CN105044283B - A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic - Google Patents

Abstract

The present invention relates to a kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic, comprise the following steps: 1) set up the polymer solution effective shear rate model in rock porous media during seepage flow；2) polymer solution viscoelasticity apparent viscosity model is set up；3) injection well polymer flooding injectability evaluation model set up the condition is given；4) set up stratified reservoir injection well geological model, provide model parameter；5) injection well Fluid Control Equation, multiple zone osmotic control equation and injection well and each oil reservoir contact surface equation of continuity are set up；6) injection well and each oil reservoir boundary condition are listed；7) equation group is set up by effective shear rate model, viscoelasticity apparent viscosity model, injection well Fluid Control Equation, each oil reservoir osmotic control equation and injection well with each oil reservoir contact surface equation of continuity, solving equation group under different injection well injection pressures；8) calculate injection rate according to solving result and inject intensity, by the injectability injecting intensity evaluation injection well.

Description

A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic

Technical field

The present invention relates to a kind of injection well injectability evaluation methodology, particularly relate to a kind of use polymer flooding and develop oil fields During consider the multiple zone injection well injectability evaluation methodology of polymer viscoelastic.

Background technology

At present, polymer flooding has become as land oilfields in high water cut period and improves the major technique of recovery ratio, also becomes simultaneously Offshore oilfield improves the important means of recovery ratio.In polymer flooding heavy industrialization application process, gradually expose Technical problem, a wherein prominent problem is: injection well Severe blockage, causes injection pressure to steeply rise unreasonably, leads Causing injectability degradation, injection well cannot complete injection allocation by injection allocation ratio, even stops note.Therefore, note is assessed the most exactly Poly-well injection pressure and injectability, be one of key issue affecting polymer flooding development effectiveness and whole economic efficiency, Ensure that the enforcement aspect that testing in Bohai heavy oil fields premature polymerization thing drives is particularly important.

The polymer solution being applied to polymer flooding belongs to non-Newtonian fluid, and oil reservoir belongs to rock porous media, in research During non-Newtonian fluid rheological behaviour in porous media, typically non-Newtonian fluid is assumed to power rate fluid.But in recent years Research finds, polymer solution shows the rheological behaviour of complexity when flowing in subsurface rock porous media, along with flowing The increase of speed, carries out from Newtonian fluid to shear thinning again to the transformation of shear thickening rheological behaviour, the most not only shows Viscous effect, also shows certain buoyancy effect.But prior art not yet finds consider polymer solution Viscoelastic effect Injection well injectability evaluation methodology, cause injection pressure and the injectability that can not assess injection well exactly.

Additionally, oil reservoir may be stratified reservoir, multiple zone has anisotropism feature, the most not yet finds to examine in prior art Consider stratified reservoir and close the injection well injectability evaluation methodology under injection-molded, again result in the note that can not assess injection well exactly Enter pressure and injectability.

Summary of the invention

For the problems referred to above, it is an object of the invention to provide and a kind of consider polymer viscoelastic and multiple zone feature simultaneously Injection well injectability evaluation methodology, can quick and precisely evaluate injection well injectability, instruct injection well Water injection rate, prevent ground Layer blocks and stops the problems such as note.

For achieving the above object, the present invention takes techniques below scheme: a kind of multiple zone considering polymer viscoelastic is noted Poly-well injectability evaluation methodology, it comprises the following steps:

1) polymer solution effective shear rate model in rock porous media during seepage flow is set up；

2) polymer solution viscoelasticity apparent viscosity model is set up；

3) set up the condition of injection well polymer flooding injectability evaluation model is given；

4) according to step 3) the model set up the condition that is given, set up and be used for evaluating stratified reservoir and close injection well note under injection-molded Enter the stratified reservoir injection well geological model of ability, and provide its model parameter；

5) according to step 3) the model set up the condition that is given and step 4) the stratified reservoir injection well geological model that is given, Set up the Fluid Control Equation of injection well, the osmotic control equation of each oil reservoir and injection well and each oil reservoir contact surface seriality Equation；

6) according to step 3) the model set up the condition that is given and step 4) the stratified reservoir injection well geological model that is given, row Go out injection well and the boundary condition of multiple oil reservoir；

7) by step 4) model parameter that is given substitutes into step 1) and step 2) effective shear rate model of obtaining and gathering In polymer solution viscoelasticity apparent viscosity model, by step 6) injection well and each oil reservoir boundary condition substitute into step 5) note set up Poly-well Fluid Control Equation, each oil reservoir osmotic control equation and injection well, with each oil reservoir contact surface equation of continuity, are unified into Vertical equation group, solves flowing velocity u of injection well interpolymer solution under different injection well injection pressures_wellWith each oil Percolation flow velocity u of layer interpolymer solution_res；

8) according to step 7) solving result, be calculated injection rate Q and inject intensity q, by inject intensity q evaluate multilamellar Oil reservoir closes the injectability of injection well under injection-molded；Injecting intensity q the biggest, the injectability of injection well is the strongest.

