CN115354991A - Coal-based gas reservoir favorable fracturing layer section optimization method - Google Patents
Coal-based gas reservoir favorable fracturing layer section optimization method Download PDFInfo
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- CN115354991A CN115354991A CN202211063248.3A CN202211063248A CN115354991A CN 115354991 A CN115354991 A CN 115354991A CN 202211063248 A CN202211063248 A CN 202211063248A CN 115354991 A CN115354991 A CN 115354991A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/006—Production of coal-bed methane
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
- Y02A10/40—Controlling or monitoring, e.g. of flood or hurricane; Forecasting, e.g. risk assessment or mapping
Abstract
The invention provides a method for optimizing a fracturing layer section of a coal-based gas reservoir, which comprises the following steps: drawing a lithologic superposition mode chart; determining an optimal fracturing position corresponding to each lithologic superposition mode and sequencing the lithologic superposition modes from good to bad; and identifying the lithology of the single well, determining the actual lithology stacking mode corresponding to each ash/sandstone by taking the ash/sandstone as a reference and comparing the lithology combination formed by the ash/sandstone in the sequence from top to bottom with the lithology stacking mode, screening out an effective lithology stacking mode from the actual lithology stacking modes, and finally determining the optimal fracturing position of the single well according to the effective lithology stacking mode. On one hand, the method provided by the invention finely describes the lithology on a single well, so that the determination of the fracturing position is more accurate; on the other hand, a reproducible, clear-organized and purpose-defined fracturing interval optimization method for a coal-series reservoir with multi-lithology combination is formed, so that the time and money cost are saved.
Description
Technical Field
The invention relates to the technical field of geology, in particular to a method for optimizing favorable fractured intervals of a coal-based gas reservoir.
Background
Coal bed gas, tight sandstone gas and shale gas in the coal-series gas reservoir have development potential, and the 'two-gas' or even 'three-gas' co-exploration mining technology is a necessary requirement for economically and efficiently developing the coal-series reservoir. Most of coal-based gas reservoirs are compact in structure and low in permeability, so that development by means of fracturing is needed. However, multiple lithologic interbed of coal-based reservoirs are frequent, which causes great longitudinal variation of mechanical properties of reservoir rocks, and makes it difficult to select fractured intervals.
Early scholars considered that coal bed gas was the main source of natural gas in coal systems, and most of them directly used the coal bed as a fracturing layer section. In recent years, some scholars construct a multi-lithology symbiotic mode of a coal-based reservoir aiming at the goal of multi-gas co-production of the coal-based reservoir, and on the basis, based on corresponding engineering constraint conditions, the interval which is difficult to be subjected to engineering fracturing transformation is eliminated, and finally, the fracturing target interval of the coal-based gas reservoir is determined. However, the conventional method is too simple to describe the symbiotic combination mode of the coal-series reservoir, and cannot systematically represent the lithological superposition relationship of the complex coal-series reservoir, so that the selection of the fracturing layer section of the coal-series gas reservoir is not accurate enough. Meanwhile, due to differences among different wells, the existing method cannot form a set of fracturing interval optimal selection system suitable for the whole area, and well-by-well analysis is needed, so that a large amount of time and financial resources are consumed.
Disclosure of Invention
The invention aims to solve the defects in the prior art and provides a method for optimizing favorable fracturing layer sections of a coal-based gas reservoir.
A coal-derived gas reservoir favorable fracturing interval optimization method comprises the following steps:
step 100: drawing corresponding lithology superposition mode charts of all drilling wells in the research area;
step 200: determining an optimal fracturing position corresponding to each lithological superposition mode, and sequencing the development potentials of the lithological superposition modes from good to bad;
step 300: identifying the lithology of a single well in the research area one by one, thereby determining the quantity of the ash/sandstone on the single well and the position of each ash/sandstone; the lithology includes: coal rock, shale, ash/sandstone;
step 400: determining a first actual lithology combination formed by the ash/sandstone and the adjacent lithology above the ash/sandstone and a second actual lithology combination formed by the adjacent lithology below the ash/sandstone according to each ash/sandstone reference;
step 500: respectively comparing the first actual lithologic combination and the second actual lithologic combination with preset lithologic superposition modes one by one, and determining all actual lithologic superposition modes corresponding to each ash/sandstone;
step 600: determining all effective actual lithologic superposition modes corresponding to each ash/sandstone;
step 700: determining an optimal lithology stacking mode corresponding to each ash/sandstone from all the effective actual lithology stacking modes;
step 800: determining an optimal fracturing position corresponding to each ash/sandstone according to the optimal lithological superposition mode corresponding to each ash/sandstone;
step 900: and taking the optimal fracturing position corresponding to each ash/sandstone as the optimal fracturing position of the whole single well.
