Material source direction quantitative judgment method suitable for glutenite deposition

Abstract

The invention discloses a source direction quantitative determination method suitable for glutenite deposition, and the method comprises the steps: reading the description about the content of gravel components in a slice description according to the slice description of a target layer sample in a research area, and carrying out the assignment of the relative content of each gravel type in the gravel components; calculating the relative content of each gravel type of each single well according to the assignment; dividing the single wells of which the gravel types and the relative content of each gravel type meet set conditions into the same valley fan body on a target stratum plane, and carrying out quantitative judgment on the source direction and the scale; the method solves the problem that the direction of a sandy conglomerate reservoir fan body sediment source cannot be judged due to the influence of development of a sandy conglomerate fan body and lack of analysis data.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field exploration and development, and in particular to a method for quantitatively determining the provenance of a sandstone conglomerate sedimentary fan. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Regarding sediment source analysis methods, the following methods are currently widely used at home and abroad: first, sedimentology methods based on oriented arrangement of particles; second, heavy mineral analysis methods based on statistics of heavy minerals of different stability; third, clastic component analysis methods based on statistics of feldspar, quartz, and feldspar content; fourth, fission track methods that analyze track characteristics during uranium fission; and fifth, elemental geochemistry methods that use geochemical methods to count characteristic elements. All of the above technical methods require specific element and mineral analyses based on the needs of source analysis, which is a cumbersome process and has poor timeliness.

[0004] Sandstone fans are mostly developed in the early event gravity flow deposition of sedimentary basins. Affected by the scale of the lake basin and the fan, fans in different directions and fans in the same direction usually interfere with each other, making it difficult to determine the source of sandstone reservoir fan sediments. Existing technical methods use element, mineral, geochemical and other analyses. Since there is no obvious difference in the relevant data of fans in each source direction, it is impossible to determine the mutual interference zone at the end of multi-directional fans. At the same time, due to the need to carry out specific element and mineral analysis, some areas are restricted by the lack of relevant data and cannot guide the source determination of related fans.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may contain information that does not constitute prior art. Summary of the invention

[0006] In view of this, the present disclosure provides a method for quantitatively determining the provenance direction of conglomerate deposits, which solves the problem that the provenance direction of conglomerate reservoir fan deposits cannot be determined due to the influence of its development and the lack of analysis data.

[0007] To achieve the above-mentioned purpose of the invention, the method for quantitatively determining the provenance direction of conglomerate sediments includes:

[0008] According to the thin section description of the target layer sample in the study area, the description of the gravel component content in the thin section description is read, and the relative content of each gravel type in the gravel component is assigned;

[0009] Calculate the relative content of each gravel type in each single well according to the assignment;

[0010] On the target layer plane, the single wells whose gravel types and relative contents of each gravel type meet the set conditions are divided into the same valley fan body to make quantitative judgment on the source direction and scale.

[0011] In the present disclosure and possible embodiments, a pie chart of gravel type content of the single well is drawn, and the pie chart is projected on a well location map;

[0012] Sector division is performed on the well location map to clarify the distribution scale of the valley sector, and the source direction is quantitatively determined based on the distribution scale.

[0013] In the present disclosure and possible embodiments, the sector division method includes:

[0014] The single wells belonging to the same valley fan are regarded as a well group, and the peripheral wells of the well group are connected with the peripheral wells of the adjacent well group. The midpoint line of the connecting line is used as the dividing line between adjacent valley fans, and the distribution scale of the valley fan is clarified through the dividing line.

[0015] In the present disclosure and possible embodiments, wells adjacent to each other on the target layer plane and having the same gravel type and similar relative contents of each gravel type are selected as the same fan body, and the mean value of the relative contents of each gravel type of each single well in the same fan body is used to draw a histogram of the relative contents of each gravel type of the fan body, so as to characterize the typical gravel type combination characteristics of the fan body;

[0016] The pie charts are compared with typical gravel type combination characteristics of the fan, and the wells that meet the set conditions are classified into the same valley fan.

[0017] In the present disclosure and possible embodiments, the set conditions are that the main gravel types are the same, and the relative content of the main gravel types differs from the typical gravel type combination characteristics by less than 10%;

[0018] The main gravel type refers to the gravel type with a content greater than 20% in the gravel component.

[0019] In the present disclosure and possible embodiments, the main components and minor components of the gravel components are determined according to the description of the gravel component content in the slice description, and the assignment is performed according to the principle of assigning 5% or 10% to the minor components and assigning an average value to the main components.

