A method for evaluating development degree of sand-mudstone reservoir-cap assemblage

Abstract

The present application belongs to the technical field of oil exploration, and discloses a method for evaluating the development degree of sand-mudstone reservoir-cap assemblage, which specifically comprises the following steps: conducting regional data analysis for a study area, and mastering the core / cuttings data, logging data and oil testing and production testing data of drilled wells, as well as the seismic data and seismic interpretation horizon data of the whole work area; conducting pre-stack deterministic inversion based on Zeoppritz equation to obtain the data body of the ratio of P-wave velocity to S-wave velocity in the work area; extracting the numerical value of the ratio of P-wave velocity to S-wave velocity along the sandstone layer interpreted by the seismic data to obtain the plan view of the sandstone reservoir; extracting the numerical value of the ratio of P-wave velocity to S-wave velocity along the mudstone layer interpreted by the seismic data to obtain the plan view of the mudstone cap rock; quantifying the relative development degree of the reservoir-cap assemblage by a development degree index calculation formula, constructing the plan view of the development degree index of the sand-mudstone reservoir-cap assemblage, and quantitatively dividing the development degree of the reservoir-cap assemblage. The present application can clearly define the development range of high-quality reservoir-cap assemblage, delineate the favorable exploration area, and further guide the well site deployment of exploration wells.

Description

Technical Field

[0001] This invention belongs to the field of petroleum exploration technology, specifically relating to a method for evaluating the development degree of sandstone-mudstone reservoir-seal assemblages. Background Technology

[0002] Sandstone and conglomerate reservoirs are an important type of oil and gas resource and represent a significant area for oil and gas exploration and development both domestically and internationally. Currently, several sandstone and conglomerate oil and gas reservoirs have been discovered and developed in the Junggar Basin, signifying their immense exploration value. Corresponding supporting technologies are also becoming increasingly sophisticated. Research on reservoirs and caprocks is essential, but accurately predicting the development degree of sandstone-mudstone reservoir-caprock assemblages remains challenging, necessitating the exploration of more efficient and accurate evaluation methods.

[0003] Currently, qualitative analyses of reservoirs and caprocks are mainly conducted using methods such as seismic attributes, pre-stack seismic inversion, and post-stack seismic inversion to gain a macroscopic understanding of their spatial distribution and lateral variation patterns. However, this approach cannot evaluate the effectiveness of reservoir-caprock assemblages and lacks a unified quantitative standard. Previous researchers often used the P-wave / S-wave velocity ratio to identify favorable sandstones and the P-wave impedance to identify mudstones, but rarely conducted a comprehensive evaluation of sandstone-mudstone reservoir-caprock assemblages.

[0004] This study focuses on sandstone reservoirs and mudstone caprocks in a work area of ​​the Junggar Basin. It evaluates the reservoirs and caprocks as a whole, clarifies the sensitive parameters of the development degree of sandstone-mudstone reservoir-caprock assemblages, and establishes a set of evaluation methods for the development degree of sandstone-mudstone reservoir-caprock assemblages, in order to better guide the exploration and development of this type of reservoir in the future. Summary of the Invention

[0005] This invention aims to provide a method for evaluating the development degree of sandstone and mudstone reservoir-capsule assemblages. It utilizes rock physical analysis results and pre-stack seismic inversion data to construct a calculation model for the development degree index of reservoir-capsule assemblages, thereby obtaining the development degree index of reservoir-capsule assemblages, clarifying the development range of high-quality reservoir-capsule assemblages, delineating favorable exploration areas, and further guiding the well location deployment.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] A method for evaluating the development degree of sandstone-mudstone reservoir-seal assemblages, the method comprising the following steps:

[0008] Step 101: Conduct regional data analysis for the study area, and obtain core / cutting data, logging data and oil testing data of drilled locations, as well as seismic data and seismic interpretation stratigraphic data for the entire work area;

[0009] Step 102: Conduct pre-stack deterministic inversion based on the Zeoppritz equation to obtain the P-wave and S-wave velocity ratio data volume for the work area;

[0010] Step 103: Extract the P-wave and S-wave velocity ratio values ​​along the sandstone layers interpreted by the seismic analysis to obtain a planar map of the P-wave and S-wave velocity ratio of the sandstone reservoir, thereby clarifying the planar variation law of the P-wave and S-wave velocity ratio of the sandstone reservoir.

[0011] Step 104: Extract the P-wave and S-wave velocity ratio values ​​along the mudstone layer interpreted by the seismic analysis to obtain a planar map of the P-wave and S-wave velocity ratio of the mudstone cap, thereby clarifying the planar variation law of the P-wave and S-wave velocity ratio of the mudstone cap.

