An experimental method for testing the imbibition efficiency of mixed accumulation rock core
By conducting contact angle tests and clay mineral analysis on mixed sedimentary rock cores, combined with heat shrink tubing wrapping and automatic recording by electronic balance, and by calculating permeation efficiency using gravimetric and nuclear magnetic resonance methods, the problem of large experimental errors in mixed sedimentary rock reservoirs has been solved, achieving higher-precision permeation efficiency assessment and guiding reservoir development.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-06
- Publication Date
- 2026-06-09
AI Technical Summary
Existing permeation testing methods are prone to problems such as slag shedding, block shedding, and cracking in mixed sedimentary oil reservoirs, resulting in large errors in experimental results and making it impossible to accurately assess permeation efficiency.
Contact angle testing and clay mineral analysis were performed using cut rock cores. Heat shrink tubing was used to wrap the cores and an electronic balance was used to automatically record weight changes. Immersion efficiency was calculated using gravimetric and nuclear magnetic resonance methods. Low-temperature drying and optimized experimental procedures were used to avoid core damage and human reading errors. A weighted average method was employed to improve accuracy.
It effectively avoids core cracking and slag shedding, reduces experimental errors, improves the accuracy of permeation efficiency and the precision of data collection, and can better guide the rational development of mixed sedimentary reservoirs.
Smart Images
Figure CN122171400A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of petroleum development, and in particular to an experimental method for testing the permeation efficiency of mixed sedimentary rock cores. Background Technology
[0002] Lacustrine mixed sedimentary rocks are mainly composed of carbonate rocks, sandstone, and mudstone, and are classified as low-permeability reservoirs. Utilizing percolation can effectively improve the recovery rate and reduce the extraction cost of low-permeability oil reservoirs. Rock lithology, wettability, porosity, and other properties all affect the percolation effect.
[0003] Currently used percolation testing methods are prone to problems such as spalling, fragmentation, and cracking during the experiment, leading to large errors in the experimental results. This is especially true in mixed sedimentary reservoirs, where mineral heterogeneity is high and clay mineral content is high. During percolation experiments, clay minerals are prone to hydration and expansion, causing internal instability and fracturing of the rock sample. Therefore, it is necessary to improve percolation testing methods and establish a method suitable for mixed sedimentary reservoirs to explore the factors affecting the percolation efficiency of mixed sedimentary reservoirs, thereby effectively improving the spontaneous percolation efficiency of mixed sedimentary reservoirs. This research has reference value for the efficient development of mixed sedimentary reservoirs. Summary of the Invention
[0004] One of the purposes of this application is to provide an experimental method for testing the permeation efficiency of mixed sedimentary rock cores. This method can solve the experimental errors caused by core fragmentation and cracking during the permeation experiment, obtain a more accurate permeation efficiency, and more accurately guide the rational development of mixed sedimentary rock reservoirs.
[0005] The technical solution of this application is:
[0006] An experimental method for testing the permeability efficiency of mixed sedimentary rock cores includes the following steps:
[0007] S1, the mixed sedimentary rock core was cut into thin sections, contact angle test experiments were carried out, and clay mineral analysis was performed;
[0008] S2, take a standard core from the target section of the mixed sedimentary reservoir, dry the standard core, weigh it and record the weight m1; conduct a displacement experiment on the standard core and treat it with saturated oil.
[0009] S3, after the standard core is saturated with oil, it is placed in oil and aged in a constant temperature chamber for four days, then weighed and the weight m2 is recorded.
[0010] S4, after the standard core is saturated with oil, it is placed into a nuclear magnetic resonance core analyzer to measure the T2 spectrum at the spatial location and calculate the peak area S1;
[0011] S5. Weigh the heat shrink tubing and record the weight m0.
[0012] S6. After the nuclear magnetic resonance experiment, the standard core is wrapped circumferentially with the heat shrink tubing and placed in the lifting ring. The lifting ring is then hung on an electronic balance that automatically records the weight. Finally, the standard core is submerged in the permeate.
