Effective reservoir evaluation method based on physical property index
By calculating the physical property index of the reservoir, the problem of difficulty in establishing effective reservoir classification evaluation standards in the prior art is solved, and the quantitative description and evaluation of effective reservoirs is realized, which is suitable for the needs of oil and gas exploration.
Patent Information
- Application Number
- CN202411670979.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-03-04
AI Technical Summary
It is difficult to establish effective reservoir classification evaluation standards in the prior art, and cannot meet the demand for quantitatively describing effective reservoirs in the oil and gas exploration stage, and there are difficulties in evaluating reservoir effectiveness at different depths.
The effective reservoir evaluation method based on the physical property index is adopted to calculate the relative porosity and relative permeability of the reservoir, calculate the physical property index (PI), and classify the reservoir based on the physical property index to establish reservoir evaluation standards in the research area.
The impact of depth conditions on the lower limit of effective reservoir porosity and permeability was eliminated, and a unified reservoir evaluation standard was established, which achieved semi-quantitative evaluation of effective reservoirs, which was highly applicable, and promoted the development of quantitative reservoir evaluation.
Smart Images
Figure CN119556362A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of oil and gas field exploration, and in particular, relates to an effective reservoir evaluation method based on physical property indexes. Background Art
[0002] (1) Meaning of effective reservoir
[0003] An effective reservoir is a reservoir that has the ability to store and seep fluids (including gas, liquid hydrocarbons and formation water) and can produce industrial-value production under existing technical conditions. It is necessary to point out that the definition of an effective reservoir will change with technological progress, because the improvement of oil production technology will reduce the lower limit of physical properties, which will lead to the conversion of ineffective reservoirs that were previously considered to be effective reservoirs in the future.
[0004] (2) Current status of reservoir effectiveness research
[0005] Reservoir effectiveness research is a very complex petroleum geological issue. The evaluation of reservoir storage and seepage capacity is usually characterized by reservoir physical property parameters, including porosity and permeability. Generally, reservoirs in the same zone and the same oil-bearing stratum will define a unified physical property lower limit to evaluate effectiveness. The physical property lower limit refers to the limit value of porosity and permeability at which the reservoir has the ability to store oil and gas.
[0006] Common methods for obtaining the lower limits of effective reservoir physical properties include: oil testing method, oil occurrence method, distribution function method, etc. These methods can calculate the lower limits of effective reservoir porosity and permeability at different depths. Usually, the lower limits of effective reservoir porosity and permeability at different depths are different.
[0007] In order to intuitively reflect the distribution law of effective reservoirs of different levels, the research results related to sedimentary phase, diagenetic phase and reservoir characterization are generally used to express the comprehensive evaluation results of effective reservoirs through plane multi-element superposition. Sedimentary phase mainly includes petrological characteristics, sedimentary microfacies type, reservoir thickness, etc. Diagenetic phase includes diagenesis, diagenetic stage, etc. Reservoir characterization includes pore type, pore throat structure, physical property conditions, etc.
[0008] (3) Importance of studying reservoir effectiveness
[0009] There are six major elements in oil and gas accumulation: generation, storage, capping, circle, transportation, and preservation, among which the storage is the reservoir. The effective reservoir can provide a place for oil and gas to gather, and the distribution law of the effective reservoir indicates the distribution of oil and gas reservoirs to a certain extent. The effectiveness of the reservoir reflects the ability of the reservoir to store oil and gas, which is directly related to the enrichment of the oil and gas reservoir. Therefore, studying the effectiveness of the reservoir is very important both in theory and in the practice of oil and gas exploration and development.
[0010] At present, the commonly used method for effective reservoir evaluation is the multi-element superposition effective reservoir evaluation method. The control factors of reservoir effectiveness are comprehensively studied from multiple aspects such as sedimentation, diagenesis, and structure, and the main controlling factors of effective reservoirs in different strata in different regions are clarified. The main controlling factors generally include sedimentary microfacies, pore structure, diagenesis, abnormal high pressure, etc. Finally, the distribution of effective reservoirs is divided by superimposing the research results of multiple control factors (multiple). For example, the area where two or more favorable factors overlap in the plane superposition of sedimentary microfacies, diagenetic facies, pore throat characterization, physical property parameters, etc. is the development area of effective reservoirs.
[0011] This method does not establish effective reservoir classification evaluation standards, but only qualitatively evaluates the development area of effective reservoirs. The research results cannot meet the requirements of later zone fine exploration. With the increase of exploration degree of oil and gas basins, quantitative description of effective reservoirs is needed in the evaluation and exploration stage.
