CN105019892B - A method of simulation fracture hole type Reservoir Body electric logging response - Google Patents
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Abstract
The invention belongs to electric logging numerical simulation fields, disclose a kind of method of simulation fracture and cave reservoir electric logging response.The method comprising the steps of：A, equivalent fracture and cave reservoir stratigraphic model is established according to block geologic information, determines the underlying parameter of the equivalent fracture and cave reservoir stratigraphic model；B, the finite element functional of direct current electric logging response is established according to the equivalent fracture and cave reservoir stratigraphic model；C, according to finite element theory, and resistivity assignment discrete to the equivalent fracture and cave reservoir stratigraphic model progress grid；D, assembling and solving finite element conductance battle array obtain depth laterolog value.The method of the present invention solves the problems, such as across the scale mesh generation of fracture and cave reservoir, effectively feature fracture and cave reservoir boundary, the numerical simulation of science realized to fracture and cave reservoir electric logging provides theoretical foundation for the electric logging identification and evaluation of carbonate rock, volcanic rock fracture and cave reservoir based on electric logging data.
Description
Technical Field
The invention belongs to the field of electrical logging numerical simulation, and relates to a method for simulating the electrical logging response of a fracture-cavity type reservoir body.
Background
The reservoirs of the oil and gas reservoir fracture-cave such as carbonate rock, volcanic rock and the like are widely developed. The reservoir body has the characteristics of strong heterogeneity, obvious anisotropy, unequal fracture-cavity development scale, uneven distribution, large variation of filling material types and filling degrees and the like, so that the electrical logging response of the fracture-cavity reservoir body is complex, and the multi-solution and ambiguity of logging evaluation results are easily caused.
At present, the research on the numerical simulation of the electrical logging of fracture-cavity reservoirs at home and abroad is very little. Faivre et al developed single fracture and parallel plate fracture model studies for fracture type formations, solved the problem of fracture type formation electrical logging numerical simulation, but did not consider fracture-cavity reservoirs existing in combination of fractures and large-scale caverns (meaning caverns with length, width, height all greater than 0.5 m).
When the current fracture-cavity reservoir body electric logging response numerical simulation research is carried out, the following difficulties exist: (1) aiming at geological problems such as cracks, caves, slit-hole combinations and the like, the mathematical model is single, and proper mathematical geological abstraction and analysis are still lacked to meet the requirements of actual geological conditions; (2) when the commercial software is adopted for carrying out cross-scale grid subdivision of a stratum from a crack as small as a few microns to a plurality of tens of meters during response simulation of a fracture-cave reservoir body, the number of grids is greatly increased, the forward calculation amount is large, and the calculation speed is slow; (3) in the current electric logging simulation, a structured grid subdivision and ladder approximation method is widely adopted, and the simulation precision is low when the method is used for processing the boundary of a seam hole.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a method for simulating the response of a fracture-cavity type reservoir electrical logging, which simulates the numerical value of the fracture-cavity reservoir electrical logging based on finite element grid conformality and local encryption on the basis of an equivalent fracture-cavity reservoir stratum model, is favorable for realizing mathematical description and scientific processing of the fracture-cavity reservoir, calculates and analyzes the response rule of the fracture-cavity reservoir electrical logging, and provides a basis for qualitative recognition and quantitative evaluation of the fracture-cavity reservoir logging.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method of simulating a fracture-vug reservoir electrical logging response, comprising the steps of:
a, establishing an equivalent fracture-cavity reservoir stratum model according to block geological data, and determining basic parameters of the equivalent fracture-cavity reservoir stratum model;
b, establishing a finite element functional of direct current logging response according to the equivalent fracture-cavity reservoir stratum model;
c, carrying out grid dispersion and resistivity assignment on the equivalent fracture-cave reservoir stratum model according to a finite element theory;
d, assembling and solving the finite element conductivity array to obtain the depth lateral logging value.
Further, in the equivalent fracture-cave reservoir stratum model established in the step a,
generating equidistant flat plate cracks and crossed flat plate crack models by utilizing the equivalent crack development of the flat plate model; utilizing spherical and ellipsoidal models to obtain equivalent cave models; and combining equivalent flat plate fractures and an ellipsoidal cave into different types of complex fracture-cave reservoir body models.