Described step 1) in effective shear rate model be:

In formula,For polymer solution effective shear rate during seepage flow in rock porous media；C is that polymer is molten Liquid effective shear rate constant, relevant to the permeability of rock porous media and porosity, the present embodiment takes 1；n₁For polymer Solution shear Thinning Index；u_resFor polymer solution percolation flow velocity in rock porous media；K is that rock porous media oozes Rate thoroughly；k_rwFor polymer solution relative permeability；S_wFor polymer solution saturation；For rock porous media porosity.

Described step 2) in polymer solution viscoelasticity apparent viscosity model include when polymer solution flows in injection well Shear thinning apparent viscosity μ_{App, well}With polymer flow viscoelasticity apparent viscosity μ when the rock porous media_{App, res}, wherein:

${\mathrm{\μ}}_{app,well}={\mathrm{\μ}}_{\mathrm{\∞}}+({\mathrm{\μ}}_0-{\mathrm{\μ}}_{\mathrm{\∞}}){\left(1+{\left({\mathrm{\λ}}_1\stackrel{\·}{\mathrm{\γ}}\right)}^{\mathrm{\α}}\right)}^{(n_1-1)/\mathrm{\α}}$

${\mathrm{\μ}}_{app,res}={\mathrm{\μ}}_{\mathrm{\∞}}+({\mathrm{\μ}}_0-{\mathrm{\μ}}_{\mathrm{\∞}}){(1+{\left({\mathrm{\λ}}_1{\stackrel{\·}{\mathrm{\γ}}}_{eff}\right)}^{\mathrm{\α}})}^{(n_1-1)/\mathrm{\α}}+{\mathrm{\μ}}_{max}\left(1-e^{\left\{-{\left({\mathrm{\τ}}_r{\mathrm{\λ}}_2{\stackrel{\·}{\mathrm{\γ}}}_{eff}\right)}^{n_2-1}\right\}}\right)$

In formula, μ_∞For polymer solution high shear viscosity；μ₀For polymer solution zero-shear viscosity；λ₁、λ₂It is respectively poly- Polymer solution shear thinning constant and shear thickening constant；For polymer solution shear speed；α is empirical, typically takes 2；n₂For polymer solution shear thickening index；μ_maxPeak for shear degradation generation prepolymer solution viscosity；τ_rFor note Enter the slack time of fluid；E is natural logrithm.

Described step 3) in model set up the condition specifically include:

1. the viscoelastic effect of polymer solution is considered；

2. flowing in injection well pit shaft and the coupling of seepage flow in oil reservoir are considered；

3. single oil reservoir homogenizing, uniform thickness, isotropism are supposed；

4. barefoot completion, injection well is hydrodynamic force completely penetrating well, ignores skin effect；

5. injection well bottom end closure, ignores the centripetal stream of sphere of injection well bottom；

6. supposing that seepage flow is planar radial stationary flow in each oil reservoir, flow process ignores the impact of gravity and capillary force；

7. supposing that in flowing and oil reservoir, seepage flow is single-phase flow in pit shaft, polymer solution fluid is aqueous and two kinds of groups of polymer Point, and water and polymer complete miscibility；

8. suppose that the polymer solution injected is micro-compressible fluid；

9. ignore the reservoir permeability caused by the polymer Adsorption And Retention on porous media surface to decline；

10. polymer degraded in rock porous media during seepage flow is ignored；

Assuming that pit shaft in flowing and oil reservoir in flow event be isothermal process；

Do not consider the leakage between each oil reservoir.

Described step 4) in the stratified reservoir injection well geological model set up be the level, all being arranged in order from top to bottom Multiple oil reservoirs that matter, uniform thickness are circular, each oil reservoir belongs to rock porous media, closes up and down, and external boundary is constant-pressure boundary；Note is poly- Well is injected by injection well arrival end level pressure also cross the center of circle of multiple oil reservoirs, injection well bottom end closure, polymer solution；Described The model parameter of stratified reservoir injection well geological model is: injection well radius R_w, injection well degree of depth h, injection well injection pressure P_w, Each Oil reservoir radius R_ei, core intersection h_i, oil reservoir terminal pressure P_ei, inject τ slack time of fluid_ri, reservoir permeability k_i, poly- Polymer solution relative permeability k_rwi, oil reservoir porosityWherein, i=1,2 ..., represent the i-th oil reservoir respectively.

