Method and system for verifying water sensitivity evaluation result
By using steel cores for comparative experiments, the uncertainty in the evaluation results of water sensitivity of low-permeability clastic rock reservoirs was resolved, the accuracy and reliability of the experimental results were improved, and a method for verifying the experimental results was provided.
Patent Information
- Application Number
- CN202310900023.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-20
- Publication Date
- 2025-01-21
AI Technical Summary
Existing technologies lack a unified standard for evaluating the water sensitivity of low-permeability clastic reservoirs, resulting in large differences in experimental results and an inability to distinguish between differences in the rock samples themselves and differences in experimental methods or conditions, leading to uncertainty in experimental analysis.
A steel core made of permeable steel was used to conduct a comparative experiment according to the standard experimental procedure. The water sensitivity evaluation results were verified by the change in the permeability of the steel core. If the permeability remained unchanged, the experiment was reliable; otherwise, the experimental results were inaccurate.
It improves the accuracy of water sensitivity evaluation results, can identify errors caused by experimental methods or conditions, and provides a method for verifying the reliability of experimental results.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of oil and gas field development, and in particular to a method and system for verifying water sensitivity evaluation results. Background Art
[0002] Water sensitivity refers to the phenomenon that when injected water with low mineralization enters the reservoir, it causes clay to swell, disperse, and migrate, causing changes in the seepage channel and resulting in changes in the permeability of the reservoir rock. Water sensitivity evaluation can understand the swelling, dispersion, and migration process of clay minerals after encountering fresh water, find out the conditions for water sensitivity and the degree of reservoir damage caused by water sensitivity, and provide a basis for the design of various working fluids.
[0003] At present, the core water sensitivity test mainly refers to SYT 5358-2010 "Reservoir Sensitivity Flow Test Evaluation Method" (hereinafter referred to as the standard), because the standard is mainly applicable to gas permeability greater than 1×10 -3 μm 2 The clastic reservoir rock samples with gas permeability less than 1×10 -3 μm 2 The rock samples are not specified. Therefore, when the gas permeability is greater than 1×10 -3 μm 2 When taking clastic reservoir samples, according to the standard process, water sensitivity evaluation needs to inject experimental brine (or simulated formation water), 1 / 2 mineralization experimental brine (or 1 / 2 concentration simulated formation water), and distilled water in turn for saturation and backflow according to the flow rate of the rate-sensitive evaluation result to obtain water sensitivity results, which leads to great differences in the water sensitivity test results of low permeability reservoirs.
[0004] Illite dispersion / migration, gypsum hydration expansion, dissolution and reprecipitation, and carbonate mineral precipitation are the main reasons for the strong water sensitivity of the reservoir. However, the release, migration, and blockage of mineral particles in the core are very complex, and there are many influencing factors, such as fluid contact time, temperature, pH, etc., especially the core (rock composition, particle size, degree of cementation, core shape, pore throat uniformity, gas saturation, water saturation, applied stress, etc.) has a particularly large impact on the particle migration law, and the flow rate setting of water sensitivity evaluation is also based on the speed sensitivity evaluation results. If the speed sensitivity evaluation results are inaccurate, the water sensitivity test results of different rock samples will be quite different. Because particle migration is irreversible, water sensitivity is irreversible. When the experimenters need to analyze whether the experimental results are caused by differences in the rock samples themselves, or by differences in the experimental process and operation methods, they cannot use the same core to repeat the experiment, nor can they find several completely identical cores for comparative experiments, which brings uncertainty to the experimental analysis.
[0005] When different laboratories conduct water sensitivity experiments, they have different -3 μm2 The clastic reservoir rock samples all follow the standard experimental procedures. Even so, the results vary depending on the performance of the equipment used, the proficiency of the operator, and the core used. -3 μm 2 For clastic reservoir rock samples, there is no standard to follow, and the experimental parameters set by different laboratories and researchers are very different, and the experimental results are also very different. When it is necessary to analyze whether the experimental results are caused by the differences in the rock samples themselves, or by different experimental methods and experimental conditions, a verification method is also needed to verify different experimental methods. If it is caused by defects in the experimental methods and experimental conditions, the methods and experimental conditions should be improved in a targeted manner. Summary of the invention
[0006] The purpose of the present invention is to provide a method and system for verifying water sensitivity evaluation results, using permeable steel to make steel cores to verify the reliability of water sensitivity evaluation experimental methods, provide support for improving experimental methods, and improve the accuracy of reservoir core water sensitivity experimental results. To achieve the above purpose, the present invention provides the following technical solutions:
[0007] The present invention provides a method for verifying a water sensitivity evaluation result, the method comprising the following steps:
[0008] Step S1, preparing reservoir cores according to specifications, conducting reservoir core water sensitivity evaluation experiments, and obtaining permeability damage degree experimental results;
[0009] Step S2, using permeable steel materials to make steel cores according to the reservoir core specifications in step S1;
[0010] Step S3, drying the steel core in step S2;
[0011] Step S4, using the steel core dried in step S3, a comparative experiment is carried out according to the water sensitivity evaluation experiment in step S1 to obtain the experimental results of the permeability damage degree;
[0012] Step S5, analyzing the permeability damage degree experimental results obtained in step S4; if the permeability damage degree of the steel core does not change, it indicates that water sensitivity does not occur; if the permeability damage degree of the steel core is too large, it indicates that water sensitivity occurs and the experimental results obtained in step S1 are inaccurate.