[0012] Step 105: Using the extracted P-wave and S-wave velocity ratio data of sandstone reservoir and mudstone caprock, the relative development degree of reservoir-caprock combination is quantified by the development degree index calculation formula. A planar map of the development degree index of sandstone-mudstone reservoir-caprock combination is constructed to quantitatively classify the development degree of reservoir-caprock combination and clarify the development range of high-quality reservoir-caprock combination.

[0013] Furthermore, in step 101, the regional data includes: core / cuttings data, well logging data, oil testing and production data, and seismic data.

[0014] Further, in step 102, a pre-stack deterministic inversion based on the Zeoppritz equation is carried out to obtain the P-wave and S-wave velocity ratio data volume of the work area. Specifically, this includes: using reservoir prediction software to carry out a pre-stack deterministic inversion based on the Zeoppritz equation to obtain the P-wave and S-wave velocity ratio data volume.

[0015] Furthermore, the reservoir prediction software includes Jason software.

[0016] Further, step 105 specifically includes: utilizing the P-wave and S-wave velocity ratio data (V) extracted along the sandstone reservoir. p / V s ) 砂 P-wave and S-wave velocity ratio data extracted along the mudstone cap (V p / V s ) 泥 Establish the development level of the reservoir-seal combination Z = (V p / V s ) 砂 -(V p / V s ) 泥 The ratio of the development degree Z0 of the reservoir-capsule combination at drilled locations to the development degree Z1 of the reservoir-capsule combination at undrilled locations is used as the development degree index D to establish the relative relationship of the development degree of sandstone and mudstone reservoir-capsule combinations in the region, and to quantitatively classify the development degree of reservoir-capsule combinations.

[0017] Furthermore, the formula for calculating the developmental level index D is as follows:

[0018]

[0019] In the formula, D is the reservoir-capsule combination development degree index; Z0 is the reservoir-capsule combination development degree at drilled locations; Z1 is the reservoir-capsule combination development degree at undrilled locations; (V p / V s ) 砂 The ratio of P-wave to S-wave velocity extracted from sandstone reservoirs; (V p / V s ) 泥 The ratio of longitudinal and transverse wave velocities extracted from the mudstone caprock.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] This application represents the first time that seismic interpretation data has been used to conduct a comprehensive evaluation of sandstone-mudstone reservoir-seal assemblages. The method for evaluating the development level of these assemblages can characterize areas with high-quality reservoir-seal assemblages, providing guidance for well placement and development plan formulation during oilfield exploration and development, thereby effectively improving the efficiency and economic benefits of oilfield exploration and development. Applying this method to the Shawan slope in the Junggar Basin, favorable areas for reservoir-seal assemblage development were identified, and the ST002 well was deployed based on this identification. This well achieved excellent results in the Urho Formation, with a maximum daily oil production of 30.7 tons and a daily gas production of 2.3 × 10⁻⁶ tons. 4 m 3 This method outperforms the ST2 well, further demonstrating its reliability and its ability to improve the success rate of oil and gas exploration. Attached Figure Description

[0022] Figure 1 A flowchart of a method for evaluating the development degree of sandstone-mudstone reservoir-caprock assemblages provided by the present invention;

[0023] Figure 2 This is a cross-sectional view of the longitudinal and transverse wave velocity ratio data in an embodiment of the present invention;

[0024] Figure 3 This is a plan view of the P-wave and S-wave velocity ratio of a sandstone reservoir according to an embodiment of the present invention;

[0025] Figure 4 This is a plan view of the longitudinal and transverse wave velocity ratio of the mudstone caprock according to an embodiment of the present invention;

[0026] Figure 5 This is a plan view of the development degree index of sandstone-mudstone reservoir-seal combination according to an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] Combination Figure 1 As shown in the figure, this invention provides a method for evaluating the development degree of sandstone-mudstone reservoir-caprock assemblages, characterized in that the method includes the following steps:

[0030] Step 101: Conduct regional data analysis for the study area, and obtain core / cutting data, logging data and oil testing data of drilled locations, as well as seismic data and seismic interpretation stratigraphic data for the entire work area;

[0031] The regional data includes: core / cuttings data, well logging data, oil testing and production data, and seismic data.

[0032] Seismic interpretation horizons are determined by well-seismic calibration of well and seismic data, and then tracing laterally along the seismic axis to obtain the seismic interpretation horizons. Seismic interpretation horizons are used to describe the spatial distribution characteristics of the horizons.

