CN104750896A - Numerical simulation method of fractured-vug carbonate reservoir - Google Patents

Abstract

The invention provides a numerical simulation method of a fractured-vug carbonate reservoir and belongs to the field of oil-gas field development. The method includes: 1, judging whether a representative region of the fractured-vug reservoir has fractures and caves; if not, performing single-pore medium numerical simulation to obtain a mathematical model, and going to the step 6; if yes, going to the step 2; 2, setting dimensional limits l<v1>, l<v2>, l<f1> and l<f2> of intra-medium fractures and caves of the fractured-vug reservoir; 3, according to the determined dimensional limits, dividing a medium region of the fractured-vug reservoir into small-size fractures, medium-size fractures, large-size fractures, small-size caves, medium-size caves and large-size caves according to the fractured-vug sizes l<v> and l<f>; 4, according to medium modelling rules of the fractured-vug reservoir and experimental results of representative elementary volumes, judging whether the representative elementary volumes REV<f> and REV<v> exit; if yes, going to the step 5, and if not, returning to the step 2.

Description

A kind of fractured-cavernous carbonate reservoir method for numerical simulation

Technical field

The invention belongs to oil-gas field development field, be specifically related to a kind of fractured-cavernous carbonate reservoir method for numerical simulation.

Background technology

Research Numerical Simulation Techique research starts from the thirties in 20th century, applied in petroleum industry to the fifties, start the seventies to enter commercialization stage, and the numerical reservoir simulation eighties is to perfect, supporting, large-sized multifunction integrated synthesis software is developed by leaps and bounds, enter the nineties, perfect further Research Numerical Simulation Techique, develop Double Porosity Reservoir numerical simulation technology, and develop to large-scale integrated software, stride into 21 century, it is more accurate that the development of numerical reservoir simulation more trends towards describing, computing velocity is faster, the more accurate future development of result of calculation, the models such as multi-dielectric are further developed, and parallel computation is applied in numerical reservoir simulation.In recent years, reservoir model, mesh generation and method of value solving also all achieve large increase, and numerical reservoir simulation has become oil-field development research, solves the powerful of oil-field development decision problem.Measurement oil-field development quality, prediction investment, contrast oilfield development program, evaluate improve recovery ratio method etc. in application all very extensive.

The oil and gas reserves found in the world has over half from carbonatite reservoir of oil and gas, and fractured-cavernous carbonate reservoir is as a kind of specific type wherein, also in the hydrocarbon resources in China and even the world, also occupies very large proportion.Fractured-cavernous carbonate reservoir belongs to unconventionaloil pool and hides type, and its reserves scale is large, can form large-scale oil pool, the important component part that Ye Shi world Carbonate Reservoir is produced.

Near research object is the numerical reservoir simulation of petroclastic rock during the last ten years, and its relevant theoretical and technological studies, all based on porous medium theory, has achieved huge development, defines industrialization technology application.Complicated for fracture-pore reservoir reservoir space, be mainly hole, seam, hole, and there is different combination of media in hole, seam, hole, its flowing law from analogy method because combination of media is different and different.Single Medium is mainly for pore type Carbonate Reservoir, and model and method is ripe; Dual media was just proposed by Warren-Root as far back as the sixties in 20th century, was further developed again afterwards, and had double medium model at present in the business softwares such as Eclipse, VIP, CMG, Athos and Sure by Barenblatt, Kazemi etc.On dual media basis, within 1975, Clossman establishes hole, seam, hole treble medium darcy flow model, China Feng Wen light, Ge Jiali established multi-dielectric non-darcy high speed seepage experiment in 1985, subsequently, polyphasic flow continuum theory is generalized in multi-dielectric by the people such as Wu Yushu, Kang Zhijiang, Di Yuan, propose the numerical model method of simulation fracture-pore reservoir polyphasic flow problem, but main Problems existing is at present:

1) at present to simulation theory and the Measures compare maturation of sandstone oil reservoir, be widely used in oil-gas field development both domestic and external, for reasonable, the Efficient Development of this kind of oil reservoir provide huge support.And the huge challenge in face of current oil slip-stick artist is become to the numerical simulation of fracture-pore reservoir, it is serious governs such oil reservoir Efficient Development;

2) multi-dielectric model cannot control the larger crack of fluid flow direction and scale in oil reservoir by accurate simulation, also cannot the flowing of the large-scale solution cavity inner fluid of accurate analog;

3) existing Research Numerical Simulation Techique all with porous continuous medium for theoretical foundation, with Darcy's equation, continuity equation for core numerical simulation technology.Fracture-pore reservoir flow performance is complicated, and not only there is porous continuous medium seepage flow characteristics, also there is discrete media Navier-Stokes stream feature, current technology is inapplicable.

