CN116774309A - Shale oil reservoir brittleness evaluation method based on bedding structure - Google Patents
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- 239000003079 shale oil Substances 0.000 title claims abstract description 159
- 238000011156 evaluation Methods 0.000 title claims abstract description 37
- 239000011435 rock Substances 0.000 claims abstract description 107
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 106
- 239000011707 mineral Substances 0.000 claims abstract description 106
- 238000000034 method Methods 0.000 claims abstract description 35
- 238000011161 development Methods 0.000 claims abstract description 24
- 238000005259 measurement Methods 0.000 claims abstract description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 44
- 239000010433 feldspar Substances 0.000 claims description 43
- 229910000514 dolomite Inorganic materials 0.000 claims description 38
- 239000010459 dolomite Substances 0.000 claims description 38
- 239000004927 clay Substances 0.000 claims description 24
- 239000010453 quartz Substances 0.000 claims description 22
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 22
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- 238000012937 correction Methods 0.000 claims description 3
- 230000018109 developmental process Effects 0.000 description 20
- 238000011160 research Methods 0.000 description 9
- 238000005553 drilling Methods 0.000 description 5
- 239000011148 porous material Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
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- 230000004048 modification Effects 0.000 description 2
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- 241001522301 Apogonichthyoides nigripinnis Species 0.000 description 1
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- 230000033558 biomineral tissue development Effects 0.000 description 1
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- 230000002349 favourable effect Effects 0.000 description 1
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Abstract
The invention provides a shale oil reservoir brittleness evaluation method based on a bedding structure, which comprises the following steps: step 1, collecting logging curves of shale oil wells, rock mechanical parameters and actual measurement content of main minerals of shale; step 2, modeling the mineral content of a shale oil reservoir by utilizing a multiple regression method, and predicting the brittle mineral content and other shale mineral content of a shale oil well; step 3, solving the brittleness index of the shale oil reservoir by using the brittleness mineral content of the shale oil reservoir; step 4, calculating the brittleness index of the shale oil reservoir by using the ratio of Young modulus and Poisson ratio of the mixed minerals; step 5, calculating a stratum development indication of the shale oil by using the ratio of longitudinal waves to transverse waves of the sound waves; and 6, evaluating brittleness of the shale oil reservoir. The shale oil reservoir brittleness evaluation method based on the bedding structure breaks through the limitation of single solution, and meanwhile considers the real situation of strong heterogeneity of the shale oil reservoir, so that the practicability is strong and the evaluation reliability is high.
Description
Technical Field
The invention relates to the technical field of oilfield development, in particular to a shale oil reservoir brittleness evaluation method based on a bedding structure.
Background
Based on the characteristics of complex lithology, various storage modes, extremely low pore permeability, strong heterogeneity and the like of shale oil, the four-property relation research (reservoir property, oiliness, compressibility and mobility) is generally utilized, and shale oil desserts with the characteristics of large reservoir thickness, strong seepage capability, high organic matter content, high brittle mineral content, strong compressibility and the like are preferred. In shale oil 'four-property' relation research, compressibility is a necessary condition, and the bulls-eye and the target are determined, so that the compressibility, namely the brittleness index, is determined, and the drilling rate of the favorable lithofacies can be ensured. The brittleness evaluation of shale can help fracturing transformation, energy increasing, yield increasing and recovery ratio improving, single well EUR is improved to the greatest extent, and meanwhile, the fracture transformation, energy increasing, yield increasing and recovery ratio improving are realizedCO at present 2 Burying, and trampling green low-carbon development win-win situation. Therefore, a set of calculation method for finely evaluating the brittleness index of the shale oil reservoir is provided, and is very important for the rich land shale oil exploration and development theoretical technology system.
Currently, there are two methods for evaluating brittleness of shale oil reservoirs, one is to solve by using brittle minerals, and the other is to solve by using rock mechanical parameters (Young's modulus and Poisson's ratio), and the two methods in common use are not combined with the actual situation of shale oil reservoirs. The research area camping concave shale oil reservoir has the characteristics of complex lithology, strong heterogeneity, extremely low pore permeability, various occurrence modes and the like, so that the conventional brittleness evaluation method is difficult to characterize the brittleness, and therefore, a brittleness evaluation method aiming at the shale oil reservoir with deep burial, strong heterogeneity, complex rock mineral composition and various pore types is urgently needed.
