CN-116088042-B - Rock physical elasticity parameter modeling method containing intersecting inclined cracks

CN116088042BCN 116088042 BCN116088042 BCN 116088042BCN-116088042-B

Abstract

The invention relates to a petrophysical elasticity parameter modeling method comprising intersecting inclined cracks, which comprises the steps of obtaining a dry rock elasticity coefficient matrix of a shale oil reservoir, obtaining a dry rock elasticity coefficient matrix of a shale oil reservoir comprising a plurality of groups of intersecting inclined cracks, obtaining a saturated rock elasticity coefficient matrix of a shale oil reservoir comprising a plurality of groups of intersecting inclined cracks, and establishing the relation between the longitudinal wave velocity and the transverse wave velocity of the shale oil reservoir and the shale porosity, the crack density, the crack dip angle and the water saturation of the shale oil reservoir according to the dry rock elasticity coefficient matrix of the shale oil reservoir, the dry rock elasticity coefficient matrix of the shale oil reservoir comprising a plurality of groups of intersecting inclined cracks and the saturated rock elasticity coefficient matrix of the shale oil reservoir comprising a plurality of groups of intersecting inclined cracks. The method provides a basic tool for the seismic elastic response calculation of the low-maturity shale oil reservoir with the intersecting inclined cracks, and provides a meaningful theoretical basis for the subsequent shale oil seismic exploration and development.

Inventors

XU CHANGGUI
ZHENG YING
DU XIANGDONG
WANG JIANHUA
CHEN JIANJUN
NIU CONG
WANG QINGZHEN
LING YUN
XIE JIGAO
WEI QIANQIAN

Assignees

中海石油(中国)有限公司
中海石油（中国）有限公司北京研究中心

Dates

Publication Date: 20260512
Application Date: 20230112

Claims (10)

1. A method for modeling petrophysical elastic parameters including intersecting oblique fractures, comprising: obtaining a dry rock elastic coefficient matrix of a shale oil reservoir; Carrying out elastic coefficient matrix calculation of shale reservoirs containing single groups of inclined cracks according to logging data and crack inclination angle information of an actual working area, carrying out elastic coefficient matrix calculation of shale reservoirs containing multiple groups of inclined cracks according to logging data and crack inclination angle information of the actual working area, and carrying out elastic coefficient matrix calculation of shale reservoirs containing multiple groups of inclined cracks according to logging data and crack inclination angle information of the actual working area, so as to obtain a dry rock elastic coefficient matrix of shale oil reservoirs containing multiple groups of inclined cracks; Performing fluid replacement by using an anisotropic Gassmann formula to obtain a saturated rock elastic coefficient matrix of the shale oil reservoir with a plurality of groups of intersecting inclined cracks; And establishing the relation between the longitudinal wave speed and the transverse wave speed of the shale oil reservoir and the shale porosity, the fracture density, the fracture dip angle and the water saturation according to the dry rock elasticity coefficient matrix of the shale oil reservoir, the dry rock elasticity coefficient matrix of the shale oil reservoir with a plurality of groups of intersecting inclined fractures and the saturated rock elasticity coefficient matrix of the shale oil reservoir with a plurality of groups of intersecting inclined fractures.
2. The method of modeling petrophysical elasticity parameters including intersecting oblique fractures of claim 1, wherein obtaining a matrix of dry rock elasticity coefficients for a shale oil reservoir comprises: Obtaining the volume fraction, porosity, fluid type and saturation of shale constituent minerals through laboratory analysis or well logging interpretation; Calculating the equivalent elastic modulus of the shale matrix brittle mineral mixture through a Hill average modulus model; Adding clay pores into matrix minerals through an anisotropic differential equivalent medium model to obtain a clay-containing rock skeleton, establishing a physical model of the rock skeleton, and calculating an equivalent elastic stiffness tensor of the rock skeleton; And adding organic matter pores into the clay-containing rock skeleton through an anisotropic differential equivalent medium model to obtain a dry shale skeleton with certain pores, establishing a rock physical model of the dry shale skeleton, and calculating an equivalent elastic stiffness tensor of the dry shale skeleton.
3. The method for modeling petrophysical elasticity parameters including intersecting oblique fractures according to claim 2, wherein the Hill average modulus model is expressed as follows: Wherein: v i is the volume component of the ith constituent element; m i is the modulus of the ith constituent element; M VRH is Hill average modulus.
4. The method for modeling petrophysical elasticity parameters including intersecting oblique fractures according to claim 2, wherein the anisotropic differential equivalent medium model is expressed as follows: Wherein: C DEM (v) is the media stiffness tensor calculated by the DEM model; v is the volume content of the inclusion added to the matrix; c i is the stiffness tensor of the inclusion in the matrix; I is a unit stiffness tensor; is the stiffness tensor associated with the shape of the inclusion.
5. The method of modeling petrophysical elasticity parameters including intersecting oblique fractures of claim 1, wherein said performing an elastic coefficient matrix calculation of a shale reservoir including a single set of oblique fractures comprises: C eff ＝(M background +Z) -1 (3) Wherein: z N is the normal compliance of the fracture; Z T is the tangential compliance of the fracture; z is a crack compliance matrix; M background is a flexibility matrix of the background medium; θ is the angle between the crack surface and the horizontal plane.
6. The method for modeling petrophysical elasticity parameters including intersecting oblique fractures according to claim 5, wherein the background medium is a shale dry skeleton.
7. The method for modeling petrophysical elasticity parameters including intersecting oblique fractures according to claim 6, wherein the normal compliance and tangential compliance of the fractures are expressed as: Wherein: λ, μ is the pull Mei Jishu of the background medium; and e is the crack density.
8. The method of modeling petrophysical elasticity parameters including intersecting oblique fractures of claim 1, wherein said performing an elastic coefficient matrix calculation of a shale reservoir including a plurality of sets of oblique fractures comprises: C eff ＝ (M background + Z 1 + Z 2 +L + Z i + L +Z N ) -1 (6) Wherein: i is the directional arrangement crack of the ith group with the same inclination angle; θ i is the included angle between the crack surface and the horizontal plane; z Ni is the normal compliance of the fracture; z Ti is the tangential compliance of the fracture; Z i is a fracture compliance matrix; m background is the compliance matrix of the background medium.
9. The method for modeling petrophysical elasticity parameters including intersecting oblique fractures according to claim 8, wherein the normal compliance and tangential compliance of the fractures are expressed as: Wherein: λ, μ is the pull Mei Jishu of the background medium; and e is the crack density.
10. The method of modeling petrophysical elasticity parameters including intersecting oblique fractures of claim 1, wherein obtaining a saturated rock elasticity coefficient matrix including a plurality of sets of intersecting oblique fracture shale oil reservoirs comprises: Wherein: A pore space modulus that is an anisotropic medium; k * is the generalized bulk modulus of dry rock; k 0 is the bulk modulus of the rock matrix; k f is the bulk modulus of the pore fluid; phi is the porosity of the background dry skeleton; Beta m and beta n are weight coefficients representing the relationship between matrix modulus and dry rock stiffness tensor.