Existing numerical reservoir simulation method, all with pore type medium for goal in research, simulation thought be all based upon on continuum theory basis.Fracture-pore reservoir Reservoir Body media type complexity (comprising matrix, dissolution pore, solution cavity, crack etc.), dimensional variation are large, and (comprise the cavity of different scale, large solution cavity internal diameter can reach tens meters; Also have the crack of different scale, not only there is micron order in its fracture aperture, also there is centimetre-sized), pattern of flow various (comprise darcy flow, high speed darcy flow, underground are freely flowed, Guan Liu etc.), current research still belongs to blank.

Summary of the invention

The object of the invention is to solve the difficult problem existed in above-mentioned prior art, a kind of fractured-cavernous carbonate reservoir method for numerical simulation is provided, realize the exact value simulation of fracture-pore reservoir, improve the numerical simulation accuracy of such oil reservoir, find the distributing position of fracture-pore reservoir remaining oil accurately, quantitatively determining the reserves abundance of oil reservoir, providing foundation for developing this kind of oil field scientifically and rationally, finally reach the object improving recovery ratio.

The present invention is achieved by the following technical solutions:

A kind of fractured-cavernous carbonate reservoir method for numerical simulation, comprising:

(1), judge that fracture-pore reservoir characterizes area fractures, whether solution cavity exists, if there is no, then adopt single hole gap dielectric value analogy method to carry out simulation and obtain mathematical model, then proceed to (6) step; If existed, then proceed to step (2);

(2) the yardstick boundary l in crack, cave in fracture-pore reservoir medium, is set _v1, l _v2, l _f1, l _f2, wherein l _v1represent small scale and mesoscale solution cavity boundary, l _v2represent mesoscale and large scale solution cavity boundary, l _f1represent small scale and mesoscale crack boundary, l _f2represent mesoscale and large scale crack boundary, wherein l _f1<l _f2, l _v1<l _v2;

(3), according to the yardstick boundary determined, according to seam hole size l _v, l _ffracture-pore reservoir areas of dielectric is divided into small scale crack, mesoscale crack, large scale crack, small scale solution cavity, mesoscale solution cavity and large scale solution cavity;

(4), criterion is set up according to the model of fracture-pore reservoir medium and characterization unit body experimental result judges its characterization unit body REV _f, REV _vwhether exist, if existed, then proceed to step (5), if there is no, then return step (2);

(5) mathematical model of each fracture-pore reservoir areas of dielectric, is set up;

(6), set up numerical model corresponding to each mathematical model, the Solving Linear that logarithm value model is corresponding, and adopt automatic history matching method correction fracture-pore reservoir model, finally the result obtained is shown.

The yardstick boundary l in crack, cave in described setting fracture-pore reservoir medium in described step (2) _v1, l _v2, l _f1, l _f2be achieved in that

Size limit is determined according to fluid flow pattern, wherein l _f1, l _v1value determine according to Physical Experiment or experience when starting, after this increase gradually; l _f2, l _v2value get the size in maximum crack in fracture-pore reservoir reservoir and maximum solution cavity size respectively when starting, after this successively decrease gradually.

Described step (3) is achieved in that

For crack: if l _f≤ l _f1, then small scale crack is divided into, if l _f1<l _f≤ l _f2, then mesoscale crack is divided into, if l _f>l _f2, then large scale crack is divided into;

For solution cavity: if l _v≤ l _v1, then small scale solution cavity is divided into, if l _v1<l _v≤ l _v2, then mesoscale solution cavity is divided into, if l _v>l _v2, then large scale solution cavity is divided into.

Criterion is set up according to the model of fracture-pore reservoir medium and characterization unit body experimental result judges its characterization unit body REV described in described step (4) _f, REV _vwhether existence is achieved in that

The extensive quantity E on the volume V of in fracture-pore reservoir areas of dielectric, be spatially divided into two parts:

E=E _Ω+E _D(3)

Wherein, E _Ωfor the extensive quantity on the Ω of space; E _dfor the extensive quantity on the D of space; V=Ω ∪ D.Space D is by m disjoint subdomain D _jcomposition, d _jon extensive quantity, represent with following formula;

$E_D=\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{E}_{D_j}---\left(4\right)$

The subdomain Ω that space Ω can intersect by 3 _kcomposition; If K is respectively: M, F, V, E _{k=M, F, V}be the extensive quantity on M, F, V respectively, and have:

E _Ω=E _M+E _F+E _V(5)

If the characterization unit body of the corresponding intension amount e of fracture-pore reservoir medium one extensive quantity E does not exist;

If make formula (3) ~ formula (5) set up by the division in step (3), and meet:

$e_K\left(x_0\right)=\underset{{\mathrm{\&Omega;}}_K\left(x_0\right)\&RightArrow;{\mathrm{\&Omega;}}_{K_0}\left(x_0\right)}{\lim }\left(\frac{E_K\left({\mathrm{\&Omega;}}_K\left(x_0\right)\right)}{{\mathrm{\&Omega;}}_K\left(x_0\right)}\right),K=M,F,V---\left(6\right)$

$e_K\left(x_0\right)=\underset{x\&RightArrow;x_0}{\lim }{e}_K\left(x\right),K=M,F,V---\left(7\right)$

Then extensive quantity E _kcorresponding intension amount e _kcharacterization unit body exist;

Formula (6) and formula (7) they are two derived limits, if these two derived limits exist, and so characterization unit body REV _f, REV _vjust exist; If these two presumptions do not exist, then corresponding characterization unit body REV _f, REV _vjust do not exist.

