Method for rapid evaluation of interlayered shale oil mobility

Abstract

The application discloses a method for rapidly evaluating the mobility of interbedded shale oil, and is specifically implemented according to the following steps: step 1, selecting different types of interbedded shale oil reservoir rock samples; step 2, analyzing the oil and gas components of the samples selected in step 1 and calculating the amount of movable oil; step 3, obtaining the geological factors of the samples selected in step 1 that affect the mobility of interbedded shale oil; step 4, establishing a quantitative evaluation model for the mobility of interbedded shale oil based on multiple regression; and step 5, substituting the geological factors of the target to be evaluated that affect the mobility of interbedded shale oil into the model in step 4 to obtain the amount of movable oil of interbedded shale oil of the target to be evaluated. The method solves the problem of long evaluation period of the prior art.

Description

Technical Field

[0001] This invention belongs to the field of unconventional oil and gas exploration technology, specifically relating to a method for rapidly evaluating the mobility of interlayered shale oil. Background Technology

[0002] Shale oil is an important component of global oil and gas resources in the 21st century. In recent years, China has made continuous breakthroughs in shale oil and gas exploration and development, discovering large-scale shale oil and gas resources in the Paleogene Shahejie Formation of the Bohai Bay Basin, the Cretaceous Qingshankou Formation of the Songliao Basin, and the Upper Triassic Yanchang Formation of the Ordos Basin. In 2022, the Ordos shale oil production exceeded 210 × 10⁻⁶. 4 Shale oil will be a crucial guarantee for stable and increased oil and gas production in China. Based on geological conditions and sedimentary characteristics, the "sweet spots" of reservoirs in China's continental shale formations can be divided into three main categories: interbedded, mixed-sedimentary, and shale-type. Among them, interbedded shale oil is widely distributed in freshwater lacustrine basins such as the Ordos Basin and the Sichuan Basin, possessing immense exploration potential. Interbedded shale oil typically refers to oil that has not undergone long-distance migration and accumulation within tight sandstone and shale layers interbedded in source rock formations. It exhibits complex characteristics such as source-reservoir symbiosis, large-area continuous distribution, and near-source high-pressure charging or in-situ retention of oil and gas, leading to significant differences in the occurrence state and mobility characteristics of interbedded shale oil.

[0003] Intercalated shale oil exists primarily in two states within the pore spaces of tight reservoirs: free oil (mobile oil) and adsorbed oil (immobile oil). Free oil, often found in microfractures and larger pores, represents the portion of the reservoir that can flow and be produced under current technological conditions, and is the main contributor to production. Adsorbed oil (immobile oil), on the other hand, is mainly adsorbed in small pores and on the surfaces of minerals and kerogen; it represents the portion of the reservoir that is not flowing and difficult to produce under current technological conditions. The oil content in actual sweet spot predictions typically refers to the content of free, mobile oil. Therefore, understanding the mobility of intercalated shale oil under complex geological conditions is crucial for current intercalated shale oil research and is of great significance for the exploration and development of intercalated shale oil reserves and effective utilization.

[0004] Although there are literature reports on the evaluation methods of mobility of interlayered shale oil in reservoirs, such as (1) Wu Liyan, Zhang Zhenling, and Ma Wenling, “Quantitative Analysis Method of Oil and Gas Components in Reservoirs” (Logging Technology, No. 3, 2000), which uses rock pyrolysis experiments to obtain gasoline, kerosene, diesel, wax, and heavy oil fractions in the reservoir, and quantitatively characterizes the movable oil content in tight reservoirs; (2) Jiang Qigui, Li Maowen, Qian Menhui, Li Zhiming, Li Zheng, Huang Zhenkai, Zhang Caiming, and Ma Yuanyuan, “Quantitative Characterization Technology and Application Research of Shale Oil in Different Occurrence States” (Petroleum Experimental Geology). (2016, No. 6), in which the Rock-Eval pyrolysis and pyrolysis chromatography methods were improved, and a quantitative characterization method for shale oil in different occurrence states was established by combining the comparative experiment of pyrolysis before and after sample solvent extraction and the comprehensive analysis of different types of samples; (3) Sang Xi, Zhang Shaojie, Zhu Chaofan, Dong Mingzhe, Li Yajun “Nuclear magnetic resonance study of movable fluids in continental shale oil reservoirs” (China Science and Technology Paper, No. 9, 2017), in which nuclear magnetic resonance technology was used to test movable fluids and characterize the mobility of fluids in continental shale oil reservoir rock samples. However, although these experimental methods can obtain relatively accurate mobility characteristics of interlayered shale oil, their evaluation cycle is long. Summary of the Invention

[0005] The purpose of this invention is to provide a method for rapidly evaluating the mobility of interlayered shale oil, which solves the problem of long evaluation cycles in existing methods.