[0012] Since there are many controlling factors for effective reservoirs in different strata in different regions, it is difficult to form a relatively unified evaluation and grading standard; depth differences will lead to different lower limits of absolute porosity and absolute permeability of effective reservoirs, which brings difficulties to reservoir evaluation and prediction. For reservoirs at different depths, the corresponding lower limits of effective reservoir physical properties are also different. Summary of the invention
[0013] In response to the above problems, this application proposes an effective reservoir evaluation method based on physical property indices and establishes a reservoir classification and rating standard based on physical property indices.
[0014] The embodiment of the present application provides an effective reservoir evaluation method based on physical property index, including: S1 calculating the relative porosity of the reservoir; S2 calculating the relative permeability of the reservoir; S3 calculating the physical property index to quantitatively characterize the effective reservoir; S4 classifying the reservoir based on the physical property index and establishing a reservoir evaluation standard for the study area.
[0015] In step S1, the relative porosity Φ i is the ratio of reservoir porosity to maximum porosity.
[0016] In step S1, the relative porosity Φ i The calculation formula is: i =Φ / Φ max
[0017] Where, Φ is the reservoir porosity; Φ max —The maximum reservoir porosity under the same depth conditions; Φ i —Relative porosity.
[0018] In step S2, the relative permeability K i It is the ratio of the calculated reservoir permeability to the maximum permeability under the same depth conditions.
[0019] Wherein, in step S2, the value of the permeability is taken as a logarithmic ratio.
[0020] In step S2, the relative permeability K i The calculation formula is:
[0021] K i =lg(K) / lg(K max )
[0022] Where, K is the reservoir permeability; K max —maximum reservoir permeability under the same depth conditions; K i —Relative permeability.
[0023] In step S3, the physical property index PI is calculated, and PI is a function of the relative values of porosity and permeability.
[0024] Wherein, step S3 also includes calculating the physical property index PI as follows:
[0025] PI=(Φ i +K i ) / 2
[0026] PI—physical property index. When PI is 1, it corresponds to the best reservoir at that depth; when PI is 0, it corresponds to the worst reservoir.
[0027] Wherein, step S3 also includes drawing a plane contour map of the physical property index according to the calculated value of the physical property index.
[0028] Among them, step S4 includes classifying various reservoirs according to the physical property index reservoir rating standard, and finally drawing a reservoir evaluation plane distribution map.
[0029] The effective reservoir evaluation method based on physical property index in the embodiment of the present application has the following beneficial effects:
[0030] This application uses the physical property index (PI) to evaluate the effectiveness of the reservoir. The physical property index (PI) eliminates the influence of depth conditions on the lower limit of the porosity and permeability of the effective reservoir, and establishes a reservoir evaluation standard based on the physical property index (PI), thereby providing technical support for the evaluation of effective reservoirs and the prediction of effective reservoir distribution. It can semi-quantitatively evaluate effective reservoirs, and the research results are highly applicable, which promotes the expansion of reservoir quantitative evaluation from point to surface, and is a beneficial supplement to reservoir evaluation. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 This is a schematic flow chart of an effective reservoir evaluation method based on physical property indexes according to an embodiment of the present application;
[0032] Figure 2 This is a schematic diagram of calculating the physical property index of the embodiment of the present application;
[0033] Figure 3 This is the calculation chart of the physical property index of the third section of the Gaoyou Depression in the embodiment of the present application;
[0034] Figure 4 This is a plan view of the diagenetic facies of the third section of the Funing section of the Gaoyou Sag in the embodiment of the present application;
[0035] Figure 5 This is a contour map of physical property indices of the third section of the Gaoyou Depression in the embodiment of the present application;
[0036] Figure 6 This is the effective reservoir prediction map of the Funing 3rd Section of Gaoyou Depression in the embodiment of the present application. DETAILED DESCRIPTION
[0037] The present application is further described below in conjunction with the accompanying drawings and embodiments.
[0038] In the following introduction, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The following introduction provides multiple embodiments of the present invention, and different embodiments can be replaced or combined, so this application can also be considered to include all possible combinations of the same and / or different embodiments recorded. Therefore, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more of all other possible combinations of features A, B, C, and D, even though the embodiment may not be clearly recorded in the following text.
[0039] Embodiment 1
[0040] This application is based on the study of the main controlling factors of effective reservoirs in the study area, and selects the main controlling factor related parameters and physical property indexes to establish the reservoir evaluation standard in the study area. The reservoirs are classified based on the calculated values of the physical property index to evaluate the effective reservoir grade.
[0041] like Figure 1 As shown, an embodiment of the present application provides an effective reservoir evaluation method based on physical property indices, including: S1, calculating the relative porosity of the reservoir; S2, calculating the relative permeability of the reservoir; S3, calculating the physical property indices to quantitatively characterize the effective reservoir; S4, classifying the reservoirs based on the physical property indices and establishing reservoir evaluation standards for the study area.
