Macroscopic quantitative evaluation method for microscopic residual oil
By classifying microscopic residual oil and numerical simulation of three-dimensional geological model, the problem of quantitative evaluation of microscopic residual oil in the existing technology is solved, the connection between microscopic residual oil and macroscopic residual oil is realized, and a more effective oil field development strategy is provided.
Patent Information
- Application Number
- CN202311131874.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-04
- Publication Date
- 2025-03-04
AI Technical Summary
The prior art is difficult to accurately and quantitatively evaluate the distribution characteristics of microscopic residual oil at the macro level, and it is not possible to establish an effective connection between microscopic residual oil and macroscopic residual oil.
By classifying microscopic residual oil based on pore throat radius, the relationship between average pore throat radius and permeability was established, and the cutoff value method was used in the three-dimensional fine geological model to classify single well oil layers, and the residual reserve abundance distribution map of various microscopic residual oil models was calculated.
The quantitative evaluation of micro-surplus oil on the macroscopic level was realized, the enrichment area of micro-surplus oil was clarified, and the connection between micro-surplus oil and macro-surplus oil was established, providing a more effective strategy for oil field development and residual oil potential tapping.
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Figure CN119558508A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of oil and gas field development, and is a macroscopic quantitative evaluation method for microscopic residual oil. Background Art
[0002] With the deepening of oilfield development, many oilfields have entered the development stage of high or ultra-high water content, and the underground oil-water relationship has become increasingly complex. At this time, there is still a large amount of residual oil distributed in the reservoir. How to accurately reveal the distribution law of residual oil and provide a decision-making basis for development and adjustment measures is a difficult problem that needs to be solved urgently.
[0003] At present, there are a large number of microscopic remaining oil research methods that can display the distribution characteristics of remaining oil in microscopic pore throats, including conventional mercury injection, CT scanning, nuclear magnetic resonance, displacement experiments, digital core and other laboratory methods, which provide guidance for the formulation of methods to improve recovery and to further tap the potential of remaining oil in pore throats. The macroscopic remaining oil distribution of the reservoir is the external manifestation of the intrinsic causes of microscopic remaining oil in the actual mine field. Effectively characterizing it and seeking the remaining oil enrichment sites are of great significance to the deployment of development wells and the tapping of remaining oil potential. Among them, reservoir numerical simulation technology is an effective means to study the macroscopic remaining oil distribution law of the reservoir. The conventional method is to consider the relative permeability of the water drive mechanism, or to perform numerical simulation based on the seepage theory.
[0004] The research methods mentioned above only consider microscopic residual oil or macroscopic residual oil separately, and their limitation is that they do not establish a connection between the two. Conventional methods only consider the size of pore throats, the continuity of residual oil, the degree of displacement of residual oil, phase permeability changes, etc. The obtained microscopic residual oil only stays at the microscopic pore level, and does not show the distribution of microscopic residual oil on the macroscopic plane; and the reservoir numerical simulation method focuses on seepage theory due to the large grid scale, and does not consider the distribution characteristics of microscopic residual oil. Therefore, how to establish the corresponding relationship between microscopic residual oil and macroscopic residual oil is a key technical problem that needs to be solved. Summary of the invention
[0005] The present invention provides a macroscopic quantitative evaluation method for microscopic residual oil, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problem that the prior art is difficult to quantitatively evaluate the distribution characteristics of microscopic residual oil only from the analysis of rock pore structure.
[0006] The technical solution of the present invention is achieved by the following measures: A macroscopic quantitative evaluation method of microscopic residual oil is carried out according to the following steps: Embodiment 1: The macroscopic quantitative evaluation method of the microscopic residual oil is carried out according to the following steps: In the first step, the microscopic remaining oil is classified based on the pore throat radius; The second step is to establish the relationship between the average pore throat radius and permeability, and calculate the permeability range of different types of microscopic residual oil; The third step is to establish a three-dimensional fine geological model and establish the current oil saturation distribution model based on geological modeling and numerical simulation research; The fourth step is to classify the oil layers of individual wells based on the permeability range of different types of microscopic remaining oil using the cutoff value method in the three-dimensional fine geological model to obtain various types of microscopic remaining oil models; The fifth step is to calculate the remaining reserve abundance distribution map of various microscopic remaining oil models in the three-dimensional fine geological model according to the porosity and current oil saturation distribution, obtain the macroscopic distribution of microscopic remaining oil, and clarify the enrichment area of microscopic remaining oil.
