Sandstone porosity prediction method based on sedimentary action and diagenesis

Abstract

The invention relates to a sandstone porosity prediction method based on sedimentary action and diagenesis, which comprises the following steps: acquiring a core plug sample, a polished slice sample, a sandstone core debris sample and a sandstone slice sample from a drill hole of a target basin, and predicting the distribution of the abnormally high porosity of the target basin by using the porosity and permeability of the core plug sample, the clastic components of the polished slice sample, the volume content of diagenesis minerals and slice porosity, an SEM analysis result, the mineral components and granularity of the sandstone core clastic sample and the homogenization temperature. According to the method, a complete multi-dimensional analysis system is formed by combining a plurality of data sources. Compared with a traditional prediction method which only depends on single test data, the method integrates multiple technical means, can comprehensively reflect the influence of deposition and diagenesis on porosity evolution, and provides more accurate porosity prediction.

Description

Technical Field

[0001] This invention relates to the field of exploration technology, and in particular to a method for predicting sandstone porosity based on sedimentation and diagenesis. Background Technology

[0002] In oil and gas exploration and development, accurately predicting sandstone porosity is a key factor in evaluating reservoir quality, optimizing well location selection, and well completion design. Sandstone porosity not only directly affects the reservoir's storage capacity but is also closely related to its permeability, thus influencing oil and gas recoverability. Traditional porosity prediction methods mostly rely on single core data, laboratory tests, or sedimentological analysis; however, these methods are typically only effective within limited geological contexts and have low accuracy and reliability. Summary of the Invention

[0003] To address the aforementioned problems, the purpose of this invention is to provide a method for predicting sandstone porosity based on sedimentation and diagenesis.

[0004] A method for predicting sandstone porosity based on sedimentary and diagenetic processes includes:

[0005] Step 1: Obtain core plug samples from boreholes in the target basin, clean the core plug samples, and measure the porosity and permeability of the core plug samples.

[0006] Step 2: Obtain polished thin section samples from the boreholes in the target basin and perform staining treatment on the polished thin section samples;

[0007] Step 3: Determine the volumetric composition of detrital components, diagenetic minerals, and porosity of the stained polished thin section samples;

[0008] Step 4: Obtain sandstone core fragment samples from boreholes in the target basin, and perform SEM analysis on the sandstone core fragment samples to obtain the SEM analysis results;

[0009] Step 5: Obtain sandstone core fragment samples from boreholes in the target basin and determine the mineral composition and grain size of the sandstone core fragment samples.

[0010] Step 6: Obtain sandstone thin section samples from boreholes in the target basin and determine the homogenization temperature of diagenetic water inclusions in carbonate cement and quartz overburden.

[0011] Step 7: Predict the distribution of abnormally high porosity in the target basin using the porosity and permeability of core plug samples, the detrital composition of polished thin section samples, the volume content of diagenetic minerals and thin section porosity, SEM analysis results, and the mineral composition, grain size, and homogenization temperature of sandstone core detrital samples.

[0012] Preferably, in step 1, the core plug sample is cleaned with a mixture of chloroform and methanol to remove residual hydrocarbons. Then, the core plug sample is rinsed with flowing distilled water and dried in a constant temperature oven at 60°C. Finally, helium is injected into the core plug sample at an injection pressure of 2.758 MPa, and the porosity and permeability of the cleaned core plug sample are measured using a porosimeter and a permeability meter.

[0013] Preferably, in step 2, the polished thin film sample is embedded in blue epoxy resin and stained with alizarin red.

[0014] Preferably, in step 3, a microscope with a 10×10x objective lens is used to photograph and record each polished thin section sample after staining under plane polarized light and orthogonal polarized light conditions, and the volume content of detrital components, diagenetic minerals and thin section porosity of the stained polished thin section sample is determined by point counting method.

[0015] Preferably, in step 4, the magnification of the scanning electron microscope is set to 25-2×10⁻⁶. 5 The acceleration voltage was set to 0.2-30 kV to perform SEM analysis on sandstone core debris samples.