[0006] The technical solution adopted in this invention is a method for rapidly evaluating the mobility of interlayered shale oil, which is implemented according to the following steps:

[0007] Step 1: Select samples of different types of interbedded shale oil reservoirs;

[0008] Step 2: Analyze the oil and gas components of the sample selected in Step 1 and calculate the amount of movable oil.

[0009] Step 3: Obtain the geological factors that affect the mobility of interlayered shale oil in the samples selected in Step 1;

[0010] Step 4: Establish a quantitative evaluation model for the mobility of interlayered shale oil based on multiple regression;

[0011] Step 5: Substitute the geological factors affecting the mobility of interlayered shale oil in the target to be evaluated into the model in Step 4 to obtain the movable oil volume of the interlayered shale oil in the target to be evaluated.

[0012] The invention is further characterized in that,

[0013] In step 2, the analysis of oil and gas components is performed using a pyrolysis experiment. The specific process is as follows: natural gas (S0) is tested at a constant temperature of 90℃ for 2 minutes, gasoline (S1) is tested at a constant temperature of 200℃ for 1 minute, and then the temperature is increased to 350℃ at a rate of 50℃ / min and held for 1 minute to test the kerosene and diesel (S1) content. 21 Then, the temperature is increased to 450℃ at a heating rate of 50℃ / min and held at that temperature for 1 min to test the wax content S. 22 Then, the temperature was increased to 600℃ at a heating rate of 50℃ / min and held at that temperature for 1 min to test the content of heavy hydrocarbons and asphaltenes (S). 23 .

[0014] In step 2, the movable oil quantity = S1 + S 21 .

[0015] In step 3, the geological factors affecting the mobility of interlayered shale oil include reservoir layer thickness, reservoir porosity, average reservoir pore size, shale layer thickness, and total organic carbon content of the shale.

[0016] The thickness of a single reservoir layer was determined using well logging data and well logging lithology interpretation; the porosity of the reservoir was directly obtained based on porosity-permeability testing experiments; the average pore size of the reservoir was obtained using high-pressure mercury intrusion porosimetry experiments; the thickness of a single shale layer was determined using well logging data and well logging lithology interpretation; and the total organic carbon content was obtained through experimental analysis.

[0017] The quantitative evaluation model for the mobility of interlayer shale oil based on multiple regression is: Movable oil quantity = b0 + b1 * H sand +b2*Por+b3*R a +b4*H shale +b5*TOC;

[0018] In the formula, H sand Por is the thickness of a single reservoir layer; Por is the porosity of the reservoir; R a H represents the average pore size of the reservoir rock. shale denoted as shale single-layer thickness; TOC represents the total organic carbon content of shale; b0, b1, b2, b3, b4, and b5 are model parameters obtained from multiple regression.

[0019] Multivariate regression analysis was performed using SPSS software, and the H values ​​obtained in step 3 were analyzed. sand Por, R a H shale Select the TOC variable into the independent variable box, and select the movable oil quantity obtained in step 2 into the dependent variable box to obtain b0, b1, b2, b3, b4, and b5.

[0020] The beneficial effects of this invention are:

[0021] (1) The present invention provides a method for rapidly evaluating the mobility of interlayered shale oil. It integrates multiple factors that may affect the mobility of interlayered shale oil and transforms them into quantitative information. A quantitative evaluation model is established using the multiple regression method, which enhances the accuracy of mobility evaluation.

[0022] (2) The present invention provides a method for rapidly evaluating the mobility of interlayered shale oil. By using multiple regression, a quantitative evaluation model for the mobility of interlayered shale oil can be established in a short time, which improves efficiency and saves time. Compared with the previous evaluation method based entirely on experimental testing, it has stronger applicability. Attached Figure Description

[0023] Figure 1 This is a flowchart of the method for rapidly evaluating the mobility of interlayered shale oil according to the present invention;

[0024] Figure 2 This is a quantitative analysis spectrum of oil and gas components in Example 3 of the present invention;

[0025] Figure 3 This illustrates the relationship between the thickness of a single reservoir layer and the amount of movable oil in Example 3 of the present invention.

