Method and system for identifying high-quality lacustrine hydrocarbon source rocks

Abstract

The application discloses a method for judging high-quality lacustrine source rock, which comprises the following steps: preparing a paleo-topographic map of a source rock development layer; determining an area within a watershed according to the prepared paleo-topographic map of the source rock development layer and a seismic profile map of a depression; determining a source rock development layer depression deposition area; obtaining a source supply area according to the determined area within the watershed and the source rock development layer depression deposition area; calculating a value of the source supply area / depression deposition area; and judging the development of the high-quality lacustrine source rock in the depression according to the obtained value of the source supply area / depression deposition area. The method is quick and accurate in judging whether the high-quality lacustrine source rock is developed in a new depression, and effectively solves the problem of multiple solutions in the research of the source rock in the new depression.

Description

Technical Field

[0001] This invention relates to a method and system for identifying high-quality lacustrine source rocks based on the ratio of "source supply area / depression deposition area", which belongs to the field of oil and gas exploration. Background Technology

[0002] my country’s offshore oil and gas are mainly discovered in confirmed hydrocarbon-rich depressions. As oil and gas exploration continues to deepen, it is urgent to expand the exploration field. New depressions are important areas for future reserve and production increases. Whether a new depression has exploration potential depends on whether high-quality lacustrine source rocks are developed.

[0003] Currently, for new lacustrine sedimentary depressions, the main approach is to determine whether high-quality lacustrine source rocks have developed based on the activity rate of the control faults and the seismic facies characteristics of the source rock development sections. This method has certain ambiguities and lacks research on the material supply capacity during the development of source rocks, thus failing to provide effective indicators for the formation of high-quality lacustrine source rocks. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a method for identifying high-quality lacustrine source rocks based on the ratio of "source supply area / depression deposition area". This method starts from the development mechanism of high-quality lacustrine source rocks - the formation conditions of undercompensated depressions, and can effectively determine whether a new depression has developed high-quality lacustrine source rocks.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for identifying high-quality lacustrine source rocks, comprising the following steps:

[0007] Compile paleotopographic maps of the hydrocarbon source rock development strata;

[0008] The area within the watershed was determined based on the paleotopographic map of the hydrocarbon source rock development zone and the seismic profile of the depression.

[0009] Determine the area of ​​the depression in the hydrocarbon source rock development zone;

[0010] The source supply area is determined based on the measured area within the watershed and the area of ​​the depression sediment.

[0011] Calculate the value of "source supply area / depression deposition area";

[0012] The development of high-quality source rocks in lacustrine facies can be determined based on the obtained value of "source supply area / depression sedimentary area".

[0013] The method, preferably, involves the following: compiling paleotopographic maps of the hydrocarbon source rock development strata.

[0014] Based on drilling and seismic data, the interpretation of the top, bottom, and basement interfaces of the source rock strata was completed.

[0015] The depression area is mapped using the bottom interface of the source rock strata, while other areas are mapped using the basement interface. The maps are combined and displayed in three dimensions to complete the paleotopographic map of the source rock development strata.

[0016] The method, preferably, involves measuring the area within the watershed specifically as follows:

[0017] Based on the seismic profile of the depression and the paleotopographic map of the hydrocarbon source rock development zone, the watershed of the source rock around the depression is determined with the "ridge" as the boundary, the watershed line is delineated, and the area value within the watershed line is measured.

[0018] Preferably, in the method described, the depression depositional area of ​​the source rock development section is approximately equal to the area corresponding to the top interface of the source rock strata.

[0019] The method, preferably, involves determining the material supply area as follows:

[0020] The sediment supply area can be calculated by subtracting the depression deposition area from the measured area within the watershed.

[0021] The method, preferably, involves calculating the value of "source supply area / depression deposition area" as follows:

[0022] The value of "source area / depression deposition area" for the hydrocarbon source rock deposition period in the depression can be calculated by dividing the source area value by the depression deposition area value.