[0013] S7. The electronic balance automatically collects the weight data of the standard core every half hour. The weight of the standard core remains unchanged for 12 hours and reaches the permeation equilibrium. The weight data m3 at the permeation equilibrium is recorded.
[0014] S8. After the infiltration experiment, the standard core is put back into the nuclear magnetic resonance core analyzer to measure the T2 spectrum at the spatial location and calculate the peak area S2.
[0015] S9, calculate the gravimetric percolation efficiency E1 using the weight data from the experiment;
[0016] S10, calculate the permeation efficiency E2 using the nuclear magnetic resonance peak area data before and after the permeation experiment;
[0017] S11, combining the gravimetric method-based permeation efficiency and the nuclear magnetic resonance experimental results, the permeation efficiency E of the mixed sedimentary rock core is calculated.
[0018] As a technical solution of this application, in step S2, the standard core is taken from a mixed sedimentary rock reservoir with good hydrophilicity, easy hydration and low content of expansive clay minerals, and the standard core is 5cm in length and 2.5cm in diameter.
[0019] As one technical solution of this application, in step S2, the standard core is washed clean, dried at a low temperature of 60°C, weighed and recorded as weight m1; the standard core is placed in a displacement device and a displacement experiment is conducted using oil. When oil droplets appear at the outlet of the standard core, it indicates that the standard core is completely saturated with oil.
[0020] As one technical solution of this application, in step S9, the calculation method for the percolation efficiency E1 based on the gravimetric method is as follows:
[0021]
[0022] In the formula: ρ o ρ is the density of the oil, m0 is the weight of the heat shrink tubing used in the percolation experiment, m2 is the core mass of the saturated oil, m3 is the weight recorded by the electronic balance at percolation equilibrium, and ρ is the density of the oil. w m1 is the density of the percolating fluid, and m1 is the mass of the dry core.
[0023] As one technical solution of this application, in step S10, the permeation efficiency E2 based on the nuclear magnetic resonance experimental results before and after the permeation experiment is calculated as follows:
[0024]
[0025] In the formula: S1 is the peak area of the standard core after saturation with oil and nuclear magnetic resonance experiment, and S2 is the peak area of the standard core after permeation experiment and nuclear magnetic resonance experiment.
[0026] As one technical solution of this application, in step S11, the calculation method for the permeation efficiency of the mixed sedimentary rock core is as follows:
[0027]
[0028] In the formula: E1 is the percolation efficiency based on the gravimetric method, and E2 is the percolation efficiency based on the nuclear magnetic resonance experimental results before and after the percolation experiment.
[0029] The beneficial effects of this application are:
[0030] This application considers the complex lithology of mixed sedimentary rocks. The method focuses on core end-face permeation and employs heat-shrink tubing to avoid experimental errors caused by cracking and spalling in the mixed sedimentary rocks. Simultaneously, it uses an electronic balance to automatically record weight changes during the permeation process, avoiding experimental errors caused by manual readings. Furthermore, it characterizes core permeation efficiency by using a weighted average of core permeation efficiency obtained by gravimetric analysis and core permeation efficiency obtained by nuclear magnetic resonance analysis, thereby obtaining more accurate permeation efficiency and providing more precise guidance for the rational development of mixed sedimentary reservoirs. Attached Figure Description
[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.
[0032] Figure 1 This is a schematic diagram of the T2 spectrum results before the percolation experiment provided in the embodiments of this application;
[0033] Figure 2 This is a schematic diagram of the experimental results of the contact angle test of mixed sedimentary rocks provided in the embodiments of this application. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.
[0035] Example:
[0036] Please refer to Figure 1 (Refer to) Figure 2 This application provides an experimental method for testing the permeability efficiency of mixed sedimentary rock cores, which includes the following steps:
[0037] S1. Two standard core samples from a mixed sedimentary reservoir at a certain depth in a certain region were taken. The standard core samples were cut into thin sections and contact angle tests were conducted. The contact angle was found to be less than 75°, indicating that the mixed sedimentary samples have strong hydrophilicity. The remaining standard core waste after cutting the thin sections was washed with oil and dried before mineral composition and clay mineral analysis were performed. The experimental results showed (as shown in Tables 1 and 2) that the clay mineral content was high and the content of easily hydrated and swellable clay minerals was also high. This indicates that the core samples are prone to flaking, chipping, and cracking during the percolation test, and therefore, conventional percolation test methods are not suitable.