Further, the basic parameters of the equivalent fracture-cavity reservoir stratum model established in the step a comprise:
the size and the development position of the cave, the resistivity of a filling material in the cave, the number of cracks, the opening degree, the inclination angle of the cracks, the development position of each crack, and the resistivity of slurry filtrate and bedrock.
Further, the dc electric logging response finite element functional equation established in step b is:
in the formula, in a cylindrical coordinate system (r, phi, z), U represents the potential, sigma is the medium conductivity, IjRepresenting the transmit electrode current, omega the solution area, UjRepresenting the potential at the electrode.
Further, the step c further comprises the following steps:
c1, firstly, not considering the existence of cracks and caves, carrying out structured grid subdivision according to the borehole and a double-laterolog instrument model to generate tetrahedral elements, and assigning the resistivity of the elements in the borehole as the mud resistivity value;
c2, then carrying out local encryption processing on the cave boundary; firstly, judging whether a cave boundary passes through a tetrahedral element; if the cave boundary does not pass through the tetrahedral element, skipping the tetrahedral element; if the cave boundary passes through the tetrahedral elements, determining the number of newly-added nodes, and simultaneously dividing the tetrahedral elements into a plurality of tetrahedral elements; then judging whether the tetrahedral element is in the cave or not according to the gravity center of the tetrahedral element; if the tetrahedral elements are in the cave, assigning the tetrahedral elements as the resistivity values of the fillers in the cave; if the tetrahedral elements are outside the cave, assigning the tetrahedral elements as the resistivity values of the bedrocks;
c3, processing the conformal grid penetrated by the crack, and judging whether the crack penetrates through the tetrahedral element; skipping tetrahedral elements if the fracture does not pass through the tetrahedral elements; if the crack penetrates through the tetrahedral element, the volume of the tetrahedral element occupied by the crack and the bedrock is calculated respectively, and the resistivity of the tetrahedral element is assigned as the parallel value of the resistivity of the crack and the bedrock.
Further, in step c2, the step of dividing the tetrahedral element into a plurality of tetrahedral elements according to the new nodes is as follows:
determining the number of intersection points formed by intersection of the cave boundary and the original tetrahedral elements; and taking the intersection point of the edge of the original tetrahedral element and the cave boundary as a new node, connecting the new node and the original node, and dividing the original tetrahedral element into a plurality of tetrahedral elements.
Further, the number of the newly added nodes is one, two, three or four;
when a node is newly added, the tetrahedron penetrated by the cave boundary is directly decomposed into two tetrahedrons;
when two nodes are newly added, the tetrahedron penetrated by the cave boundary is respectively decomposed into three or four tetrahedrons;
when three nodes are newly added, the tetrahedron penetrated by the cave boundary is decomposed into four tetrahedron elements;
when four nodes are newly added, the tetrahedron penetrated by the cave boundary is directly decomposed into six tetrahedrons.
Further, in step c2, the step of determining whether the tetrahedral element is in the cave according to the center of gravity of the tetrahedral element is as follows:
calculating the gravity center of the tetrahedral elements, and then judging the distance from the gravity center to the center of the cave; if the distance value is smaller than the radius of the cave, the tetrahedral element is positioned in the cave; and if the distance value is larger than the radius of the cave, the tetrahedral element is positioned outside the cave.
Compared with the prior art, the invention has the following advantages:
(1) the method provided by the invention aims at the complex fracture-cavity reservoir body, reasonable equivalence is carried out according to the actual geological condition, and mathematical description of the fracture-cavity reservoir body is realized;
(2) the method respectively treats the cracks and the caves of the fracture-cave reservoir body, adopts grid conformal treatment on the cracks, and solves the problem of fracture cross-scale grid subdivision; the local encryption is carried out on the cave boundary, so that the calculation speed and the calculation precision are ensured;
(3) the method not only carries out electric logging numerical simulation aiming at the condition that the borehole penetrates through the fracture-cavity reservoir body, but also calculates the electric logging response rule of the well-side fracture-cavity reservoir body which the borehole does not penetrate through.