Described step (5) is achieved in that

For the crack in fracture-pore reservoir medium, if be large scale crack, adopt discrete fracture network model value analogy method to simulate, set up discrete fractures model mathematical model; If be mesoscale crack, adopt equivalent multi-dielectric method for numerical simulation to simulate, set up equivalent multi-dielectric mathematical model, if be small scale crack, adopt single hole gap dielectric value analogy method to carry out simulation and obtain mathematical model;

For the solution cavity in fracture-pore reservoir medium, if be large scale solution cavity, adopt coupled mode method for numerical simulation to simulate, set up coupled mode mathematical model; If be mesoscale solution cavity, adopt equivalent multi-dielectric method for numerical simulation to simulate, set up equivalent multi-dielectric mathematical model, if be small scale solution cavity, adopt single hole gap dielectric value analogy method to carry out simulation and obtain mathematical model.

Compared with prior art, the invention has the beneficial effects as follows:

(1) result of calculation utilizing the present invention to obtain and physical simulation match (Fig. 2 is exactly numerical result and physical computing result);

(2) the fracture-cavity units history matching relative error utilizing the present invention to obtain is 9.6%, and average individual well index relative error is 18.3%

(3) accurate simulation achieving the numerical simulation of such oil reservoir of methodological science of the present invention, can be applied to the fields such as the exploitation of the exploitation of fracture-pore reservoir and the underground water of this geologic structure;

(4) along with exploration and the development of Review of geologic model building techniques, this invention more can embody the advantage in its fracture-pore reservoir numerical simulation, will promote the progress of fracture-pore reservoir numerical simulation.

Accompanying drawing explanation

Fig. 1 is the step block diagram of the inventive method.

Fig. 2 is water displacing oil Physical Experiment phenomenon.

Fig. 3 is numerical reservoir simulation experiment oil saturation figure.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail:

Existing numerical reservoir simulation method, all with pore type medium for goal in research, simulation thought be all based upon on continuum theory basis.Fracture-pore reservoir Reservoir Body media type complexity (comprising matrix, dissolution pore, solution cavity, crack etc.), dimensional variation are large, and (comprise the cavity of different scale, large solution cavity internal diameter can reach tens meters; Also have the crack of different scale, not only there is micron order in its fracture aperture, also there is centimetre-sized), pattern of flow various (comprise darcy flow, high speed darcy flow, underground are freely flowed, Guan Liu etc.), current research still belongs to blank.

The present invention proposes a kind of technology path of simulation fracture-pore reservoir newly.Seam hole type calcareous type rock salt oil reservoir have reservoir space change yardstick greatly, the feature such as medium is complicated, fluid flow patterns is various, the Sand Reservoir Simulation Theory and technology of comparative maturity cannot be utilized, therefore stitch the hole numerical reservoir simulation difficult point that become our times to face and emphasis, it governs the reasonable Efficient Development of this kind of oil reservoir.For this reason, have studied characterization unit body for oil reservoir reservoir space different scale theoretical, what propose model sets up criterion.On the oil reservoir yardstick of seam hole, according to the thought frame of continuity medium, develop dual media, defined equivalent multi-dielectric theoretical; Need the problem of meticulous depiction to propose coupled mode numerical simulation technology for fluid flowing in the large-scale solution cavity of fracture-pore reservoir simultaneously; And utilize discrete fracture network model realization to the simulation of discrete large seam, fine description has been carried out to it, with the impact that accurate description crack convection cell flows in oil reservoir, the character of basement rock in comprehensive oil reservoir, establish the mathematical model of the discrete fracture network of the micro-compressible fluid of water-oil phase, and then establish the finite element numerical model of discrete fracture network.Finally according to the Three phase 3 D liquid numerical simulation device that the fracture-pore reservoir numerical simulation technology formed has been worked out, a displacement of reservoir oil by filling water process is simulated by physical simulation experiment and Numerical Experiment, the consistency checking of the result correctness of method, and pass through the simulation of fracture-pore reservoir typical unit, achieve good effect.