[0013] Furthermore, the method further comprises the following steps:
[0014] Step S6: After the experiment is completed, clean water is used to displace the steel core under high pressure, and then the steel core is dried for the next experiment.
[0015] As a preferred implementation, in step S1, the reservoir core production specifications include: a diameter of 2.50-2.55 cm and a length of 5.0-9.0 cm.
[0016] As a preferred implementation, in step S2, the permeable steel material is breathable, rust-resistant and corrosion-resistant steel material.
[0017] As a preferred implementation, in step S3, the drying conditions include: temperature ≤ 105°C, time ≥ 5h.
[0018] As a preferred implementation, in step S5, the degree of damage to the permeability of the steel core is based on the standard "SY / T5358-2010 Reservoir Sensitivity Flow Experiment Evaluation Method".
[0019] As a preferred implementation, in step S6, the time for displacing the steel core is ≥ 2 hours.
[0020] The present invention also provides a system for verifying water sensitivity evaluation results, the system comprising: a first acquisition unit, a production unit, a drying unit, a second acquisition unit and an analysis unit; wherein,
[0021] The first acquisition unit is used to prepare reservoir cores according to specifications, carry out water sensitivity evaluation experiments on reservoir cores, and obtain permeability damage degree experimental results;
[0022] The production unit is used to produce steel cores according to the reservoir core specifications in the first acquisition unit using permeable steel;
[0023] The drying unit is used to dry the steel core in the production unit in an oven and take it out to carry out the next experiment;
[0024] The second acquisition unit is used to use the steel core in the drying unit to carry out a comparative experiment according to the water sensitivity evaluation experimental process and experimental parameters in the first acquisition unit to obtain the permeability damage degree experimental results;
[0025] The analysis unit is used to analyze the permeability damage degree experimental results obtained in the second acquisition unit; if the permeability damage degree of the steel core does not change, it indicates that water sensitivity does not occur; if the permeability damage degree of the steel core is too large, it indicates that water sensitivity occurs and the experimental results obtained in the first acquisition unit are inaccurate.
[0026] Further, the system further comprises: a displacement unit;
[0027] The displacement unit is used to displace the steel core with clean water under high pressure after the experiment is completed, and then dry it for the next experiment.
[0028] Technical effects and advantages of the present invention:
[0029] The method for verifying water sensitivity of the present invention can not only be used for verifying water sensitivity results, but also can be used for laboratory capability / experimental method comparison of water sensitivity experiments, and can greatly improve the accuracy of reservoir water sensitivity evaluation results.
[0030] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 A flow chart of a method for verifying water sensitivity evaluation results according to an embodiment of the present invention;
[0032] Figure 2 A schematic diagram of a system for verifying water sensitivity evaluation results according to an embodiment of the present invention. DETAILED DESCRIPTION
[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0034] In addition, the flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the steps. For example, some steps can be decomposed, and some steps can be combined or partially combined, so the actual execution order may change according to the actual situation.
[0035] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.
[0036] In order to solve the deficiencies of the prior art, the present invention discloses a method for verifying water sensitivity evaluation results. Figure 1 FIG. 1 is a flow chart of a method for verifying water sensitivity evaluation results according to an embodiment of the present invention. Figure 1 As shown, the method comprises the following steps:
[0037] Step S1: Prepare reservoir cores according to relevant standards or other methods, conduct water sensitivity evaluation experiments on reservoir cores, and obtain permeability damage degree experimental results.