[0016] Preferably, in step 5, the sandstone core fragment sample is coarsely ground using an agate mortar and pestle, and then the particles are crushed to below 40 μm in a grinder to obtain sample powder; 20 ± 0.05 mg of sample powder is weighed, thoroughly mixed with 100 mL of distilled water and stirred, and the powder is dispersed by ultrasonic vibration. After standing for at least 24 hours, the powder is separated and filtered to collect the suspension with a particle size of less than 10 μm. The separated sample powder is then dried in a constant temperature drying oven, and the mineral composition is determined using an X-ray diffractometer.

[0017] Preferably, in step 5, the sandstone core fragment sample is struck with a rubber hammer to obtain broken particles. A mixed solution of methanol and distilled water is used to remove residual salts from the broken particles, and a 10% hydrochloric acid solution is used to remove cementitious materials from the broken particles. Subsequently, the broken particles are rinsed with distilled water through filter paper until the pH of the effluent is neutralized. The rinsed broken particles are placed in an oven at a constant temperature of 105°C to evaporate moisture. The broken particles are further processed using ultrasonic vibration to obtain the sample to be tested. The particle size of the sample to be tested is measured using a laser particle size analyzer.

[0018] The present invention also provides a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps in the above-described method for predicting sandstone porosity based on sedimentation and diagenesis.

[0019] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0020] This invention relates to a method for predicting sandstone porosity based on sedimentation and diagenesis. Compared with existing technologies, this invention integrates the evolution of sedimentation, diagenesis, and porosity, combining multiple data sources, including porosity and permeability of core samples, detrital composition and mineral composition of polished thin section samples, SEM analysis results, and homogenization temperature of water inclusions from diagenesis, forming a complete multi-dimensional analysis system. Compared with traditional prediction methods that rely solely on single test data, this invention integrates multiple techniques, comprehensively reflecting the influence of sedimentation and diagenesis on porosity evolution and providing more accurate porosity predictions.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A flowchart of a sandstone porosity prediction method based on sedimentation and diagenesis provided by the present invention;

[0024] Figure 2 Images of core plug samples provided for this invention; wherein, image A represents the sample collected from 3699.17m, image B represents the sample collected from 3764.12m, image C represents the sample collected from 3752.8m, image D represents the sample collected from 3729.49m, and G2 represents the drilling number;

[0025] Figure 3 Another set of core plug sample images provided for this invention; Image E represents the sample collected from 3777.35mm, Image F represents the sample collected from 3803.45m, Image G represents the sample collected from 3826.1m, Image H represents the sample collected from 3692.88m, and G2 represents the well number;

[0026] Figure 4The following are samples under plane polarized light views provided by the present invention; wherein, Figure A represents a sample collected from 3710.5m, Figure B represents a sample collected from 3739.4m, Figure C represents a sample collected from 3749.1m, Figure D represents a sample collected from 3728.0m, Figure E represents a sample collected from 3719.4m, Figure F represents a sample collected from 3702.5m, and G2 represents the drilling number;

[0027] Figure 5 The images provided for this invention are scanning electron microscope images; wherein image A represents a sample collected from 3755.0m, image B represents a sample collected from 3798.5m, image C represents a sample collected from 3716.0m, image D represents a sample collected from 3718.5m, image E represents a sample collected from 3746.9m, image F represents a sample collected from 3724.5m, and G2 represents the well number. Detailed Implementation

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] Please see Figure 1 A method for predicting sandstone porosity based on sedimentation and diagenesis, comprising:

[0032] Step 1: Obtain core plug samples from boreholes in the target basin, clean the core plug samples, and measure the porosity and permeability of the core plug samples.

[0033] In step 1, a mixture of chloroform and methanol is used to treat... Figure 2-3 The core plug samples shown were cleaned to remove residual hydrocarbons, then rinsed with flowing distilled water and dried in a constant temperature oven at 60°C. Finally, helium was injected into the core plug samples at an injection pressure of 2.758 MPa, and their porosity and permeability were measured using a Poro™ 300 porosimeter and a Perm™ 400 permeability meter from Corey Laboratories, Inc.

[0034] Step 2: Obtain polished thin section samples from the boreholes in the target basin and perform staining treatment on the polished thin section samples;

[0035] In step 2, the polished thin-film sample was embedded in blue epoxy resin and stained with alizarin red.