[0033] Step 102: Conduct pre-stack deterministic inversion based on the Zeoppritz equation to obtain the P-wave and S-wave velocity ratio data volume for the work area; specifically: use reservoir prediction software such as Jason to conduct pre-stack deterministic inversion based on the Zeoppritz equation to obtain the P-wave and S-wave velocity ratio data volume.

[0034] Step 103: Extract the P-wave and S-wave velocity ratio values ​​along the sandstone layers interpreted by the seismic analysis to obtain a planar map of the P-wave and S-wave velocity ratio of the sandstone reservoir, thereby clarifying the planar variation law of the P-wave and S-wave velocity ratio of the sandstone reservoir.

[0035] Step 104: Extract the P-wave and S-wave velocity ratio values ​​along the mudstone layer interpreted by the seismic analysis to obtain a planar map of the P-wave and S-wave velocity ratio of the mudstone cap, thereby clarifying the planar variation law of the P-wave and S-wave velocity ratio of the mudstone cap.

[0036] Step 105: Using the extracted P-wave and S-wave velocity ratio data of sandstone reservoirs and mudstone caprocks, the relative development degree of the reservoir-caprock assemblages is quantified using the development degree index calculation formula. A development degree index map of sandstone-mudstone reservoir-caprock assemblages is constructed to quantitatively classify the development degree of reservoir-caprock assemblages and clarify the development range of high-quality reservoir-caprock assemblages. This step specifically includes:

[0037] Using P-wave and S-wave velocity ratio data extracted along sandstone reservoirs (V p / V s ) 砂 P-wave and S-wave velocity ratio data extracted along the mudstone cap (V p / V s ) 泥 Establish the development level of the reservoir-seal combination Z = (V p / V s ) 砂 -(V p / V s ) 泥 The ratio of the development degree Z0 of the reservoir-capsule combination at drilled locations to the development degree Z1 of the reservoir-capsule combination at undrilled locations is used as the development degree index D to establish the relative relationship of the development degree of sandstone and mudstone reservoir-capsule combinations in the region, and to quantitatively classify the development degree of reservoir-capsule combinations.

[0038] The formula for calculating the developmental level index D is as follows:

[0039]

[0040] In the formula, D is the reservoir-capsule combination development degree index; Z0 is the reservoir-capsule combination development degree of drilled wells; Z1 is the reservoir-capsule combination development degree of other undrilled locations; (V p / V s ) 砂 The ratio of P-wave to S-wave velocity extracted from sandstone reservoirs; (V p / V s ) 泥 The ratio of longitudinal and transverse wave velocities extracted from the mudstone caprock.

[0041] Example 2

[0042] This embodiment applies the evaluation method for the development degree of sandstone-mudstone reservoir-caprock combination from Example 1 to the Permian Wuerhe Formation oil reservoir in a certain work area of ​​the Junggar Basin. One exploration well (designated ST2) in the work area has achieved a maximum daily oil production of 10.3 tons in the Wuerhe Formation, demonstrating the potential for further exploration and development of the Wuerhe Formation in this area. Drilling data indicates that the target layer is a sandstone-conglomerate reservoir with a mudstone caprock at the top. The physical properties of the sandstone reservoir and mudstone caprock in this area change rapidly, and the vertical and lateral development degree of the reservoir and caprock is currently unclear. Therefore, it is necessary to conduct a comprehensive evaluation of the development degree of the reservoir-caprock combination to provide a decision-making basis for the next well location deployment.

[0043] First, using previously collected 3D seismic data, seismic interpretation horizons, well logging data, and oil testing results, pre-stack seismic inversion based on the Zeoppritz equation was conducted to obtain the P-wave and S-wave velocity ratio data volume of the Permian Wuerhe Formation in the 3D work area, such as... Figure 2 As shown;

[0044] like Figure 3 As shown, based on the three-dimensional P-wave and S-wave velocity ratio data volume, the P-wave and S-wave velocity ratio data of the previously collected seismically interpreted sandstone reservoir are extracted to obtain a numerical plane map of the P-wave and S-wave velocity ratio of the sandstone layer, thereby clarifying the lateral variation law of the sandstone reservoir.

[0045] like Figure 4 As shown, based on the three-dimensional P-wave and S-wave velocity ratio data volume, the P-wave and S-wave velocity ratio data of the previously collected seismic interpretation mudstone cap were extracted to obtain a numerical plane map of the P-wave and S-wave velocity ratio of the mudstone layer, thereby clarifying the lateral variation law of the mudstone cap.