In application number: in CN202110408102.7, the method for evaluating rock brittleness based on logging while drilling data includes: step 1, acquiring three-dimensional digital rock core microcosmic parameters according to logging data of rock chips while drilling to be logged; step 2, generating a three-dimensional digital core sample according to the obtained while-drilling rock chip microscale parameters; step 3, carrying out uniaxial or triaxial compression numerical experiments on the three-dimensional digital core sample to obtain a stress-strain curve of the three-dimensional digital core, and calculating the elastic modulus and poisson ratio of the core; step 4, calculating normalized elastic modulus, poisson ratio and brittle mineral ratio; step 5, calculating to obtain a brittleness index comprehensively considering the mineral components and mechanical properties of the rock; and 6, selecting rock fragments while drilling of different well depths to be measured, repeating the steps 1 to 5, and calculating to obtain the rock brittleness index of the reservoir section, wherein the rock brittleness index is continuously distributed along the well depths. According to the invention, coring operation is not required, the influence of the brittle mineral composition and rock elasticity parameters on brittleness is comprehensively considered, and the evaluation result of the reservoir rock brittleness is more accurate.
In application number: the Chinese patent application of CN201810269812.4 relates to a method for evaluating the brittleness of compact sandstone reservoir rock, which is characterized by comprising the following steps: 1) Obtaining a core brittleness index of the compact sandstone of the target interval; 2) Acquiring the rock mineral component content of the compact sandstone of the target interval; 3) Determining brittle minerals of the target interval compact sandstone; 4) Acquiring the rock brittleness index of each depth point of the compact sandstone of the target interval; 5) And (3) evaluating the fracturing property of the tight sandstone reservoir according to the rock brittleness index of each depth point of the tight sandstone of the target interval and the comprehensive stratum fracturing result. The method can effectively avoid errors caused by brittle mineral judgment differences and equal weights, is efficient and quick, has small calculation errors and has strong usability.
In application number: in the Chinese patent application of CN201410790723.6, a method for evaluating brittleness of a shale reservoir is related, and belongs to the technical field of unconventional oil and gas reservoir evaluation; carrying out intersection analysis on the Young modulus density and other elastic parameters and/or brittle mineral parameters, and determining a value range of the Young modulus density according to the result of the intersection analysis; constructing a Young modulus density attribute body according to the longitudinal and transverse wave impedance obtained through prestack reverse modeling; and evaluating the brittleness of the shale reservoir to be evaluated in the value range by using the Young modulus density attribute body. The method improves the evaluation precision of the brittleness of the shale reservoir, realizes the prediction of the brittle plane spread of the whole research area, and has wide application prospect in the field of shale gas exploration and development.
The prior art is greatly different from the shale oil reservoir brittleness evaluation method, and the technical problem to be solved by the shale oil reservoir brittleness evaluation method based on the bedding structure is solved.
Disclosure of Invention
The invention aims to provide the shale oil reservoir brittleness evaluation method based on the lamellar structure, which integrates lamellar structure characteristics of the shale oil reservoir into brittleness indexes, has strong practicability and high evaluation reliability.
The aim of the invention can be achieved by the following technical measures: the shale oil reservoir brittleness evaluation method based on the lamellar structure comprises the following steps:
step 1, collecting logging curves of shale oil wells, rock mechanical parameters and actual measurement content of main minerals of shale;
step 2, modeling the mineral content of a shale oil reservoir by utilizing a multiple regression method, and predicting the brittle mineral content and other shale mineral content of a shale oil well;
step 3, solving the brittleness index of the shale oil reservoir by using the brittleness mineral content of the shale oil reservoir;
step 4, calculating the brittleness index of the shale oil reservoir by using the ratio of Young modulus and Poisson ratio of the mixed minerals;
step 5, calculating a stratum development indication of the shale oil by using the ratio of longitudinal waves to transverse waves of the sound waves;
and 6, evaluating brittleness of the shale oil reservoir.
The aim of the invention can be achieved by the following technical measures:
in step 1, the log of the shale well is collected, including the conventional 5 curves, namely natural gamma GR, deep resistivity RT, acoustic moveout AC, neutron CNL, density DEN, and longitudinal and transverse wave curves Vp and Vs.
In step 1, rock mechanical parameters include Young's modulus YM and Poisson's ratio PR, measured contents of main minerals of shale including carbonate, quartz, feldspar, clay, dolomite.