[0038] In step S1 of the present invention, the standards currently adopted for sensitivity evaluation are: "SY / T 5358-2010 Reservoir Sensitivity Flow Experiment Evaluation Method"; "QSY / TZ 0534-2018 Tight Sandstone Gas Reservoir Reservoir Sensitivity Flow Experiment Evaluation Method", and the reservoir core production specifications include: diameter of 2.50-2.55 cm, length of 5.0-9.0 cm.
[0039] Step S2: using permeable steel that is breathable, rust-resistant and corrosion-resistant, preferably Japan Shinto PM series breathable steel, or permeable mold steel, to produce steel cores according to the reservoir core specifications in step S1.
[0040] Step S3, drying the steel core in an oven at a temperature below 105° C. for more than 5 h, and taking it out to carry out the next experiment.
[0041] Step S4: using the steel core, carry out comparative experiments according to the water sensitivity evaluation experimental process and experimental parameters in step S1, and obtain the permeability damage degree experimental results.
[0042] Step S5, analyzing the experimental results of the permeability damage degree obtained in step S4; if the permeability of the steel core does not change, it indicates that water sensitivity does not occur; if the permeability damage rate of the steel core is too large, it indicates that water sensitivity occurs and the experimental results obtained in step S1 are inaccurate.
[0043] In step S5 of the present invention, the magnitude of the damage rate is specified in detail in the standard "SY / T 5358-2010 Reservoir Sensitivity Flow Experiment Evaluation Method", specifically:
[0044] Table 1 Water sensitivity damage rate and damage degree standard
[0045] Water sensitivity damage rate Extent of damage <![CDATA[D w ≤5%]]> none <![CDATA[5%<D w ≤30%]]> weak <![CDATA[30%<D w ≤50%]]> Medium to weak <![CDATA[50%<D w ≤70%]]> Medium to strong <![CDATA[70%<D w ≤90%]]> powerful <![CDATA[D w >90%]]> Very strong
[0046] Because there is no particle shedding or particle migration in steel cores under general water-sensitive experimental conditions, the Young's modulus of steel cores is relatively high (about 200 GPa), much higher than the Young's modulus of rocks (5-20 GPa), and the effect of stress on steel cores is also very small, that is, in theory, the permeability of steel cores will not change when non-reactive fluids (do not chemically react with steel) are introduced, that is, water sensitivity will not occur. If the core permeability damage rate obtained in step S4 is too large (i.e., water sensitivity occurs), it indicates that the experimental results obtained in step S1 are unreliable, and it is necessary to check whether there are defects in the experimental method and whether there are problems with the personnel operation.
[0047] After step S6 and step S5 are completed, clean water is used to displace the steel core under high pressure for more than 2 hours, and then dried for the next experiment.
[0048] Example
[0049] Step S1, a water sensitivity evaluation experiment is carried out on the reservoir core of Ditan 2 well according to "QSY / TZ 0534-2018 Tight Sandstone Gas Reservoir Reservoir Sensitivity Flow Experiment Evaluation Method", and the experimental results are shown in Table 2 below. The permeability damage rate of the two cores of Ditan 2 well will basically not change, and the degree of damage is weak damage, indicating that the water sensitivity result is weak.
[0050] Table 2 Experimental results of reservoir core water sensitivity evaluation
[0051]
[0052] Step S2: using permeable steel (Japan Shinto PM series breathable steel) to produce steel cores according to the reservoir core specifications in step S1.
[0053] Step S3, drying the steel core in an oven at a temperature below 105° C. for more than 5 h, and taking it out to carry out the next experiment.
[0054] Step S4: Using the steel core, a comparative experiment was carried out according to the water sensitivity evaluation experimental process and experimental parameters in step S1, and the permeability damage degree experimental results were obtained as shown in Table 3 below.
[0055] Table 3 Experimental results of steel core permeability damage degree
[0056]
[0057] Step S5, analyzing the experimental results of step S4, as shown in Table 2, because the permeability damage rate of the steel core does not change substantially, and the degree of damage is no damage, that is, no water sensitivity occurs, indicating that the experimental method used in step S1 is reliable and does not need to be improved.
[0058] Step S6: Use clean water to displace the steel core under high pressure for 2 hours, and then dry it for the next experiment.