Further, in the preferred method for a fracturing interval of a coal-derived gas reservoir as described above, step 100 includes the steps of:
step 110: acquiring logging information, logging information and drilling coring information corresponding to all drilling wells in a research area;
step 120: determining the lithology of the research area according to the logging information, the logging information and the drilling coring information corresponding to all the drilled wells; the lithology comprises the following steps: ash/sandstone, shale, coal;
step 130: dividing the ash/sandstone, the shale and the coal into reservoir lithology and non-reservoir lithology according to the electrical characteristic, the lithology characteristic, the physical characteristic and the gas containing characteristic;
step 140: determining a thickness corresponding to the non-reservoir lithology;
step 150: under the condition that the thickness corresponding to the non-reservoir lithology is more than 3 meters, dividing the non-reservoir lithology into interlayers; under the condition that the thickness corresponding to the non-reservoir lithology is less than 3 meters, dividing the non-reservoir lithology into interlayers;
step 160: and drawing a lithology superposition mode chart corresponding to the lithology combination by taking all lithologies between the two interlayer as a lithology combination.
Further, according to the preferable method for the coal-derived gas reservoir advantageous fracturing interval, all the well-drilling corresponding lithological stacking mode charts comprise 6 lithological stacking modes, and the 6 lithological stacking modes respectively comprise, in order from top to bottom:
mode 1: ash/sandstone, shale, coal;
mode 2: coal, ash/sandstone, shale;
mode 3: shale, coal, ash/sandstone;
mode 4: coal, shale, ash/sandstone;
mode 5: ash/sandstone, coal, shale;
mode 6: shale, ash/sandstone, coal.
Further, according to the method for optimizing the fracturing intervals of the coal-derived gas reservoir, the fracturing positions are sorted in a good-to-poor order:
Further, according to the preferable method for the coal-derived gas reservoir favorable fracturing interval, the step 600 specifically includes the following steps:
step 610: respectively determining the distance between the optimal fracturing positions of all actual lithologic superposition modes corresponding to each ash/sandstone and the coal seam;
step 620: the lithologic stacking mode is effective when the distance is greater than a certain preset value; otherwise, the litho-stacking mode is invalid;
step 630: and screening effective lithologic stacking modes from all the actual lithologic stacking modes as all the effective actual lithologic stacking modes corresponding to each ash/sandstone.
Further, the coal-derived gas reservoir advantageous fracturing interval preferred method as described above, the step 200 comprising:
and determining the optimal fracturing position corresponding to each lithology superposition mode according to the gas content distribution characteristics, the fracturing sequence of various lithologies and the mineral distribution characteristics of lithology combination.
Further, as described above, the coal-derived gas reservoir advantageous fracturing interval optimization method includes:
arranging the fracturability of various rocks from top to bottom according to the elastic modulus and the Poisson ratio respectively corresponding to the lithology of various rocks, and obtaining:
ash/sandstone fracability > shale fracability > coal fracability.
Has the advantages that:
according to the coal-based gas reservoir favorable fracturing interval optimization method, on one hand, according to drawn lithological superposition mode charts corresponding to all drilled wells in the whole research area, the optimal fracturing position and the optimal lithological superposition mode of each lithological superposition mode are determined, then lithological combinations on a single well are compared with the lithological superposition mode charts one by one, so that the optimal lithological superposition mode on the single well is determined, the optimal fracturing position on the single well is determined according to the optimal lithological superposition mode on the single well, and the lithological performance on the single well is finely carved by the method, so that the determination of the fracturing position is more accurate; on the other hand, the optimal fracturing position is directly locked through each lithologic stacking mode, so that the fracturing position of the whole area is preferably changed into the selection of the lithologic stacking mode on a single well, and the method forms a reproducible, clear-organized and purpose-defined fracturing interval optimization method for the coal-series reservoir with multiple lithologic combinations, so that the time and money cost is saved.
Drawings
FIG. 1 is a flow chart of a preferred method for fracturing a favorable interval of a coal-based gas reservoir provided by the invention;
FIG. 2 is a plot of the intersection of non-reservoir lithologic monolayer thickness and the frequency of its occurrence;
FIG. 3 is a plot of the intersection of non-reservoir lithologic monolayer thickness and its total hydrocarbon content;
FIG. 4 is a diagram of a lithology stacking pattern layout for different lithology combinations;
FIG. 5 is a diagram showing the intersection of shale brittle mineral content and distance from limestone/sandstone;
FIG. 6 is a plot of the convergence of clay mineral content of shale with distance from the coal seam;
FIG. 7 is a diagram of a lithology stacking pattern in a mud-sand/ash-coal lithology combination;
FIG. 8 is a cross-sectional view of the X1 well lithology combination lithology stacking pattern.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described clearly and completely below, and it is obvious that the described embodiments are some, not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The method mainly solves the problem of optimal fracturing positions of coal-series reservoirs with various lithologies, thin single layers and complex stacking relation. Aiming at the characteristics of a coal reservoir, dividing a non-reservoir into an interlayer and an interlayer by a thickness boundary by determining the properties of each lithologic reservoir and the non-reservoir in an area; on the basis, all lithologies between the interlayers are regarded as a lithology combination, the lithology superposition relationship of all lithology combinations in the region is statistically analyzed, and a lithology combination lithology superposition mode chart in the whole region is drawn.
