A method for characterizing the imbibition limit migration of sedimentary rock reservoirs

Abstract

The present invention provides a method for characterizing the migration of imbibition limits of sedimentary rock reservoirs, which relates to the field of shale oil and gas reservoirs and resource evaluation, and includes the following steps: selecting core samples; determining the mineralogical characteristics of all core samples, and determining the lithofacies types of all core samples based on the mineralogical characteristics of the core samples; selecting core samples with different lithofacies types to conduct imbibition experiments: obtaining imbibition experiment parameters; establishing a data correlation model for reservoir imbibition limits, and quantitatively characterizing the imbibition limits of different sedimentary rock reservoirs. The beneficial effects of the present invention are: this method combines petrology, reservoir evaluation, macro-micro characteristics, and multi-sensitive quantitative parameter recorders to quantitatively evaluate the imbibition polarity migration characteristics of various types of sedimentary rocks, revealing the permeability of different sedimentary rocks, and providing more accurate and stable parameters for reservoir evaluation of sedimentary rocks, thereby effectively evaluating resource reserves and providing a more reliable evaluation technology method for the exploration and development of shale oil and gas.

Description

Technical Field

[0001] The present invention relates to the field of shale oil and gas reservoirs and resource evaluation, and in particular to a method for characterizing the imbibition limit migration of sedimentary rock reservoirs. Background Art

[0002] Shale oil and gas reservoir and resource evaluation is a key area of ​​focus in oil and gas exploration. Sedimentary rocks, as heterogeneous, highly dense rocks, exhibit low porosity and permeability, characteristics that can further influence reservoir characteristics and the total amount of unconventional resources stored. Currently, the permeability of sedimentary rocks is primarily evaluated using the flotation-gravimetric method. However, this method has certain drawbacks. It ignores the critical thickness for liquid migration, which affects the characterization and evaluation of sedimentary rock permeability. Furthermore, the traditional flotation-gravimetric method requires prolonged immersion of the rock sample in the imbibition fluid, making it difficult for experimenters to determine whether the rock sample has fully imbibed the imbibition fluid. Excessively long imbibition times can extend the experiment, increasing the difficulty of the experiment. Furthermore, excessive imbibition times can prevent the rock sample from reaching imbibition saturation, leading to significant experimental errors. This impacts the experimental results, significantly reducing the accuracy of shale oil and gas reservoir and resource evaluation, and hindering the evaluation of sedimentary rock reservoirs and oil and gas reserves. Summary of the Invention

[0003] In view of this phenomenon, in order to improve the accuracy of sedimentary rock permeability characterization, effectively evaluate resource reserves, and reduce the difficulty of sedimentary rock permeability experiments, a sedimentary rock reservoir imbibition limit migration characterization method is proposed, which includes the following steps:

[0004] S1: Select multiple core samples;

[0005] S2: Determine the mineralogical characteristics of all core samples and determine the lithofacies types of all core samples based on the mineralogical characteristics of the core samples;

[0006] S3: Select core samples with different lithofacies types for experiments: obtain the apparent volume, self-imbibition time and self-imbibition water volume of core samples with different thicknesses and types;

[0007] S4: Establish a data correlation model for core facies type, apparent volume, imbibition time, and imbibition water volume, so as to quantitatively characterize the imbibition limit values ​​of different sedimentary reservoirs.

[0008] Furthermore, in step S3, a reservoir imbibition experiment is performed on the core sample, and the experiment includes the following steps:

[0009] S31: dividing the core sample into core sample slices of different thicknesses;

[0010] S32: measuring the volume thickness, apparent volume and weight of the core sample slice;

[0011] S33: placing the container filled with the imbibition solution on a measuring balance, fixing the core sample slice by a fixing frame, and immersing the core sample slice in the imbibition solution;

[0012] S34: After the reading on the measuring balance remains stable, that is, the core sample slice reaches the imbibition extreme value, the imbibition time is recorded and the amount of self-imbibed water is calculated.

[0013] Furthermore, in step S32, a rock micro-cutter with a vernier caliper is used to cut the core sample into core sample slices with thicknesses of 400um, 600um, 800um, 1000um, 1200um, and 1400um, respectively.