In the step 2, modeling the mineral content of the shale oil reservoir by utilizing a multiple regression method, homing and correcting the rock core and the logging curve, removing abnormal points, and matching the mineral content measured by utilizing a full rock diffraction experiment with the logging curve, wherein a sensitive curve of each mineral is preferably obtained; modeling the mineral content of a shale oil reservoir by a segment-to-segment and multiple regression method, and predicting the brittle mineral content and other shale mineral content of the whole well segment of the shale oil well.
In step 2, the shale oil reservoir has mineral content including carbonate, quartz, feldspar, clay, dolomite, brittle minerals including carbonate, quartz, feldspar, and other shale minerals including clay, dolomite.
In step 3, solving the brittleness index of the shale oil reservoir by using the brittle mineral content of the shale oil reservoir; and taking carbonate rock, feldspar and quartz as main brittle minerals of the shale oil reservoir, clay and dolomite as other minerals, and solving the brittleness index of the shale oil reservoir by using the brittle minerals.
In step 3, the formula for solving the shale reservoir brittleness index is as follows:
Brit brittle minerals ＝(V Feldspar +V Quartz +V Carbonate rock )/(V Feldspar +V Quartz +V Clay +V Carbonate rock +V Dolomite rock ) (1)
Wherein: brit (Brit) Brittle minerals Is the brittleness index of shale oil reservoir, V Feldspar Is feldspar content, V Quartz Is of quartz content, V Carbonate rock For carbonate content, V Dolomite rock For dolomite content, V Clay Is the clay content.
In step 4, calculating the brittleness index of the shale oil reservoir by using the ratio of the Young modulus of the mixed minerals to the Poisson ratio, wherein the brittleness index is expressed as follows;
wherein: e (E) sta For Young's modulus of rock, E sta_min Minimum value of Young's modulus of rock in certain stratum section, E sta_max Maximum value of Young's modulus of rock in certain stratum, V sta Poisson ratio of rock, V sta_min Minimum value of Poisson's ratio in a certain interval, V sta_max Maximum value of rock poisson ratio in a certain interval, YM C And PR (PR) C Brit is the brittleness index calculated by Young's modulus and Poisson's ratio Rock mechanics Is a brittleness index.
In step 5, taking into account the bedding structural characteristics in the friability evaluation of the shale reservoir; the method comprises the steps of calculating the bedding structure development degree of shale oil by utilizing the ratio of longitudinal waves to transverse waves of acoustic waves, wherein the displacement direction of particles of transverse waves is perpendicular to a well axis according to the longitudinal and transverse wave propagation principle, and in bedding and low-angle cracks, part of energy of the transverse waves propagates along bedding and low-angle cracks, so that the propagation speed of transverse waves collected by an instrument is reduced, the propagation direction of the longitudinal waves and the displacement direction of the particles are parallel to the well axis, the bedding and low-angle cracks have little influence on the speed of the shale oil, and then the longitudinal and transverse wave speed ratio Vp/Vs is increased at the place where the bedding and low-angle cracks develop.
In step 5, the brittleness index is calculated as follows;
Y layer structure ＝V P /V S (5)
Wherein: y is Y Layer structure The structure is a layer structure of a shale oil reservoir, vp is longitudinal wave, and Vs is transverse wave;
when the longitudinal-transverse wave ratio Vp/Vs is increased, the grain layer is developed more, otherwise, the lamellar structure is not developed.
In step 6, the shale layer development indication solved in step 5 is added into the brittleness index of the shale oil reservoir layer solved in step 3 and step 4, wherein the brittleness index can reflect the layer structure of the shale oil reservoir layer and also consider the rock mechanical structure and mineral component composition of shale.
In step 6, the formula for evaluating the brittleness of the shale oil reservoir is:
Brit＝(Vp/Vs)*((V feldspar +V Quartz +V Carbonate rock )/(V Feldspar +V Quartz +V Clay +V Carbonate rock +V Dolomite rock ))*((YM C +PR C )/2) (6)。
According to the shale oil reservoir brittleness evaluation method based on the lamellar structure, provided by the invention, the lamellar structure characteristics of the shale oil reservoir are integrated into the brittleness index by taking the development characteristics of strong heterogeneity of the shale oil reservoir into consideration, so that the practicability is strong, the evaluation reliability is high, and an important technical support is provided for the exploration and development of shale oil.
Compared with the prior art, the invention has the following advantages:
the brittleness evaluation method is superior to the existing method for evaluating brittleness by using brittle minerals and Young modulus and Poisson ratio for shale oil reservoir exploration, breaks through the limitation of single solution, considers the real situation of strong heterogeneity of the shale oil reservoir, has strong practicability and high evaluation reliability, and provides important technical support for shale oil exploration and development.