On the basis, the lithology combination gas-containing distribution characteristic depth analysis is carried out, and the optimal fracturing positions in various lithology superposition modes are determined according to the mechanical property test results of all lithologies in the region and the distribution conditions of minerals in the lithology combination; in consideration of lithologic combined gas distribution characteristics and a gas flow rule after fracturing, a method for judging the effectiveness of the lithologic superposition modes in the region is provided, and the advantages and the disadvantages of various lithologic superposition modes are sequenced; and finally, constructing an effective lithological stacking mode from top to bottom on the basis of sandstone/limestone with the thickness of less than 3m on a single well, and selecting a corresponding optimal fracturing position of the optimal lithological stacking mode as a final fracturing layer section after determining the effectiveness of the constructed lithological stacking mode.
The method provided by the present invention is further illustrated below:
fig. 1 is a flow chart of a preferred method for selecting a favorable fracturing interval of a coal-derived gas reservoir, which comprises the following steps:
step 100: and drawing corresponding lithologic superposition mode charts of all the drilling wells in the research area.
Wherein the drawing of the litho-stacking mode plate comprises the following steps:
step 110: and acquiring logging information, logging information and drilling coring information corresponding to all drilling wells in the research area.
Step 120: determining the lithology of the research area according to the logging information, the logging information and the drilling coring information corresponding to all the drilled wells; the lithology includes: ash/sandstone, shale, coal;
step 130: the ash/sandstone, shale and coal are divided into reservoir lithology and non-reservoir lithology according to the characteristics of electrical property, lithology, physical property and gas bearing property.
Specifically, the electrical characteristics, the lithological characteristics, the physical characteristics and the gas-containing characteristics corresponding to the ash/sandstone, the shale and the coal are respectively obtained, and the characteristics are compared with the reservoir stratum and the non-reservoir stratum standard of the relevant country, so that whether the ash/sandstone, the shale and the coal belong to the reservoir stratum or the non-reservoir stratum is determined. Wherein, the ash/sandstone is a non-reservoir, and the coal and the shale are reservoirs.
Step 140: determining a thickness corresponding to the non-reservoir lithology.
Step 150: dividing the non-reservoir lithology as an interlayer under the condition that the thickness corresponding to the non-reservoir lithology is more than 3 meters; and under the condition that the thickness corresponding to the non-reservoir lithology is less than 3 meters, dividing the non-reservoir lithology into interlayers.
It should be noted that: the non-reservoir properties are poor, so that the gas is difficult to flow in the non-reservoir properties, but the gas can pass through the non-reservoir properties if the non-reservoir properties are not too thick; and too thick to pass through, so that too thick non-reservoirs are divided into compartments, and the small-thickness non-reservoir compartments are called compartments. And all lithologies between the two interlayers are regarded as a lithology combination, and the interlayer and other lithologies form the lithology combination. And the determination that the non-reservoir is the interlayer or the interlayer is based on the division of a thickness limit, and the determination method of the limit is as follows: counting the frequency of the occurrence of single-layer thickness of non-reservoir (sand/ash) in a research area (figure 2), and seeing that the frequency has a remarkable turn at 3m, which indicates that the lithology thickness of most non-reservoir is less than 3m, and simultaneously, the lithology thickness of the non-reservoir is intersected with the total hydrocarbon content of lithology combination (figure 3), wherein the total hydrocarbon content is a parameter capable of representing the gas content, and the lithology thickness of the non-reservoir exceeds 3m, and the total hydrocarbon content is at a lower level (the lithology combination is disconnected and is separated by sandstone/ash rock). Thus 3 meters is defined as the non-reservoir lithology as the thickness limit of the interval or interbed.
Step 160: and drawing a lithology superposition mode chart corresponding to the lithology combination by taking all lithologies between the two interlayer as a lithology combination.
Specifically, all lithologies in the two interlayers are regarded as a lithology combination, the lithology superposition relationship of each lithology combination in the work area is counted, and a lithology combination lithology superposition mode layout capable of covering all conditions of the work area is drawn according to the lithology combination lithology superposition relationship. As shown in fig. 4, the all well drilling corresponding lithological stacking pattern charts comprise 6 lithological stacking patterns, and the 6 lithological stacking patterns are respectively as follows according to the lithological characters from top to bottom: mode 1: ash/sandstone, shale, coal; mode 2: coal, ash/sandstone, shale; mode 3: shale, coal, ash/sandstone; mode 4: coal, shale, ash/sandstone; mode 5: ash/sandstone, coal, shale; mode 6: shale, ash/sandstone, coal.
Step 200: and determining the optimal fracturing position corresponding to each lithology stacking mode, and sequencing the development potentials of the lithology stacking modes from good to bad.
Specifically, the determination of the optimal fracture location for each litho-stacking mode is based on three factors: (1) Lithology combined gas bearing distribution characteristics (high gas bearing near coal seam); (2) fracability ordering of various types of rock; (3) lithologic combination of mineral distribution characteristics. The determined optimal fracture locations for each litho-stacking mode are integrated.