Drawings
FIG. 1 is a flow chart of a method of simulating a fracture-vug reservoir electrical logging response in accordance with the present invention;
FIG. 2 is a schematic representation of a model of an equivalent wellbore drilled-through fracture-cavity reservoir;
FIG. 3 is a schematic diagram of a model of an equivalent parawell fracture-cavity reservoir;
FIG. 4 is a schematic view of a tetrahedron subdivision of a triangular prism without a cavity boundary passing through according to an embodiment of the present invention;
fig. 5 is a schematic view of a tetrahedron subdivision of a triangular prism with 1 new node added according to an embodiment of the present invention;
fig. 6 is a schematic view of a tetrahedron subdivision of a triangular prism with 2 new nodes added according to an embodiment of the present invention;
fig. 7 is a schematic view of a tetrahedron subdivision of a triangular prism with 2 nodes added in the embodiment of the present invention;
fig. 8 is a schematic view of a tetrahedron subdivision of a triangular prism with 3 new nodes added according to an embodiment of the present invention;
fig. 9 is a schematic view of a tetrahedron subdivision of a triangular prism with 4 new nodes added according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of a conformal tetrahedral mesh with cracks present according to an embodiment of the present invention;
FIG. 11 is a deep lateral log numerical simulation of a borehole through fracture-cavity reservoir model provided by an embodiment of the present invention;
FIG. 12 is a shallow lateral log numerical simulation of a borehole through a fracture-cavity reservoir model provided by an embodiment of the present invention;
FIG. 13 is a deep lateral log numerical simulation of a parawell fracture-cavity reservoir model provided by an embodiment of the present invention;
FIG. 14 is a shallow lateral log numerical simulation of a parawell fracture-cavity reservoir model provided by an embodiment of the invention.
Detailed Description
The invention is described in further detail below with reference to the following figures and detailed description:
as shown in fig. 1, a method of simulating a fracture-vug reservoir electrical well response, comprising the steps of:
a, establishing an equivalent fracture-cave reservoir stratum model according to block geological data
The equivalent fracture-cavity reservoir formation model includes at least undisturbed formations, equivalent caverns, fractures, and wellbores.
In the equivalent fracture-cave reservoir body stratum model, generating an equidistant flat plate fracture and cross flat plate fracture model by utilizing the equivalent fracture development of the flat plate model; utilizing spherical and ellipsoidal models to obtain equivalent cave models; and combining equivalent flat plate fractures and an ellipsoidal cave into different types of complex fracture-cave reservoir body models.
Since only the situation that the borehole penetrates through the equivalent cavern and the center of the equivalent cavern is in the center of the borehole is considered in the prior art, the established reservoir stratum model has small application range.
The invention can simulate relative position relations of more boreholes and equivalent fracture-cavity reservoirs through the equivalent model, comprises two situations of the borehole drilled fracture-cavity reservoir and the borehole non-drilled well side fracture-cavity reservoir, is suitable for various actual geological conditions, satisfies the analysis and can simulate the electrical logging response value of the fracture-cavity reservoir more accurately.
And setting undisturbed stratum parameters, equivalent fracture-cavity reservoir parameters and borehole parameters in the equivalent fracture-cavity reservoir stratum model to simulate different geological conditions of the stratum model. In particular, the method comprises the following steps of,
determining basic parameters of an equivalent fracture-cave reservoir stratum model, including the size and the development position of a cave, the resistivity of a filling material in the cave, the number of cracks, the opening degree, the inclination angle of the cracks, the development position of each crack, the resistivity of slurry filtrate and bedrock and the like;
wherein the radius of the equivalent cave is larger than 0.5m, and the equivalent crack opening is 1-200 μm.
b establishing a finite element functional of direct current logging response according to the equivalent fracture-cavity reservoir stratum model
The response finite element functional equation of the direct current logging is as follows:
in the formula, in a cylindrical coordinate system (r, phi, z), U represents the potential, sigma is the medium conductivity, IjRepresenting the transmit electrode current, omega the solution area, UjRepresenting the potential at the electrode.
c, carrying out grid dispersion and resistivity assignment on the equivalent fracture-cavity reservoir stratum model according to a finite element theory so as to enable the numerical simulation of the fracture-cavity reservoir to be closer to a real value, and the method specifically comprises the following steps:
c1, FIG. 2 and FIG. 3 show the fracture-cavity reservoir formation model being grid discretized.