[0020] In the present disclosure and possible embodiments, the relative content of each gravel type in the single well is calculated using the arithmetic average method.

[0021] In the present disclosure and possible embodiments, the arithmetic mean method is:

[0022] The relative content of the same gravel type in each sample slice of the single well is summed and divided by the number of sample slices of the single well to obtain the relative content of the gravel type in the single well. Similarly, the relative content of other gravel types in the single well is obtained.

[0023] The present disclosure has the following beneficial effects:

[0024] The method disclosed in the present invention is applicable to the quantitative determination method of the provenance direction of sandstone and conglomerate deposits. On the one hand, the method uses the gravel type characteristics that directly reflect the characteristics of the sedimentary parent rock as the basis for source determination, so the determination result is more convincing; on the other hand, the traditional sediment source determination method requires a relatively complex analysis process such as statistical unstable minerals and specific element contents. The present invention is the first to propose the idea of ​​using the gravel type characteristics observed under a microscope to determine the sediment source, which specifically makes full use of the existing thin section data and has the advantages of large data volume and easy acquisition; on the third hand, a method for assigning relative contents of different conglomerates is established for the first time to realize the qualitative to quantitative description of conglomerates, so that the conglomerate content data can be statistically analyzed, and the quantitative determination of sediment sources is realized, which solves the problem that the sediment source direction of the conglomerate reservoir fan cannot be determined due to the influence of its development and the lack of analysis data. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0026] Figure 1 is a histogram of the relative contents of various types of gravel in five sectors of a T oil layer in an oil field according to an embodiment of the present disclosure, and is used to characterize the typical gravel type combination characteristics of the five sectors;

[0027] Figure 2 It is the division result of 5 valley fans of the T oil layer in a certain oil field according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] The present disclosure is described below based on embodiments, but it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, some specific details are described in detail. However, for the parts that are not described in detail, those skilled in the art can also fully understand the present disclosure.

[0029] In addition, those skilled in the art should understand that the drawings are only provided to illustrate the purpose, features and advantages of the present disclosure, and the drawings are not actually drawn to scale.

[0030] At the same time, unless the context clearly requires otherwise, the words "include", "comprises" and similar words throughout the specification and claims should be interpreted as inclusive rather than exclusive or exhaustive; that is, the meaning is "including but not limited to".

[0031] The method for quantitatively determining the provenance direction of conglomerate deposits according to the embodiment of the present disclosure comprises: step S10: reading the description of gravel component content in the thin section description according to the target layer sample description in the study area, and assigning a value to the relative content of each gravel type in the gravel component; step S20: calculating the relative content of each gravel type in each single well according to the assignment; step S30: dividing the single wells whose gravel types and relative contents of each gravel type meet the set conditions into the same valley fan on the target layer plane, and performing quantitative determination of the provenance direction and scale.

[0032] Among them, step S10: according to the thin slice description of the target layer sample in the study area, read the description of the gravel component content in the thin slice description, and assign the relative content of each gravel type in the gravel component. The specific process is as follows:

[0033] This embodiment makes full use of a large amount of existing core sample thin section data in the sandstone core sample thin section analysis and identification report, which has the advantages of large data volume and easy acquisition. Then, according to the description of the gravel component content in the core sample thin section description, the main components and minor components of the gravel components of the corresponding core samples are determined, and the values ​​are assigned according to the principle of assigning 5% or 10% to the minor components and assigning an average value to the main components.

[0034] Regarding the customary techniques in this field, in the core sample thin section analysis and identification report, the description of gravel is often seen as "the gravel is mainly of a certain type", "the gravel is mainly of a certain type, with a small amount of a certain type". There are 5-6 common gravel types (among which the main components and minor components of gravel are mostly of the same type, such as a main component in sample No. 1 may be a minor component in sample No. 2).

[0035] According to the principle of "assigning 5% or 10% to minor components and similar values ​​to major components", the relative contents of different gravel components described in the rock thin section identification report of a single sample are assigned. Specifically for different types of gravel type combinations with different gravel components, the relative contents of each gravel type are assigned, as shown in Table 1.

[0036] Table 1 Gravel type assignment table for different gravel composition combinations

[0037]

[0038] In the actual determination process, the gravel type of the gravel composition of each core sample can be assigned accordingly by referring to the idea in Table 1.