Drawings
FIG. 1 is a flow chart of one embodiment of a method of evaluating shale oil reservoir brittleness based on a bedding structure of the present invention;
FIG. 2 is a schematic diagram of a conventional method for evaluating the brittleness of a shale oil reservoir according to an embodiment of the invention;
FIG. 3 is a diagram showing results of a shale oil reservoir brittleness evaluation method based on a bedding structure according to an embodiment of the present invention.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular forms also are intended to include the plural forms unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, and/or combinations thereof.
The shale oil reservoir brittleness evaluation method based on the bedding structure comprises the following steps:
step 1, collecting logging curves of shale oil wells, rock mechanical parameters and actual measurement contents of main minerals of shale, including carbonate rock, quartz, feldspar, clay and dolomite;
step 2, modeling the mineral content of a shale oil reservoir by utilizing a multiple regression method, and predicting the brittle mineral content and other shale mineral content of a shale oil well;
step 3, solving the brittleness index of the shale oil reservoir by using the brittleness mineral content of the shale oil reservoir;
step 4, calculating the brittleness index of the shale oil reservoir by using the ratio of Young modulus and Poisson ratio of the mixed minerals;
step 5, calculating a stratum development indication of the shale oil by using the ratio of longitudinal waves to transverse waves of the sound waves;
and 6, adding the tattoo development indication into the brittleness index of the shale oil reservoir obtained in the step 3 and the step 4 according to the development characteristics of the shale oil reservoir with strong heterogeneity, so as to obtain a novel brittleness evaluation method suitable for the shale oil reservoir.
The following are several embodiments of the invention
Example 1
In a specific embodiment 1 to which the present invention is applied, the shale oil reservoir brittleness evaluation method based on a bedding structure includes the following steps:
in step 1, collecting logging curves of shale oil wells, including conventional 5 curves (natural gamma GR, deep resistivity RT, sonic moveout AC, neutron CNL, density DEN) and longitudinal and transverse wave curves (Vp and Vs), rock mechanical parameters (young's modulus YM and poisson's ratio PR), measured content of main minerals of shale, including carbonate, quartz, feldspar, clay, dolomite;
in the step 2, modeling the mineral content of the shale oil reservoir by utilizing a multiple regression method, homing correction is carried out on the rock core and the logging curve, abnormal points are removed, and then the mineral content measured by utilizing a full rock diffraction experiment is matched with the logging curve, so that a sensitive curve of each mineral is preferably obtained. Modeling the mineral content (carbonate, quartz, feldspar, clay and dolomite) of a shale oil reservoir by a segment-to-segment and multiple regression method, and predicting the brittle mineral (carbonate, quartz and feldspar) and other shale mineral content (clay and dolomite) of the whole well segment of the shale oil well;
in step 3, solving the brittleness index of the shale oil reservoir by using the brittle mineral content of the shale oil reservoir; taking carbonate rock, feldspar and quartz as main brittle minerals of a shale oil reservoir, clay and dolomite as other minerals, and solving the brittleness index of the shale oil reservoir by using the brittle minerals, wherein the formula is as follows:
Brit brittle minerals ＝(V Feldspar +V Quartz +V Carbonate rock )/(V Feldspar +V Quartz +V Clay +V Carbonate rock +V Dolomite rock ) (1)
Wherein: brit (Brit) Brittle minerals Is the brittleness index of shale oil reservoir, V Feldspar Is feldspar content, V Quartz Is of quartz content, V Carbon dry active acid salt rock For carbonate content, V Dolomite rock For dolomite content, V Clay Is clay content;
in step 4, calculating the brittleness index of the shale oil reservoir by using the ratio of the Young modulus of the mixed minerals to the Poisson ratio, wherein the brittleness index is expressed as follows;
wherein: e (E) sta For Young's modulus of rock, E sta_min Minimum value of Young's modulus of rock in certain stratum section, E sta_max Maximum value of Young's modulus of rock in certain stratum, V sta Poisson ratio of rock, V sta_min Minimum value of Poisson's ratio in a certain interval, V sta_max Maximum value of rock poisson ratio in a certain interval, YM C And PR (PR) C Brit is the brittleness index calculated by Young's modulus and Poisson's ratio Rock mechanics Is a brittleness index;
in step 5, because shale oil reservoirs are complex and various in argillaceous-argillite interbedded, different in bedding structure, different in storage space and storage capacity, for example, the argillite interbedded in the same interval has two conditions of homogeneity and non-homogeneity, and the situation that the development thickness of the bedding structure is non-uniform is also possible, so that the bedding structure characteristics are considered in the brittleness evaluation of the shale reservoirs. Calculating the bedding structure development degree of shale oil by using the ratio of longitudinal waves and transverse waves of sound waves, wherein the displacement direction of particles of transverse waves is perpendicular to a well axis according to the longitudinal wave propagation principle, and part of energy of transverse waves propagates along bedding and low-angle cracks in bedding and low-angle cracks, so that the propagation speed of transverse waves acquired by an instrument is reduced, the propagation direction of longitudinal waves and the displacement direction of particles are parallel to the well axis, the influence of bedding and low-angle cracks on the speed of the shale oil is small, and the longitudinal wave speed ratio Vp/Vs is increased at the place where the bedding and low-angle cracks develop, and the formula is as follows;
Y layer structure ＝V P /V S (5)
Wherein: y is Y Layer structure The structure is a layer structure of a shale oil reservoir, vp is longitudinal wave, and Vs is transverse wave;
when the longitudinal-transverse wave ratio Vp/Vs is increased, the grain layer is developed more, otherwise, the lamellar structure is not developed.