Meanwhile, rock mechanical property measurement is carried out on different lithologies of the research area, and the elasticity modulus, the Poisson ratio and other parameters are integrated, so that the sequence of the fracturing property in the research area is considered as limestone/sandstone fracturing property > shale fracturing property > coal rock fracturing property. Meanwhile, the distribution characteristics of minerals are integrally considered by lithological combination, and the fact that the shale layer section close to the limestone/sandstone layer and far away from the coal layer is high in brittle mineral content and better in brittleness is found, and subsequent fracturing is facilitated (fig. 5 and 6). Accordingly, as shown in fig. 7, in the case where the ash/sandstone and the shale are distributed on both sides of the coal seam, the reservoir where the ash/sandstone is located is selected as the optimal fracturing location (as shown in modes 3 and 5 in the figure). The interface of the ash/sandstone and the shale is selected as the optimal fracturing position (such as mode 1, mode 2, mode 4 and mode 6 in the figure) when the ash/sandstone and the shale are distributed on the same side of the coal seam. In the case of modes 3 and 5, the coal-based gas development potential of mode 5 is relatively higher because the gas is upstream. In modes 1, 2, 4, and 6, although the air supply capacity of the sand/limestone is minimal, subsequent fracturing is more facilitated when the sand/limestone is above the coal seam or shale. Based on the above analysis, the optimal fracture horizon corresponding to the coal-sand/ash-mud coexisting lithology stacking mode is: modes 1 and 2 suggest the option of fracturing at the top of the lithologic composite sand/limestone and shale, modes 4 and 6 suggest the option of fracturing at the bottom of the lithologic composite sand/limestone and shale, and modes 3 and 5 suggest the option of fracturing in the middle of the lithologic composite sand/limestone.
The method is characterized in that the gas-bearing property distribution characteristic research is carried out on the lithologic combination of the research area, and the coal bed gas is found to be the main gas source of the coal reservoir, so that the closer to the coal bed, the higher the gas-bearing property is. However, for the lithologic combination, the distribution characteristics of minerals are considered integrally, and the gas content of different lithologic intervals of a single well in a research area is compared, so that the gas content is high close to the coal seam, but the coal seam cannot be directly fractured, because the fracturing capability of the coal seam is low. Meanwhile, the seepage influence is considered, and gas can be in an upward diffusion trend along a fracturing fracture in the fracturing process, so that the subsequent fracturing of the fracturing interval (sand/limestone) on the upper part of the main gas supply interval (coal bed/shale) is facilitated. Thus, the development potential of each litho-stacking mode is in order from good to bad: mode 5> mode 3> mode 1> mode 4> mode 6> mode 2.
Step 300: identifying the lithology of a single well in the research area one by one, thereby determining the quantity of the ash/sandstone on the single well and the position of each ash/sandstone; the lithology includes: coal, shale, ash/sandstone.
As shown in fig. 8, the lithology of a certain single well is identified one by one from top to bottom, where the lithology combination corresponding to the profile lithology is the result of the lithology identification of the single well, and as can be seen from the profile lithology diagram, there are 4 ash/sand rock layers, which are: an ash/sandstone layer (1), an ash/sandstone layer (2), an ash/sandstone layer (3), and an ash/sandstone layer (4). From the depth of a single well it can be determined the location of each ash/sandstone and what its adjacent lithologies are respectively.
Step 400: and determining an actual lithology combination I formed by the ash/sandstone and the adjacent lithology above the ash/sandstone and an actual lithology combination II formed by the adjacent lithology below the ash/sandstone according to each ash/sandstone standard.
Step 500: and comparing the first actual lithology combination and the second actual lithology combination with preset lithology superposition modes one by one, and determining all actual lithology superposition modes corresponding to each ash/sandstone.
As can be seen from fig. 8, the limestone/sandstone layer (1) and the adjacent lithology above the limestone/sandstone layer form the actual lithology combination one, and the adjacent lithology below the limestone/sandstone layer form the actual lithology combination two. Comparing the actual lithology combination one with all lithology superposition modes (mode 1-mode 6) one by one, and finding that the actual lithology combination one is consistent with the lithology combination of the mode 6; comparing the actual lithology combination two with all the lithology superposition modes (mode 1-mode 6) one by one, and finding that the actual lithology combination two is consistent with the lithology combination of mode 5, so that the actual lithology superposition modes corresponding to the limestone/sandstone layer (1) comprise two types, namely: mode 6, mode 5. Similarly, all the actual lithological superposition modes corresponding to the ash/sandstone layer (2) are determined, and finally 1 actual lithological superposition mode corresponding to the ash/sandstone layer (2) is determined, wherein the actual lithological superposition mode is as follows: mode 6. The corresponding actual lithologic superposition modes of the ash/sand rock layer (3) are 2 types, respectively: mode 1 and mode 2. The corresponding actual lithologic superposition modes of the ash/sand rock layer (4) are 3 types, respectively: mode 4, mode 5 and mode 6.
Step 600: all valid actual lithologic stacking patterns for each ash/sandstone are determined.