[0026] Figure 4 This illustrates the relationship between porosity and movable oil volume in Embodiment 3 of the present invention.

[0027] Figure 5 This is the correspondence between the average orifice diameter and the movable oil volume in Embodiment 3 of the present invention;

[0028] Figure 6 This illustrates the relationship between the thickness of a single shale layer and the amount of movable oil in Example 3 of the present invention.

[0029] Figure 7 This is the correspondence between total organic carbon content and movable oil content in Example 3 of the present invention;

[0030] Figure 8 This is the fitting relationship between the modeled movable oil quantity and the multivariate regression movable oil quantity results in Embodiment 3 of the present invention;

[0031] Figure 9 This is the fitting relationship between the measured movable oil volume in region J of this invention and the results of the multiple regression evaluation of movable oil volume. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0033] Example 1

[0034] This invention provides a method for rapidly evaluating the mobility of interlayered shale oil, such as... Figure 1 As shown, please follow these steps:

[0035] Step 1: Select reservoir rock samples of different types of interlayered shale oil. The selected samples need to cover the geological factors that affect the mobility of interlayered shale oil, including reservoir rock single layer thickness, reservoir rock porosity, reservoir rock average pore size, shale single layer thickness and total organic carbon content characteristics.

[0036] Step 2: Analyze the oil and gas components of the sample selected in Step 1 and calculate the amount of movable oil.

[0037] Step 3: Obtain the geological factors that affect the mobility of interlayered shale oil in the samples selected in Step 1;

[0038] Step 4: Establish a quantitative evaluation model for the mobility of interlayered shale oil based on multiple regression;

[0039] Step 5: Substitute the geological factors affecting the mobility of interlayered shale oil in the target to be evaluated into the model in Step 4 to obtain the movable oil volume of the interlayered shale oil in the target to be evaluated.

[0040] Example 2

[0041] The present invention provides a method for rapidly evaluating the mobility of interlayered shale oil, which is implemented according to the following steps:

[0042] Step 1: Select reservoir rock samples of different types of interlayered shale oil. The selected samples need to cover the geological factors that affect the mobility of interlayered shale oil, including reservoir rock single layer thickness, reservoir rock porosity, reservoir rock average pore size, shale single layer thickness and total organic carbon content characteristics.

[0043] Step 2: Analyze the oil and gas components of the sample selected in Step 1 and calculate the amount of mobile oil (free oil).

[0044] The analysis of oil and gas components employed a pyrolysis experiment. The specific procedure was as follows: natural gas (S0) was tested at a constant temperature of 90℃ for 2 minutes; then, the temperature was increased to 200℃ at a rate of 50℃ / min and held at 200℃ for 1 minute to test gasoline (S1); finally, the temperature was increased to 350℃ at a rate of 50℃ / min and held at 350℃ for 1 minute to test kerosene and diesel (S2). 21 Then, the temperature is increased to 450℃ at a heating rate of 50℃ / min and held at that temperature for 1 min to test the wax content S. 22 Then, the temperature was increased to 600℃ at a heating rate of 50℃ / min and held at that temperature for 1 min to test the content of heavy hydrocarbons and asphaltenes (S). 23 ;

[0045] Movable oil quantity = S1 + S 21 ; Amount of adsorbed hydrocarbons = S 22 +S 23 Total oil content in reservoir rocks = S1 + S 21 +S 22+S 23 ;

[0046] Step 3: Obtain the geological factors that affect the mobility of interlayered shale oil in the samples selected in Step 1;

[0047] Geological factors affecting the mobility of interlayered shale oil include reservoir layer thickness, reservoir porosity, average reservoir pore size, shale layer thickness, and total organic carbon content of the shale.