In the step 6, the shale layer development indication solved in the step 5 is added into the brittleness index of the shale oil reservoir layer solved in the step 3 and the step 4, and the brittleness index provided by the patent can reflect the layer structure of the shale oil reservoir layer and also consider the rock mechanical structure and mineral component composition of the shale, so that a novel brittleness evaluation method suitable for the shale oil reservoir layer is obtained;
Brit＝(Vp/Vs)*((V feldspar +V Quartz +V Carbonate rock )/(V Feldspar +V Quartz +V Clay +V Carbonate rock +V Dolomite rock ))*((YM C +PR C )/2) (6)
Example 2
In a specific example 2 of the application of the present invention, a specific embodiment of the calculation method will be described by taking the oil well purpose interval (Shateu) of the depression of the eastern camping of the victory oil field.
As shown in fig. 1, the shale oil reservoir brittleness evaluation method based on the bedding structure comprises the following steps:
in step 1, collecting logging curves of shale oil wells in a research area, wherein the logging curves comprise conventional 5 curves (natural gamma GR, deep resistivity RT, acoustic time difference AC, neutron CNL, density DEN) and longitudinal and transverse wave curves (Vp and Vs), rock mechanical parameters (Young modulus YM and Poisson ratio PR), and measured content of main minerals of shale oil reservoirs, including carbonate rock, long-english sandstone (quartz, feldspar), clay and dolomite, measured by a full-rock diffraction experiment;
in step 2, the mineral content of the shale oil reservoir is modeled using a multiple regression method.
And (3) homing correction is carried out on the core and the logging curve, abnormal points are removed, and certain data quality is ensured.
The mineral content measured by the all-rock diffraction experiment is matched with a logging curve, and a sensitivity curve of each mineral is preferably obtained. The resistivity RT is greatly influenced by the mineralization degree of the stratum water and the stratum environment, and the curve is removed, so that the measured basic mineral content in a research area has better correlation with the natural Gamma (GR), the acoustic time difference (AC), the Density (DEN) and the neutrons (CNL) of a logging curve, and 4 sensitive new curves are preferably selected.
And (3) by a section-to-section mode, averaging all data points with good quality within the range of 0.5 m above and below the data point, and ensuring the reliability of the mineral content model.