Described step 5) in set up injection well interpolymer solution Fluid Control Equation be:

$\mathrm{\ρ}({\stackrel{\→}{u}}_{well}\·\▿{\stackrel{\→}{u}}_{well})=\▿\·\{p_{well}+{\mathrm{\μ}}_{app,well}(\▿{\stackrel{\→}{u}}_{well}+{\left(\▿{\stackrel{\→}{u}}_{well}\right)}^T)\}$

Multiple oil reservoir interpolymer fluid flow governing equations are:

$\▿\·{\stackrel{\→}{u}}_{res,i}=0;{\stackrel{\→}{u}}_{res,i}=-\frac{k_i}{{\mathrm{\μ}}_{app,res,i}}\▿\·p_{res,i}(i=1,2,\mathrm{......})$

Injection well and the first oil reservoir contact surface equation of continuity be:

$\begin{array}{c}{p}_{well}=p_{res,1}\\ u_{well}=u_{res,1}\end{array}(r=R_w,0\≤z\≤h_1)$

Injection well with other each oil reservoir contact surface equation of continuity is:

$\begin{array}{c}{p}_{well}=p_{res,i}\\ u_{well}=u_{res,i}\end{array}\left(r=R_w,\underset{1}{\overset{i-1}{\Σ}}{h}_{i-1}\≤z\≤\underset{1}{\overset{i}{\Σ}}{h}_i,i=2,3,\mathrm{......}\right)$

Above-mentioned various in, ρ is the density of polymer solution, u_wellFor the flowing velocity of injection well 4 interpolymer solution, u_{Res, i}For the percolation flow velocity of i-th oil reservoir interpolymer solution, p_wellFor the pressure of injection well 4 interpolymer solution, p_{Res, i}For The pressure of i-th oil reservoir interpolymer solution, T is the temperature of polymer solution.

Described step 6) in the injection well boundary condition that obtains be:

p_well=P_w(z=h, 0≤r≤R_w)

u_well=0 (z=0,0≤r≤R_w)

The boundary condition of multiple oil reservoirs is:

p_{Res, 1}=P_e1(r=R_e1, 0≤z≤h₁)

u_{Res, 1}=0 (z=0, R_w≤r≤R_e1)

$u_{res,i}=0(z={\mathrm{\Σ}}_1^i{h}_i,R_w\≤r\≤R_{ei},i=1,2,\mathrm{......})$

$p_{res,i}=P_{ei}(r=R_{ei},{\mathrm{\Σ}}_1^{i-1}{h}_{i-1}\≤z\≤{\mathrm{\Σ}}_1^i{h}_i,i=1,2,\mathrm{......}).$

Described step 8) in the computing formula of injection rate Q be:

Q=π R_w ²u_well(z=h, 0≤r≤R_w)

The computing formula injecting intensity q is:

$q=\frac{Q}{P_w}.$

Use analysis of finite element method solve described step 7) in equation group.

The polymer solution injected is polyacrylamide solution.

Due to the fact that and take above technical scheme, it has the advantage that 1, the present invention proposes and a kind of considers polymerization Thing viscoelastic multiple zone injection well injectability evaluation methodology, characterizes the polymer of polymer viscoelastic by introducing quantification The computing formula of solution apparent viscosity, and couple flowing and seepage flow condition in oil reservoir porous media in injection well, consider heavy wool simultaneously Layer anisotropism feature, sets up stratified reservoir and closes injection well injectability evaluation model under injection-molded, it is achieved inject injection well The accurate quantitative analysis evaluation of ability, thus instruct the Water injection rate of injection well in oilfield development process, prevent formation blockage and stop note Etc. problem；2, the present invention uses analysis of finite element method to solve injection well injectability evaluation model, it is achieved quick and precisely evaluate Injection well injectability, makes the practicality of the technology of the present invention method and operability higher.

Accompanying drawing explanation

Fig. 1 is the decomposition texture schematic diagram of stratified reservoir geological model of the present invention；

Fig. 2 is the partial enlargement structural representation of stratified reservoir geological model of the present invention.

