CN105089612A - Determining method for distance of well-drain and length of pressure break of low penetration oil reservoir artificial fracture - Google Patents

Abstract

The invention provides a determining method for a distance of well-drain and the length of a pressure break of low penetration oil reservoir artificial fracture. The determining method comprises the following steps of first, establishing a well yield formula under a non-darcy flow condition, second, establishing water drive sweeping efficiency calculating formula of different well patterns under the non-darcy flow condition, third, drawing matching plates of different well distances, well-drain distances and pressure-break lengths of a target oil reservoir based on the water drive sweeping efficiency calculating formula, and fourth, evaluating a reservoir stratum use condition of the reservoir stratum, optimizing the well-drain distance and optimizing the matching pressure-break length according to the matching plates of the different well distances, well-drain distances and pressure-break lengths in the third step. Optimized combination between pressure-break half length and the well-drain distance can be achieved when water drive sweeping efficiency and economic and rational well-drain distance of the target oil reservoir are determined; and the method requires less parameters, quick calculation and strong application.

Description

Low-permeability oil deposit man-made fracture pressure-break length and well array are apart from defining method

Technical field

The present invention relates to oil field development technical field, particularly relate to a kind of low-permeability oil deposit man-made fracture pressure-break length with well array apart from defining method.

Background technology

Low permeability oil reservoirs of Shengli petroliferous area aboundresources, but oil reservoir poor quality (buried depth is large, reservoir properties is poor, pore throat is tiny, reservoir thickness thinning), present the situation that single well productivity is low, water injection capacity is low, often need artificial fracturing method to improve single well productivity and injectability.But in waterflooding extraction process, because man-made fracture and well spacing array pitch lack the adaptive optimization method of system, development effectiveness is subject to restriction in various degree.Such as, Shengli Oil Field carried out waterflooding extraction test at dam, hyposmosis beach sand oil reservoirs such as 4 pieces, beam, 8 pieces, beam, Fan 144, but due to man-made fracture and well spacing, to reject matching poor, after water filling, oil well takes effect slowly, the rate that takes effect only 52%, effective development degree is low, and development effectiveness is poor.Be exactly mainly micro-judgment in the adaptive optimization of man-made fracture in the past, subjectivity was strong, lacked operating procedure that is clear and definite, reliable, science.We have invented a kind of new low-permeability oil deposit man-made fracture pressure-break length and well array distance defining method for this reason, solve above technical problem.

Summary of the invention

The object of this invention is to provide the water drive sweep efficiency design formulas of different well pattern form under a kind of non-darcy flow condition of setting up of deriving, descend long the and well array distance defining method of the low-permeability oil deposit man-made fracture pressure-break of man-made fracture and array pitch adapter combination based on this.

Object of the present invention realizes by following technical measures: low-permeability oil deposit man-made fracture pressure-break length and well array are apart from defining method, this low-permeability oil deposit man-made fracture pressure-break is long to be comprised apart from defining method with well array: step 1, sets up the formula of well yield under non-darcy flow condition; Step 2, the water drive sweep efficiency design formulas of different well pattern form under setting up non-darcy flow condition; Step 3, utilizes water drive sweep efficiency design formulas, and the different well spacing of drafting target reservoir, array pitch mate plate with fracturing fracture; And step 4, mate plate according to the different well spacings obtained in step 3, array pitch with fracturing fracture, the reservoir evaluating such reservoir is employed situation and is carried out the optimization of well spacing array pitch and the long coupling of pressure-break preferably.

Object of the present invention also realizes by following technical measures:

In step 1, a note one is adopted unit well yield formula and is:

$q={\∫}_0^{{\mathrm{\α}}_1}\frac{\frac{\mathrm{kh}}{\mathrm{\μ}}(P_i-P_w-\mathrm{\λ}(\frac{\mathrm{\ωd}(\sin \mathrm{\α}+\sin )}{\sin (\mathrm{\α}+\mathrm{\β})}-2r_w))}{\ln \left(\frac{\mathrm{\ω}d\sin \mathrm{\β}}{r_w\sin \left(\text{\α+\β}\right)}\right)+\frac{{\mathrm{\α}}_m}{{\mathrm{\β}}_m}\ln \left(\frac{\mathrm{\ω}d\sin \mathrm{\α}}{r_w\sin (\mathrm{\α}+\mathrm{\β})}\right)}\mathrm{d\α}$

In formula: q is flow, cm ³/ s; K is reservoir permeability, 10 ^-3μm ²; H is effective thickness, m; μ is FFV, mPas; P _ifor water injection well bottomhole injection pressure, MPa; Pw is extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m; α is Injection Well angle, (°); β is oil well angle, (°), r _wfor well radius; α _mand β _mfor the angle of computing unit, (°), ω is length factor, α ₁for the maximum angle of computing unit, (°).

