Complex broken basin hydrocarbon source rock evaluation method

Abstract

The invention belongs to the technical field of petroleum energy, and discloses a complex broken basin hydrocarbon source rock evaluation method. Comprising the steps of rock core observation, hydrocarbon generation simulation experiment, establishment of a hydrocarbon conversion rate profile, establishment of an abundance relationship, establishment of an abundance evaluation standard and establishment of a corresponding relationship. According to the method, a set of standard evaluation process for the hydrocarbon source rocks in the complex fault with large differences in lithology and maturity is designed, the quality characteristics of the hydrocarbon source rocks can be accurately and effectively evaluated, and regional resource potential evaluation and reservoir effective analysis are supported.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum energy, and in particular relates to a method for evaluating hydrocarbon source rocks in complex fault basins. Background Art

[0002] With the continuous deepening of oil and gas exploration and development, the evaluation of source rocks in a general and large area can no longer meet the needs of exploration and development. Although the current industry standards or enterprise standards have corresponding evaluation standards for reference, due to the complexity of underground geology, there are many lithological differences in the same basin due to differences in sedimentary environments, and the abundance of source rocks of different lithologies varies greatly, and their evaluation standards are also different. At the same time, due to the influence of ups and downs or faults, the geological history and thermal history are not unified, the evolution degree of source rocks is also different, and the hydrocarbon expulsion efficiency is different. At this time, the residual abundance obtained in the experiment is far from representing the true quality characteristics of the source rocks. Therefore, it is no longer applicable to use a single low-maturity source rock evaluation standard to evaluate the entire basin, especially when it is refined to a smaller fault or region, the contradiction of the difference in the evaluation results will be more prominent. In this context, the present invention fully proposes a detailed evaluation process method based on the lithology differences and maturity changes of source rocks. By carefully evaluating the quality of source rocks in relatively independent enclosures, it is of great significance in oil and gas exploration and discovery, finding new areas and selecting profitable areas. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a method for evaluating source rocks in complex fault basins. Through the formulated system process method, a detailed classification evaluation of single wells is carried out to carry out regional source rock quality evaluation, clarify the quality of source rocks at different depths and different lithologies in different regions, and provide a basis for reservoir analysis and exploration deployment.

[0004] The above object of the present invention is achieved through the following technical scheme: A method for evaluating source rocks in a complex fault basin, comprising the following steps:

[0005] 1. Core observation;

[0006] 2. Hydrocarbon generation simulation experiment;

[0007] 3. Establish hydrocarbon conversion profile;

[0008] 4. Establish abundance relationships;

[0009] 5. Establish abundance evaluation criteria;

[0010] 6. Establish corresponding relationships;

[0011] 7. Re-understand the quality of source rocks.

[0012] Furthermore, the step 1 is specifically as follows: conducting core observations in the study area to clarify the lithological characteristics, logging responses and geochemical characteristics of the developed source rocks.

[0013] Furthermore, the step 2 is specifically as follows: conducting hydrocarbon generation simulation experiments on various types of kerogen source rocks in the study area, obtaining the activation energy and pre-exponential factor of hydrocarbon generation reactions of various types of kerogen, and establishing hydrocarbon conversion rate profiles of various kerogen types of source rocks in combination with geological history and thermal evolution history.

[0014] Furthermore, the step 3 is specifically as follows: according to the proportion of organic matter types in different regions and different layers, combined with different geological and thermal evolution histories, hydrocarbon conversion rate profiles of source rocks in different layers in different fault depressions are established respectively.

[0015] Furthermore, the step 4 specifically includes: restoring the original organic carbon content and hydrocarbon generation potential, and establishing the relationship between the residual abundance and the original abundance.

[0016] Furthermore, the step 5 is specifically as follows: establishing residual abundance classification evaluation standards for different lithology source rocks at different maturity levels in different fault depressions according to industry standards.

[0017] Furthermore, the step 6 specifically includes: establishing a corresponding relationship between different fault depths and maturity.

[0018] Furthermore, the step 7 is specifically as follows: selecting corresponding evaluation criteria according to the fault depression, lithology and depth range to re-recognize the quality of the source rock.

[0019] The beneficial effect of the present invention compared with the prior art is that the present invention designs a set of standard evaluation processes for source rocks in complex faults with large differences in lithology and maturity, which can accurately and effectively evaluate the quality characteristics of source rocks and support regional resource potential evaluation and effective analysis of oil reservoirs.

[0020] Technical point 1: Establish logging response characteristics of different lithologies to effectively determine the lithology;

[0021] Technical Point 2: Establish the abundance evaluation standard of different lithologies in different regions at different maturity levels to effectively evaluate the quality of source rocks;

[0022] Technical point 3: Establish the corresponding relationship between maturity and depth of different fault depressions to effectively determine the maturity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0024] Figure 1 is a characteristic diagram of well logging responses of different lithologies according to an embodiment of the present invention;

[0025] Figure 2 It is a characteristic diagram of the relationship between TOC and Pg before and after recovery at different depths in an embodiment of the present invention;

[0026] Figure 3 This is a characteristic diagram of source rock development in a certain fault depression section according to an embodiment of the present invention;

[0027] Figure 4 It is a schematic diagram of the distribution range of good source rocks in a certain layer of a certain fault depression in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0029] Figure 1 The different response characteristics of different lithologies in well logging provided by the embodiment of the present invention can be used to formulate well logging evaluation standards for different lithologies;

[0030] Figure 2 It is a characteristic schematic diagram of the relationship between TOC and Pg before and after recovery at different depths provided by an embodiment of the present invention, and the recovery coefficient at different regions and depths can be calculated based on it;

[0031] Figure 3 It is a schematic diagram of the development characteristics of source rocks on a certain fault section provided by an embodiment of the present invention, and is a distribution characteristic of the quality characteristics of source rocks in a vertical region based on the fine evaluation of a single well;

[0032] Figure 4 It is a schematic diagram of the distribution of good source rocks in a certain layer of a certain fault depression provided by an embodiment of the present invention, and is based on the detailed evaluation of a single well, and the distribution characteristics of good source rocks in a certain layer are statistically analyzed.