[0048] The thickness of a single reservoir layer is determined by well logging data and well logging lithology interpretation; reservoir porosity is directly obtained based on porosity-permeability testing experiments, but when the available measured data is limited, it can be indirectly obtained by well logging calculation, specifically using Archie's formula, which is well known to those skilled in the art; the average pore size of the reservoir is obtained by high-pressure mercury injection experiments; the thickness of a single shale layer is determined by well logging data and well logging lithology interpretation; the total organic carbon content is obtained through experimental analysis, which is a conventional technique in the field and well known to those skilled in the art, but when the available measured TOC data is limited, it can be indirectly determined by calculation and prediction based on the well logging ΔlogR method;

[0049] Step 4: Based on the movable oil volume obtained in Step 2 and the geological factors obtained in Step 3, establish a quantitative evaluation model for the mobility of interlayer shale oil with multiple regression, using the geological factors as independent variables and the movable oil volume (free oil volume) as dependent variables.

[0050] The quantitative evaluation model for the mobility of interlayered shale oil based on multiple regression is as follows:

[0051] Movable oil volume = b0 + b1 * H sand +b2*Por+b3*R a +b4*H shale +b5*TOC;

[0052] In the formula, H sand Por is the thickness of a single reservoir layer; Por is the porosity of the reservoir; R a H represents the average pore size of the reservoir rock. shale denoted as shale single-layer thickness; TOC represents the total organic carbon content of shale; b0, b1, b2, b3, b4, and b5 are model parameters obtained from multiple regression.

[0053] Then, multivariate regression analysis was performed using SPSS software, and the H values ​​obtained in step 3 were used to... sand Por, R a H shale Select the TOC variable into the independent variable box, and select the movable oil quantity obtained in step 2 into the dependent variable box to obtain b0, b1, b2, b3, b4, b5;

[0054] Step 5: Substitute the geological factors affecting the mobility of interlayered shale oil of the target to be evaluated into the model of Step 4 to obtain the movable oil volume of the interlayered shale oil of the target to be evaluated, that is, determine the mobility characteristics of the interlayered shale oil of the target to be evaluated.

[0055] Example 3

[0056] Sampling and analysis were performed on well Z1-A-1, following these steps:

[0057] Step 1: Collect samples of different types of interbedded shale oil reservoirs in the study area. The samples cover various geological conditions that affect mobility, including reservoir layer thickness, reservoir porosity, average reservoir pore size, shale layer thickness, and total organic carbon content.

[0058] Step 2: Conduct reservoir rock pyrolysis experiments on the samples from Step 1. Quantitatively analyze the oil and gas components in the reservoir rocks using a Rock-Eval pyrolysis instrument. Specifically, test the natural gas (S0) content at 90℃ for 2 minutes, test the gasoline content (S1) at 200℃ for 1 minute, and then heat to 350℃ at a rate of 50℃ / min and hold for 1 minute to test the kerosene and diesel content (S). 21 Then, the temperature is increased to 450℃ at a heating rate of 50℃ / min and held at that temperature for 1 min to test the wax content S. 22 Then, the temperature was increased to 600℃ at a heating rate of 50℃ / min and held at that temperature for 1 min to test the content of heavy hydrocarbons and asphaltenes (S). 23 ; after calculating the movable oil volume, the quantitative analysis spectra of oil and gas components in the reservoir are shown in Table 1 and Figure 2 As shown;

[0059] Table 1. Analysis of oil and gas components in well Z1-A-1 with a cycle of 1.

[0060] Analysis number quality <![CDATA[S0]]> <![CDATA[S1]]> <![CDATA[S 21 ]]> <![CDATA[S 22 ]]> <![CDATA[S 23 ]]> <![CDATA[S4]]> residual oil 1 53.8 0.00 0.25 0.65 0.94 0.37

[0061] Step 3: Obtain the geological factors affecting the mobility of interbedded shale oil in the samples selected in Step 1, including reservoir layer thickness, reservoir porosity, average reservoir pore size, shale layer thickness, and total organic carbon content of the shale. Then determine the relationship between individual geological factors and the amount of movable oil. The results are as follows: Figure 3-7 As shown;