Detailed description of the invention

As a example by below using three-layer reservoir as goal in research, in conjunction with the accompanying drawings and embodiments the present invention is carried out detailed retouching State.

Accompanying drawing 1, accompanying drawing 2 hollow core arrow and filled arrows are the flow direction of polymer solution.

A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic of the present invention, including following step Rapid:

1) polymer solution effective shear rate model in rock porous media during seepage flow is set up:

In formula,For polymer solution effective shear rate during seepage flow in rock porous media；C is that polymer is molten Liquid effective shear rate constant, relevant to the permeability of rock porous media and porosity, the present embodiment takes 1；n₁For polymer Solution shear Thinning Index；u_resFor polymer solution percolation flow velocity in rock porous media；K is that rock porous media oozes Rate thoroughly；k_rwFor polymer solution relative permeability；S_wFor polymer solution saturation；For rock porous media porosity.

2) polymer solution viscoelasticity apparent viscosity model is set up:

Shear thinning when polymer solution apparent viscosity can be divided into polymer solution to flow in injection well by situation regards viscous Degree μ_{App, well}With polymer flow viscoelasticity apparent viscosity μ when the rock porous media_{App, res}, it is characterized as respectively:

${\mathrm{\μ}}_{app,well}={\mathrm{\μ}}_{\mathrm{\∞}}+({\mathrm{\μ}}_0-{\mathrm{\μ}}_{\mathrm{\∞}}){(1+{\left({\mathrm{\λ}}_1\stackrel{\·}{\mathrm{\γ}}\right)}^{\mathrm{\α}})}^{(n_1-1)/\mathrm{\α}}---\left(2\right)$

${\mathrm{\μ}}_{app,res}={\mathrm{\μ}}_{\mathrm{\∞}}+({\mathrm{\μ}}_0-{\mathrm{\μ}}_{\mathrm{\∞}}){(1+{\left({\mathrm{\λ}}_1{\stackrel{\·}{\mathrm{\γ}}}_{eff}\right)}^{\mathrm{\α}})}^{(n_1-1)/\mathrm{\α}}+{\mathrm{\μ}}_{max}(1-e^{\left\{-{\left({\mathrm{\τ}}_r{\mathrm{\λ}}_2{\stackrel{\·}{\mathrm{\γ}}}_{eff}\right)}^{n_2-1}\right\}})---\left(3\right)$

In formula, μ_∞For polymer solution high shear viscosity；μ₀For polymer solution zero-shear viscosity；λ₁、λ₂It is respectively poly- Polymer solution shear thinning constant and shear thickening constant；For polymer solution shear speed；α is empirical, typically takes 2；n₂For polymer solution shear thickening index；μ_maxPeak for shear degradation generation prepolymer solution viscosity；τ_rFor note Enter the slack time of fluid；E is natural logrithm.

From formula (3), viscoelasticity apparent viscosity μ_{App, res}Closely related with reservoir geology parameter, therefore different oil reservoirs are cohesion The viscoelasticity apparent viscosity μ of polymer solution_{App, res}It is different.

3) provide the set up the condition of injection well polymer flooding injectability evaluation model, specifically include:

1. the viscoelastic effect of polymer solution is considered；

2. flowing in injection well pit shaft and the coupling of seepage flow in oil reservoir are considered；

3. single oil reservoir homogenizing, uniform thickness, isotropism are supposed；

4. barefoot completion, injection well is hydrodynamic force completely penetrating well, ignores skin effect；

5. injection well bottom end closure, ignores the centripetal stream of sphere of injection well bottom；

6. supposing that seepage flow is planar radial stationary flow in each oil reservoir, flow process ignores the impact of gravity and capillary force；

7. supposing that in flowing and oil reservoir, seepage flow is single-phase flow in pit shaft, polymer solution fluid is aqueous and two kinds of groups of polymer Point, and water and polymer complete miscibility；

8. suppose that the polymer solution injected is micro-compressible fluid；

9. ignore the reservoir permeability caused by the polymer Adsorption And Retention on porous media surface to decline；

10. polymer degraded in rock porous media during seepage flow is ignored；

Assuming that pit shaft in flowing and oil reservoir in flow event be isothermal process；

Do not consider the leakage between each oil reservoir.

4) according to step 3) model set up the condition, set up and be used for evaluating three-layer reservoir and close injection well under injection-molded and inject energy The three-layer reservoir injection well geological model of power, and provide model parameter.