The following is a detailed description of how to determine whether the litho-stacking mode is valid:
the distance from the optimal fracture location to the coal seam for all actual lithologic stacking patterns corresponding to each ash/sandstone is first determined separately. Secondly, when the distance is larger than a certain preset value, the lithology superposition mode is effective; otherwise, the superposition is invalid; and finally, screening effective lithologic stacking modes from all the actual lithologic stacking modes as all the effective lithologic stacking modes corresponding to each ash/sandstone.
Specifically, because the optimal fracturing location under various lithologic stacking patterns is close to the coal seam, which is the worst in terms of fracability, the too thin interval to which the optimal fracturing location belongs may cause the fracture to extend directly to the softer coal seam, which is not conducive to forming a complex fracture network and greatly reduces the effectiveness of the fracture when proppant is embedded into the coal seam. Therefore, the optimal fracturing location should be maintained at a distance from the coal seam that is not too far away. And (3) integrating the lithologic combined gas distribution rule, the crack extension rule and the compressible property of each lithologic, and considering that the distance between the optimal fracturing position and the coal bed in each lithologic superposition mode is within 1-2m, and if the distance is less than 1m, an effective lithologic superposition mode is not formed. And if the optimal fracture position corresponding to the mode 5 in the lithologic stacking mode corresponding to the sandstone layer (4) is less than 1m away from the coal bed, deleting the mode 5, and leaving only the mode 4 and the mode 6 in the actual lithologic stacking mode corresponding to the sandstone layer (4).
Step 700: and determining an optimal lithologic stacking mode corresponding to each ash/sandstone from all the effective actual lithologic stacking modes, wherein the optimal lithologic stacking mode is the lithologic stacking mode with the optimal fracture position.
Step 800: determining an optimal fracturing position corresponding to each ash/sandstone according to the optimal lithological superposition mode corresponding to each ash/sandstone;
step 900: and taking the optimal fracturing position corresponding to each ash/sandstone as the optimal fracturing position of the whole single well.
Specifically, taking fig. 8 as an example, after deleting mode 5 from the actual litho-stacking mode corresponding to the limestone/sandstone layer (4), modes 4 and 6 remain, and the fracture positions according to the litho-stacking mode are in order from good to bad: mode 5> mode 3> mode 1> mode 4> mode 6> mode 2, then mode 4 and mode 6 are preferred over mode 4, so the fracture location corresponding to the grey/sandstone layer (4) is the optimal fracture location corresponding to mode 4. Similarly, the actual lithology superposition mode corresponding to the ash/sandstone layer (1) is preferably selected from the modes 6 and 5 to be the mode 5, so that the optimal fracturing position corresponding to the ash/sandstone layer (1) is the optimal fracturing position corresponding to the mode 5; the actual lithological stacking pattern for the ash/sandstone layer (2) is: mode 6, but mode 6 is a disadvantaged mode, and therefore, the ash/sandstone formation (2) does not have an optimal fracture location. The actual lithological stacking pattern corresponding to the ash/sandstone layer (3) is as follows: mode 1. Then, finally, there are 3 optimal fracture positions for the single well corresponding to fig. 8, from top to bottom: the method comprises the following steps that a mode 5 corresponding to an ash/sand rock layer (1), a mode 1 corresponding to an ash/sand rock layer (3) and a mode 4 corresponding to an ash/sand rock layer (4) (at this time, the distance between the fracturing position of the mode 5 and a coal bed is assumed to be less than 1 m), the 3 modes respectively correspond to optimal fracturing positions, the optimal fracturing position of each mode can be directly obtained according to a graph 7, and finally, it can be determined that the single well lithology combination is most beneficial to fracturing by selecting sand (1), sand (3) and sand (4).
The method provided by the invention is explained in a complete detail below, and specifically comprises the following steps:
(1) Acquiring logging information, logging information and drilling coring information corresponding to all drilling in a target research area;
(2) Determining the lithology of the research area according to the logging information, the logging information and the drilling coring information corresponding to all the drilled wells; the lithology comprises the following steps: ash/sandstone, shale, coal;
(3) Dividing the ash/sandstone, the shale and the coal into reservoir lithology and non-reservoir lithology according to the electrical characteristic, the lithology characteristic, the physical characteristic and the gas containing characteristic;
(4) Determining the thickness of a reservoir corresponding to the non-reservoir lithology; dividing the reservoir as a barrier if the thickness is greater than 3 meters; in the case that the thickness is less than 3 meters, dividing the reservoir into interbeds;
(5) Taking all lithologies between the two interlayer layers as a lithology combination, and drawing a lithology superposition mode chart corresponding to the lithology combination;
(6) Determining the optimal fracturing position corresponding to each lithology superposition mode according to the gas-bearing distribution characteristics, the fracturing sequencing of various lithologies and the mineral distribution characteristics of lithology combination; sequencing the development potentials of all lithologic stacking modes in a good to bad order;
(7) On a single well, identifying the lithology of the single well one by one, thereby determining the quantity of the ash/sandstone on the single well and the position of each ash/sandstone; the lithology includes: coal, shale, ash/sandstone;
(8) Determining an actual lithology combination I formed by the ash/sandstone and the adjacent lithology above the ash/sandstone and an actual lithology combination II formed by the adjacent lithology below the ash/sandstone according to each ash/sandstone standard;
(9) Comparing the first actual lithology combination and the second actual lithology combination with preset lithology superposition modes one by one, and determining all actual lithology superposition modes corresponding to each ash/sandstone;
(10) Determining whether all lithologic stacking modes corresponding to each ash/sandstone are effective; if the optimal fracturing position is more than 1m away from the coal reservoir, the lithologic superposition mode chart is valid, otherwise, the lithologic superposition mode chart is invalid, and the corresponding lithologic superposition mode chart is deleted;
(11) On the premise that the lithological superposition mode chart is effective, determining the optimal lithological superposition mode corresponding to each ash/sandstone according to the quality sequence of the lithological superposition mode;
(12) Determining an optimal fracturing position corresponding to each ash/sandstone according to the optimal lithological superposition mode corresponding to each ash/sandstone;
(13) And taking the optimal fracturing position corresponding to each ash/sandstone as the optimal fracturing position of the whole single well.