[0046] like Figure 5 As shown, the extracted P-wave and S-wave velocity ratio data of the sandstone reservoir and mudstone caprock are substituted into the calculation formula of the development degree index D to calculate the reservoir-caprock combination development degree index of the Urho Formation in this work area. A planar map of the reservoir-caprock combination development degree index is obtained. The range of development degree index values ​​greater than 1 is marked to obtain the development zone of high-quality reservoir-caprock combination. Figure 5 The area within the circle (the part inside the circle) is the favorable area for exploration and deployment.

[0047] Based on the development of a high-quality reservoir-seal combination area and taking into full account the hydrocarbon accumulation patterns, it was decided to deploy well ST002. This well achieved excellent results in the Wuerhe Formation, with a maximum daily oil production of 30.7 tons and a daily gas production of 2.3 × 10⁻⁶ tons. 4 m 3 This is superior to the ST2 well, further proving the reliability of the method.

[0048] The above description is merely an embodiment of this application and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the scope of this application should be included within the protection scope of this invention.

Claims

1. A method for evaluating the development degree of sandstone-mudstone reservoir-seal assemblages, characterized in that, The method includes the following steps: Step 101: Conduct regional data analysis for the study area, and obtain core / cutting data, logging data and oil testing data of drilled locations, as well as seismic data and seismic interpretation stratigraphic data for the entire work area; Step 102: Conduct pre-stack deterministic inversion based on the Zeoppritz equation to obtain the P-wave and S-wave velocity ratio data volume for the work area; Step 103: Extract the P-wave and S-wave velocity ratio values ​​along the sandstone layers interpreted by the seismic analysis to obtain a planar map of the P-wave and S-wave velocity ratio of the sandstone reservoir, thereby clarifying the planar variation law of the P-wave and S-wave velocity ratio of the sandstone reservoir. Step 104: Extract the P-wave and S-wave velocity ratio values ​​along the mudstone layer interpreted by the seismic analysis to obtain a planar map of the P-wave and S-wave velocity ratio of the mudstone cap, thereby clarifying the planar variation law of the P-wave and S-wave velocity ratio of the mudstone cap. Step 105: Using the extracted P-wave and S-wave velocity ratio data of sandstone reservoir and mudstone caprock, the relative development degree of reservoir-caprock combination is quantified by the development degree index calculation formula. A planar map of the development degree index of sandstone-mudstone reservoir-caprock combination is constructed to quantitatively classify the development degree of reservoir-caprock combination and clarify the development range of high-quality reservoir-caprock combination.

2. The method for evaluating the development degree of sandstone-mudstone reservoir-seal assemblages according to claim 1, characterized in that, In step 101, the regional data includes: core / cuttings data, well logging data, oil testing and production data, and seismic data.

3. The method for evaluating the development degree of sandstone-mudstone reservoir-caprock assemblages according to claim 1, characterized in that, In step 102, a pre-stack deterministic inversion based on the Zeoppritz equation is carried out to obtain the P-wave and S-wave velocity ratio data volume of the work area. Specifically, this includes: using reservoir prediction software to carry out a pre-stack deterministic inversion based on the Zeoppritz equation to obtain the P-wave and S-wave velocity ratio data volume.

4. The method for evaluating the development degree of sandstone-mudstone reservoir-seal assemblages according to claim 3, characterized in that, The reservoir prediction software includes Jason software.

5. The method for evaluating the development degree of sandstone-mudstone reservoir-caprock assemblages according to claim 1, characterized in that, Step 105 specifically includes: utilizing the P-wave and S-wave velocity ratio data (V) extracted along the sandstone reservoir. p / V s ) 砂 P-wave and S-wave velocity ratio data extracted along the mudstone cap (V p / V s ) 泥 Establish the development level of the reservoir-seal combination Z = (V p / V s ) 砂 -(V p / V s ) 泥 The ratio of the development degree Z0 of the reservoir-capsule combination at drilled locations to the development degree Z1 of the reservoir-capsule combination at undrilled locations is used as the development degree index D to establish the relative relationship of the development degree of sandstone and mudstone reservoir-capsule combinations in the region, and to quantitatively classify the development degree of reservoir-capsule combinations.

6. The method for evaluating the development degree of sandstone-mudstone reservoir-seal assemblages according to claim 5, characterized in that, The formula for calculating the developmental level index D is as follows: In the formula, D is the reservoir-capsule combination development degree index; Z0 is the reservoir-capsule combination development degree at drilled locations; Z1 is the reservoir-capsule combination development degree at undrilled locations; (V p / V s ) 砂 The ratio of P-wave to S-wave velocity extracted from sandstone reservoirs; (V p / V s ) 泥 The ratio of longitudinal and transverse wave velocities extracted from the mudstone caprock.

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