[0062] Step 4: Based on the movable oil quantity obtained in Step 2 and the geological factors acquired in Step 3, establish a quantitative evaluation model for the mobility of interlayered shale oil based on multiple regression; use SPSS software to perform multiple regression analysis on 36 sets of data from the study area, selecting Hsand, Por, Ra, Hshale, and TOC variables into the independent variable box, and defining the movable oil quantity (S1+S...) as the independent variable. 21Select the dependent variable box, analyze and obtain the constants and coefficients of each independent variable in the multiple regression model, and finally obtain the quantitative evaluation model of mobility of interlayer shale oil based on multiple regression as follows: Movable oil quantity (S1+S 21 = -0.510 - 0.130 * H sand -0.039*Por + 5.640*R a +0.126*H shale +0.162*TOC

[0063] Evaluation results as follows Figure 8 As shown, the measured results are consistent with the movable oil quantity (S1+S) obtained by the quantitative evaluation model of the mobility of interlayered shale oil based on multiple regression in this invention. 21 The correlation between them is significant, R 2 The value of 0.8419 indicates that the quantitative evaluation model for the mobility of interlayered shale oil based on multiple regression has good applicability.

[0064] Example 4

[0065] The reliability of the quantitative evaluation model for the mobility of interlayered shale oil obtained in Example 3, based on multiple regression, was verified using 18 new data points from region J. The relevant data are shown in Table 2.

[0066] Table 2 Evaluation results of the quantitative evaluation model for the mobility of interlayered shale oil in region J based on multiple regression.

[0067]

[0068]

[0069] Based on the data in Table 2 and Figure 9 The correlation R between the obtained evaluation results and the measured movable oil volume 2 It is 0.8094.

Claims

1. A method for rapidly evaluating the mobility of interlayered shale oil, characterized in that, The specific steps are as follows: Step 1: Select samples of different types of interbedded shale oil reservoirs; Step 2: Analyze the oil and gas components of the sample selected in Step 1 and calculate the amount of movable oil. In step 2, the analysis of oil and gas components is performed using a pyrolysis experiment. The specific process is as follows: the natural gas content (S0) is tested by holding the temperature at 90℃ for 2 min, the gasoline content (S1) is tested by holding the temperature at 200℃ for 1 min, and then the temperature is increased to 350℃ at a rate of 50℃ / min and held for 1 min to test the kerosene and diesel contents (S1). 21 Then, the temperature is increased to 450℃ at a heating rate of 50℃ / min and held at that temperature for 1 min to test the wax content S. 22 Then, the temperature was increased to 600℃ at a heating rate of 50℃ / min and held at that temperature for 1 min to test the content of heavy hydrocarbons and asphaltenes (S). 23 ; In step 2, the movable oil quantity = S1 + S 21 ; Step 3: Obtain the geological factors that affect the mobility of interlayered shale oil in the samples selected in Step 1; In step 3, the geological factors affecting the mobility of interlayered shale oil include reservoir layer thickness, reservoir porosity, average reservoir pore size, shale layer thickness, and total organic carbon content of shale. Step 4: Establish a quantitative evaluation model for the mobility of interlayered shale oil based on multiple regression; The quantitative evaluation model for the mobility of interlayered shale oil based on multiple regression is as follows: ； In the formula, H sand Por is the thickness of a single reservoir layer; Por is the porosity of the reservoir; R a H represents the average pore size of the reservoir rock. shale denoted as shale single-layer thickness; TOC represents the total organic carbon content of shale; b0, b1, b2, b3, b4, and b5 are model parameters obtained from multiple regression. Step 5: Substitute the geological factors affecting the mobility of interlayered shale oil in the target to be evaluated into the model in Step 4 to obtain the movable oil volume of the interlayered shale oil in the target to be evaluated.

2. The method for rapidly evaluating the mobility of interlayered shale oil as described in claim 1, characterized in that, The thickness of a single reservoir layer was determined using well logging data and well logging lithology interpretation; the porosity of the reservoir was directly obtained based on porosity-permeability testing experiments; the average pore size of the reservoir was obtained using high-pressure mercury intrusion porosimetry; the thickness of a single shale layer was determined using well logging data and well logging lithology interpretation; and the total organic carbon content was obtained through experimental analysis.

3. The method for rapidly evaluating the mobility of interlayered shale oil as described in claim 1, characterized in that, Multivariate regression analysis was performed using SPSS software, and the H values ​​obtained in step 3 were analyzed. sand Por, R a H shale Select the TOC variable into the independent variable box, and select the movable oil quantity obtained in step 2 into the dependent variable box to obtain b0, b1, b2, b3, b4, and b5.

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