Carried out the numerical simulation work of fracture-pore reservoir typical unit, main simulated technological process is: 1. set up digital-to-analogue grid model, carries out alligatoring to the grid data of three-dimensional geological model; 2. according to the result of Reservoir Description, the data files such as oil reservoir basic parameter, rock and fluid PVT are set up; 3. arrange Production development data and individual well well history number scale, with daily fluid production rate and production time for controling parameters, being formed can for the history data file of software application; 4. carry out Reserve Fitting and wellblock, individual well history matching for production, in fit procedure, revise relevant parameter, to form coincidently lower actual parameter field; 5. in conjunction with fitting result, the distribution characteristics of remaining oil is analyzed.In conjunction with numerical simulation technology, simulate individual well, many wells fracture-cavity units water filling stimulation machanism, remaining oil distribution feature etc., S48 fracture-cavity units 25 mouthfuls of well numerical simulation studies, fracture-cavity units history matching relative error is 9.6%, average individual well index relative error is 18.3%, carry out the research of S48 fracture-cavity units waterflooding program, achieve good economic benefit.

In fracture-pore reservoir, fluid flowing law is different from sandstone oil reservoir, its medium dimensional variation is large, there is continuous medium and discrete media, cannot describe by a set of theory of single description sandstone oil reservoir, therefore the solution of fracture-pore reservoir numerical simulation is proposed, namely the confining method of media type is first studied, then its numerical simulation technology be suitable for is studied according to the media type of fracture-pore reservoir, i.e. coupled mode numerical simulation technology, network of fracture numerical simulation technology and equivalent multi-dielectric numerical simulation technology.

The confining method of fracture-pore reservoir media type is the basis of fracture-pore reservoir numerical simulation, the prerequisite that continuum theory is set up is that its characterization unit body exists, propose fracture-pore reservoir characterization unit body method, what define model in fracture-pore reservoir sets up criterion for this reason.

If Ω is (x ₀) volume in fracture-pore reservoir areas of dielectric, x ₀volume Ω (x ₀) barycenter.If E is the extensive quantity (fluid mass etc. that quality, void space, unit interval pass through) of this fracture-pore reservoir medium, e is the intension amount (density, factor of porosity, mass rate etc.) that this extensive quantity is corresponding.E (Ω (x ₀)) represent volume Ω (x ₀) in extensive quantity, e (x) represent some place an intension amount.

If there are following derived limits:

$e\left(x_0\right)=\underset{\mathrm{\&Omega;}\left(x_0\right)\&RightArrow;{\mathrm{\&Omega;}}_0\left(x_0\right)}{\lim }\left(\frac{E\left(\mathrm{\&Omega;}\left(x_0\right)\right)}{\mathrm{\&Omega;}\left(x_0\right)}\right)---\left(1\right)$

And E (Ω (x)) puts x ₀neighbouring change is smooth, that is:

$e\left(x_0\right)=\underset{x\&RightArrow;x_0}{\lim }e\left(x\right)---\left(2\right)$

Then Ω ₀(x ₀) being called the characterization unit body (REV) of fracture-pore reservoir medium, Continuum Methods (a kind of existing method) is set up.

But because the space scale of lash types different in fracture-pore reservoir medium is widely different, in space, the nowed forming of heterogeneous fluid is also varied, and therefore in the range scale of research, the characterization unit body of fracture-pore reservoir medium does not often exist.For addressing this problem, the present invention, the extensive quantity E on the volume V of in fracture-pore reservoir areas of dielectric, is spatially divided into two parts:

E=E _Ω+E _D(3)

Wherein, E _Ωfor the extensive quantity on the Ω of space; E _dfor the extensive quantity on the D of space; V=Ω ∪ D.Space D is by m disjoint subdomain D _jcomposition, d _jon extensive quantity.

$E_D=\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{E}_{D_j}---\left(4\right)$

The subdomain Ω that space Ω can intersect by 3 _kcomposition.If K is respectively: M, F, V, E _{k=M, F, V}be the extensive quantity on M, F, V respectively, and have:

E _Ω=E _M+E _F+E _V(5)

If the characterization unit body of the corresponding intension amount e of fracture-pore reservoir medium one extensive quantity E does not exist, then Continuum Methods is inapplicable.

If being divided by certain makes formula (3) ~ formula (5) set up, and meets:

$e_K\left(x_0\right)=\underset{{\mathrm{\&Omega;}}_K\left(x_0\right)\&RightArrow;{\mathrm{\&Omega;}}_{K_0}\left(x_0\right)}{\lim }\left(\frac{E_K\left({\mathrm{\&Omega;}}_K\left(x_0\right)\right)}{{\mathrm{\&Omega;}}_K\left(x_0\right)}\right),K=M,F,V---\left(6\right)$

$e_K\left(x_0\right)=\underset{x\&RightArrow;x_0}{\lim }{e}_K\left(x\right),K=M,F,V---\left(7\right)$

Then, extensive quantity E _kcorresponding intension amount e _kcharacterization unit body exist, Continuum Methods can be used, and need adopt equivalent multi-dielectric technology.Formula (3) ~ formula (7) is namely that criterion set up by the model of fracture-pore reservoir medium.Formula (6) and formula (7) they are two derived limits, if these two derived limits exist, and so characterization unit body REV _f, REV _vjust exist; If these two presumptions do not exist, then corresponding characterization unit body REV _f, REV _vjust do not exist.