[0014] Furthermore, before selecting a plurality of core samples in step S1, a research area is first determined and geological data of the research area is analyzed. The core samples selected in step S1 are from the research area.

[0015] Furthermore, the mineralogical characteristics in step S2 include mineral composition and pore structure characteristics.

[0016] Furthermore, the method for determining the mineralogical characteristics of all core samples in step S2 is as follows: the process of determining the mineralogical characteristics of all core samples is as follows: using XRD mineral testing to determine the mineral composition of the core samples, using a scanning electron microscope to scan the core samples, obtaining a scanned image, and obtaining the pore structure characteristics of the core samples.

[0017] Furthermore, in step S2, the process of determining the lithofacies type of all core samples is as follows: judging the lithofacies type of the core samples according to the mineralogical characteristics and comparing the three-end member analysis diagram.

[0018] Furthermore, the measuring balance is also connected to a processor with a display screen, and the processor is used to collect the readings of the measuring balance in real time, and calculate and display the self-absorption time and self-absorbed water volume.

[0019] Furthermore, performing a reservoir imbibition experiment on the core sample in step S3 further includes S35:

[0020] S35: Calculate the critical time data of the self-imbibition amount of core samples of different thicknesses. Based on the critical time diagram, the correlation between the imbibition limit thickness and the imbibition critical time can be established, and the porosity of the core sample slice can be quantitatively characterized. The porosity is matched with the pore structure characteristics of the core sample obtained in step S2 to verify whether the imbibition experimental data is accurate. If the error between the two data exceeds the predetermined range, repeat the imbibition experimental process of step S3 until the porosity of the core sample slice quantitatively characterized matches the structural characteristics obtained in step S2 within the predetermined range.

[0021] The beneficial effects of the method for characterizing the migration of imbibition limits of sedimentary rock reservoirs of the present invention are as follows: a method for characterizing the migration of imbibition limits of sedimentary rock reservoirs, comprising the following steps: selecting multiple core samples; determining the mineralogical characteristics of all core samples, and determining the lithofacies types of all core samples based on the mineralogical characteristics of the core samples; selecting core samples with different lithofacies types to conduct imbibition experiments: obtaining imbibition experiment parameters; establishing a data correlation model for reservoir imbibition limits to quantitatively characterize the imbibition limits of different sedimentary rock reservoirs. This method combines petrology, reservoir evaluation, macro-micro characteristics, and multi-sensitive quantitative parameter recorders to quantitatively evaluate the imbibition polarity migration characteristics of various types of sedimentary rocks, revealing the permeability of different sedimentary rocks, and providing more accurate and stable parameters for reservoir evaluation of sedimentary rocks, thereby effectively evaluating resource reserves and providing a more reliable evaluation technology method for the exploration and development of shale oil and gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A technical roadmap for a method for characterizing the imbibition limit migration of a sedimentary rock reservoir according to an embodiment of the present invention;

[0023] Figure 2 This is a flow chart of a method for characterizing the imbibition limit migration of a sedimentary rock reservoir according to an embodiment of the present invention;

[0024] Figure 3 Characteristic diagrams of mineral and pore structure of different samples of a sedimentary rock reservoir imbibition limit migration characterization method according to an embodiment of the present invention;

[0025] Figure 4 A distribution diagram of the self-imbibition time and self-imbibed water volume of a sedimentary rock reservoir imbibition limit migration characterization method according to an embodiment of the present invention;

[0026] Figure 5 This is a critical time distribution diagram of the self-imbibition amount of water at different thicknesses according to a method for characterizing the imbibition limit migration of a sedimentary rock reservoir according to an embodiment of the present invention;

[0027] Figure 6 A comparative analysis chart of experimental analysis test results of different thicknesses of a sedimentary rock reservoir imbibition limit migration characterization method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0029] Please refer to Figure 1 and Figure 2 , Figure 1 Figure 2 They are respectively a flow chart and a technical roadmap of a method for characterizing the imbibition limit migration of a sedimentary rock reservoir according to the present invention, and the method comprises the following steps:

[0030] S1: Determine the study area, analyze the geological data of the study area, determine the characteristics of its core strata, and select multiple core samples from the study area.