[0023] The method, preferably, specifically involves determining the development of high-quality lacustrine source rocks in the depression as follows:

[0024] By statistically analyzing the "source area / depression sedimentary area" values ​​of depressions in the basin or larger area where the depression is located, which have been confirmed to have developed high-quality lacustrine source rocks, a threshold is determined, and based on this, it is judged whether a new depression has developed high-quality lacustrine source rocks.

[0025] Secondly, the present invention provides a system for identifying high-quality lacustrine source rocks, comprising:

[0026] The first processing unit is used to compile paleotopographic maps of the hydrocarbon source rock development strata;

[0027] The second processing unit is used to determine the area within the watershed based on the paleotopographic map and seismic profile of the hydrocarbon source rock development zone.

[0028] The third processing unit is used to determine the area of ​​the depression in the hydrocarbon source rock development zone;

[0029] The fourth processing unit is used to determine the source supply area based on the measured area value within the watershed and the area of ​​the depression sediment.

[0030] The fifth processing unit is used to calculate the value of "source supply area / depression deposition area";

[0031] The sixth processing unit is used to determine the development of high-quality source rocks in the lacustrine facies based on the obtained "source supply area / depression sedimentary area" value.

[0032] Thirdly, the present invention provides a computer storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of the method described in the first aspect of the present invention.

[0033] Fourthly, the present invention provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described in the first aspect of the present invention.

[0034] The present invention has the following advantages due to the adoption of the above technical solutions:

[0035] The method for identifying high-quality lacustrine source rocks based on the ratio of "source supply area / depression sedimentary area" provided by this invention starts from the formation conditions of source rocks and uses the correspondence between the source supply area and the depression sedimentary area to determine the development of high-quality lacustrine source rocks. This method provides a quick and relatively accurate assessment of whether high-quality lacustrine source rocks have developed in newly formed depressions, effectively solving the problem of multiple solutions in the study of new depression source rocks. Theoretically, a smaller "source supply area / depression sedimentary area" ratio is more conducive to the development of high-quality lacustrine source rocks, and this method is also applicable to the "depression" level. Attached Figure Description

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0037] Figure 1 A flowchart of a method for identifying high-quality lacustrine source rocks according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the paleotopographic map of the hydrocarbon source rock development zone compiled according to this embodiment of the invention;

[0039] Figure 3 This is a schematic cross-sectional view of the provenance range of the depression source rock development section and the depression deposition range in this embodiment of the present invention;

[0040] Figure 4 This is a planar schematic diagram of the source rock development zone and the sedimentary range of the depression in this embodiment of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., used to define components are merely for the convenience of distinguishing the aforementioned components. Unless otherwise stated, these terms have no special meaning and should not be construed as indicating or implying relative importance.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] The method for identifying high-quality lacustrine source rocks provided by this invention includes the following steps: compiling a paleotopographic map of the source rock development zone; determining the area within the watershed based on the compiled paleotopographic map and seismic profile; determining the depression depositional area of ​​the source rock development zone; calculating the source supply area based on the measured area within the watershed and the depression depositional area; calculating the "source supply area / depression depositional area" value; and determining the development status of high-quality lacustrine source rocks in the depression based on the obtained "source supply area / depression depositional area" value. This invention, starting from the source rock formation conditions, utilizes the correspondence between the source supply area and the depression depositional area to determine the development status of high-quality lacustrine source rocks. This provides a quick and relatively accurate way to determine whether high-quality lacustrine source rocks have developed in newly formed depressions, effectively solving the problem of multiple solutions in the study of new depression source rocks.

[0045] The method for identifying high-quality lacustrine source rocks provided in the embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0046] Example 1:

[0047] Please see Figure 1 The method for identifying high-quality lacustrine source rocks provided in this embodiment includes the following steps:

[0048] Step S100. Compile paleotopographic maps of the hydrocarbon source rock development strata, specifically as follows:

[0049] Sub-step S101. Based on drilling and seismic data, complete the interpretation of the top, bottom, and basement structures of the source rock strata;

[0050] Sub-step S102. The depression area is mapped using the bottom surface of the source rock strata, and other areas using the basal surface. This is combined to create a three-dimensional map, completing the paleotopographic map of the source rock development strata (see [link to relevant documentation]). Figure 2 ).