As shown in Figure 1 and Figure 2, by assumed condition 1.～Three-layer reservoir injection well geological model includes the most successively The first oil reservoir the 1, second oil reservoir 2 and the 3rd oil reservoir 3 that the level of arrangement, homogenizing, uniform thickness are circular, each oil reservoir belongs to rock porous Medium, closes up and down, and external boundary is constant-pressure boundary；Injection well 4 also cross the center of circle of three oil reservoirs, injection well 4 bottom end closure, Polymer solution is injected by injection well 4 arrival end level pressure；With injection well 4 wellbore bottom center (be also bottom the first oil reservoir 1 in The heart) it is that zero, radial distance r are pointed to outer, highly z by initial point and pointed to injection well 4 entrance by initial point and set up cylindrical-coordinate system (due to the equal isotropism of each oil reservoir, modeling need not user's parallactic angle, therefore omit), then three-layer reservoir injection well geology Each oil reservoir of model is the circular reservoir model with r=0 as radial symmetry axis, setting model parameter: injection well 4 radius R_w, Injection well 4 degree of depth h, injection well 4 injection pressure P_w, each Oil reservoir radius R_ei, core intersection h_i, oil reservoir terminal pressure P_ei, inject τ slack time of fluid_ri, reservoir permeability k_i, polymer solution relative permeability k_rwi, oil reservoir porosityWherein, i=1, 2,3, represent the first oil reservoir the 1, second oil reservoir 2 and the 3rd oil reservoir 3 respectively.

5) Fluid Control Equation of injection well 4, the osmotic control equation of three oil reservoirs and injection well 4 and three oil are set up Layer contact surface equation of continuity.

According to step 3) the model set up the condition that is given 1.～And step 4) the three-layer reservoir injection well geology that is given Model understands, and the flowing of injection well 4 interpolymer solution is controlled by Navier-Stokes (Neville-Stokes) equation, and Polymer solution flows in injection well 4 and shear thinning behavior only occurs, and its apparent viscosity is determined by shear thinning model, i.e. note is poly- The apparent viscosity of well 4 interpolymer solution is shear thinning apparent viscosity μ_{App, well}；Three oil reservoirs are rock porous media, and rock is many The seepage flow of hole medium interpolymer solution is by Darcy's law control, and polymer solution regarding during seepage flow in rock porous media Viscosity is determined by viscoelasticity apparent viscosity model, and the apparent viscosity of i.e. three oil reservoir interpolymer solution is viscoelasticity apparent viscosity μ_{App, res, i}；Meanwhile, the sidewall of injection well 4 and the contact surface of three oil reservoirs all should meet the condition of continuity.Can according to above-mentioned conclusion To draw:

Injection well 4 interpolymer solution Fluid Control Equation:

$\mathrm{\ρ}({\stackrel{\→}{u}}_{well}\·\▿{\stackrel{\→}{u}}_{well})=\▿\·\{p_{well}+{\mathrm{\μ}}_{app,well}(\▿{\stackrel{\→}{u}}_{well}+{\left(\▿{\stackrel{\→}{u}}_{well}\right)}^T)\}---\left(4\right)$

Three oil reservoir interpolymer fluid flow governing equations:

$\▿\·{\stackrel{\→}{u}}_{res,i}=0;{\stackrel{\→}{u}}_{res,i}=-\frac{k_i}{{\mathrm{\μ}}_{app,res,i}}\▿\·p_{res,i}(i=1,2,3)---\left(5\right)$

Injection well 4 and the first oil reservoir 1 contact surface equation of continuity:

$\begin{array}{c}{p}_{well}=p_{res,1}\\ u_{well}=u_{res,1}\end{array}(r=R_w,0\≤z\≤h_1)---\left(6\right)$

Injection well 4 and the second oil reservoir the 2, the 3rd oil reservoir 3 contact surface equation of continuity:

$\begin{array}{c}{p}_{well}=p_{res,i}\\ u_{well}=u_{res,i}\end{array}(r=R_w,{\Σ}_1^{i-1}{h}_{i-1}\≤z\≤{\Σ}_1^i{h}_i,i=2,3)---\left(7\right)$

Above-mentioned various in, ρ is the density of polymer solution, u_wellFor the flowing velocity of injection well 4 interpolymer solution, u_{Res, i}For the percolation flow velocity of i-th oil reservoir interpolymer solution, p_wellFor the pressure of injection well 4 interpolymer solution, p_{Res, i}For The pressure of i-th oil reservoir interpolymer solution, T is the temperature of polymer solution.