[0036] Step 3: Determine the volumetric composition of detrital components, diagenetic minerals, and porosity of the stained polished thin section samples;

[0037] In step 3, using a microscope with a 10×10x objective lens, the light is observed under plane polarized light (e.g., ...). Figure 4 As shown in the figure, each polished thin section sample after staining was photographed and recorded under orthogonal polarized light conditions, and the volume content of detrital components, diagenetic minerals and thin section porosity of the stained polished thin section sample was determined by point counting method.

[0038] Step 4: Obtain sandstone core fragment samples from boreholes in the target basin, and perform SEM analysis on the sandstone core fragment samples to obtain the SEM analysis results;

[0039] In step 4, a Quanta 200 environmental scanning electron microscope from FEI Corporation (USA) was used, with the magnification set to 25-2×10⁻⁶. 5 The accelerating voltage was set to 0.2-30 kV, and a fresh surface was selected for SEM analysis. Figure 5 As shown.

[0040] Step 5: Obtain sandstone core fragment samples from boreholes in the target basin and determine the mineral composition and grain size of the sandstone core fragment samples.

[0041] In step 5, the sandstone core fragments were coarsely ground using an agate mortar and pestle, and then the particles were crushed to below 40 μm in a grinder to obtain sample powder. 20 ± 0.05 mg of sample powder was weighed, thoroughly mixed with 100 mL of distilled water and stirred. The powder dispersion was accelerated by ultrasonic vibration. After standing for at least 24 hours, the powder was separated and filtered to collect the suspension with a particle size of less than 10 μm. The separated sample powder was dried in a constant temperature drying oven and the mineral composition was determined using an X-ray diffractometer.

[0042] The sandstone core fragments were broken into fragments by striking them with a rubber hammer. Residual salts in the fragments were removed using a mixture of methanol and distilled water, and cementitious materials were removed using a 10% hydrochloric acid solution. The fragments were then rinsed with distilled water through filter paper until the pH of the effluent was neutralized. The rinsed fragments were then placed in an oven at a constant temperature of 105°C to evaporate moisture. The fragments were further processed using ultrasonic vibration to obtain the sample to be tested. The particle size of the sample was measured using a laser particle size analyzer.

[0043] Step 6: Obtain sandstone thin section samples from boreholes in the target basin and determine the homogenization temperature of diagenetic water inclusions in carbonate cement and quartz overburden.

[0044] Step 7: Predict the distribution of abnormally high porosity in the target basin using the porosity and permeability of core plug samples, the detrital composition of polished thin section samples, the volume content of diagenetic minerals and thin section porosity, SEM analysis results, and the mineral composition, grain size, and homogenization temperature of sandstone core detrital samples.

[0045] While sandstone porosity and permeability typically decrease with depth, anomalously high porosity (AHP) zones are frequently observed in multiple oil and gas fields. AHP is defined as a statistically significant value exceeding that of typical sandstone samples of the same age, thermal burial history, sedimentary facies, and lithological characteristics. The distribution mechanism of AHP has significant economic value for oil and gas reservoir assessment and prediction.

[0046] In step 7, the present invention uses the porosity and permeability of core plug samples, the clastic composition of polished thin section samples, the volumetric content of diagenetic minerals and thin section porosity, SEM analysis results, and the mineral composition, grain size, and homogenization temperature of sandstone core clastic samples as initial samples. Feature values ​​highly correlated with abnormally high porosity are extracted from these initial samples as filtered samples. The filtered samples are then used to train a deep learning model to obtain a predictive distribution model for abnormally high porosity. This model is used to predict the abnormally high porosity of the basin to be explored. When the predicted value is within a set range, the area may contain oil and gas, requiring detailed exploration.

[0047] This invention integrates the evolution of sedimentation, diagenesis, and porosity, combining multiple data sources, including porosity and permeability of core plug samples, detrital composition and mineral composition of polished thin section samples, SEM analysis results, and homogenization temperature of water inclusions from diagenesis, forming a complete multi-dimensional analysis system. Compared with traditional prediction methods that rely solely on single test data, this invention integrates multiple techniques to comprehensively reflect the influence of sedimentation and diagenesis on porosity evolution, providing more accurate porosity predictions.