[0031] S2: All selected core samples are subjected to XRD mineralogy and scanning electron microscopy petrological analysis to obtain their mineralogical characteristics. The three-terminal element analysis diagram is used to determine the lithofacies type of the core samples and the study area. The mineralogical characteristics include mineral composition and pore structure characteristics. The mineral composition is obtained by XRD mineralogy testing of the core samples. The pore structure characteristics are obtained as follows:

[0032] Scan the core sample with a scanning electron microscope to obtain the scanning image of its microstructure, and judge its pore structure characteristics based on the scanning image. Figure 3 By scanning the microstructure of different core samples, the pore structure characteristics can be clearly displayed according to the image.

[0033] S3: Based on the mineralogical analysis in step S2, core samples with different lithofacies are selected to conduct reservoir imbibition experiments; the process is as follows:

[0034] S31: Divide the core sample into core sample slices of different thicknesses; wherein the core sample is divided by a rock micro-cutter with a vernier caliper, and the thickness of the cut core sample slices is an arithmetic progression. In this embodiment, the thicknesses of the core sample slices are 400um, 600um, 800um, 1000um, 1200um, and 1400um, respectively.

[0035] S32: Using a vernier caliper and a high-sensitivity balance, the diameter, length, volume, and weight of dry rock samples of different thicknesses are measured;

[0036] S33: Use a carrier fixing frame to fix the beaker containing the imbibition solution, and use a threaded fixing frame to fix the core sample slice. The core sample slice is completely immersed in the imbibition solution. The threaded fixing frame allows the sample to fully contact the solution, which is conducive to the core sample slice to fully absorb the imbibition solution; place the beaker together with the fixing frame on a measuring balance, and the threaded fixing frame is supported on the table, and it is not supported on the measuring balance. The core sample will absorb the imbibition solution that penetrates its pores, and the imbibition solution will be partially absorbed into the core sample slice. The liquid level will gradually decrease, and the mass of the imbibition solution measured by the measuring balance will gradually decrease until the core sample slice absorbs the imbibition solution to saturation.

[0037] S34: After the reading of the measuring balance remains stable, that is, the core sample slice reaches the imbibition extreme value, record the self-imbibition time and calculate the self-imbibition water volume. In this real-time example, the measuring balance is also connected to a processor with a display screen, which is used to collect the reading of the measuring balance in real time, and calculate and display the self-imbibition time and self-imbibition water volume. Figure 4 , Figure 4 The processor can accurately determine whether the core sample slice has absorbed the imbibition solution to a saturated state and automatically calculate the imbibition time and water content, thus shortening the experimental time and accurately and completely recording the experimental process.

[0038] S35: The processor can also calculate the critical time data of the self-absorption of water at different thicknesses using the above recorded experimental data. Figure 5 The processor calculates and displays a critical time data graph of self-imbibition water at different thicknesses. Based on the critical time graph, the correlation between the imbibition limit thickness and the imbibition critical time can be established, the limit migration thickness (the limit migration thickness is the imbibition limit thickness of the core sample slice) is clarified, and the porosity of the core sample slice is quantitatively characterized. The porosity is matched with the pore structure characteristics of the core sample obtained in step S2 to verify whether the imbibition experimental data is accurate. If the data error between the two exceeds a predetermined range, the imbibition experimental process of step S3 is repeated until the porosity of the core sample slice quantitatively characterized matches the structural characteristics obtained in step S2 within a predetermined range. This process can ensure the accuracy of the imbibition experimental data.