[0033] Example 1

[0034] In order to better describe the technical solution in the embodiment of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The following steps are included:

[0035] a. Carry out core observation in the study area to clarify the lithological characteristics, logging response and geochemical characteristics of the developed source rocks; core observation is used to describe the physical characteristics of different lithologies, geochemical characteristics mainly reflect the abundance characteristics of the core, and logging response is mainly used for rock physics analysis and geostatistical inversion identification; logging response generally includes: acoustic wave, resistivity, natural potential, gamma, density, imaging and other logging data;

[0036] b. On the basis of step a, select samples of various organic matter types with low maturity and high abundance, carry out hydrocarbon generation simulation experiments on various types of kerogen source rocks in the study area, obtain the activation energy and reaction pre-exponential factor of hydrocarbon generation reaction of various types of kerogen, and establish hydrocarbon conversion rate profiles of various kerogen type source rocks in combination with geological history and thermal evolution history; among which: the samples selected for hydrocarbon generation simulation experiments should be rock samples of different kerogen types with high organic matter abundance and low maturity as much as possible, so as to fully present the entire evolution process;

[0037] c. On the basis of step b, according to the proportion of organic matter types in different regions and layers, combined with different geological and thermal evolution histories, hydrocarbon conversion rate profiles of source rocks in different layers in different fault depressions are established respectively; wherein: based on the experimental results of the above step b, the key point of this step is the proportion of each type of kerogen;

[0038] d. recovering the original organic carbon content and hydrocarbon generation potential, and establishing the relationship between the residual abundance and the original abundance; wherein: in this step, in the process of recovering the original organic carbon and the original hydrocarbon generation potential, a corresponding relationship can be established between the residual organic carbon, the residual hydrocarbon generation potential, the original organic carbon, and the original hydrocarbon generation potential of all samples;

[0039] e. Establishing residual abundance classification and evaluation standards for different lithology source rocks in different fault depressions at different maturity levels according to industry standards; wherein: the original organic carbon and original hydrocarbon generation potential in the above step d correspond to the data in the industry standard in this step, and combined with the corresponding relationship between the parameters in step d, the residual abundance evaluation standard under the current lithology and maturity can be calculated;

[0040] f. Establish the corresponding relationship between different fault depression depths and maturity; among them: the corresponding relationship between different fault depression depths and maturity is different. This step mainly clarifies the different corresponding relationships and provides a basis for selecting evaluation standards for different well sections in different regions;

[0041] g. Select the corresponding evaluation criteria according to the fault depression, lithology and depth range to re-recognize the quality of source rocks. Among them: This step combines the contents of steps a and f, firstly identifies the lithology, then determines the maturity according to the depth, and then selects the applicable standards to finely evaluate the quality characteristics of source rocks.

[0042] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating source rocks in complex fault basins, characterized in that: Here are the steps: S1. Core observation; S2. Hydrocarbon generation simulation experiment; S3. Establishing hydrocarbon conversion rate profile; S4. Establish abundance relationships; S5. Establish abundance evaluation criteria; S6. Establishing a corresponding relationship; S7. Re-understand the quality of source rocks.

2. The method for evaluating source rocks in complex fault basins according to claim 1, characterized in that: The step S1 specifically includes: conducting core observation in the study area to clarify the lithological characteristics, logging response and geochemical characteristics of the developed source rocks.

3. The method for evaluating source rocks in complex fault basins according to claim 1, characterized in that: The step S2 is specifically as follows: conducting hydrocarbon generation simulation experiments on various types of kerogen source rocks in the study area, obtaining the activation energy and pre-exponential factor of hydrocarbon generation reactions of various types of kerogen, and establishing hydrocarbon generation conversion rate profiles of various kerogen type source rocks in combination with geological history and thermal evolution history.

4. The method for evaluating source rocks in complex fault basins according to claim 1, characterized in that: The step S3 is specifically as follows: according to the proportion of organic matter types in different regions and different layers, combined with different geological and thermal evolution histories, hydrocarbon conversion rate profiles of source rocks in different layers in different fault depressions are established respectively.

5. The method for evaluating source rocks in complex fault basins according to claim 1, characterized in that: The step S4 specifically includes: restoring the original organic carbon content and hydrocarbon generation potential, and establishing the relationship between the residual abundance and the original abundance.

6. The method for evaluating source rocks in complex fault basins according to claim 1, characterized in that: The step S5 specifically includes: establishing residual abundance classification evaluation standards for different lithology source rocks at different maturity levels in different fault depressions according to industry standards.

7. The method for evaluating source rocks in complex fault basins according to claim 1, characterized in that: The step S6 specifically includes: establishing a corresponding relationship between different fault depths and maturity.

8. The method for evaluating source rocks in complex fault basins according to claim 1, characterized in that: The step S7 specifically includes: selecting corresponding evaluation criteria according to the fault depression, lithology and depth range to re-recognize the quality of the source rock.

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