[0051] Step S200. Measure the area within the watershed, specifically:

[0052] Based on the seismic profile of the depression and the paleotopographic map of the hydrocarbon source rock development zone, the watershed of the source rock area around the depression was determined with the "ridge" as the boundary, the watershed line was delineated, and the area value within the watershed line was measured (see [link to relevant documentation]). Figure 3 and Figure 4 In this embodiment, the area S within the watershed is measured. a 1260km 2 .

[0053] Step S300. Determine the sedimentary area of ​​the depression in the hydrocarbon source rock development zone;

[0054] Typically, the area corresponding to the top surface of the source rock strata is approximately equal to the area of ​​the depression. In this embodiment, based on the structural interpretation results of the source rock strata, the area S of the top surface of the source rock strata is determined. b 540km 2 .

[0055] Step S400. Calculate the material supply area, specifically:

[0056] The sediment supply area can be calculated by subtracting the depression deposition area from the measured area within the watershed. In this embodiment, the calculation formula is S = S a -S b The result was 720km. 2 .

[0057] Step S500. Calculate the value of "source supply area / depression deposition area", specifically:

[0058] The "source area / depression deposition area" value for the hydrocarbon source rock deposition period in the depression can be calculated by dividing the source area value by the depression deposition area value. In this embodiment, the calculation formula is R = S / S b The result was 1.3.

[0059] Step S600. Determine the development of high-quality lacustrine source rocks in the depression, specifically:

[0060] By statistically analyzing the basin or larger area where the depression is located, the ratio of "source area" to "depression sedimentary area" for depressions with confirmed lacustrine high-quality source rocks is determined, and a threshold is established (see Table 1 below). This threshold is then used to determine whether a new depression has developed lacustrine high-quality source rocks. In this embodiment, the threshold is set to 2. Figure 2 The ratio of "source supply area / depression sedimentary area" in the new depression is 1.3, which is less than the threshold, indicating that it is a lacustrine source rock development area.

[0061] Table 1. Statistical sample table of "source supply area / depression sedimentary area" for depressions in basins where lacustrine high-quality source rocks have been confirmed.

[0062]

[0063] Example 2:

[0064] The above-described embodiment 1 provides a method for identifying high-quality lacustrine source rocks. Correspondingly, this embodiment provides a system for identifying high-quality lacustrine source rocks. The system for identifying high-quality lacustrine source rocks provided in this embodiment can implement the method for identifying high-quality lacustrine source rocks in embodiment 1. This system can be implemented through software, hardware, or a combination of both. For example, the three-dimensional characterization system may include integrated or separate functional modules or units to perform the corresponding steps in the methods of embodiment 1. Since the system for identifying high-quality lacustrine source rocks in this embodiment is basically similar to the method embodiment, the description process in this embodiment is relatively simple. For relevant details, please refer to the description in embodiment 1. The system for identifying high-quality lacustrine source rocks in this embodiment is merely illustrative.

[0065] The system for identifying high-quality lacustrine source rocks provided in this embodiment includes:

[0066] The first processing unit is used to compile paleotopographic maps of the hydrocarbon source rock development strata;

[0067] The second processing unit is used to determine the area within the watershed based on the paleotopographic map and seismic profile of the hydrocarbon source rock development zone.

[0068] The third processing unit is used to determine the area of ​​the depression in the hydrocarbon source rock development zone;

[0069] The fourth processing unit is used to determine the source supply area based on the measured area value within the watershed and the area of ​​the depression sediment.

[0070] The fifth processing unit is used to calculate the value of "source supply area / depression deposition area";

[0071] The sixth processing unit is used to determine the development of high-quality source rocks in the lacustrine facies based on the obtained "source supply area / depression sedimentary area" value.