[0039] S4: Using the above experimental data, a data correlation model is established for core facies type, apparent volume, self-imbibition time, self-imbibition water volume, and imbibition limit thickness, so as to quantitatively characterize the imbibition limit values ​​of different sedimentary rock reservoirs. In this data correlation model, the thickness of the sedimentary rock reservoir is the required input value. The sedimentary rock reservoir thickness value is input into the data correlation model, and then the corresponding parameters (core facies type, apparent volume, self-imbibition time, self-imbibition water volume, imbibition limit thickness, etc.) are set to obtain the corresponding imbibition limit value of the sedimentary rock reservoir. The above-mentioned imbibition limit values ​​of different sedimentary rock reservoirs are obtained through the above-mentioned processor, with reference to Figure 6 , Figure 6 This is a comparison chart of the test results of the core sample slice analysis experiment with different thicknesses.

[0040] In this document, directional terms such as front, back, top, and bottom are defined based on the positions of components in the accompanying drawings and relative to each other, and are intended only for clarity and convenience in describing the technical solution. It should be understood that the use of these directional terms should not limit the scope of protection claimed in this application.

[0041] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for characterizing the imbibition limit migration of a sedimentary rock reservoir, characterized in that: The steps include: S1: Select multiple core samples; S2: Determine the mineralogical characteristics of all core samples and determine the lithofacies types of all core samples based on the mineralogical characteristics of the core samples; S3: Select core samples with different lithofacies types for experiments: obtain the apparent volume, imbibition time, imbibition water volume and imbibition limit thickness of core samples with different thicknesses and types; S4: Establish a data correlation model for core facies type, apparent volume, imbibition time, imbibition volume, and imbibition limit thickness, thereby quantitatively characterizing the imbibition limit values ​​of different sedimentary reservoirs; The process of determining the mineralogical characteristics of all core samples in step S2 is as follows: using XRD mineralogy to test the mineral composition of the core samples; using a scanning electron microscope to scan the core samples, obtain scanned images, and obtain the pore structure characteristics of the core samples; In step S3, a reservoir imbibition experiment is performed on the core sample, and the experiment includes the following steps: S31: Obtain sample slices of different thicknesses in different facies; S32: measuring the volume thickness, apparent volume and weight of the core sample slice; S33: placing the container filled with the imbibition solution on a measuring balance, fixing the core sample slice by a fixing frame, and immersing the core sample slice in the imbibition solution; S34: After the reading of the measuring balance remains stable and the core sample slice reaches the imbibition limit, the imbibition time is recorded, and the amount of imbibition water and the imbibition limit thickness are calculated; S35: Calculate the critical time data of the self-imbibition amount of core samples of different thicknesses, establish the correlation between the sample thickness and the critical time of imbibition based on the calculated critical time data, obtain the value of the imbibition limit thickness, quantitatively characterize the porosity of the core sample slice, and use the porosity to match the pore structure characteristics of the core sample obtained in step S2 to verify whether the imbibition experimental data is accurate. If the error between the two data exceeds the predetermined range, repeat the imbibition experimental process of step S3 until the porosity of the core sample slice quantitatively characterized matches the structural characteristics obtained in step S2 within the predetermined range.

2. A sedimentary rock reservoir imbibition limit migration characterization method according to claim 1, characterized in that: The process of obtaining core sample slices of different thicknesses in step S31 is as follows: a rock micro-cutter with a vernier caliper is used to cut the core sample into multiple core sample slices of different thicknesses.

3. The method for characterizing the imbibition limit migration of a sedimentary rock reservoir according to claim 2, wherein the thickness of the core sample slices are 400um, 600um, 800um, 1000um, 1200um, and 1400um, respectively.

4. The method for characterizing the imbibition limit migration of a sedimentary rock reservoir according to claim 1, wherein: Before selecting a plurality of core samples in step S1, a research area is first determined and geological data of the research area is analyzed. The core samples selected in step S1 are from the research area.

5. The method for characterizing the imbibition limit migration of a sedimentary rock reservoir according to claim 1, characterized in that: The process of determining the lithofacies type of all core samples in step S2 is as follows: judging the lithofacies type of the core samples based on the mineralogical characteristics and comparing the three-terminal member analysis diagram.

6. A sedimentary rock reservoir imbibition limit migration characterization method according to claim 1, characterized in that: The measuring balance is also connected to a processor with a display screen, and the processor is used to collect the readings of the measuring balance in real time, and calculate and display the self-absorption time and the self-absorbed water volume.

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