Experimental example:
example analysis was performed on a single well using the method provided by the present invention. Taking the X1 well in the study area as an example, fig. 5 shows a lithology stacking mode diagram of the combination of the mud-sand-coal lithology of the X1 well. 4 sandstone layers with the thickness less than 3m are co-developed in the X1 well mud-sand-coal lithology combination, and compared with a lithology superposition pattern diagram of FIG. 1, the lithology superposition pattern diagram is totally divided into 5 lithology superposition patterns. Wherein sand (1) corresponds to two lithologic stacking modes, mode 5 and mode 6; sand (2) corresponds to pattern 6 only; sand (3) corresponds to two lithologic superposition modes of a mode 1 and a mode 2; sand (4) corresponds to three litho-stacking patterns, pattern 4, pattern 5, and pattern 6. And judging whether each lithologic superposition mode meets the validity and sorting according to the quality of the lithologic superposition mode, and finally, optimizing the sand (1) in the mode 5, optimizing the sand (3) in the mode 1 and optimizing the sand (4) in the mode 5. In summary, in the 4 sets of sandstone, the lithological superposition mode corresponding to the sand (1), the sand (3) and the sand (4) is the dominant mode, and the lithological superposition mode corresponding to the sand (2) is the disadvantaged mode, so that the selection of the sand (1), the sand (3) and the sand (4) for fracturing is most beneficial for the X1 well mud-sand-coal lithological combination.
The method specifically describes lithologic superposition mode charts in the region aiming at the coal reservoir, thereby deepening the knowledge of the coal reservoir; the optimal fracturing positions of all the modes are determined, the single-well lithology superposition mode optimal selection scheme is provided, the fracturing positions are selected on the basis of the single-well lithology superposition mode analysis result, the execution difficulty of optimal fracturing layer sections is greatly reduced, the method is suitable for the whole area, and the time and money cost is greatly saved.
Aiming at coal reservoirs with various lithologies, thin single layers and complex stacking relation, the lithological stacking relation is comprehensively described, and related lithological stacking mode charts are drawn.
By analyzing the gas-bearing distribution characteristic depth of the lithological combination, and combining the mechanical property test results of various lithologies in the region and the distribution condition of minerals in the lithological combination, the optimal fracturing positions in various lithological superposition modes are determined, the effectiveness judging method and the quality sequencing of the lithological superposition modes are finally given, the selection method of the lithological superposition modes on a single well is provided, the execution difficulty of optimal fracturing layer sections is reduced, and the method is suitable for the whole region.
Aiming at the characteristic of frequent alternate symbiosis of multiple lithologies of coal reservoirs, the lithology superposition mode is established, the optimal fracturing positions under various lithology superposition modes are deeply analyzed and directly locked, and the optimal selection of the fracturing layer section is converted into the selection of the optimal lithology superposition mode on a single well. And finally, providing a selection basis of an effective lithological superposition mode and carrying out quality sequencing on each lithological superposition mode. The method can be directly applied to a single well and applied to the whole area, and great convenience is brought to the optimization of the fracturing interval.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (7)
1. A coal-derived gas reservoir favorable fracturing interval optimization method is characterized by comprising the following steps:
step 100: drawing corresponding lithology superposition mode charts of all drilling wells in a research area;
step 200: determining an optimal fracturing position corresponding to each lithologic stacking mode, and sequencing the development potentials of the lithologic stacking modes in a good-to-bad order;
step 300: identifying the lithology of a single well in the research area one by one, thereby determining the quantity of the ash/sandstone on the single well and the position of each ash/sandstone; the lithology includes: coal rock, shale, ash/sandstone;
step 400: determining a first actual lithology combination formed by the ash/sandstone and the adjacent lithology above the ash/sandstone and a second actual lithology combination formed by the adjacent lithology below the ash/sandstone according to each ash/sandstone reference;
step 500: comparing the first actual lithology combination and the second actual lithology combination with preset lithology superposition modes one by one, and determining all actual lithology superposition modes corresponding to each ash/sandstone;
step 600: determining all effective actual lithologic superposition modes corresponding to each ash/sandstone;
step 700: determining an optimal lithology superposition mode corresponding to each ash/sandstone from all the effective actual lithology superposition modes;
step 800: determining an optimal fracturing position corresponding to each ash/sandstone according to the optimal lithological superposition mode corresponding to each ash/sandstone;
step 900: and taking the optimal fracturing position corresponding to each ash/sandstone as the optimal fracturing position of the whole single well.