[0038] Table 1. Results of mineral composition analysis
[0039]
[0040] Table 2. Results of mineral composition analysis
[0041]
[0042] S2, take standard core washing oil and dry it at a low temperature of 60℃, weigh and record the weight m1, then put it into the displacement device and use tetradecane to carry out the displacement experiment until oil droplets appear at the outlet.
[0043] S3, put the standard core saturated with tetradecane into tetradecane, age it in a constant temperature oven for 4 days, weigh it, and record the weight m2;
[0044] S4. The aged core is placed into a nuclear magnetic resonance core analyzer to measure the T2 spectrum at the spatial location and calculate the peak area S1.
[0045] S5, take a heat shrink tube of the same length as the standard core, weigh it and record the weight m0;
[0046] S6. After the nuclear magnetic resonance experiment, the cylindrical standard core was wrapped circumferentially with heat shrink tubing and placed in a lifting ring. The lifting ring was then suspended on an electronic balance that automatically records the weight. The standard core was then immersed in a 2% KCl solution.
[0047] S7. The electronic balance automatically collects the weight data of the standard core every half hour. If the reading of the electronic balance remains unchanged for 12 hours after 8 days, it is considered that the standard core has reached the permeation-absorption balance. Record the weight data m3.
[0048] S8. After the infiltration experiment, the standard core is put back into the nuclear magnetic resonance core analyzer to measure the T2 spectrum at the spatial location and calculate the peak area S2.
[0049] S9, using the weight data from the experiment, the gravimetric percolation efficiency was calculated to be 23.65%;
[0050] S10, the percolation efficiency was calculated to be 24.13% using the nuclear magnetic resonance peak area data before and after the percolation experiment;
[0051] Based on the gravimetric method and the nuclear magnetic resonance experimental results, the permeation efficiency of the S11 core was calculated to be 23.89%.
[0052] In summary, this application considers the complex lithology of mixed sedimentary rocks. The method focuses on core end-face permeation, and through improved methods of core physical stability, employs low-temperature drying and heat-shrink tubing to avoid experimental errors caused by cracking and spalling in the mixed sedimentary rocks. This effectively prevents core damage during the experiment and avoids internal core fractures and structural instability caused by clay mineral hydration and expansion, thus ensuring the stability of the experimental process and the reliability of the results, and improving the stability of core processing. Simultaneously, the use of precise measuring tools, such as electronic balances, to automatically record weight changes during permeation avoids experimental errors caused by manual readings. Furthermore, it characterizes core permeation efficiency by using a weighted average of core permeation efficiency obtained by gravimetric and nuclear magnetic resonance methods. The introduction of advanced measurement technologies, such as nuclear magnetic resonance and automated weight recording systems, reduces human error, improves the accuracy of data collection and experimental repeatability, and significantly improves the precision of data collection and the accuracy of permeation efficiency. This results in more accurate permeation efficiency and more precise guidance for the rational development of mixed sedimentary reservoirs. Furthermore, it employs an optimized method for assessing permeation efficiency, combining traditional gravimetric methods with modern nuclear magnetic resonance (NMR) technology to provide a more scientific and comprehensive approach to evaluating the permeation efficiency of mixed sedimentary rock cores. This integrated assessment method not only increases the dimensions of measurement but also improves the accuracy of permeation efficiency calculations, making the assessment results more reliable and more consistent with actual rock permeation behavior, thus better guiding reservoir development. In addition, it optimizes the experimental procedures, detailing the specific steps from core preparation to permeation experiments, including core cutting, drying, oil saturation treatment, aging, NMR testing, and permeate treatment. Each step is meticulously designed to ensure experimental efficiency and reproducibility. Moreover, it provides a more accurate and reliable method for assessing the permeation efficiency of mixed sedimentary rock cores, offering more effective scientific evidence for the development of mixed sedimentary reservoirs. Accurate assessment of permeation efficiency allows for better formulation and adjustment of development strategies, maximizing reservoir production efficiency and economic benefits. Therefore, this invention not only improves the stability and accuracy of experimental methods, but also provides strong technical support for the rational development and management of mixed sedimentary reservoirs, and has important practical application value and prospects for promotion.