[0007] The following are further optimizations and / or improvements to the above technical solutions: The specific operations of the first step are: conducting laboratory analysis on the core pore structure and the relative percentage of remaining oil at different pore throat radii, establishing the relationship between different pore throat radii and microscopic remaining oil content, and classifying the microscopic remaining oil according to the average pore throat radius.
[0008] In the first step above, the microscopic residual oil types are divided into four categories according to the pore throat radius: the throat radius range of type I is 0.001µm to 1µm, the throat radius range of type II is 1µm to 5µm, the throat radius range of type III is 5µm to 10µm, and the throat radius range of type IV is 10µm to 100µm. Specifically, the microscopic residual oil types and the corresponding permeability ranges are shown in Table 1.
[0009] In the second step above, a scatter data distribution diagram of the average pore throat radius and permeability obtained from laboratory core analysis is drawn, and the average pore throat radius and permeability are fitted to obtain a relationship between the average pore throat radius and permeability.
[0010] The specific operation of the third step is: to establish a three-dimensional fine geological model, and based on the three-dimensional fine geological model, to conduct numerical simulation research on the reservoir, and to calculate the current oil saturation distribution model through historical reservoir numerical fitting.
[0011] The present invention provides a macroscopic quantitative evaluation method for microscopic residual oil, which can effectively solve the problem that microscopic residual oil is difficult to quantitatively evaluate at a macroscopic level; at the same time, according to this method, the residual oil distribution characteristics of pore throats, layers, and planes can be effectively connected, and the residual oil distribution situation can be better displayed, laying a foundation for subsequent oil field development and improving recovery. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Attached Figure 1 The present invention is a flow chart of the macroscopic quantitative evaluation method of microscopic residual oil.
[0013] Attached Figure 2 This is a schematic diagram of the distribution of pore throat radius and relative content of remaining oil in Example 6 of the present invention.
[0014] Attached Figure 3 Schematic diagram of the relationship between throat radius and permeability in Example 6 of the present invention.
[0015] Attached Figure 4 Schematic diagram of the reservoir numerical simulation results of Example 6 of the present invention.
[0016] Attached Figure 5 This is a schematic cross-sectional diagram of the current oil saturation model of Example 6 of the present invention.
[0017] Attached Figure 6 This is a schematic diagram of the microscopic remaining oil classification of a single well in Example 6 of the present invention.
[0018] Attached Figure 7 This is a schematic diagram of the abundance of Class I microscopic remaining oil reserves in Example 6 of the present invention, with the corresponding throat radius ranging from 0.001µm to 1µm and the permeability ranging from 0.001mD to 4.12mD.
[0019] Attached Figure 8 This is a schematic diagram of the abundance of Class II microscopic remaining oil reserves in Example 6 of the present invention, with the corresponding throat radius ranging from 1µm to 5µm and the permeability ranging from 4.12mD to 53.46mD.
[0020] Attached Fig. 9 This is a schematic diagram of the abundance of Class III microscopic remaining oil reserves in Example 6 of the present invention, with the corresponding throat radius ranging from 5µm to 10µm and the permeability ranging from 53.46mD to 161.28mD.
[0021] Attached Fig.10 This is a schematic diagram of the abundance of Class IV microscopic remaining oil reserves in Example 6 of the present invention, with a corresponding throat radius range of >10µm and a permeability range of >161.28mD. DETAILED DESCRIPTION
[0022] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.
[0023] The present invention will be further described below in conjunction with embodiments: Embodiment 1: The macroscopic quantitative evaluation method of the microscopic residual oil is carried out according to the following steps: In the first step, the microscopic remaining oil is classified based on the pore throat radius; The second step is to establish the relationship between the average pore throat radius and permeability, and calculate the permeability range of different types of microscopic residual oil; The third step is to establish a three-dimensional fine geological model and establish the current oil saturation distribution model based on geological modeling and numerical simulation research; The fourth step is to classify the oil layers of single wells based on the permeability range of different types of microscopic remaining oil by using the cutoff value method in the three-dimensional fine geological model to obtain various types of microscopic remaining oil models (i.e., the distribution model of each type of microscopic remaining oil in the three-dimensional fine geological model); The fifth step is to calculate the remaining reserve abundance distribution map of various microscopic remaining oil models in the three-dimensional fine geological model according to the porosity and current oil saturation distribution, obtain the macroscopic distribution of microscopic remaining oil, and clarify the enrichment area of microscopic remaining oil.
[0024] Example 2: As an optimization of the above example, the specific operation of the first step is: conduct laboratory analysis on the core pore structure and the relative percentage of remaining oil at different pore throat radii, establish the relationship between different pore throat radii and microscopic remaining oil content, and classify the microscopic remaining oil according to the average pore throat radius.