2. The coal-derived gas reservoir advantageous fracturing interval preferred method of claim 1, wherein step 100 comprises the steps of:
step 110: acquiring logging information, logging information and drilling coring information corresponding to all drilling wells in a research area;
step 120: determining the lithology of the research area according to the logging information, the logging information and the drilling coring information corresponding to all the drilled wells; the lithology comprises the following steps: ash/sandstone, shale, coal;
step 130: dividing the ash/sandstone, the shale and the coal into reservoir lithology and non-reservoir lithology according to the electrical characteristic, the lithology characteristic, the physical characteristic and the gas containing characteristic;
step 140: determining a thickness corresponding to the non-reservoir lithology;
step 150: under the condition that the thickness corresponding to the non-reservoir lithology is more than 3 meters, dividing the non-reservoir lithology into interlayers; under the condition that the thickness corresponding to the non-reservoir lithology is less than 3 meters, dividing the non-reservoir lithology into interlayers;
step 160: and drawing a lithology superposition mode chart corresponding to the lithology combination by taking all lithologies between the two interlayer as a lithology combination.
3. The coal-derived gas reservoir advantageous fracturing interval preferred method of claim 1, wherein the all well-drilling corresponding lithology stacking pattern charts comprise 6 lithology stacking patterns, and the 6 lithology stacking patterns are respectively as follows according to the lithology from top to bottom:
mode 1: ash/sandstone, shale, coal;
mode 2: coal, ash/sandstone, shale;
mode 3: shale, coal, ash/sandstone;
mode 4: coal, shale, ash/sandstone;
mode 5: ash/sandstone, coal, shale;
mode 6: shale, ash/sandstone, coal.
4. The coal-derived gas reservoir advantageous fracturing interval optimization method according to claim 2, characterized in that the fracturing positions are ordered from good to bad:
mode 5> mode 3> mode 1> mode 4> mode 6> mode 2.
5. The coal-derived gas reservoir advantageous fracturing interval preferred method according to claim 1, wherein the step 600 specifically comprises the steps of:
step 610: respectively determining the distance between the optimal fracturing positions of all actual lithological superposition modes corresponding to each ash/sandstone and a coal bed;
step 620: in the case where the distance is greater than a certain preset value, the lithological stacking mode is active; otherwise, the lithologic stacking mode is invalid;
step 630: and screening effective lithological superposition patterns from all the actual lithological superposition patterns as all the effective actual lithological superposition patterns corresponding to each ash/sandstone.
6. The coal-derived gas reservoir advantageous fracturing interval preferred method of claim 2, wherein the step 200 comprises:
and determining the optimal fracturing position corresponding to each lithology superposition mode according to the gas content distribution characteristics, the fracturing sequence of various lithologies and the mineral distribution characteristics of lithology combination.
7. The coal-derived gas reservoir advantageous fracturing interval preferred method of claim 5, wherein the fracturability ordering of the lithology types comprises:
arranging the fracturability of various rocks from top to bottom according to the elastic modulus and Poisson's ratio respectively corresponding to various lithologies to obtain:
ash/sandstone fracability > shale fracability > coal fracability.
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Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110120702A1 (en) * | 2009-11-25 | 2011-05-26 | Halliburton Energy Services, Inc. | Generating probabilistic information on subterranean fractures |
| WO2012003027A1 (en) * | 2010-06-28 | 2012-01-05 | Exxonmobil Upstream Research Company | Method and system for modeling fractures in ductile rock |
| FR3007165A1 (en) * | 2013-06-13 | 2014-12-19 | IFP Energies Nouvelles | METHOD FOR OPTIMIZING THE OPERATION OF A FLUID DEPOSITION BY TAKING INTO ACCOUNT A TERM OF GEOLOGICAL AND TRANSIENT EXCHANGE BETWEEN MATRIX BLOCKS AND FRACTURES |
| CN104481524A (en) * | 2014-11-17 | 2015-04-01 | 中国石油天然气股份有限公司长庆油田分公司勘探开发研究院 | Optimization method for reformation of multi-stratum tight sandstone gas reservoirs |
