characterized in that, The method includes: S1. Preparation of standard rock cores: Pure calcite powder is subjected to constant pressure cold pressing and high temperature calcination to remove impurities, and standard artificial rock cores with uniform physical properties and no interference from impurities are prepared. S2. Sample loading and system setup: The standard artificial rock core is loaded into a triaxial pressure chamber with independent closed-loop control of temperature, pore pressure and confining pressure. Controllable triaxial mechanical stress is applied to the standard artificial rock core through the confining pressure. S3. Two-way reaction grouping design: Set up a dissolution experimental group, a cementation experimental group and a blank control group, and inject the corresponding matching reaction solution into the triaxial pressure chamber; S4. Multi-field coupled gradient experiment: For each group of experiments, the sensitive range of variables is first locked through single-factor experiments. Then, with temperature, pore pressure and confining pressure as three experimental factors, a three-factor, five-level standard orthogonal experimental scheme is adopted to carry out continuous flow dynamic diagenetic reaction experiments under the set working conditions. S5. Dynamic sampling and steady-state determination: Based on the reaction process, the effluent is collected at regular intervals to detect the Ca²⁺ ion concentration in the effluent. The steady-state of the reaction is determined by continuous sampling data, and the corrected effective ion concentration data is obtained. S6. Quantitative calculation of reaction rate: Based on the effective ion concentration data, combined with the inlet and outlet ion concentration difference, fluid flow rate, and effective contact surface area between calcite and fluid in the core, the dissolution rate or cementation rate of calcite under the corresponding working conditions is quantitatively calculated. S7. Evaluation of multi-field coupling effect: For the two-way reaction of dissolution and cementation, a grey relational analysis model containing single-field variables and two-field interaction terms is constructed respectively. The grey relational degree of each factor and the multi-field coupling contribution rate of each reaction direction are calculated to clarify the influence weight and coupling law of each factor on the reaction direction and rate.

2. The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling as described in claim 1, characterized in that: The specific process for preparing the standard artificial rock core in step S1 is as follows: pure calcite powder is placed into a cylindrical rock core mold, and then cold-pressed at a constant pressure of 200MPa on a press to obtain a molded sample. Subsequently, the molded sample is placed in a temperature-controlled furnace and calcined at a constant temperature of 450℃ for 10 hours to obtain a standard artificial rock core with consistent geometric dimensions, porosity, and permeability parameters.

3. The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling as described in claim 1, characterized in that: The specific setup for the grouped experiments in step S3 is as follows: the dissolution experimental group is injected with deionized water as the reaction solution, and the cementation experimental group is injected with a simulated formation aqueous solution with a Ca²⁺ concentration of 100 mmol / L as the reaction solution; the blank control group uses an equal volume of inert quartz sand column to replace the standard artificial core, and the experiments are carried out simultaneously with the dissolution experimental group and the cementation experimental group.

4. The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling as described in claim 3, characterized in that: The gradient and rules for the single-factor experiment described in step S4 are as follows: Temperature single-factor experiment: The temperature gradient was set to 30℃, 80℃, 120℃, 160℃ and 200℃. During the experiment, the confining pressure was fixed at 10MPa and the pore pressure was fixed at 10MPa. The dissolution experiment group and the cementation experiment group were carried out simultaneously. Single-factor confining pressure experiment: The confining pressure gradient was set to 10MPa, 20MPa, 30MPa, 40MPa and 50MPa. The temperature was fixed at 100℃ and the pore pressure was fixed at 10MPa during the experiment. The dissolution experimental group and the cementation experimental group used the same fixed parameters. Pore ​​pressure single-factor experiment: The pore pressure gradient was set to 5MPa, 10MPa, 15MPa, 20MPa and 25MPa. During the experiment, the confining pressure was fixed at 10MPa and the temperature was fixed at 100℃. The effluent data of the corresponding experimental group and blank control group were collected simultaneously. For each single-factor working condition and each level combination of orthogonal experiments, at least three parallel repeated experiments were set up for the dissolution group and the cementation group. The relative deviation of the parallel experimental data was less than 3% to be considered valid data.

5. The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling as described in claim 4, characterized in that: The dynamic sampling and steady-state determination rules in step S5 are as follows: After each working condition has been continuously and stably reacted for 15 minutes, at least 3 groups of 1 mL effluent samples are continuously collected at 30-minute intervals; when the relative deviation of the Ca²⁺ concentration detection values ​​of the adjacent 3 groups of samples is less than 2%, the reaction is determined to have reached dynamic steady state, and the average value of the 3 groups of detection values ​​is taken and the blank control group correction value is subtracted as the effective ion concentration data of the working condition.

6. The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling as described in claim 1, characterized in that: The formulas for calculating the dissolution rate and cementation rate in step S6 are as follows: In the formula, The value represents the calcite reaction rate, expressed in mol / (m²·s). Positive values ​​correspond to the dissolution rate, while negative values ​​correspond to the cementation rate. The molar concentration of Ca²⁺ at the inlet of the reaction solution is expressed in mol / m³. The corrected Ca²⁺ molar concentration of the outlet liquid obtained in step S5 is expressed in mol / m³. The steady-state volumetric velocity of the fluid is expressed in m³ / s. This represents the effective contact surface area between calcite and fluid within the core, expressed in m².