Data fitting is carried out on mineral contents (carbonate rock, long-english sandstone (quartz, feldspar), clay and dolomite) of shale oil reservoirs by utilizing a multiple regression method, and the brittle mineral contents (carbonate rock, long-english sandstone (quartz, feldspar)) and other shale mineral contents (clay and dolomite) of the target layer sand four pure (pure 1, pure 2 and pure 3) of the ox Zhuang Waxian shale oil well in a layered prediction research area are shown in the following formula;
clay content (pure upper 1) = -79.61+0.62 gr-0.29 ac+29.11 den+1.02 cnl
Clay content (pure upper 2) =80.93+0.07×gr-3.47×ac+40.11×den+7.34×cnl
Clay content (pure upper 3) = -65.21-0.23 gr+0.71 ac+227.51 den+2.23 cnl
Carbonate content (1 on purity) =95.26-1.58 gr+1.17 ac+50.33 den-0.52 cnl
Carbonate content (pure upper 2) =13.01-0.48 gr-1.19 ac-41.73 den-3.78 cnl
Carbonate content (pure upper 3) =88.28+0.04 gr-0.79 ac-27.10 den-4.02 cnl
Long-english-quality sandstone content (pure upper 1) =24.98+0.17×gr+0.19×ac+72.81×den+0.81×cnl
Long-english sandstone content (pure upper 2) =34.78+0.37×gr+0.23×ac+26.52×den+0.33×cnl
Long-english-quality sandstone content (pure upper 3) =23.78+0.27×gr-0.02×ac+86.76×den+1.04×cnl
Dolomite content (pure 1) = 57.58-0.07 gr-1.29 ac-174.44 den-0.28 cnl
Dolomite content (pure upper 2) =43.93-0.19×gr+0.42×ac+15.97×den+0.87×cnl
Dolomite content (pure upper 3) =32.19-0.34×gr-1.70×ac-75.74×den+2.78×cnl
In step 3, solving the brittleness index of the shale oil reservoir by using the brittleness mineral content of the shale oil reservoir; the content of depressed carbonate rock and long-english sandstone (feldspar and quartz) in the eastern camping of the research area is high, can reach 40% -50% and 20% -30%, can be used as main brittle minerals of shale oil reservoirs, clay and dolomite are used as other minerals, and the brittle minerals are used for solving the brittleness index of the shale reservoirs, and the formula is as follows:
Brit brittle minerals ＝(V Feldspar +V Quartz +V Carbonate rock )/(V Feldspar +V Quartz +V Clay +V Carbonate rock +V Dolomite rock ) (1)
Wherein: brit (Brit) Brittle minerals Is the brittleness index of shale oil reservoir, V Feldspar Is feldspar content, V Quartz Is of quartz content, V Carbon dry active acid salt rock For carbonate content, V Dolomite rock For dolomite content, V Clay Is clay content;
in step 4, calculating the brittleness index of the shale oil reservoir according to the ratio of Young's modulus to Poisson's ratio of the mixed minerals for reacting brittleness of the shale oil reservoir, wherein the formula is as follows;
wherein: e (E) sta For Young's modulus of rock, E sta_min Minimum value of Young's modulus of rock in certain stratum section, E sta_max Maximum value of Young's modulus of rock in certain stratum, V sta Poisson ratio of rock, V sta_min Minimum value of Poisson's ratio in a certain interval, V sta_max Maximum value of rock poisson ratio in a certain interval, YM C And PR (PR) C Brit is the brittleness index calculated by Young's modulus and Poisson's ratio Rock mechanics Is a brittleness index;
in step 5, because shale oil reservoirs are complex and various in argillaceous-argillite interbedded, different in bedding structure, different in storage space and storage capacity, for example, the argillite interbedded in the same interval has two conditions of homogeneity and non-homogeneity, and the situation that the development thickness of the bedding structure is non-uniform is also possible, so that the characteristics of the bedding structure are considered in the brittleness evaluation of the shale reservoir. According to the longitudinal and transverse wave ratio of the sound wave, the bedding structure development degree of shale oil is calculated, according to the longitudinal and transverse wave propagation principle, the displacement direction of particles of transverse waves is perpendicular to a well axis, in bedding and low-angle cracks, part of energy of the transverse waves propagates along bedding and low-angle cracks, so that the propagation speed of transverse waves collected by an instrument is reduced, the propagation direction of the longitudinal waves and the particle displacement direction are parallel to the well axis, the bedding and low-angle cracks have little influence on the speed of the shale oil, and then the longitudinal and transverse wave speed ratio Vp/Vs is increased at the place where the bedding and low-angle cracks develop, and the formula is as follows;
Y layer structure ＝V P /V S (5)
Wherein: y is Y Layer structure The structure is a layer structure of a shale oil reservoir, vp is longitudinal wave, and Vs is transverse wave;
when the longitudinal and transverse wave ratio Vp/Vs is increased, the grain layer is developed more, otherwise, the lamellar structure is not developed;
in step 6, the shale layer development indication solved in step 5 is added into the brittleness index of the shale oil reservoir solved in step 3 and step 4, so that the new brittleness index can not only reflect the lamellar structure of the shale oil reservoir, but also consider the rock mechanical structure and mineral component composition of the shale, thereby obtaining a new brittleness evaluation method suitable for the shale oil reservoir
Brit＝(Vp/Vs)*((V Feldspar +V Quartz +V Carbonate rock )/(V Feldspar +V Quartz +V Clay +V Carbonate rock +V Dolomite rock ))*((YM C +PR C )/2) (6)
Wherein: brit is the brittleness index, vp is the longitudinal wave, vs is the transverse wave; v (V) Feldspar Is feldspar content, V Quartz Is of quartz content, V Carbonate rock For carbonate content, V Dolomite rock For dolomite content, V Clay Clay content; YM (YM) C And PR (PR) C The brittleness index was calculated by Young's modulus and Poisson's ratio.