6) according to step 3) the model set up the condition that is given and step 4) the three-layer reservoir injection well geological model that is given, row Go out injection well 4 boundary condition and the boundary condition of three oil reservoirs.

As in figure 2 it is shown, three-layer reservoir injection well geological model is with r=0 as axis of symmetry, injection well 4 arrival end level pressure is injected Polymer solution, injection well 4 bottom end closure, then injection well 4 boundary condition is:

p_well=P_w(z=h, 0≤r≤R_w) (8)

u_well=0 (z=0,0≤r≤R_w)

Oil reservoir is lower on the whole is closed boundary, does not consider the leakage between each oil reservoir, and external boundary is constant-pressure boundary, Then the boundary condition of three oil reservoirs is:

p_{Res, 1}=P_e1(r=R_e1, 0≤z≤h₁) (9)

u_{Res, 1}=0 (z=0, R_w≤r≤R_e1)

$\begin{array}{c}{u}_{res,i}=0(z={\Σ}_1^i{h}_i,R_w\≤r\≤R_{ei},i=1,2,3)\\ p_{res,i}=P_{ei}(r=R_{ei},{\Σ}_1^{i-1}{h}_{i-1}\≤z\≤{\Σ}_1^i{h}_i,i=1,2,3)\end{array}---\left(10\right)$

7) model parameter and boundary condition are substituted into step 2) formula that is given and step 5) in the equation set up, simultaneous is asked Solving equations.

The geologic parameter of Polymer Solution Property parameter and i-th oil reservoir is substituted in formula (1), (2), (3), obtains the The effective shear rate of polymer solution of i oil reservoirShear thinning apparent viscosity μ_{App, well, i}With viscoelasticity apparent viscosity μ_{App, res, i}, wherein i=1,2,3；By step 6) boundary condition (8)～(10) and Polymer Solution Property parameter and three The geologic parameter of oil reservoir substitutes in equation (4)～(7), is unified into vertical equation group；In different injection well 4 injection pressures P_wUnder ask Flowing velocity u of any position polymer solution in solution injection well 4_wellWith any position polymer solution in three oil reservoirs Percolation flow velocity u_{Res, i}。

8) according to step 7) solving result, calculate injection rate Q and inject intensity q, by inject intensity q evaluate three-layer reservoir Close the injectability of injection well under injection-molded.

Under conditions of injection pressure is less than formation rock fracture pressure, injection well injectability can be with under unit pressure reduction Injection rate i.e. inject intensity q and represent, injecting intensity q can be by injection rate Q and injection pressure P_wRelation obtain.

Wherein, the computing formula of injection rate Q is:

Q=π R_w ²u_well(z=h, 0≤r≤R_w) (11)

The computing formula injecting intensity q is:

$q=\frac{Q}{p_w}---\left(12\right)$

Inject intensity q the biggest, then it represents that the injectability of injection well is the strongest.

In above-described embodiment, step 7) in solving equation group analysis of finite element method can be used to solve.Owing to polymer is molten Liquid is non-Newtonian fluid, and polymer solution apparent viscosity is the nonlinear function of shear rate, considers the viscous of polymer solution simultaneously Bounce effect, the analytical expression solving injectability will be more difficult；And according to setting up three-layer reservoir injection well geological model Mathematical model, uses analysis of finite element method to solve, and can quickly obtain different injection pressure P of injection well 4_wLower injection well 4 is cohesion Flowing velocity u of polymer solution_wellPercolation flow velocity u with three oil reservoir interpolymer solution_{Res, i}Numerical solution, thus noted Enter amount Q and injection pressure P_wRelation, and then obtain inject intensity q.

In above-described embodiment, the polymer solution of injection is polyacrylamide (Hydrolyzed Polyacryamide, contracting Write HPAM) solution.

The present invention is possible not only to be widely used in oil field development research field, it is also possible to being widely used in other has with seepage flow In the research field closed or as reference, such as Groundwater movement research etc..

The various embodiments described above are merely to illustrate the present invention, the structure of the most each parts, arrange position and connected mode etc. thereof All can be varied from, every equivalents carried out on the basis of technical solution of the present invention and improvement, the most should not arrange In addition in protection scope of the present invention.