As shown in Figure 1, the present invention is according to fracture-pore reservoir feature, characterization unit body method is adopted to obtain the technology that in different reservoir space, fluid should be taked, comprising coupled mode numerical simulation technology, network of fracture numerical simulation technology and equivalent multi-dielectric numerical simulation technology, and adopt corresponding method to study, concrete grammar and step as follows:

1, judge that fracture-pore reservoir characterizes area fractures, whether solution cavity exists, if there is no then adopt single pore media to simulate; If there is solution cavity, then proceed to step 2;

2, the yardstick boundary l in crack, cave in fracture-pore reservoir medium is set _v1, l _v2, l _f1, l _f2: l _f1, l _v1, wherein l _f1<l _f2, l _v1<l _v2;

3, according to the yardstick boundary determined, according to seam hole size l _v, l _ffracture-pore reservoir areas of dielectric is divided, for crack: l _f≤ l _f1for small scale crack, l _f1<l _f≤ l _f2for mesoscale crack, l _f>l _f2for large scale crack; For solution cavity: l _v≤ l _v1for small scale hole, l _v1<l _v≤ l _v2for mesoscale solution cavity, l _v>l _v2for large scale solution cavity;

4, in fracture-pore reservoir medium: Small-scale space intends adopting that single pore media is simulated, mesoscale region intends adopting that equivalent multi-dielectric model is simulated, Large-scale areas just needs opposite joint, hole explicit representation is simulated, and sets up criterion and characterization unit body experimental result judges its characterization unit body REV according to the model of fracture-pore reservoir medium _f, REV _vwhether exist (being exactly realized by (3) to (7) formula), if existed, then proceed to step 5, if there is no, then return step 2 adjust size boundary l _f1, l _v1(l _f1, l _v1value determine according to Physical Experiment or experience, after this increase gradually; l _f2, l _v2value get the size in maximum crack in fracture-pore reservoir reservoir and maximum solution cavity size respectively when starting, after this successively decrease gradually.)；

5, for the crack in fracture-pore reservoir medium, if be large scale crack, adopt discrete fracture network model value analogy method to simulate, set up discrete fractures model mathematical model, be intended to the impact of the discrete large fracture of fine analog on flowing; If be mesoscale crack, adopt equivalent multi-dielectric method for numerical simulation to simulate, set up equivalent multi-dielectric mathematical model, otherwise adopt single hole gap dielectric value analogy method to simulate; For the solution cavity in fracture-pore reservoir medium, if be large scale solution cavity, adopt coupled mode method for numerical simulation to simulate, set up coupled mode mathematical model, be intended to the fluid flowing of Exact calculation large groove part hole assembly; If be mesoscale solution cavity, adopt equivalent multi-dielectric method for numerical simulation to simulate, set up equivalent multi-dielectric mathematical model, otherwise adopt single hole gap dielectric value analogy method to simulate;

6, the numerical model that in establishment step 5, each mathematical model is corresponding, the Solving Linear that logarithm value model is corresponding, and (the application adopts the approximating method in existing history-matching method or the patent of applying in the past can to adopt automatic history matching method, application number such as can be adopted to be 201010199122.X, the method of patent name for providing in " a kind of method improving fracture-pore reservoir automatic history matching efficiency based on genetic algorithm ") revise fracture-pore reservoir model, finally the result obtained is shown.

In described step 5, the detailed step of described coupled mode method for numerical simulation please refer to that related application number is 201010228296.4, name is called the patent of " a kind of method of analysis mode fracture-pore reservoir fluid flowing ", only provides brief introduction herein as follows:

For the feature of fracture and vug carbonate reservoir reservoir medium complexity, first coupled mode mathematical model is set up, in Mathematical Models, have three key method difficult problems, cave stream beats the computational problem in solution cavity with two-phase flow interface tracking in seepage flow interface coupling, cave and well.By the derivation of equation, solve the method problem of three aspects.Simultaneous solution method with, by obtain based on complex dielectrics cave stream with seepage flow coupling process; Many two-dimentional single-phase incompressible fluid coupled mode equation numerical value researchs, define seam hole equivalent way, better solve seam hole grid alligatoring problem.In D beam element incompressible fluid coupled mode equation Study on numerical solution, by the thinking of simultaneous solution, solve hole, seam, hole coupling computational problem first.Meanwhile, in the fundamental research of multi-dielectric method for numerical simulation, establish the computing method in process cave, solve the hole of oil reservoir yardstick, seam, hole computational problem.