[0039] Step S20: Calculate the relative content of each gravel type in each single well according to the assignment. The specific process is as follows:

[0040] According to the gravel component assignment of different samples, statistics are conducted on the samples of the target layer of a single well in the study area, and the arithmetic average is obtained by using the arithmetic average method as the relative content of different gravel components in the single well. The arithmetic average method is: summing the relative content of the same gravel type in each sample slice of the single well according to the assignment in step S10, and then dividing the number of sample slices of the single well to obtain the relative content of the gravel type in the single well, and so on, to obtain the relative content of other gravel types in the single well.

[0041] Taking the A-type gravel of a certain well as an example, the calculation formula for the relative content of the A-type gravel components is obtained by using the arithmetic average method as follows:

[0042]

[0043] Where:

[0044] S A —Relative content of Class A gravel components in a single well;

[0045] S Ai —Relative content of type A gravel components in the ith sample;

[0046] n—number of samples.

[0047] In this way, the relative contents of all types of gravel components in the well are calculated.

[0048] The obtained gravel types and the relative content of each type can be defined as the gravel type combination characteristics of the single well.

[0049] Step S30: On the target layer plane, the single wells whose gravel types and relative contents of each gravel type meet the set conditions are divided into the same valley fan body, and the source direction and scale are quantitatively determined. The specific process is as follows:

[0050] 1. Since the well location map shows the distribution of each single well on a rough plane, the valley fan body can be divided with the help of the well location map. To this end, the determination method of this embodiment uses the calculation results of the relative content of all types of gravel components in a single well, and according to the conventional technology in this field, a pie chart of the gravel type content of the single well is drawn. By analogy, pie charts of the gravel type content of other single wells in the study area are drawn, and then these pie charts are projected on the well location map. Then, the valley fan body can be divided on the well location map to clarify the distribution scale of the fan body, and the direction and scale of the material source can be quantitatively determined by the distribution scale of the fan body.

[0051] 2. According to the conventional technology in this field, because the gravel type combination of each single well in the same fan body should have similar characteristics, and is slightly different at the edge and local parts of the fan body due to other factors, the wells that are adjacent on the target layer plane and have the same gravel type and similar relative content of each gravel are identified as the same fan body. The mean value of the relative content of each gravel type in each single well in the same fan body is used to draw a histogram of the relative content of each gravel type in the fan body, which is used to characterize the typical gravel type combination characteristics of the fan body.

[0052] 3. Compare the pie charts of each single well by the typical gravel type combination characteristics of each fan, and classify the single wells that meet the set condition that the main gravel type is the same and the relative content of the main gravel type is less than 10% different from the typical gravel type combination characteristics into the same valley fan. Among them, the main gravel type refers to the gravel type with a content of >20% in the gravel component. Of course, the present disclosure does not limit this setting condition, and it can be set differently according to its own characteristics in actual use.

[0053] 4. Divide the valley sectors on the well location map with the pie chart projected above, and determine the boundary between the valley sectors by treating the single wells belonging to the same valley sector as a well group, connecting the peripheral wells of the well group with the peripheral wells of the adjacent well group using the proximity principle, and then connecting the midpoints of the connecting lines as the boundary between adjacent valley sectors.

[0054] The specific process of the present invention is described below using the sediment source determination process of a certain oil field T oil layer:

[0055] (1) Thin section analysis samples from the T oil layer of a certain oil field were analyzed, the gravel composition description of a single sample was read, and the values ​​were assigned according to Table 1. After arithmetic averaging, the relative content of various gravels in a single well in the study area was obtained (Table 2).

[0056] Table 2 Gravel composition assignment of different samples in a single well of the T oil layer in an oil field

[0057]

[0058]

[0059] (2) According to the conventional technical means in this field, single wells with similar gravel type combination characteristics are analyzed, and the gravel parent rock types with the same gravel type and similar main gravel type content on the statistical plane are identified. For example, Well B38 and Well B48 are both dominated by rhyolite and tuff, and the content is close to 50%. It is determined that the two wells have similar gravel parent rock types, and the wells with similar gravel parent rock types are delineated as the same fan.