Claims (8)

1. considering a multiple zone injection well injectability evaluation methodology for polymer viscoelastic, it comprises the following steps:

1) set up the polymer solution effective shear rate model in rock porous media during seepage flow, wherein, effectively shear speed Rate model is:

In formula,For polymer solution effective shear rate during seepage flow in rock porous media；C is that polymer solution has Effect shear rate constant, takes 1；n₁For polymer solution shear Thinning Index；u_resFor polymer solution in rock porous media Percolation flow velocity；K is rock porous media permeability；k_rwFor polymer solution relative permeability；S_wSaturated for polymer solution Degree；For rock porous media porosity；

2) setting up polymer solution viscoelasticity apparent viscosity model, polymer solution viscoelasticity apparent viscosity model includes polymer solution Shear thinning apparent viscosity μ when flowing in injection well_app,wellRegard viscous with polymer flow viscoelasticity when the rock porous media Degree μ_app,res, wherein:

${\mathrm{\μ}}_{app,well}={\mathrm{\μ}}_{\mathrm{\∞}}+({\mathrm{\μ}}_0-{\mathrm{\μ}}_{\mathrm{\∞}}){(1+{\left({\mathrm{\λ}}_1\stackrel{\·}{\mathrm{\γ}}\right)}^{\mathrm{\α}})}^{(n_1-1)/\mathrm{\α}}$

${\mathrm{\μ}}_{app,res}={\mathrm{\μ}}_{\mathrm{\∞}}+({\mathrm{\μ}}_0-{\mathrm{\μ}}_{\mathrm{\∞}}){(1+{\left({\mathrm{\λ}}_1{\stackrel{\·}{\mathrm{\γ}}}_{eff}\right)}^{\mathrm{\α}})}^{(n_1-1)/\mathrm{\α}}+{\mathrm{\μ}}_{max}(1-e^{\{-{\left({\mathrm{\τ}}_r{\mathrm{\λ}}_2{\stackrel{\·}{\mathrm{\γ}}}_{eff}\right)}^{n_2-1}\}})$

In formula, μ_∞For polymer solution high shear viscosity；μ₀For polymer solution zero-shear viscosity；λ₁、λ₂It is respectively polymer Solution shear desaturation constant and shear thickening constant；For polymer solution shear speed；α is empirical, takes 2；n₂For polymerization Thing solution shear thickening index；μ_maxPeak for shear degradation generation prepolymer solution viscosity；τ_rFor injecting the pine of fluid The relaxation time；E is natural logrithm；

3) set up the condition of injection well polymer flooding injectability evaluation model is given；

4) according to step 3) the model set up the condition that is given, set up and be used for evaluating stratified reservoir and close injection well under injection-molded and inject energy The stratified reservoir injection well geological model of power, and provide its model parameter；

5) according to step 3) the model set up the condition that is given and step 4) the stratified reservoir injection well geological model that is given, set up The Fluid Control Equation of injection well, the osmotic control equation of each oil reservoir and injection well and each oil reservoir contact surface seriality side Journey；

6) according to step 3) the model set up the condition that is given and step 4) the stratified reservoir injection well geological model that is given, list note Poly-well and the boundary condition of multiple oil reservoir；

7) by step 4) model parameter that is given substitutes into step 1) and step 2) effective shear rate model of obtaining and polymer In solution viscoelasticity apparent viscosity model, by step 6) injection well and each oil reservoir boundary condition substitute into step 5) injection well set up In Fluid Control Equation, each oil reservoir osmotic control equation and injection well and each oil reservoir contact surface equation of continuity, it is unified into cube Journey group, solves flowing velocity u of injection well interpolymer solution under different injection well injection pressures_wellWith in each oil reservoir Polymer solution percolation flow velocity u in rock porous media_res；

8) according to step 7) solving result, be calculated injection rate Q and inject intensity q, by inject intensity q evaluate stratified reservoir Close the injectability of injection well under injection-molded；Injecting intensity q the biggest, the injectability of injection well is the strongest.

A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic the most as claimed in claim 1, its Be characterised by, described step 3) in model set up the condition specifically include:

1. the viscoelastic effect of polymer solution is considered；

2. flowing in injection well pit shaft and the coupling of seepage flow in oil reservoir are considered；

3. single oil reservoir homogenizing, uniform thickness, isotropism are supposed；

4. barefoot completion, injection well is hydrodynamic force completely penetrating well, ignores skin effect；

5. injection well bottom end closure, ignores the centripetal stream of sphere of injection well bottom；

6. supposing that seepage flow is planar radial stationary flow in each oil reservoir, flow process ignores the impact of gravity and capillary force；

7. supposing that in flowing and oil reservoir, seepage flow is single-phase flow in pit shaft, polymer solution fluid is aqueous and two kinds of components of polymer, And water and polymer complete miscibility；

8. suppose that the polymer solution injected is micro-compressible fluid；

9. ignore the reservoir permeability caused by the polymer Adsorption And Retention on porous media surface to decline；

10. polymer degraded in rock porous media during seepage flow is ignored；

Assuming that pit shaft in flowing and oil reservoir in flow event be isothermal process；

Do not consider the leakage between each oil reservoir.