Solver uses implicit operator partitioning algorithm (the Pressure Implicit with Splittingof Operators of pressure, be called for short PISO algorithm), iterative matrix is conjugate gradient method, for symmetric matrix, the Cholesky preconditioned conjugate gradient solver (ICCG) cannoing be used up complete, unsymmetrical matrix can use Bi-CGSTAB method, also multiple grid method (Multi-GridMethod can be used for challenge, be called for short MGM), it solves more quick, achieve the technology of the flow performance in the assembly of accurate Calculation seam hole.

The detailed step of described network of fracture method for numerical simulation please refer to that application number is 201010228294.5, name is called the patent of " a kind of method analyzing the flowing of discrete fractures reservoir fluid ", only provides brief introduction herein as follows:

The complicacy of growing for fracture-pore reservoir some areas network of fracture and its strong nonuniformity, cause its flow numerical simulation research difficulty very large.Traditional continuous medium seepage theory development comparative maturity, is but difficult to the essence and the hydraulics characteristic thereof that describe Fractured rock mass discrete media.And larger Crack Control direction and the scale of fluid flowing in oil reservoir, need to adopt discrete fractures model to the every crack all physical simulations in oil reservoir, therefore, carried out discrete fracture network Numerical Method Study.Establish the mathematical model of the two and three dimensions oil-water two-phase flow of fracture-pore reservoir, utilize Finite Element Method, namely Galerkin weighted residual method is adopted to obtain the pressure of discrete fracture network numerical simulation and equivalent point " weak " form of saturation equation, define element characteristics matrix and the array of discrete fracture network numerical simulation, establish the finite element numerical model of discrete fracture network; Adopt Bowyer-Watson algorithm to realize Delaunay triangular mesh subdivision, and achieve Delaunay tetrahedron mesh generation on this basis.

By the comparative analysis of gradient method, method of conjugate gradient and Conjugate Gradient Method With Preconditioning, according to the preferred Conjugate Gradient Method With Preconditioning of the feature such as speed of convergence, demand storage space, and define the pre-conditional conjugate gradient method for solving of the finite element numerical model of discrete fracture network model.

The detailed step of described equivalent multi-dielectric method for numerical simulation please refer to that application number is 201010234800.1, name is called the patent of " a kind of method analyzing fracture-pore reservoir remaining oil distribution ", only provides brief introduction herein as follows:

For fracture and vug carbonate reservoir, dual media basis is developed multi-dielectric theoretical; Establish multi-dielectric heterogeneous fluid Darcy Flow and the swiftly flowing numerical computation method of non-darcy of simulation fracture-pore reservoir; Have studied the applicable elements with non-darcy flow at high speed simulation cave stream, determine the Approximate Simulation Method of cave stream; Propose equilibrium,transient and gravity separation supposition, determine the Approximate Simulation Method of heterogeneous fluid in huge cave; For deformable medium seepagestress coupling analysis problem, propose the numerical computation method of finite element-limited bulk mixing, suggested the simplified calculation method of multi-dielectric distortion-seepage flow coupling; Adopt finite volume method and Newton-Raphson iterative solution method, work out multi-dielectric Numerical Simulation of Multi phase kernel program.By the swiftly flowing analytic solution of the non-darcy of one dimension two-phase fluid of the analytic solution of treble medium monophasic fluid Radial Flow, derivation, one dimension saturated porous media Deformation analyses solution and indoor physical test, demonstrate above-mentioned computing method and program correctness.Based on object oriented analysis method, work out multi-dielectric model data loading routine and result of calculation analysis and processing program, with multi-dielectric numerical simulation together, define the numerical simulation software that a set of complex dielectrics three-dimensional multiphase flow is dynamic.Take Tahe 4 Oilfield as goal in research, observed by core and microcosmic description, utilize the in-situ data such as geology, well logging, collaborative seismic data volume, establishes fracture-cavity type carbonate three-dimensional geological model; And grid alligatoring research is carried out to dissimilar reservoir; In conjunction with dynamic data analysis, define the research method of Dynamic Permeability field.