[0042] This application uses the physical property index (PI) to evaluate the effectiveness of the reservoir. The physical property index (PI) eliminates the influence of depth conditions on the lower limit of the effective reservoir porosity and permeability. It characterizes the average value of relative porosity and relative permeability under certain depth conditions. A reservoir evaluation standard based on the physical property index (PI) has been established, which can semi-quantitatively evaluate the effective reservoir, and the research results are highly applicable.
[0043] Embodiment 2
[0044] The implementation process of this application is as follows:
[0045] Step S1, use formula (1) to calculate the relative porosity Φ of the reservoir i , is the ratio of reservoir porosity to maximum porosity;
[0046] Step S2, using formula (2) to calculate the reservoir relative permeability K i , that is, the ratio of the reservoir permeability to the maximum permeability at the same depth is calculated. Since the permeability value spans several orders of magnitude, the logarithmic ratio is taken.
[0047] Step S3, using formula (3) to calculate the physical property index PI to quantitatively characterize the effective reservoir. PI is a function of the relative values of porosity and permeability.
[0048] The specific formula is:
[0049] Φ i =Φ / Φ max (1)
[0050] K i =lg(K) / lg(K max ) (2)
[0051] PI=(Φ i + K i ) / twenty three)
[0052] Where, Φ is the reservoir porosity, %; Φ max —Maximum reservoir porosity under the same depth conditions, %; Φ i —Relative porosity. K—Reservoir permeability, ×10 -3 μm 2 ; K max —Maximum reservoir permeability under the same depth conditions, ×10 -3 μm 2 ; K i —Relative permeability. PI—physical property index. When PI is 1, it corresponds to the best reservoir at that depth; when PI is 0, it corresponds to the worst reservoir. Figure 2 As shown, the larger the value of PI is, the better the reservoir effectiveness is.
[0053] Step S4, classify the reservoirs based on the physical property index (PI) and establish the reservoir evaluation criteria for the study area, as shown in Table 1:
[0054] Table 1 Reservoir evaluation criteria using physical property index method
[0055]
[0056] In this application, the physical property index (PI) is used to evaluate the effectiveness of the reservoir, eliminating the influence of depth on the lower limit of the effective reservoir, and establishing a reservoir evaluation standard using the physical property index method, thereby providing technical support for effective reservoir evaluation and prediction of effective reservoir distribution, promoting the expansion of reservoir quantitative evaluation from point to surface, and is a beneficial supplement to reservoir evaluation.
[0057] Embodiment 3
[0058] This application fully considers the relationship between depth and the lower limit of reservoir physical properties, and adopts the physical property index (PI) to eliminate the influence of depth on the lower limit of effective reservoir porosity and permeability; various parameters in the calculation model can be obtained through experimental measured data in the study area, and have good operability.
[0059] The embodiments of the present application are described below in conjunction with the accompanying drawings.
[0060] The third member of the Funing Formation in the Gaoyou Sag of the Subei Basin is the main oil-bearing stratum. The third member of the Funing Formation is a delta sedimentary system with developed sandstone reservoirs. The effective reservoir controls the distribution of oil reservoirs to a certain extent, so predicting the distribution of effective reservoirs can effectively guide the next exploration.
[0061] S101: Use the physical property index calculation formula to obtain the physical property index of the sandstone reservoir of the drilled Funan 3 section in Gaoyou Sag.
[0062] First, the relationship between the measured porosity, permeability and depth is fitted. Then, according to the research results of the lower limit of effective reservoir physical properties, the relationship between the lower limit of porosity, permeability and depth is fitted. Finally, the physical property index calculation chart is formed as shown in the figure. Figure 3 As shown in the figure, the Φ corresponding to the depth of the measured physical core of the well point can be obtained according to the chart. max , K max The value is obtained by taking the average value of the core measured and substituting it into the physical property index calculation formula to obtain the physical property index PI at the well point. Taking Hua 24 well as an example, the core depth is 2800m, the measured porosity (Φ) is 17.8%, and the permeability (K) is 23×10 -3 μm 2 The average value of the test data from the same well was selected to calculate the porosity and permeability. The Φ of the reservoir with a burial depth of 2800m was obtained based on the physical property index calculation chart. max 23% and K max 100×10 -3 μm 2 , and finally the physical property index (PI) of all well points with measured physical property data was calculated to be 0.72.
[0063] S103: Draw a plane contour map of the physical property index based on the calculated values of the physical property index of the well point.
[0064] The physical property index plane map is mainly based on the calculated value of the physical property index at the well point. In addition, the factors affecting the development of the effective reservoir of the third member of the Funing Formation and diagenesis are also referred to. The porosity and permeability of the reservoir of the third member of the Funing Formation are related to the sedimentary microfacies and diagenesis of the sandstone to which it belongs. When drawing the plane map, refer to the sedimentary facies map and diagenetic facies map of the study area, such as Figure 4 As shown. Finally, the Figure 5 The physical property index plane diagram shown includes physical property index, sedimentary phase, diagenesis and other elements.