[0053] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. An experimental method for testing the permeability efficiency of mixed sedimentary rock cores, characterized in that, Includes the following steps: S1, the mixed sedimentary rock core was cut into thin sections, contact angle test experiments were carried out, and clay mineral analysis was performed; S2, take a standard core from the target section of the mixed sedimentary reservoir, dry the standard core, weigh it and record the weight m1; conduct a displacement experiment on the standard core and treat it with saturated oil. S3, after the standard core is saturated with oil, it is placed in oil and aged in a constant temperature chamber for four days, then weighed and the weight m2 is recorded. S4, The aged standard core is placed into a nuclear magnetic resonance core analyzer, the T2 spectrum at the spatial location is measured, and the peak area S1 is calculated; S5. Weigh the heat shrink tubing and record the weight m0. S6. After the nuclear magnetic resonance experiment, the standard core is wrapped circumferentially with the heat shrink tubing and placed in the lifting ring. The lifting ring is then hung on an electronic balance that automatically records the weight. Finally, the standard core is submerged in the permeate. S7. The electronic balance automatically collects the weight data of the standard core every half hour. The weight of the standard core remains unchanged for 12 hours and reaches the permeation equilibrium. The weight data m3 at the permeation equilibrium is recorded. S8. After the infiltration experiment, the standard core is put back into the nuclear magnetic resonance core analyzer to measure the T2 spectrum at the spatial location and calculate the peak area S2. S9, calculate the gravimetric percolation efficiency E1 using the weight data from the experiment; S10, calculate the permeation efficiency E2 using the nuclear magnetic resonance peak area data before and after the permeation experiment; S11, combining the gravimetric method-based permeation efficiency and the nuclear magnetic resonance experimental results, the permeation efficiency E of the mixed sedimentary rock core is calculated.
2. The experimental method for testing the permeability efficiency of mixed sedimentary rock cores according to claim 1, characterized in that, In step S2, the standard core is taken from a mixed sedimentary rock reservoir with good hydrophilicity, easy hydration and low content of expansive clay minerals, and the standard core is 5 cm long and 2.5 cm in diameter.
3. The experimental method for testing the permeability efficiency of mixed sedimentary rock cores according to claim 1, characterized in that, In step S2, the standard core is washed clean, dried at a low temperature of 60°C, weighed and recorded as m1; the standard core is placed in a displacement device and a displacement experiment is conducted using oil. When oil droplets appear at the outlet of the standard core, it indicates that the standard core is completely saturated with oil.
4. The experimental method for testing the permeability efficiency of mixed sedimentary rock cores according to claim 1, characterized in that, In step S9, the gravimetric absorption efficiency E1 is calculated as follows: In the formula: ρ o ρ is the density of the oil, m0 is the weight of the heat shrink tubing used in the percolation experiment, m2 is the core mass of the saturated oil, m3 is the weight recorded by the electronic balance at percolation equilibrium, and ρ is the density of the oil. w m1 is the density of the percolating fluid, and m1 is the mass of the dry core.
5. The experimental method for testing the permeability efficiency of mixed sedimentary rock cores according to claim 1, characterized in that, In step S10, the percolation efficiency E2 based on the nuclear magnetic resonance experimental results before and after the percolation experiment is calculated as follows: In the formula: S1 is the peak area of the standard core after saturation with oil and nuclear magnetic resonance experiment, and S2 is the peak area of the standard core after permeation experiment and nuclear magnetic resonance experiment.
6. The experimental method for testing the permeability efficiency of mixed sedimentary rock cores according to claim 1, characterized in that, In step S11, the permeability efficiency of the mixed sedimentary rock core is calculated as follows: In the formula: E1 is the percolation efficiency based on the gravimetric method, and E2 is the percolation efficiency based on the nuclear magnetic resonance experimental results before and after the percolation experiment.