A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic the most as claimed in claim 1, its Be characterised by, described step 4) in the stratified reservoir injection well geological model set up be the level, all being arranged in order from top to bottom Multiple oil reservoirs that matter, uniform thickness are circular, each oil reservoir belongs to rock porous media, closes up and down, and external boundary is constant-pressure boundary；Note is poly- Well is injected by injection well arrival end level pressure also cross the center of circle of multiple oil reservoirs, injection well bottom end closure, polymer solution；Described The model parameter of stratified reservoir injection well geological model is: injection well radius R_w, injection well degree of depth h, injection well injection pressure P_w, Each Oil reservoir radius R_ei, core intersection h_i, oil reservoir terminal pressure P_ei, inject τ slack time of fluid_ri, reservoir permeability k_i, poly- Polymer solution relative permeability k_rwi, oil reservoir porosityWherein, i=1,2 ..., represent the i-th oil reservoir respectively.

A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic the most as claimed in claim 3, its Be characterised by, described step 5) in set up injection well interpolymer solution Fluid Control Equation be:

$\mathrm{\ρ}({\stackrel{\→}{u}}_{well}\·\▿{\stackrel{\→}{u}}_{well})=\▿\·\{p_{well}+{\mathrm{\μ}}_{app,well}(\▿{\stackrel{\→}{u}}_{well}+{\left(\▿{\stackrel{\→}{u}}_{well}\right)}^T)\}$

Multiple oil reservoir interpolymer fluid flow governing equations are:

$\▿\·{\stackrel{\→}{u}}_{res,i}=0;{\stackrel{\→}{u}}_{res,i}=-\frac{k_i}{{\mathrm{\μ}}_{app,res,i}}\▿\·p_{res,i},(i=1,2,......)$

Injection well and the first oil reservoir contact surface equation of continuity be:

$\begin{array}{c}{p}_{well}=p_{res,1}\\ u_{well}=u_{res,1}\end{array},(r=R_w,0\≤z\≤h_1)$

Injection well with other each oil reservoir contact surface equation of continuity is:

$\begin{array}{c}{p}_{well}=p_{res,i}\\ u_{well}=u_{res,i}\end{array},(r=R_w,\underset{1}{\overset{i-1}{\Σ}}{h}_{i-1}\≤z\≤\underset{1}{\overset{i}{\Σ}}{h}_i,i=2,3,......)$

Above-mentioned various in, ρ is the density of polymer solution, u_wellFor the flowing velocity of injection well interpolymer solution, u_res,iFor The percolation flow velocity of i-th oil reservoir interpolymer solution, p_wellFor the pressure of injection well interpolymer solution, p_res,iFor i-th oil The pressure of layer interpolymer solution, T is the temperature of polymer solution.

A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic the most as claimed in claim 4, its Be characterised by, described step 6) in the injection well boundary condition that obtains be:

p_well=P_w(z=h, 0≤r≤R_w)

u_well=0 (z=0,0≤r≤R_w)

The boundary condition of multiple oil reservoirs is:

p_res,1=P_e1(r=R_e1,0≤z≤h₁)

u_res,1=0 (z=0, R_w≤r≤R_e1)

$\begin{array}{c}{u}_{res,i}=0\left(z={\mathrm{\Σ}}_1^i{h}_i,R_w\≤r\≤R_{ei},i=1,2,......\right)\\ p_{res,i}=P_{ei}\left(r=R_{ei},{\mathrm{\Σ}}_1^{i-1}{h}_{i-1}\≤z\≤{\mathrm{\Σ}}_1^i{h}_i,i=1,2,......\right)\end{array}.$

A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic the most as claimed in claim 5, its Be characterised by, described step 8) in the computing formula of injection rate Q be:

Q=π R_w ²u_well(z=h, 0≤r≤R_w)

The computing formula injecting intensity q is:

$q=\frac{Q}{P_w}.$

A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic the most as claimed in claim 1, its Be characterised by, use analysis of finite element method solve described step 7) in equation group.

A kind of multiple zone injection well injectability evaluation methodology considering polymer viscoelastic the most as claimed in claim 1, its Being characterised by, the polymer solution of injection is polyacrylamide solution.