[0025] Example 3: As an optimization of the above example, in the first step, the microscopic residual oil types are divided into four categories according to the pore throat radius, the throat radius range of type I is 0.001µm to 1µm, the throat radius range of type II is 1µm to 5µm, the throat radius range of type III is 5µm to 10µm, and the throat radius range of type IV is 10µm to 100µm. Specifically, the microscopic residual oil types and the corresponding permeability ranges are shown in Table 1.
[0026] Example 4: As an optimization of the above example, in the second step, a scatter data distribution diagram of the average pore throat radius and permeability obtained from laboratory core analysis is drawn, and the average pore throat radius and permeability are fitted to obtain a relationship between the average pore throat radius and permeability.
[0027] Example 5: As an optimization of the above example, the specific operation of the third step is: establish a three-dimensional fine geological model, and based on the three-dimensional fine geological model, conduct numerical simulation research on the reservoir, and calculate the current oil saturation distribution model through historical reservoir numerical fitting.
[0028] The macroscopic quantitative evaluation method of microscopic residual oil provided by the present invention aims at the problem that microscopic residual oil in sandstone reservoirs in the high water-cut period is difficult to be macroscopically quantitatively evaluated. Through the analysis of the microscopic pore structure of the core and the displacement experiment, the relationship between the pore throat radius, the permeability and the relative content of residual oil is established, and the classification standard of microscopic residual oil is established according to the pore throat radius. Through numerical simulation of the reservoir, the current oil saturation is obtained, and thus the planar distribution of the current remaining reserve abundance can be obtained. According to the classification standard of microscopic residual oil, the planar distribution diagram of the remaining reserve abundance of different types of microscopic residual oil is obtained. Different types of microscopic residual oil have different pore throat radii. Therefore, different development technical countermeasures can be adopted for different types of microscopic residual oil, which has important guiding significance for tapping the potential of residual oil in the high water-cut period.
[0029] Example 6: The specific implementation of the macroscopic quantitative evaluation method of microscopic residual oil in Shanshan Oilfield is as follows: The study area is located in the southern part of the Tuha Basin. It has a relatively simple structure and is a dome anticline with many faults in the oilfield. The main target layer in the study area is the Jurassic Sanjianfang Formation. The main sedimentary background is the delta front and the prodelta subfacies sedimentation. There are three main microfacies: underwater distributary channel, underwater distributary channel and prodelta mud. The main S34 sandstone group is mainly fine sandstone, followed by silt-fine sandstone. The particles are mostly angular-subcircular, the debris is severely weathered, the sorting and rounding are moderate, point-line contact, and the average porosity is 9.76%; the average effective permeability is 0.35×10 -3 μm 2 The average sand thickness is 24m, the shape of the logging curve is mainly "box-shaped", the sand body thickness is stable, and the continuity is good.
[0030] The comprehensive water content of Shanshan Oilfield has reached 96.93%, but the recovery rate is about 26.9%. Therefore, the reservoir contains huge potential residual oil, but this residual oil is retained in the pore throat network of the reservoir. Some of it has been affected by the development fluid but not completely driven out (low micro displacement efficiency), and some has not yet been affected by the development fluid (low volumetric sweep efficiency). The amount of this crude oil is huge, and its existence and distribution in the reservoir are discontinuous and microscopic. Through the study of microscopic oil displacement mechanism, macroscopic residual oil distribution, and the establishment of the relationship between microscopic residual oil and macroscopic residual oil, effective measures can be taken to mobilize this part of residual oil.
[0031] The first step is to conduct laboratory analysis on the cores of the water-washed inspection wells in Shanshan Oilfield to obtain the core pore structure, permeability, relative content of remaining oil, etc. The experimental analysis of the water-washed inspection wells in Shanshan Oilfield shows that, affected by the heterogeneity between pores, during the water flooding experiment, the injected water advances along the large pores with less resistance, and the remaining oil is distributed in the pores with smaller throat sizes in the form of continuous or porous forms. Based on the laboratory analysis results, the relationship between different pore throat radii and the relative content of microscopic remaining oil is established (such as Figure 2 According to the average pore throat radius and the relative content of microscopic remaining oil, the classification standard of microscopic remaining oil is established (Table 1).
[0032] The second step is to establish the relationship between the average pore throat radius and permeability based on the laboratory analysis data of the core (see Figure 3 ), where the mathematical expression after the average pore throat radius and permeability are fitted is y=4.1171x 1.593 The permeability ranges of different types of microscopic residual oil are calculated, see Table 1.