The stratigraphic model includes both the through-wellbore fracture-cavity reservoir model and the well-side fracture-cavity reservoir, 1 represents a dual laterolog instrument, and the fracture-cavity reservoir model may consider a single fracture-cavity reservoir: the vertical slits 2, the oblique slits 3, the horizontal slits 4, and the ellipsoidal cavity model 5, as shown in fig. 2, may also include a plurality of slit models such as the parallel plate-shaped slits 7 in fig. 3.
Firstly, the existence of cracks and caves is not considered, only the boundary of instruments, boreholes and the like is considered, structured grid subdivision is carried out according to the borehole and a double-lateral logging instrument model, and a stratum model is discretized into a plurality of tetrahedral elements n1n2n3n4 shown in figure 4. Meanwhile, the resistivity of the tetrahedral elements in the well bore is assigned as the mud resistivity value.
c2, carrying out local encryption processing on the position grid of the cave boundary, which comprises the following steps:
c21, first judging whether the cavern boundary passes through the tetrahedral element:
if the cave boundary does not pass through the tetrahedral element, skipping the tetrahedral element;
if the cave boundary passes through the tetrahedral elements, determining the number of newly-added nodes, and simultaneously dividing the tetrahedral elements into a plurality of tetrahedral elements. Specifically, determining the number of intersection points formed by intersection of cave boundaries and tetrahedral elements;
and taking the intersection point of the edge of the original tetrahedral element n1n2n3n4 and the cave boundary as a new node, connecting the new node and the original node, and dividing the original tetrahedral element into a plurality of tetrahedral elements.
The intersection point of the edge of the original tetrahedral element n1n2n3n4 and the cave boundary is taken as a newly added node, and four conditions are shared: and adding 1 node, 2 nodes, 3 nodes and 4 nodes. Wherein,
when 1 node n5 is newly added, the tetrahedron penetrated by the cave is directly decomposed into two tetrahedrons, as shown in fig. 5, tetrahedron n1n3n4n5 and tetrahedron n2n3n4n5 respectively;
when 2 nodes n5 and n6 are newly added, the edges where the intersection points are located can be divided into two cases, namely, adjacent edges and opposite edges, so that the tetrahedrons penetrated by the cave are respectively decomposed into three tetrahedrons, namely a tetrahedron n1n4n5n6, a tetrahedron n2n3n4n5 and a tetrahedron n3n4n5n6 as shown in fig. 6, or four tetrahedrons, namely a tetrahedron n2n4n5n6, a tetrahedron n1n4n5n6, a tetrahedron n1n3n5n6 and a tetrahedron n2n3n5n6 as shown in fig. 7;
when 3 nodes n5, n6 and n7 are newly added, the tetrahedron penetrated by the cave can be decomposed into four tetrahedral elements, as shown in fig. 8, which are tetrahedron n1n5n6n7, tetrahedron n4n5n6n7, tetrahedron n3n4n5n6 and tetrahedron n2n3n4n 5;
when adding 4 new nodes n5, n6, n7 and n8, the tetrahedron penetrated by the cave is directly decomposed into 6 tetrahedrons, as shown in fig. 9, tetrahedron n1n5n6n7, tetrahedron n1n2n5n7, tetrahedron n2n5n7n8, tetrahedron n4n5n7n8, tetrahedron n3n4n5n6 and tetrahedron n4n5n6n 7.
c22, judging whether the tetrahedral element is in the cave according to the gravity center of the tetrahedral element, wherein the judgment standard is as follows: calculating the gravity center of the tetrahedral elements, and then judging the distance from the gravity center to the center of the cave; if the distance value is smaller than the radius of the cave, the tetrahedral element is positioned in the cave, and if the distance value is larger than the radius of the cave, the tetrahedral element is positioned outside the cave.
After judgment, if the tetrahedral elements outside the well are in the cave, assigning the tetrahedral elements as the resistivity values of the fillers in the cave; and if the tetrahedral elements outside the well hole are outside the cave, assigning the tetrahedral elements to be the resistivity values of the bedrocks.
The method carries out local self-adaptive encryption processing on the tetrahedral elements at the cave boundary, the number of nodes is basically kept unchanged, and the complex cave boundary can be more accurately equivalent and carved, so that the accuracy of numerical simulation is ensured.
c3 treating the conformal grid through which the crack passes
Due to the extremely small opening degree of the crack, if the cross-scale mesh subdivision is carried out on the crack according to the physical size of the crack, the number of nodes can be increased sharply, and the solving speed can be increased.