Description

Rock physical elasticity parameter modeling method containing intersecting inclined cracks Technical Field The invention relates to the field of geophysical exploration petrophysics, in particular to a method for modeling elasticity parameters of a low-maturity shale oil reservoir with intersecting inclined cracks. Background The shale is generally sedimentary rock with a lamellar structure, and the sedimentary rock is composed of clay minerals, clastic minerals and organic matters, wherein the clay minerals are main components of the shale and comprise kaolinite, montmorillonite and the like, the clastic minerals comprise quartz, feldspar and the like, and the organic matters comprise immature organic matters and oil gas. Shale has relatively low porosity and permeability, typically in the range of 2-15%, and permeability typically less than 1mD, and is an unconventional reservoir, but shale reservoirs tend to have higher oil and gas production than expected due to the presence of high angle seams intersecting the bedding, faults, parallel bedding cracks, early compaction cracks, and cracks associated with tuberculosis. These cracks are not only the effective reservoir space of oil gas, but also the important channels for oil gas migration, and can greatly improve the oil gas output efficiency. Modeling shale reservoir elastic parameters containing these natural fractures can provide theoretical basis and explanation basis for shale fracture seismic exploration. At present, aiming at the elastic modeling of shale oil reservoirs, effective medium models such as SCA, DEM and the like are mainly adopted to model elastic parameters of rock skeletons formed by different minerals, clay and pores, then fluid effect modeling is carried out by utilizing Gassmann fluid replacement theory, and however, the cementing relation of shale organic matter maturity and mineral particles is not considered enough. Shale is a special hydrocarbon source rock, and oil and gas generation and storage are homologous, so that the influence of the maturity of organic matters on the physical properties of shale is not negligible. Under low maturity, shale pores mainly contain kerogen, asphalt and a small amount of gas, when kerogen and asphalt are further cracked to form oil and gas, the shale reaches a complete maturity stage, and finally, as organic matters are continuously cracked, the shale only contains gas and very little residual solids to reach an overmaturity stage, the arrangement and cementation relation among shale components are required to be fully considered according to different maturity. In addition, the influence of shale reservoir cracks on elastic parameters is often considered only by vertical cracks or horizontal cracks, an anisotropic DEM model or a Hudson model is adopted, and the condition is assumed to be too ideal and simple, so that the influence of multiple groups of cracks with different dip angles is required to be considered. Disclosure of Invention Aiming at the problems, the method is mainly used for directly calculating the rock elasticity parameters of the shale oil reservoir with the cracks and low maturity, and determining the influence of the parameters such as the organic matter content, the porosity, the fluid type, the crack inclination angle, the crack density and the like on the elasticity parameters. In order to achieve the above purpose, the present invention adopts the following technical scheme: a method for modeling petrophysical elastic parameters including intersecting oblique fractures, comprising: obtaining a dry rock elastic coefficient matrix of a shale oil reservoir; Carrying out elastic coefficient matrix calculation of shale reservoirs containing single groups of inclined cracks according to logging data and crack inclination angle information of an actual working area, carrying out elastic coefficient matrix calculation of shale reservoirs containing multiple groups of inclined cracks according to logging data and crack inclination angle information of the actual working area, and carrying out elastic coefficient matrix calculation of shale reservoirs containing multiple groups of inclined cracks according to logging data and crack inclination angle information of the actual working area, so as to obtain a dry rock elastic coefficient matrix of shale oil reservoirs containing multiple groups of inclined cracks; Performing fluid replacement by using an anisotropic Gassmann formula to obtain a saturated rock elastic coefficient matrix of the shale oil reservoir with a plurality of groups of intersecting inclined cracks; And establishing the relation between the longitudinal wave speed and the transverse wave speed of the shale oil reservoir and the shale porosity, the fracture density, the fracture dip angle and the water saturation according to the dry rock elasticity coefficient matrix of the shale oil reservoir, the dry rock elasticity coefficient matrix of the shale oil rese