7. The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling as described in claim 6, characterized in that: The specific method for constructing the grey relational analysis model described in step S7 is as follows: For the dissolution reaction, the dissolution rate calculated in step S6 is used as the reference sequence. For the cementation reaction, the cementation rate calculated in step S6 is used as the reference sequence. ; With temperature Confining pressure pore pressure The effective confining pressure obtained The pore pressure This is a single-factor comparison sequence, corresponding sequentially. , , ;, with the interaction term of temperature and confining pressure Temperature and pore pressure interaction term Interaction term between confining pressure and pore pressure For the two-field interaction term comparison sequence, corresponding sequentially , , ; Based on the above sequences, the original data matrices for dissolution and cementation reactions were constructed respectively. After dimensionless normalization, difference sequence and two-level extreme value calculations, and correlation coefficient calculations, the grey relational degree corresponding to the dissolution reaction was finally obtained. Grey relational degree corresponding to cementation reaction ,in =1,2,3,4,5,6 with sequence One-to-one correspondence.

8. The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling as described in claim 1, characterized in that: The multi-field coupling contribution rate mentioned in step S7 is calculated independently for dissolution and cementation reactions, and the specific formula and judgment rules are as follows: Formula for calculating the contribution rate of dissolution reaction coupling: Formula for calculating the contribution rate of cementation reaction coupling: In the formula, Single-factor comparison sequence corresponding to temperature in the dissolution reaction. Grey relational degree; Single-factor comparison sequence corresponding to effective confining pressure in the dissolution reaction. Grey relational degree; Single-factor comparison sequence of pore pressure in dissolution reaction Grey relational degree; In the dissolution reaction, the two-field comparison sequence corresponding to the interaction term of temperature and confining pressure. Grey relational degree; Two-field comparison sequences corresponding to the temperature-pore pressure interaction term in the dissolution reaction. Grey relational degree; : The two-field comparison sequence corresponding to the interaction term of confining pressure and pore pressure in the dissolution reaction Grey relational degree; Single-factor comparison sequence corresponding to temperature in the cementation reaction. Grey relational degree; In the cementation reaction, the single-factor comparison sequence corresponding to the effective confining pressure. Grey relational degree; Single-factor comparison sequence of pore pressure in cementation reaction Grey relational degree; : Two-field comparison sequence corresponding to the temperature-confining pressure interaction term in the cementation reaction Grey relational degree; Two-field comparison sequence corresponding to the interaction term of temperature and pore pressure in the cementation reaction. Grey relational degree; In the cementation reaction, the two-field comparison sequence corresponding to the interaction term of confining pressure and pore pressure. Grey relational degree; When the contribution rate of dissolution reaction coupling is greater than 25%, it is determined that the influence of multi-field coupling on the formation of reservoir-generated dissolution porosity cannot be ignored. When the contribution rate of cementation reaction coupling is greater than 20%, it is determined that the influence of multi-field coupling on the cementation failure of reservoir pores is not negligible. When the difference in the coupling contribution rate between dissolution and cementation reactions is greater than 15%, it is determined that multi-field coupling has a directional regulatory effect on the direction of diagenetic reaction.

9. The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling as described in claim 8, characterized in that: For both dissolution and cementation reactions, determine the influence weights and order of control according to the following steps: Grey relational analysis based on corresponding single-factor sequences and The independent influence weights of each factor are calculated using the normalization method. The calculation formula is as follows: ； In the formula: For the first The influence weight of each single factor The grey relational degree corresponds to the single-factor sequence, and the relational degree value is positively correlated with the influence weight; Introducing effective stress coefficient The combined influence weight of confining pressure and pore pressure is adjusted using the following formula: ； Among them, the effective stress coefficient The value ranges from 0.5 to 1.0, and is determined based on the measured porosity of the standard artificial rock core. When the measured porosity of the rock core is ≤5%, Take 0.5; when the porosity is 5%~10%, Take 0.7; when porosity > 10%, Set the value to 1.0; Based on the revised influence weights from high to low, the order of factors controlling the dissolution reaction and cementation reaction is established respectively. Factors with a weight ratio of ≥40% are determined as the first controlling factor of the corresponding reaction.

10. The method for evaluating the dissolution and cementation rate of calcite minerals under multi-field coupling as described in claim 9, characterized in that: Establish a reservoir evaluation and prediction method using the following steps: Combining the independent influence weights, main control order, and corresponding coupling contribution rates of dissolution and cementation reactions, and using the measured geothermal gradient, geostress profile, and formation pore pressure parameters of the target oil and gas reservoir as inputs, and dissolution rate and cementation rate as output indicators, a dynamic evolution model of calcite diagenesis is established. Using the dissolution rate being greater than the cementation rate as the core criterion, and combined with the critical threshold of reservoir porosity of 2%, favorable dissolution reservoir zones are delineated, thus completing the quantitative evaluation and prediction of favorable dissolution reservoir zones in deep oil and gas reservoirs.

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