Automatic history matching method in described step 7 is as follows: 1. automatic history matching technique study was subject to the attention of more and more people in recent years, and studying more is in recent years modern optimization algorithm, as evolution algorithmic, Kalman filtering, adjoint method, agent model.These methods by search volume restrictive condition (as whether can micro-, continuity, peak value etc.) constraint and do not need the feature of other supplementarys (as derivative), be not easy the impact being subject to random disturbance, its advantage is also admitted gradually.But these optimized algorithms all need repeatedly to call simulator carries out simulation trial, so algorithm optimization efficiency becomes the key issue of algorithm application.For the paper delivered the comparatively horn of plenty of Different Optimization method, but the concrete technology of algorithm realization rarely has disclosure in numerous papers.So optimization method and specific implementation technical research thereof are the Focal point and difficult points of this research.By analyzing a large amount of fitting operation example, propose new matching evaluation function (detailed process please refer to that application number is 201010199122.X, name is called the patent of " a kind of method improving fracture-pore reservoir automatic history matching efficiency based on genetic algorithm ")

Matching evaluation function has taken into full account the relative size of error, effectively eliminates the abnormal large point of error to the impact of overall assessment, can evaluate fitting result better.New matching evaluation function objective function is:

$F=\frac{1}{N\&times;K}\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{K}{\mathrm{\&Sigma;}}}|P_{\mathrm{ij}}-P_{\mathrm{ij}}^{\&prime;}|/\mathrm{Max}(P_{\mathrm{ij}}+\mathrm{\&xi;},P_{\mathrm{ij}}^{\&prime;}+\mathrm{\&xi;})$

Wherein, N is producing well number, and K is the measured data number of well, P _ijbe the actual measurement production data in the jth moment of i-th mouthful of well, P ' _ijbe the analog computation output in the jth moment of i-th mouthful of well, ξ is a very little arithmetic number.Adding ξ is in order to avoid divisor is 0 occur that division operation is abnormal.

2. by the analysis to reservoir history matching workflow and genetic algorithm feature, devise the automatic history matching algorithm process flow process based on genetic algorithm, be described below:

I initialization population;

Ii, the correspondence position of parameter read-in corresponding for current individual to simulator input file, calls simulator and carries out simulation trial;

Iii wait until simulation trial complete after yield data in reading simulator output file, and and actual measurement data contrast, use the objective function set to evaluate fitting result.If error reaches requirement forward vi to, otherwise forward iv to;

If iv has all evaluated when individuality in former generation and has forwarded v to, otherwise forwards ii to;

V uses selection, and intersect, mutation operator produces population of new generation;

Vi terminates and Output rusults.

Now just completing automatic history matching, make model more approach actual geologic model, laying a good foundation for more correctly carrying out production forecast.This completes method of the present invention.

In order to the correctness of verification method, according to numerical reservoir simulation method result of study, carry out corresponding Physical Experiment, work out corresponding numerical simulation software, namely the Physical Experiment of displacement in flooding oil has been carried out, in experiment, stuff are right-hand part is 5mm white marble, left side is 3mm white marble, injected clear water speed is 0.9L/min, model inside is full of oil, the oil of displacement from left to right, experimental result as shown in Figure 2, identical parameter is adopted to carry out numerical simulation, result as shown in Figure 3, by relatively showing that Numerical Experiment is consistent with Physical Experiment trend, thus demonstrate the correctness of method.; Be cavity in the middle of model in Fig. 2, left and right is that white marble is filled, and then carries out water displacing oil Physical Experiment and obtains this phenomenon.According to Physical Experiment model, devise numerical simulator and simulate, Fig. 3 is oil saturation figure after simulation.

In conjunction with numerical simulation technology, simulate individual well, many wells fracture-cavity units water filling stimulation machanism, remaining oil distribution feature etc., S48 fracture-cavity units 25 mouthfuls of well numerical simulation studies, fracture-cavity units history matching relative error is 9.6%, average individual well index relative error is 18.3%, carry out the research of S48 fracture-cavity units waterflooding program, achieve good economic benefit.

Present invention achieves the numerical simulation of fracture-pore reservoir, improve the numerical simulation accuracy of such oil reservoir, achieve the scientific disposal to fracture-pore reservoir, providing foundation for developing this kind of oil field scientifically and rationally, finally reach the object improving recovery ratio.

Technique scheme is one embodiment of the present invention, for those skilled in the art, on the basis that the invention discloses application process and principle, be easy to make various types of improvement or distortion, and the method be not limited only to described by the above-mentioned embodiment of the present invention, therefore previously described mode is just preferred, and does not have restrictive meaning.

Claims (5)

1. a fractured-cavernous carbonate reservoir method for numerical simulation, is characterized in that: described method comprises:

(1), judge that fracture-pore reservoir characterizes area fractures, whether solution cavity exists, if there is no, then adopt single hole gap dielectric value analogy method to carry out simulation and obtain mathematical model, then proceed to (6) step; If existed, then proceed to step (2);

(2) the yardstick boundary l in crack, cave in fracture-pore reservoir medium, is set _v1, l _v2, l _f1, l _f2, wherein l _v1represent small scale and mesoscale solution cavity boundary, l _v2represent mesoscale and large scale solution cavity boundary, l _f1represent small scale and mesoscale crack boundary, l _f2represent mesoscale and large scale crack boundary, wherein l _f1<l _f2, l _v1<l _v2;

(3), according to the yardstick boundary determined, according to seam hole size l _v, l _ffracture-pore reservoir areas of dielectric is divided into small scale crack, mesoscale crack, large scale crack, small scale solution cavity, mesoscale solution cavity and large scale solution cavity;

(4), criterion is set up according to the model of fracture-pore reservoir medium and characterization unit body experimental result judges its characterization unit body REV _f, REV _vwhether exist, if existed, then proceed to step (5), if there is no, then return step (2);

(5) mathematical model of each fracture-pore reservoir areas of dielectric, is set up;

(6), set up numerical model corresponding to each mathematical model, the Solving Linear that logarithm value model is corresponding, and adopt automatic history matching method correction fracture-pore reservoir model, finally the result obtained is shown.