In step 2, water drive sweep efficiency is the area that arrives of water filling energy displacement and the ratio of whole cellar area, adopts according to a note one angle [alpha] that unit well yield formula obtains maximum Injection Well and the producing well can employed when well yield is zero ₀, β ₀, as shown in the formula:

$P_i-P_w-\mathrm{\λ}\frac{\mathrm{\ωd}(\sin {\mathrm{\α}}_0+\sin {\mathrm{\β}}_0)}{\sin ({\mathrm{\α}}_0+{\mathrm{\β}}_0)}=0$

Thus determining water drive sweep efficiency, in formula: Pi is water injection well bottomhole injection pressure, MPa; Pw is extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m.

In step 2, for square Five-point method pattern, water drive sweep efficiency design formulas is as follows:

Water drive sweep efficiency=tan α

Wherein, in above formula, parameter is obtained by Solving Equations below:

$(P_i-P_w-\mathrm{\λ}\frac{d}{\cos \mathrm{\α}})=0$

In formula: Pi is water injection well bottomhole injection pressure, MPa; Pw is extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m; α is Injection Well angle, (°).

In step 2, for rectangular pattern, water drive sweep efficiency design formulas is:

Wherein, in above formula, parameter is obtained by Solving Equations below:

(1) $\begin{array}{c}\mathrm{tg}{\mathrm{\α}}_1=\frac{L-L_2}{d},{\mathrm{\α}}_1=\mathrm{arctg}\frac{L-L_2}{d},{\mathrm{\β}}_1=\frac{\mathrm{\π}}{2}-{\mathrm{\α}}_1,d_1=\sqrt{d^2+{(L-L_2)}^2}\\ (P_i-P_w-\mathrm{\λ}\left(\frac{d_1(\sin \mathrm{\α}+\sin )}{\sin (\mathrm{\α}+\mathrm{\β})}\right))=0,\mathrm{\β}=\frac{{\mathrm{\β}}_1}{{\mathrm{\α}}_1}\mathrm{\α}\end{array}$

(2) $\begin{array}{c}\mathrm{tg}{\mathrm{\α}}_2=\frac{d}{L-L_1},{\mathrm{\α}}_2=\mathrm{arctg}\frac{d}{L-L_1},{\mathrm{\β}}_2=\frac{\mathrm{\π}}{2}-{\mathrm{\α}}_2,d_2=\sqrt{d^2+{(L-L_1)}^2}\\ (P_i-P_w-\mathrm{\λ}\left(\frac{d_2(\sin \mathrm{\α}+\sin )}{\sin (\mathrm{\α}+\mathrm{\β})}\right))=0,\mathrm{\β}=\frac{{\mathrm{\β}}_2}{{\mathrm{\α}}_2}\mathrm{\α}\end{array}$

(3) $\begin{array}{c}{L}_2=m{L}_1,m\≠1,d_1=\sqrt{{d_1}^2+{(1-m)}^2{l}^2-2d_1(1-m)l\cos {\mathrm{\α}}_l},{\mathrm{\α}}_l=\frac{\mathrm{\π}}{2}-{\mathrm{\α}}_1\\ \frac{\mathrm{kh}}{\mathrm{\μ}}(P_i-P_w-\mathrm{\λ}{d}_1)=0\end{array}$

In formula: P _ifor water injection well bottomhole injection pressure, MPa; P _wfor extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m; α is Injection Well angle, (°); β is oil well angle, (°); α _mand β _mfor the angle of computing unit, (°); r _wfor well radius, m; d ₁for well is to the distance of oil well crack end, m; d ₂for oil well is to the distance of well crack end, m; △ t is the width that arbitrary stream pipe sewed on by well, m; M is that oil well seam length stitches the ratio of length with well, zero dimension; d _lfor well crack is to the distance in oil well crack, m; α ₁, β ₁, β ₂, α ₁for the maximum angle of computing unit, (°).

This low-permeability oil deposit man-made fracture pressure-break is long also to be comprised apart from defining method with well array, and after step 2, obtain target reservoir known parameters, needing gets parms comprises target reservoir permeability, md; Oil reservoir free-boundary problem, MPa/m; Water injection well injection pressure, Mpa; Extraction well flowing bottomhole pressure (FBHP), MPa.

In the step obtaining target reservoir known parameters, the well testing of evaluating objects block, well logging or core analyzing data calculate target reservoir permeability; Evaluating objects block rock core free-boundary problem testing experiment, obtains oil reservoir free-boundary problem; In conjunction with oil reservoir and site technique determination target block Reasonable Injection well injection pressure and extraction well flowing bottomhole pressure (FBHP).