[0048] The present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it implements the steps in the above-described method for predicting sandstone porosity based on sedimentation and diagenesis. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided by the present invention are the same as the beneficial effects of the above-described method for predicting sandstone porosity based on sedimentation and diagenesis, and will not be elaborated here.

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for predicting sandstone porosity based on sedimentary and diagenetic processes, characterized in that, include: Step 1: Obtain core samples from boreholes in the target basin, clean the core samples, and measure the porosity and permeability of the core samples. Step 2: Obtain polished thin section samples from the boreholes in the target basin and perform staining treatment on the polished thin section samples; Step 3: Determine the volumetric composition of detrital components, diagenetic minerals, and porosity of the stained polished thin section samples; Step 4: Obtain sandstone core fragment samples from boreholes in the target basin, and perform SEM analysis on the sandstone core fragment samples to obtain the SEM analysis results; Step 5: Obtain sandstone core fragment samples from boreholes in the target basin and determine the mineral composition and grain size of the sandstone core fragment samples. Step 6: Obtain sandstone thin section samples from boreholes in the target basin and determine the homogenization temperature of diagenetic water inclusions in carbonate cement and quartz overburden. Step 7: Predict the distribution of abnormally high porosity in the target basin using the porosity and permeability of core plug samples, the detrital composition of polished thin section samples, the volume content of diagenetic minerals and thin section porosity, SEM analysis results, and the mineral composition, grain size, and homogenization temperature of sandstone core detrital samples.

2. The method for predicting sandstone porosity based on sedimentation and diagenesis according to claim 1, characterized in that, In step 1, the core plug sample was cleaned with a mixture of chloroform and methanol to remove residual hydrocarbons. The core plug sample was then rinsed with flowing distilled water and dried in a constant temperature oven at 60°C. Finally, helium was injected into the core plug sample at an injection pressure of 2.758 MPa, and the porosity and permeability of the cleaned core plug sample were measured using a porosimeter and a permeameter.

3. The method for predicting sandstone porosity based on sedimentation and diagenesis according to claim 1, characterized in that, In step 2, the polished thin-film sample was embedded in blue epoxy resin and stained with alizarin red.

4. The method for predicting sandstone porosity based on sedimentation and diagenesis according to claim 1, characterized in that, In step 3, a microscope with a 10×10x objective lens was used to photograph and record each polished thin section sample after staining under plane polarized light and orthogonal polarized light conditions, and the volume content of detrital components, diagenetic minerals and thin section porosity of the stained polished thin section sample was determined by point counting method.

5. The method for predicting sandstone porosity based on sedimentation and diagenesis according to claim 1, characterized in that, In step 4, the magnification of the scanning electron microscope is set to 25-2×10⁻⁶. 5 The acceleration voltage was set to 0.2-30 kV to perform SEM analysis on sandstone core debris samples.

6. The method for predicting sandstone porosity based on sedimentation and diagenesis according to claim 1, characterized in that, In step 5, the sandstone core fragments were coarsely ground using an agate mortar and pestle, and then the particles were crushed to below 40 μm in a grinder to obtain sample powder. 20 ± 0.05 mg of sample powder was weighed, thoroughly mixed with 100 mL of distilled water and stirred. The powder dispersion was accelerated by ultrasonic vibration. After standing for at least 24 hours, the powder was separated and filtered to collect the suspension with a particle size of less than 10 μm. The separated sample powder was dried in a constant temperature drying oven and the mineral composition was determined using an X-ray diffractometer.

7. The method for predicting sandstone porosity based on sedimentation and diagenesis according to claim 1, characterized in that, In step 5, the sandstone core fragments were struck with a rubber hammer to obtain broken particles. A mixture of methanol and distilled water was used to remove residual salts from the broken particles, and a 10% hydrochloric acid solution was used to remove cementitious materials from the broken particles. The broken particles were then rinsed with distilled water through filter paper until the pH of the effluent was neutralized. The rinsed broken particles were placed in an oven at a constant temperature of 105°C to evaporate moisture. The broken particles were further processed using ultrasonic vibration to obtain the sample to be tested. The particle size of the sample to be tested was measured using a laser particle size analyzer.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps in the sandstone porosity prediction method based on sedimentation and diagenesis as described in any one of claims 1-7.

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