2. fractured-cavernous carbonate reservoir method for numerical simulation according to claim 1, is characterized in that: the yardstick boundary l in crack, cave in the described setting fracture-pore reservoir medium in described step (2) _v1, l _v2, l _f1, l _f2be achieved in that

Size limit is determined according to fluid flow pattern, wherein l _f1, l _v1value determine according to Physical Experiment or experience when starting, after this increase gradually; l _f2, l _v2value get the size in maximum crack in fracture-pore reservoir reservoir and maximum solution cavity size respectively when starting, after this successively decrease gradually.

3. fractured-cavernous carbonate reservoir method for numerical simulation according to claim 2, is characterized in that: described step (3) is achieved in that

For crack: if l _f≤ l _f1, then small scale crack is divided into, if l _f1<l _f≤ l _f2, then mesoscale crack is divided into, if l _f>l _f2, then large scale crack is divided into;

For solution cavity: if l _v≤ l _v1, then small scale solution cavity is divided into, if l _v1<l _v≤ l _v2, then mesoscale solution cavity is divided into, if l _v>l _v2, then large scale solution cavity is divided into.

4. fractured-cavernous carbonate reservoir method for numerical simulation according to claim 3, is characterized in that: set up criterion according to the model of fracture-pore reservoir medium described in described step (4) and characterization unit body experimental result judges its characterization unit body REV _f, REV _vwhether existence is achieved in that

The extensive quantity E on the volume V of in fracture-pore reservoir areas of dielectric, be spatially divided into two parts:

E=E _Ω+E _D(3)

Wherein, E _Ωfor the extensive quantity on the Ω of space; E _dfor the extensive quantity on the D of space; V=Ω ∪ D.Space D is by m disjoint subdomain D _jcomposition, d _jon extensive quantity, represent with following formula;

$E_D=\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{E}_{D_j}---\left(4\right)$

The subdomain Ω that space Ω can intersect by 3 _kcomposition; If K is respectively: M, F, V, E _{k=M, F, V}be the extensive quantity on M, F, V respectively, and have:

E _Ω=E _M+E _F+E _V(5)

If the characterization unit body of the corresponding intension amount e of fracture-pore reservoir medium one extensive quantity E does not exist;

If make formula (3) ~ formula (5) set up by the division in step (3), and meet:

$e_K\left(x_0\right)=\underset{{\mathrm{\&Omega;}}_K\left(x_0\right)\&RightArrow;{\mathrm{\&Omega;}}_{K_0}\left(x_0\right)}{\lim }\left(\frac{E_K\left({\mathrm{\&Omega;}}_K\left(x_0\right)\right)}{{\mathrm{\&Omega;}}_K\left(x_0\right)}\right),K=M,F,V---\left(6\right)$

$e_K\left(x_0\right)=\underset{x\&RightArrow;x_0}{\lim }{e}_K\left(x\right),K=M,F,V---\left(7\right)$

Then extensive quantity E _kcorresponding intension amount e _kcharacterization unit body exist;

Formula (6) and formula (7) they are two derived limits, if these two derived limits exist, and so characterization unit body REV _f, REV _vjust exist; If these two presumptions do not exist, then corresponding characterization unit body REV _f, REV _vjust do not exist.

5. fractured-cavernous carbonate reservoir method for numerical simulation according to claim 4, is characterized in that: described step (5) is achieved in that

For the crack in fracture-pore reservoir medium, if be large scale crack, adopt discrete fracture network model value analogy method to simulate, set up discrete fractures model mathematical model; If be mesoscale crack, adopt equivalent multi-dielectric method for numerical simulation to simulate, set up equivalent multi-dielectric mathematical model, if be small scale crack, adopt single hole gap dielectric value analogy method to carry out simulation and obtain mathematical model;

For the solution cavity in fracture-pore reservoir medium, if be large scale solution cavity, adopt coupled mode method for numerical simulation to simulate, set up coupled mode mathematical model; If be mesoscale solution cavity, adopt equivalent multi-dielectric method for numerical simulation to simulate, set up equivalent multi-dielectric mathematical model, if be small scale solution cavity, adopt single hole gap dielectric value analogy method to carry out simulation and obtain mathematical model.