[0033] The third step is to establish a three-dimensional fine geological model of the Shanshan Oilfield through Petrel software, and based on this, use Eclipse software to conduct numerical simulation research on the reservoir, and calculate the current oil saturation model through historical fitting. The construction process of the three-dimensional fine geological model: through the establishment and constraint of the structural model, various attribute models are established in combination with step-by-step control of parameters such as the variogram, and the reservoir numerical simulation (that is, using the black oil numerical simulation process, through historical fitting, to ensure that the errors of various parameters are small and the fitting accuracy is high), calculate the current oil saturation model; the schematic diagram of the reservoir numerical simulation results is shown in Figure 4 , verify the error between the corresponding index fitting results and the actual production dynamics; the current oil saturation model profile diagram is shown in Figure 5 , Figure 5 It shows the vertical distribution of the overall remaining oil in the oil fields in this area.
[0034] The fourth step is to classify the oil layers of individual wells according to the microscopic residual oil classification standard and the permeability range of different microscopic residual oils in the three-dimensional fine geological model by using the cutoff value method, so as to obtain the classification of microscopic residual oil in individual wells. The schematic diagram of the classification of microscopic residual oil in individual wells is shown in Figure 6 This provides conditions for adopting more targeted potential tapping measures for different oil layers.
[0035] The fifth step is to calculate the remaining reserve abundance distribution map of various microscopic remaining oil models in the three-dimensional fine geological model according to the porosity and current oil saturation (see Figures 7 to 10 ), judge the macroscopic distribution of microscopic residual oil and identify the enrichment area of microscopic residual oil. Figures 7 to 10 It can be seen that as the oil field development and production enters the later stage, the remaining oil is stored more in smaller pores.
[0036] Generally speaking, Type I microscopic residual oil has low permeability, and the pore throats with small contribution to permeability have not been effectively used. Type II microscopic residual oil has low permeability, and the pore throats with large contribution to permeability are prone to form seepage channels, resulting in ineffective water injection. Types III and IV microscopic residual oil have high permeability values and less residual oil distribution.
[0037] The macroscopic quantitative evaluation method of microscopic residual oil provided by the present invention can establish the connection between microscopic residual oil and macroscopic residual oil, indicate the distribution state of microscopic residual oil in plane and section, and formulate more reasonable and effective potential tapping technical countermeasures according to different pore throat radii.
[0038] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.
Claims
1. A macroscopic quantitative evaluation method for microscopic residual oil, characterized in that Follow these steps: In the first step, the microscopic remaining oil is classified based on the pore throat radius; The second step is to establish the relationship between the average pore throat radius and permeability, and calculate the permeability range of different types of microscopic residual oil; The third step is to establish a three-dimensional fine geological model and establish the current oil saturation distribution model based on geological modeling and numerical simulation research; The fourth step is to classify the oil layers of individual wells based on the permeability range of different types of microscopic remaining oil using the cutoff value method in the three-dimensional fine geological model to obtain various types of microscopic remaining oil models; The fifth step is to calculate the remaining reserve abundance distribution map of various microscopic remaining oil models in the three-dimensional fine geological model according to the porosity and current oil saturation distribution, obtain the macroscopic distribution of microscopic remaining oil, and clarify the enrichment area of microscopic remaining oil.
2. The macroscopic quantitative evaluation method of microscopic residual oil according to claim 1 is characterized in that The specific operations of the first step are: conduct laboratory analysis on the core pore structure and the relative percentage of remaining oil at different pore throat radii, establish the relationship between different pore throat radii and microscopic remaining oil content, and classify the microscopic remaining oil according to the average pore throat radius.
3. The macroscopic quantitative evaluation method of microscopic residual oil according to claim 2 is characterized in that In the first step, the microscopic remaining oil types are divided into four categories according to the pore throat radius: the throat radius of type I ranges from 0.001µm to 1µm, the throat radius of type II ranges from 1µm to 5µm, the throat radius of type III ranges from 5µm to 10µm, and the throat radius of type IV ranges from 10µm to 100µm.
4. The macroscopic quantitative evaluation method of microscopic residual oil according to claim 1, 2 or 3, characterized in that In the second step, a scatter data distribution diagram of the average pore throat radius and permeability obtained from laboratory core analysis was drawn, and the average pore throat radius and permeability were fitted to obtain the relationship between the average pore throat radius and permeability.
5. The macroscopic quantitative evaluation method of microscopic residual oil according to claim 1, 2, 3 or 4, is characterized in that The specific operations of the third step are: establishing a three-dimensional fine geological model, and based on the three-dimensional fine geological model, conducting numerical simulation research on the reservoir, and calculating the current oil saturation distribution model through historical reservoir numerical fitting.