Example 3
In a specific embodiment 3 of the present invention, taking the study area N55-X1 as an example, according to two conventional brittleness evaluation methods, the brittleness index is calculated by using the two methods of the brittleness mineral content, the young modulus and the poisson ratio rock mechanics, and the results prove that the brittleness index curve of the shale oil well objective interval is not greatly fluctuated and is not differentiated, as shown in fig. 2. Because shale oil reservoir layers develop, the lamellar structure is complex and various, the thickness is different, in order to solve the problem, the shale oil reservoir brittleness evaluation method based on lamellar structure, provided by the invention, considers the real situation of strong heterogeneity of the shale oil reservoir, has strong practicability and high evaluation reliability, integrates lamellar structure into the formula of brittleness index, reflects the influence of brittle mineral content and rock mechanics, also considers lamellar structure of the shale oil reservoir, is more in line with the real situation of the shale oil reservoir, can obviously see that the brittleness of pure 2 is better, and pure 1 and pure 3 are worse when applied to an N55-X1 well in a research area, as shown in figure 3.
The shale oil reservoir brittleness evaluation method based on the bedding structure is superior to the existing shale oil reservoir exploration method which uses brittle minerals singly to calculate and Young modulus and Poisson ratio to evaluate brittleness, breaks through the limitation of single calculation, considers the real situation of strong heterogeneity of the shale oil reservoir, is high in practicability and evaluation reliability, and provides important technical support for shale oil exploration and development.
Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but although the present invention has been described in detail with reference to the foregoing embodiment, it will be apparent to those skilled in the art that modifications may be made to the technical solution described in the foregoing embodiment, or equivalents may be substituted for some of the technical features thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Other than the technical features described in the specification, all are known to those skilled in the art.
Claims (12)
1. The shale oil reservoir brittleness evaluation method based on the bedding structure is characterized by comprising the following steps of:
step 1, collecting logging curves of shale oil wells, rock mechanical parameters and actual measurement content of main minerals of shale;
step 2, modeling the mineral content of a shale oil reservoir by utilizing a multiple regression method, and predicting the brittle mineral content and other shale mineral content of a shale oil well;
step 3, solving the brittleness index of the shale oil reservoir by using the brittleness mineral content of the shale oil reservoir;
step 4, calculating the brittleness index of the shale oil reservoir by using the ratio of Young modulus and Poisson ratio of the mixed minerals;
step 5, calculating a stratum development indication of the shale oil by using the ratio of longitudinal waves to transverse waves of the sound waves;
and 6, evaluating brittleness of the shale oil reservoir.
2. The method for evaluating the brittleness of the shale oil reservoir based on the bedding structure as set forth in claim 1, wherein in step 1, logging curves of the shale oil well are collected, including conventional 5 curves, namely natural gamma GR, deep resistivity RT, acoustic time difference AC, neutrons CNL, density DEN, and longitudinal and transverse wave curves Vp and Vs.
3. The method for evaluating the brittleness of a shale oil reservoir based on a bedding structure as claimed in claim 1, wherein in step 1, the rock mechanical parameters include young's modulus YM and poisson's ratio PR, and the measured content of main minerals of shale includes carbonate rock, quartz, feldspar, clay, dolomite.
4. The method for evaluating the brittleness of the shale oil reservoir based on the bedding structure as set forth in claim 1, wherein in the step 2, the mineral content of the shale oil reservoir is modeled by utilizing a multiple regression method, the rock core and the logging curve are subjected to homing correction and abnormal points are removed, and then the mineral content measured by utilizing a full rock diffraction experiment is matched with the logging curve, so that a sensitive curve of each mineral is optimized; modeling the mineral content of a shale oil reservoir by a segment-to-segment and multiple regression method, and predicting the brittle mineral content and other shale mineral content of the whole well segment of the shale oil well.
5. The method for evaluating the brittleness of a shale oil reservoir based on a bedding structure as set forth in claim 4, wherein in the step 2, the mineral content of the shale oil reservoir comprises carbonate rock, quartz, feldspar, clay, dolomite, the brittle mineral comprises carbonate rock, quartz, feldspar, and the other shale mineral content comprises clay, dolomite.