[0072] Example 3:

[0073] This embodiment provides a processing device for implementing the method for identifying high-quality lacustrine source rocks provided in Embodiment 1. The processing device can be a client-side processing device, such as a mobile phone, laptop, tablet computer, desktop computer, etc., to execute the method of Embodiment 1.

[0074] The processing device includes a processor, a memory, a communication interface, and a bus. The processor, memory, and communication interface are connected via the bus to enable communication between them. The memory stores a computer program that can run on the processor. When the processor runs the computer program, it executes the method for identifying high-quality lacustrine source rocks provided in Embodiment 1.

[0075] Preferably, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0076] Preferably, the processor can be any type of general-purpose processor such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation herein.

[0077] Example 4:

[0078] The method for identifying high-quality lacustrine source rocks in Embodiment 1 can be specifically implemented as a computer program product. The computer program product may include a computer-readable storage medium on which computer-readable program instructions for executing the method described in Embodiment 1 are loaded.

[0079] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for identifying high-quality lacustrine source rocks, characterized in that, Includes the following steps: Compile paleotopographic maps of the hydrocarbon source rock development strata; The area within the watershed was determined based on the paleotopographic map of the hydrocarbon source rock development zone and the seismic profile of the depression. Determine the area of ​​the depression in the hydrocarbon source rock development zone; The source supply area is determined based on the measured area within the watershed and the area of ​​the depression sediment. Calculate the value of "source supply area / depression deposition area"; The development of high-quality source rocks in lacustrine facies can be determined based on the obtained value of "source supply area / depression sedimentary area".

2. The method according to claim 1, characterized in that, The specific steps involved in compiling paleotopographic maps of the hydrocarbon source rock development strata are as follows: Based on drilling and seismic data, the interpretation of the top, bottom, and basement interfaces of the source rock strata was completed. The depression area is mapped using the bottom interface of the source rock strata, while other areas are mapped using the basement interface. The maps are combined and displayed in three dimensions to complete the paleotopographic map of the source rock development strata.

3. The method according to claim 1, characterized in that, The specific measurement of the area within the watershed is as follows: Based on the seismic profile of the depression and the paleotopographic map of the hydrocarbon source rock development zone, the watershed of the source rock around the depression is determined with the "ridge" as the boundary, the watershed line is delineated, and the area value within the watershed line is measured.

4. The method according to claim 1, characterized in that, The area of ​​the depression in the source rock development section is approximately equal to the area corresponding to the top interface of the source rock strata.

5. The method according to claim 1, characterized in that, The specific method for determining the material supply area is as follows: The sediment supply area can be calculated by subtracting the depression deposition area from the measured area within the watershed.

6. The method according to claim 1, characterized in that, The calculation of the "source supply area / depression deposition area" value is specifically as follows: The value of "source supply area / depression deposition area" for the hydrocarbon source rock deposition period in the depression can be calculated by dividing the source supply area value by the depression deposition area value.

7. The method according to claim 1, characterized in that, The specific steps for determining the development of high-quality lacustrine source rocks in the depression are as follows: By statistically analyzing the "source supply area / depression sedimentary area" values ​​of depressions in the basin or larger area where the depression is located, which have been confirmed to have developed high-quality lacustrine source rocks, a threshold is determined, and based on this, it is judged whether a new depression has developed high-quality lacustrine source rocks.

8. A system for identifying high-quality lacustrine source rocks, characterized in that, include: The first processing unit is used to compile paleotopographic maps of the hydrocarbon source rock development strata; The second processing unit is used to determine the area within the watershed based on the paleotopographic map of the hydrocarbon source rock development zone and the seismic profile of the depression. The third processing unit is used to determine the area of ​​the depression in the hydrocarbon source rock development zone; The fourth processing unit is used to determine the source supply area based on the measured area value within the watershed and the area of ​​the depression sediment. The fifth processing unit is used to calculate the value of "source supply area / depression deposition area"; The sixth processing unit is used to determine the development of high-quality source rocks in the lacustrine facies based on the obtained "source supply area / depression sedimentary area" value.

9. A computer storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-7.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-7.

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