[0065] S105: Establish effective reservoir rating standards based on physical property indices.
[0066] Based on "physical property index, physical property characteristics, pore structure, diagenetic phase, and sedimentary characteristics", the reservoir classification and evaluation standard of the third member of the Fuzhou section of the Gaoyou Sag was established. The PI of the Class I reservoir is ≥ 0.7, the main body of the distributary channel, weak compaction and strong dissolution diagenetic phase, primary pores and secondary pores are developed, and the reservoir porosity is about 20% to 30%; the PI of the Class II reservoir is between 0.5 and 0.7, the distributary channel, estuary bar, medium pressure-medium dissolution diagenetic phase, secondary pores are developed, and the porosity is about 15% to 20%; the PI of the Class III reservoir is between 0.3 and 0.5, the beach bar sand body, medium compaction and medium cementation diagenetic phase, and the porosity is about 10% to 15%; the PI of the Class IV reservoir is ﹤0.3, corresponding to the poor reservoir to the non-reservoir, with strong compaction and carbonate cementation, the diagenetic phase is strong compaction diagenetic phase and strong cementation phase, and the porosity is generally less than 10%, as shown in Table 2:
[0067] Table 2 Reservoir evaluation criteria of physical property index method for the third section of Funing in Gaoyou Sag
[0068]
[0069] S107: Classify various reservoirs according to the physical property index reservoir rating standard, and finally draw a reservoir evaluation plane distribution map.
[0070] Based on the intervals of various reservoir physical property indices, with 0.7, 0.5, and 0.3 as the boundaries, the following are drawn: Figure 6 The distribution map of reservoir types shown in the figure indicates the development area of favorable reservoirs well, providing an important basis for the selection of belts for the next exploration.
[0071] This application is an effective reservoir evaluation method based on physical property index. Through the test data of drilling experiments, combined with the research results of the main controlling factors of reservoir effectiveness, the reservoir evaluation standard of physical property index method is established, thereby providing technical support for effective reservoir evaluation and prediction of effective reservoir distribution. The research results of pore structure, diagenetic phase and sedimentary phase are introduced to establish reservoir rating standards suitable for the study area, and the final evaluation results can be well applied to the exploration practice in the study area.
[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. An effective reservoir evaluation method based on physical property index, characterized in that: include: S1, calculate the relative porosity of the reservoir; S2, calculate the relative permeability of the reservoir; S3, calculate physical property index to quantitatively characterize effective reservoir; S4, classify reservoirs based on physical property indices and establish reservoir evaluation standards for the study area.
2. The effective reservoir evaluation method based on physical property index according to claim 1, characterized in that: In step S1, the relative porosity Φ i is the ratio of reservoir porosity to maximum porosity.
3. The effective reservoir evaluation method based on physical property index according to claim 2 is characterized in that: In step S1, the relative porosity Φ i The calculation formula is: i =Φ / Φ max Where, Φ is the reservoir porosity; Φ max —The maximum reservoir porosity under the same depth conditions; Φ i —Relative porosity.
4. The effective reservoir evaluation method based on physical property index according to any one of claims 1 to 3, characterized in that: In step S2, the relative permeability K i It is the ratio of the calculated reservoir permeability to the maximum permeability under the same depth conditions.
5. The effective reservoir evaluation method based on physical property index according to claims 1-3 is characterized in that: In step S2, the value of the permeability is taken as a logarithmic ratio.
6. The effective reservoir evaluation method based on physical property index according to claims 1-3, characterized in that: In step S2, the relative permeability K i The calculation formula is: K i =lg(K) / lg(K max ) Where, K is the reservoir permeability; K max —maximum reservoir permeability under the same depth conditions; K i —Relative permeability.
7. The effective reservoir evaluation method based on physical property index according to any one of claims 1 to 4, characterized in that: In step S3, the physical property index PI is calculated, and PI is a function of the relative values of porosity and permeability.
8. The effective reservoir evaluation method based on physical property index according to claims 1-4, characterized in that: In step S3, the formula for calculating the physical property index PI is: PI=(Φ i +K i ) / 2 PI—physical property index. When PI is 1, it corresponds to the best reservoir at that depth; when PI is 0, it corresponds to the worst reservoir.
9. The effective reservoir evaluation method based on physical property index according to claims 1-4, characterized in that: Step S3 also includes drawing a plane contour map of the physical property index according to the calculated values of the physical property index.
10. The effective reservoir evaluation method based on physical property index according to claims 1-4, characterized in that: Step S4 includes classifying various reservoirs according to the physical property index reservoir rating standard, and finally drawing a reservoir evaluation plane distribution map.