6. The method for evaluating the brittleness of the shale oil reservoir based on the bedding structure as set forth in claim 1, wherein in step 3, the brittleness index of the shale oil reservoir is solved by using the brittleness mineral content of the shale oil reservoir; and taking carbonate rock, feldspar and quartz as main brittle minerals of the shale oil reservoir, clay and dolomite as other minerals, and solving the brittleness index of the shale oil reservoir by using the brittle minerals.
7. The method for evaluating the brittleness of a shale oil reservoir based on a bedding structure as set forth in claim 6, wherein in step 3, the formula for solving the brittleness index of the shale oil reservoir is as follows:
Brit brittle minerals ＝(V Feldspar +V Quartz +V Carbonate rock )/(V Feldspar +V Quartz +V Clay +V Carbonate rock +V Dolomite rock ) (1)
Wherein: brit (Brit) Brittle minerals Is the brittleness index of shale oil reservoir, V Feldspar Is feldspar content, V Quartz Is of quartz content, V Carbonate rock For carbonate content, V Dolomite rock For dolomite content, V Clay Is the clay content.
8. The method for evaluating the brittleness of the shale oil reservoir based on the bedding structure as set forth in claim 7, wherein in step 4, the brittleness index of the shale oil reservoir is calculated by using the ratio of the young's modulus of the mixed minerals to the poisson's ratio, and the formula is as follows;
wherein: e (E) sta For Young's modulus of rock, E sta_min Minimum value of Young's modulus of rock in certain stratum section, E sta_max Maximum value of Young's modulus of rock in certain stratum, V sta Poisson ratio of rock, V sta_min Minimum value of Poisson's ratio in a certain interval, V sta_max Maximum value of rock poisson ratio in a certain interval, YM C And PR (PR) C Brit is the brittleness index calculated by Young's modulus and Poisson's ratio Rock mechanics Is a brittleness index.
9. The method for evaluating the brittleness of a shale oil reservoir based on a bedding structure as set forth in claim 8, wherein in step 5, the bedding structure characteristics are considered in evaluating the brittleness of the shale oil reservoir; according to the longitudinal-transverse wave ratio of the sound wave, the bedding structure development degree of shale oil is calculated, according to the longitudinal-transverse wave propagation principle, the displacement direction of particles of transverse waves is perpendicular to a well axis, in bedding and low-angle cracks, part of energy of the transverse waves propagates along bedding and low-angle cracks, so that the propagation speed of transverse waves collected by an instrument is reduced, the propagation direction of the longitudinal waves and the particle displacement direction are parallel to the well axis, the bedding and low-angle cracks have little influence on the speed of the shale oil, and then the longitudinal-transverse wave speed ratio Vp/Vs is increased at the place where the bedding and low-angle cracks develop.
10. The method for evaluating the brittleness of the shale oil reservoir based on the bedding structure as set forth in claim 9, wherein in step 5, the calculation formula of the bedding structure is as follows;
Y layer structure ＝V P /V S (5)
Wherein: y is Y Layer structure The structure is a layer structure of a shale oil reservoir, vp is longitudinal wave, and Vs is transverse wave;
when the longitudinal-transverse wave ratio Vp/Vs is increased, the grain layer is developed more, otherwise, the lamellar structure is not developed.
11. The method for evaluating the brittleness of the shale oil reservoir based on the lamellar structure as set forth in claim 10, wherein in step 6, the shale lamellar development instruction solved in step 5 is added into the brittleness index of the shale oil reservoir solved in step 3 and step 4, wherein the brittleness index can reflect the lamellar structure of the shale oil reservoir and considers the rock mechanical structure and mineral composition of the shale.
12. The method for evaluating the brittleness of a shale oil reservoir based on a bedding structure as set forth in claim 11, wherein in step 6, the formula for evaluating the brittleness of the shale oil reservoir is:
Brit＝(Vp/Vs)*((V feldspar +V Quartz +V Carbonate rock )/(V Feldspar +V Quartz +V Clay +V Carbonate rock +V Dolomite rock ))*((YM C +PR C )/2) (6)。
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| CN117370718B (en) * | 2023-10-18 | 2024-03-29 | 中国地质大学（北京） | Shale brittleness index acquisition method, shale brittleness index acquisition device, shale brittleness index acquisition terminal and shale brittleness index storage medium |
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