Therefore, the method adopts the conformal tetrahedral elements penetrated by the cracks in parallel treatment, calculates the volume occupied by the cracks in the tetrahedral elements, and determines the conformal grid resistivity value according to the parallel conduction principle. In particular, the method comprises the following steps of,
judging whether the crack passes through the tetrahedral element, and skipping the tetrahedral element if the crack does not pass through the tetrahedral element;
if the crack passes through the tetrahedral element, the volume of the tetrahedral element occupied by the crack and the bedrock is calculated respectively, and the resistivity of the element is assigned as the parallel value of the resistivity of the crack and the bedrock. The determination steps are as follows:
the volume of the tetrahedral element is V, the volume V1 of the tetrahedral element above the fracture top interface is determined first, and then the volume V2 of the tetrahedral element above the fracture top interface is obtained, so that the tetrahedral volume V penetrated by the fracture 6fracV2-V1, as shown in fig. 10.
The V1 and the V2 are solved by splitting the fracture penetrating element into the sum of the volumes of a plurality of tetrahedrons, wherein the nodes formed by the intersection of the fracture and the tetrahedrons are only used for solving the fracture volume, and the number of the nodes is not increased.
According to the principle of double lateral logging, the element resistivity penetrated by the crack is regarded as the parallel connection of the crack and the partial volume occupied by the bedrock, and according to the parallel connection conduction principle, the element resistivity penetrated by the crack is regarded as the element resistivityWherein Rb is the resistivity of the bedrock. The embodiment of the invention carries out grid conformal and parallel processing on the cracks, avoids cross-scale grid subdivision, reduces the number of nodes and further ensures the speed of numerical simulation.
And sequentially carrying out the conformal grid treatment on all the cracks of the fracture-cavity reservoir until all the cracks are treated, and finishing the grid subdivision and resistivity assignment of the fracture-cavity reservoir at the moment.
Step c is to disperse the seam hole reservoir body to change phi into a multi-element function of the electric potential values U on a finite number of nodes, and the node potentials are respectively U1，…,UN；
And then, the extreme value of the multivariate function is obtained by using a variational method, so that a finite element equation with the node potential U as an unknown quantity can be obtained.
d assembling and solving finite element conductivity array to obtain deep and shallow lateral logging values
And finally, assembling and solving the potential value of each node after the finite element conductivity array is assembled. Acquiring potential response at the position of the monitoring electrode M, and converting the potential response into formation resistivity according to the magnitude of the emission current, namely measured logging response:
in the formula, RaIs the formation resistivity; k is the electrode coefficient of the electric logging and is respectively determined according to the depth and the lateral direction; u shapeM1To monitor the potential of the electrodes, IAThe current is supplied to the constant current electrode.
The results of the dual-laterolog simulation of the fracture-cavity reservoir model formed by combining a single cavity and a single horizontal fracture are respectively given below. A borehole is established through the fracture cavity reservoir formation model as shown in figures 2 and 3.
Assuming a bedrock resistivity of 5000 Ω. m, a mud and cavern filler resistivity of 0.1 Ω. m, and a horizontal fracture fluid resistivity of 0.1 Ω. m. The radius of the equivalent cave is 0.5m, and the opening degree of the equivalent crack is increased from 0 to 500 μm.
Fig. 11 and 12 are depth log numerical simulations of a single fracture and single cavern combined fracture-reservoir model with a wellbore through the center of the sphere and horizontal fractures through the center of the cavern provided by embodiments of the present invention.
As can be seen in fig. 11 and 12, the shallow and deep laterolog responses at the cavity location are significantly reduced in the presence of a single cavity, and dual laterologs are sensitive to the cavity through the borehole. When the crack exists and the opening degree is increased, the depth lateral logging apparent resistivity value at the crack depth position is continuously reduced. In this case, the dual laterolog response is not only influenced by the cave, but also obviously influenced by the crack, and the existence of the crack causes the dual laterolog response of the reservoir body passing through the hole of the well hole to be complicated.