[0060] According to the data in Table 2, 5 different combination characteristics were determined. Among them, fan No. 1 is mainly composed of rhyolite and granite, with relative contents > 40% (B40 well is a typical well); fan No. 2 is mainly composed of granite, with a relative content > 60%, and a considerable amount of rhyolite is also developed (B13, B3304, and B3305 wells are typical wells); fan No. 3 is mainly composed of rhyolite and granite, with relative contents > 30%, and a certain amount of granite is developed (B1901 well is a typical well); fan No. 4 is mainly composed of rhyolite, with a relative content > 60% (B33-2 well is a typical well); fan No. 5 is mainly composed of tuff and rhyolite, with relative contents of about 50% respectively (B48 well is a typical well).

[0061] The average contents of each type of gravel of the five gravel combination types in the five fans are counted, and a histogram of the relative contents of each type of gravel in the five fans is drawn. Figure 1 As shown, the gravel type combination characteristics of fans 1, 2, 3, 4 and 5 are clarified, and the five fans developed in the study area are characterized.

[0062] Draw a pie chart of the gravel composition of the T oil layer and project the pie chart onto the well location map. According to the typical gravel type combination characteristics of the five sectors established in the previous step, the valley sectors are delineated on the well location map projected with the pie chart. The boundary between the valley sectors is divided by treating the single wells belonging to the same sector as a well group, connecting the peripheral wells of the well group with the peripheral wells of the adjacent well group, and then connecting the midpoints of the connecting lines as the boundary between adjacent sectors. The results are shown in the figure below. Figure 2 shown.

[0063] The above-described embodiments are only embodiments of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the present disclosure. It should be noted that, for a person of ordinary skill in the art, without departing from the concept of the present disclosure, several variations, equivalent substitutions, improvements, etc. may be made, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the attached claims.

Claims

1. A method for quantitatively determining the provenance direction of conglomerate sediments, characterized in that: include: According to the thin section description of the target layer sample in the study area, the description of the gravel component content in the thin section description is read, and the relative content of each gravel type in the gravel component is assigned; Calculate the relative content of each gravel type in each single well according to the assignment; On the target layer depth plane, the single wells whose gravel types and relative contents of each gravel type meet the set conditions are divided into the same valley fan body to make quantitative judgment on the source direction and scale.

2. The method for quantitatively determining the provenance direction of conglomerate sediments according to claim 1 is characterized in that: Draw a pie chart of gravel type content of the single well, and project the pie chart onto a well location map; Sector division is performed on the well location map to clarify the distribution scale of the valley sector, and the source direction is quantitatively determined based on the distribution scale.

3. The method for quantitatively determining the provenance direction of conglomerate sediments according to claim 2, characterized in that: The sector division method comprises: The single wells belonging to the same valley fan are regarded as a well group, and the peripheral wells of the well group are connected with the peripheral wells of the adjacent well group. The midpoint line of the connecting line is used as the dividing line between adjacent valley fans, and the distribution scale of the valley fan is clarified through the dividing line.

4. The method for quantitatively determining the provenance direction of conglomerate sediments according to claim 3 is characterized in that: Wells that are adjacent on the target layer plane and have the same gravel type and similar relative content of each gravel type are selected as the same fan body. The mean value of the relative content of each gravel type in each single well in the same fan body is used to draw a histogram of the relative content of each gravel type in the fan body, which is used to characterize the typical gravel type combination characteristics of the fan body; The pie charts are compared with typical gravel type combination characteristics of the fan, and the wells that meet the set conditions are classified into the same valley fan.

5. The method for quantitatively determining the provenance direction of conglomerate sediments according to claim 4 is characterized in that: The setting conditions are that the main gravel types are the same, and the relative content of the main gravel types differs from the combination characteristics of the typical gravel types by less than 10%; The main gravel type refers to the gravel type with a content greater than 20% in the gravel component.

6. The method for quantitatively determining the provenance direction of conglomerate sediments according to claims 1 to 5, characterized in that: According to the description of gravel content in the thin section description, the main components and minor components of the gravel are determined, and the assignment is performed according to the principle of assigning 5% or 10% to the minor components and assigning an average value to the main components.

7. The method for quantitatively determining the provenance direction of conglomerate sediments according to claim 6 is characterized in that: The relative content of each gravel type in the single well was calculated using the arithmetic mean method.

8. The method for quantitatively determining the provenance direction of conglomerate sediments according to claim 7, characterized in that: The arithmetic mean is: The relative content of the same gravel type in each sample slice of the single well is summed and divided by the number of sample slices of the single well to obtain the relative content of the gravel type in the single well. Similarly, the relative content of other gravel types in the single well is obtained.

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