[0059] The present invention discloses a system for verifying water sensitivity evaluation results. Figure 2 FIG. 1 is a schematic diagram of a system for verifying water sensitivity evaluation results according to an embodiment of the present invention. Figure 2As shown, the system includes: a first acquisition unit 11, a production unit 12, a drying unit 13, a second acquisition unit 14, an analysis unit 15 and a displacement unit 16; wherein the first acquisition unit 11 is used to produce reservoir cores according to specifications, carry out reservoir core water sensitivity evaluation experiments, and obtain permeability damage degree experimental results; the production unit 12 is used to use permeable steel to produce steel cores according to the reservoir core specifications in the first acquisition unit 11; the drying unit 13 is used to dry the steel cores in the production unit 12 in an oven, take them out for the next One-step experiment; the second acquisition unit 14 is used to use the steel core in the drying unit 13, and carry out comparative experiments according to the water sensitivity evaluation experimental process and experimental parameters in the first acquisition unit 11 to obtain the experimental results of the degree of permeability damage; the analysis unit 15 is used to analyze the experimental results of the degree of permeability damage obtained in the second acquisition unit 14; if the degree of permeability damage of the steel core does not change, it indicates that water sensitivity does not occur; if the degree of permeability damage of the steel core is too large, it indicates that water sensitivity occurs, and the experimental results obtained in the first acquisition unit 11 are inaccurate. The displacement unit 16 is used to displace the steel core with clean water under high pressure after the experiment is completed, and then dry it for the next experiment.
[0060] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for verifying water sensitivity evaluation results, characterized in that: The method comprises the following steps: Step S1, preparing reservoir cores according to specifications, conducting reservoir core water sensitivity evaluation experiments, and obtaining permeability damage degree experimental results; Step S2, using permeable steel materials to make steel cores according to the reservoir core specifications in step S1; Step S3, drying the steel core in step S2; Step S4, using the steel core dried in step S3, a comparative experiment is carried out according to the water sensitivity evaluation experiment in step S1 to obtain the experimental results of the permeability damage degree; Step S5, analyzing the permeability damage degree experimental results obtained in step S4; if the permeability damage degree of the steel core does not change, it indicates that water sensitivity does not occur; if the permeability damage degree of the steel core is too large, it indicates that water sensitivity occurs and the experimental results obtained in step S1 are inaccurate.
2. A method for verifying water sensitivity evaluation results according to claim 1, characterized in that: The method further comprises the steps of: Step S6: After the experiment is completed, clean water is used to displace the steel core under high pressure, and then the steel core is dried for the next experiment.
3. A method for verifying water sensitivity evaluation results according to claim 1 or 2, characterized in that: In the step S1, the reservoir core production specifications include: a diameter of 2.50-2.55 cm and a length of 5.0-9.0 cm.
4. A method for verifying water sensitivity evaluation results according to claim 1, characterized in that: In step S2, the permeable steel material is a steel material that is breathable, not prone to rust and corrosion.
5. A method for verifying water sensitivity evaluation results according to claim 1, characterized in that: In step S3, the drying conditions include: temperature ≤ 105°C, time ≥ 5h.
6. A method for verifying water sensitivity evaluation results according to claim 1, characterized in that: In step S5, the degree of damage to the permeability of the steel core is based on the standard "SY / T5358-2010 Reservoir Sensitivity Flow Experiment Evaluation Method".
7. A method for verifying water sensitivity evaluation results according to claim 2, characterized in that: In step S6, the time for displacing the steel core is ≥ 2 hours.
8. A system for verifying water sensitivity evaluation results, characterized in that: The system comprises: a first acquisition unit, a production unit, a drying unit, a second acquisition unit and an analysis unit; wherein, The first acquisition unit is used to prepare reservoir cores according to specifications, carry out water sensitivity evaluation experiments on reservoir cores, and obtain permeability damage degree experimental results; The production unit is used to produce steel cores according to the reservoir core specifications in the first acquisition unit using permeable steel; The drying unit is used to dry the steel core in the production unit in an oven and take it out to carry out the next experiment; The second acquisition unit is used to use the steel core in the drying unit to carry out a comparative experiment according to the water sensitivity evaluation experimental process and experimental parameters in the first acquisition unit to obtain the permeability damage degree experimental results; The analysis unit is used to analyze the permeability damage degree experimental results obtained in the second acquisition unit; if the permeability damage degree of the steel core does not change, it indicates that water sensitivity does not occur; if the permeability damage degree of the steel core is too large, it indicates that water sensitivity occurs and the experimental results obtained in the first acquisition unit are inaccurate.
9. A system for verifying water sensitivity evaluation results according to claim 8, characterized in that: The system further comprises: a displacement unit; The displacement unit is used to displace the steel core with clean water under high pressure after the experiment is completed, and then dry it for the next experiment.