Fig. 13 and 14 are simulation results of deep and shallow laterals of a fracture-cavity reservoir model of a single horizontal fracture and single cavern combination at the well side provided by an embodiment of the invention. The distance between the left boundary of the cave and the well wall is 0.25m, and the horizontal cracks pass through the center of the cave. The result shows that when a single hole beside a well exists, the deep lateral current and the shallow lateral current are difficult to penetrate through the high-resistance bedrock, so that the current flowing through the hole part is small, and the double-lateral logging response is not obvious. When the crack exists, the focusing current flows through the cave through the low-resistance crack to enable the measuring signal to be small, the depth lateral logging visual resistivity value at the crack depth position is rapidly reduced along with the increase of the crack opening degree, and the double lateral logging response of the near-well fracture-cave reservoir body is mainly controlled by the crack.
It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Claims (4)
1. A method of simulating a fracture-vug reservoir electrical logging response, comprising the steps of:
a, establishing an equivalent fracture-cavity reservoir stratum model according to block geological data, and determining basic parameters of the equivalent fracture-cavity reservoir stratum model; in the equivalent fracture-cave reservoir stratum model established in the step a:
generating equidistant flat plate cracks and crossed flat plate crack models by utilizing the equivalent crack development of the flat plate model; utilizing spherical and ellipsoidal models to obtain equivalent cave models; combining equivalent flat plate cracks and ellipsoidal caves into reservoir body models with different types of complex caves;
b, establishing a finite element functional of direct current logging response according to the equivalent fracture-cavity reservoir stratum model;
c, carrying out grid dispersion and resistivity assignment on the equivalent fracture-cave reservoir stratum model according to a finite element theory;
the step c further comprises the following steps:
c1, firstly, not considering the existence of cracks and caves, carrying out structured grid subdivision according to the borehole and a double-laterolog instrument model to generate tetrahedral elements, and assigning the resistivity of the elements in the borehole as the mud resistivity value;
c2, then carrying out local encryption processing on the cave boundary; firstly, judging whether a cave boundary passes through a tetrahedral element; if the cave boundary does not pass through the tetrahedral element, skipping the tetrahedral element; if the cave boundary passes through the tetrahedral elements, determining the number of newly-added nodes, and simultaneously dividing the tetrahedral elements into a plurality of tetrahedral elements; then judging whether the tetrahedral element is in the cave or not according to the gravity center of the tetrahedral element; if the tetrahedral elements are in the cave, assigning the tetrahedral elements as the resistivity values of the fillers in the cave; if the tetrahedral elements are outside the cave, assigning the tetrahedral elements as the resistivity values of the bedrocks;
the method comprises the following steps of dividing the tetrahedral elements into a plurality of tetrahedral elements according to the newly added nodes:
determining the number of intersection points formed by intersection of the cave boundary and the original tetrahedral elements; connecting the newly added nodes and the original nodes by taking the intersection points of the edges of the original tetrahedral elements and the cave boundary as the newly added nodes, and dividing the original tetrahedral elements into a plurality of tetrahedral elements;
the step of judging whether the tetrahedral element is in the cave or not according to the gravity center of the tetrahedral element is as follows:
calculating the gravity center of the tetrahedral elements, and then judging the distance from the gravity center to the center of the cave; if the distance value is smaller than the radius of the cave, the tetrahedral element is positioned in the cave; if the distance value is larger than the radius of the cave, the tetrahedral element is positioned outside the cave;
after judgment, if the tetrahedral elements outside the well are in the cave, assigning the tetrahedral elements as the resistivity values of the fillers in the cave; if the tetrahedral element outside the well hole is outside the cave, assigning the tetrahedral element as a bedrock resistivity value;
c3, processing the conformal grid penetrated by the crack, and judging whether the crack penetrates through the tetrahedral element; skipping tetrahedral elements if the fracture does not pass through the tetrahedral elements; if the crack penetrates through the tetrahedral element, respectively calculating the volume of the tetrahedral element occupied by the crack and the bedrock, and assigning the resistivity of the tetrahedral element as a parallel value of the resistivity of the crack and the bedrock;
the determination steps are as follows:
the volume of the tetrahedral element is V, firstly, the volume V1 of the tetrahedral element above the fracture top interface is determined, and then the volume V2 of the tetrahedral element above the fracture top interface is obtained, so that the tetrahedral volume V penetrated by the fracture is obtainedfrac＝V2-V1；
When the V1 and the V2 are obtained, the fracture penetrating element is also split into the sum of the volumes of a plurality of tetrahedrons, and the nodes formed by intersecting the fracture and the tetrahedrons are only used for obtaining the fracture volume without increasing the number of the nodes;
according to the principle of double lateral logging, the element resistivity penetrated by the crack is regarded as the parallel connection of the crack and the partial volume occupied by the bedrock;
sequentially carrying out the conformal grid treatment on all cracks of the fracture-cavity reservoir until all cracks are treated, and finishing the grid subdivision and resistivity assignment of the fracture-cavity reservoir at the moment;
d, assembling and solving the finite element conductivity array to obtain the depth lateral logging value.