| US20150247394A1 (en) * | 2012-09-21 | 2015-09-03 | ENN Coal Gasification Mining Co., Ltd. | Method for fracture communication, passage processing, and underground gasification of underground carbon-containing organic mineral reservoir |
| RU2612061C1 (en) * | 2016-05-05 | 2017-03-02 | Публичное акционерное общество "Татнефть" им. В.Д.Шашина | Recovery method of shale carbonate oil field |
| US20180094514A1 (en) * | 2015-04-30 | 2018-04-05 | Landmark Graphics Corporation | Shale geomechanics for multi-stage hydraulic fracturing optimization in resource shale and tight plays |
| CN110516016A (en) * | 2019-07-26 | 2019-11-29 | 中国矿业大学 | A kind of coal measure gas longitudinal direction exploitation interval preferred method based on GIS technology |
| CN111042788A (en) * | 2019-12-19 | 2020-04-21 | 西南石油大学 | Volume fracturing treatment method for coal layer |
| CN112765807A (en) * | 2021-01-15 | 2021-05-07 | 西南石油大学 | Method for calculating deviation angle of lithologic interface of transition facies of crossing sea and land by crack |
| CN114114396A (en) * | 2021-11-09 | 2022-03-01 | 成都理工大学 | Transformer-terrace facies thick-layer limestone sedimentary facies characterization and prediction system and prediction method |
| CN114427425A (en) * | 2020-09-16 | 2022-05-03 | 中国石油化工股份有限公司 | Thin interbed through-layer fracturing method and application thereof |
| CN114607334A (en) * | 2020-12-08 | 2022-06-10 | 中国石油化工股份有限公司 | Continental facies shale gas reservoir fracturing method |
| CN114970935A (en) * | 2022-03-01 | 2022-08-30 | 山西蓝焰煤层气工程研究有限责任公司 | Resform-based coal bed gas horizontal well fracturing layer section optimization method |
-
2022
- 2022-08-31 CN CN202211063248.3A patent/CN115354991B/en active Active
Patent Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110120702A1 (en) * | 2009-11-25 | 2011-05-26 | Halliburton Energy Services, Inc. | Generating probabilistic information on subterranean fractures |
| WO2012003027A1 (en) * | 2010-06-28 | 2012-01-05 | Exxonmobil Upstream Research Company | Method and system for modeling fractures in ductile rock |
| US20150247394A1 (en) * | 2012-09-21 | 2015-09-03 | ENN Coal Gasification Mining Co., Ltd. | Method for fracture communication, passage processing, and underground gasification of underground carbon-containing organic mineral reservoir |
| FR3007165A1 (en) * | 2013-06-13 | 2014-12-19 | IFP Energies Nouvelles | METHOD FOR OPTIMIZING THE OPERATION OF A FLUID DEPOSITION BY TAKING INTO ACCOUNT A TERM OF GEOLOGICAL AND TRANSIENT EXCHANGE BETWEEN MATRIX BLOCKS AND FRACTURES |
| CN104481524A (en) * | 2014-11-17 | 2015-04-01 | 中国石油天然气股份有限公司长庆油田分公司勘探开发研究院 | Optimization method for reformation of multi-stratum tight sandstone gas reservoirs |
| US20180094514A1 (en) * | 2015-04-30 | 2018-04-05 | Landmark Graphics Corporation | Shale geomechanics for multi-stage hydraulic fracturing optimization in resource shale and tight plays |
| RU2612061C1 (en) * | 2016-05-05 | 2017-03-02 | Публичное акционерное общество "Татнефть" им. В.Д.Шашина | Recovery method of shale carbonate oil field |
| CN110516016A (en) * | 2019-07-26 | 2019-11-29 | 中国矿业大学 | A kind of coal measure gas longitudinal direction exploitation interval preferred method based on GIS technology |
| CN111042788A (en) * | 2019-12-19 | 2020-04-21 | 西南石油大学 | Volume fracturing treatment method for coal layer |
| CN114427425A (en) * | 2020-09-16 | 2022-05-03 | 中国石油化工股份有限公司 | Thin interbed through-layer fracturing method and application thereof |
| CN114607334A (en) * | 2020-12-08 | 2022-06-10 | 中国石油化工股份有限公司 | Continental facies shale gas reservoir fracturing method |
| CN112765807A (en) * | 2021-01-15 | 2021-05-07 | 西南石油大学 | Method for calculating deviation angle of lithologic interface of transition facies of crossing sea and land by crack |
| CN114114396A (en) * | 2021-11-09 | 2022-03-01 | 成都理工大学 | Transformer-terrace facies thick-layer limestone sedimentary facies characterization and prediction system and prediction method |
| CN114970935A (en) * | 2022-03-01 | 2022-08-30 | 山西蓝焰煤层气工程研究有限责任公司 | Resform-based coal bed gas horizontal well fracturing layer section optimization method |
Non-Patent Citations (5)
| Title |
|---|
| WANG, RY等: "Analysis of developmental characteristics and dominant factors of fractures in Lower Cambrian marine shale reservoirs: A case study of Niutitang formation in Cen\'gong block, southern China", JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING * |
| 刘欣佳;张遂安;靳建虎;肖凤朝;王瑞杰;万毅;张守仁;: "煤成(层)气资源综合开发中的合层压裂可行性评价", 煤炭学报, no. 06 * |
| 周文等: "四川盆地陆相富有机质层段剖面结构划分及特征", 岩性油气藏 * |
| 张红杰等: "煤系储层综合开发中的压裂射孔方案优化研究", 特种油气藏 * |
| 胥帅帅;刘坤鹏;: "滇东威信煤系地层岩石力学性质及其对煤储层压裂的影响", 能源与环保, no. 09 * |
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