2. The method of simulating a fracture-cavity type reservoir electrical logging response of claim 1, wherein the basic parameters of the equivalent fracture-cavity reservoir formation model established in step a comprise:
the size and the development position of the cave, the resistivity of a filling material in the cave, the number of cracks, the opening degree, the inclination angle of the cracks, the development position of each crack, and the resistivity of slurry filtrate and bedrock.
3. The method of simulating a fracture-cavity type reservoir body electrical logging response of claim 1, wherein the d.c. electrical logging response finite element functional equation established in step b is:
in the formula, in a cylindrical coordinate system (r, phi, z), U represents the potential, sigma is the medium conductivity, IjRepresenting the transmit electrode current, omega the solution area, UjRepresenting the potential at the electrode.
4. A method of simulating a fracture-vug type reservoir electrical logging response as claimed in claim 1 wherein the number of newly added nodes is one, two, three or four;
when a node is newly added, the tetrahedron penetrated by the cave boundary is directly decomposed into two tetrahedrons;
when two nodes are newly added, the tetrahedron penetrated by the cave boundary is respectively decomposed into three or four tetrahedrons;
when three nodes are newly added, the tetrahedron penetrated by the cave boundary is decomposed into four tetrahedron elements;
when four nodes are newly added, the tetrahedron penetrated by the cave boundary is directly decomposed into six tetrahedrons.
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| CN107229083B (en) * | 2016-03-25 | 2019-05-07 | 中国石油化工股份有限公司 | A kind of crack induction logging response simulator |
| CN107355219B (en) * | 2016-05-09 | 2020-09-04 | 中国石油化工股份有限公司 | Fractured formation model and method of use thereof |
| CN109281644B (en) * | 2017-07-21 | 2021-06-11 | 中国石油化工股份有限公司 | Induction logging crack simulation device |
| CN113738344B (en) * | 2020-05-29 | 2024-05-24 | 中国石油化工股份有限公司 | Oil-water interface depth determining method and early warning method for preventing production well water channeling |
| CN113803055B (en) * | 2020-06-11 | 2024-05-24 | 中国石油化工股份有限公司 | Oil-water interface depth determining method and early warning method for preventing production well water channeling |
| CN112415614B (en) * | 2020-11-13 | 2021-08-06 | 重庆科技学院 | Method for constructing three-dimensional fine stratum model with logging detection scale |
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| US4703279A (en) * | 1985-07-31 | 1987-10-27 | Chevron Research Company | Method of interpreting impedance distribution of an earth formation penetrated by a borehole using precursor data provided by a moving logging array having a single continuously emitting current electrode and a multiplicity of potential electrodes |
| CN103077548B (en) * | 2012-05-14 | 2015-08-26 | 中国石油化工股份有限公司 | The modeling method of fracture and vug carbonate reservoir corrosion hole Reservoir Body distributed model |
| CN103116192A (en) * | 2012-07-30 | 2013-05-22 | 中国石油化工股份有限公司 | Fissure-cave type carbonate-reservoir reservoir body modeling method |
| CN103615238B (en) * | 2013-11-07 | 2016-01-20 | 中国石油大学(华东) | A kind of cavernous formation dual laterolog physical simulating device of scaled down and experimental technique |
| CN104750896B (en) * | 2013-12-31 | 2016-07-06 | 中国石油化工股份有限公司 | A kind of fractured-cavernous carbonate reservoir method for numerical simulation |
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