Low-permeability oil deposit man-made fracture pressure-break length in the present invention and well array distance defining method, desired parameters is few, calculating is quick, application is strong, be particularly suitable for development of low-permeability oil reservoir early stage, under the method is included in oil reservoir target water drive sweep efficiency and economic and reasonable well spacing known conditions, determine that pressure break dummy joint is long, the optimum combination of array pitch two parameters.The method relates to important component part in the programming of LOW PERMEABILITY OILFIELD DEVELOPMENT oil reservoir---man-made fracture and the adaptive optimizing research of well spacing array pitch under different well pattern condition, the low-permeability oil deposit that this invention is developed mainly for artificial fracturing, the water drive sweep efficiency design formulas of different well pattern form under establishing non-darcy flow condition by theory deduction, proposes man-made fracture and array pitch adapter combination method under different well pattern condition based on this.The water drive sweep efficiency design formulas of different well pattern form under the non-darcy flow condition that the method is set up based on deriving, Method And Principle is as follows: formula shows, the water drive sweep efficiency of the different well pattern of non-darcy flow is except geology static parameter, determined by pressure break dummy joint length, well spacing, array pitch, free-boundary problem and injection production pressure difference five development parameters, the water drive sweep efficiency of same target can be realized by the various combination of five parameters; To known oil reservoir in well pattern, well spacing, starting pressure, injection production pressure difference determination situation, the water drive sweep efficiency of same target can be realized by multiple combination that is long by pressure break dummy joint, array pitch two parameters, such as under known pressure break dummy joint elongate member, determine reasonable array pitch, vice versa.Low-permeability oil deposit man-made fracture pressure-break length in the present invention and well array distance defining method, need parameter few, calculate fast, application is strong, be particularly suitable for development of low-permeability oil reservoir early stage, under the method is included in oil reservoir target water drive sweep efficiency known conditions, by the various combination of pressure break dummy joint length, array pitch two parameters.

Accompanying drawing explanation

Fig. 1 is low-permeability oil deposit man-made fracture pressure-break of the present invention length and the flow chart of well array apart from a specific embodiment of defining method;

Fig. 2 is that a note one adopts cell schematics;

Fig. 3 is water drive sweep efficiency schematic diagram;

Fig. 4 is man-made fracture and rectangular pattern schematic diagram;

Fig. 5 is pressure break dummy joint long 120m rectangular pattern well spacing array pitch plate;

Fig. 6 is pressure break dummy joint long 160m rectangular pattern well spacing array pitch plate;

Fig. 7 is pressure break dummy joint long 200m rectangular pattern well spacing array pitch plate.

Detailed description of the invention

For making above and other object of the present invention, feature and advantage can become apparent, cited below particularly go out preferred embodiment, and coordinate institute's accompanying drawings, be described in detail below.

As shown in Figure 1, Fig. 1 is the flow chart of low-permeability oil deposit man-made fracture of the present invention and well spacing array pitch defining method.

In step 101, set up the formula of well yield under non-darcy flow condition.Assumed condition: (l) fluid is single-phase homogeneous liquid; (2) porous media is not considered; (3) stable percolation; (4) flow event is isothermal; (5) stratum homogeneous.

Streamline is the route that fluid particle is followed when producing well moves from Injection Well, is called " stream pipe " with the district that two streamlines are border.Arbitrary not with parallel face, stream pipe side by the part area flowing pipe and intercepts, so-called stream tube section, stream pipe has following character: flowing pipe can not intersect; The shape of stream pipe and position, do not change in time when Steady Flow, and when unsteadiness flows, may change in time; Stream pipe can not in flow field internal interrupt.Suppose to be made up of a series of stream pipe between oil-water well, appoint and get a flooding unit (containing a water injection well and a producing well), as Fig. 2, well radius r _w; Oil-water well distance is d: get first-class pipe infinitesimal as shown in the figure, and stream pipe center line X is by X ₁and X ₂composition, X ₁: AD, X ₂: BD; Angle step gets △ α respectively, and △ β, ω are length factor.

Derived can be obtained by elementary geometry:

$X_1=\frac{\mathrm{\ω}d\sin \mathrm{\β}}{\sin (\mathrm{\α}+\mathrm{\β})},X_2=\frac{\mathrm{\ω}d\sin \mathrm{\α}}{\sin (\mathrm{\α}+\mathrm{\β})}---\left(1\right)$

Formula (1) can be converted to:

$\mathrm{\Δq}\frac{\mathrm{d\ξ}}{A\left(\mathrm{\ξ}\right)}=\frac{k}{\mathrm{\μ}}(\mathrm{dp}-\mathrm{\λd\ξ})---\left(2\right)$

Both sides are again along streamline integration:

$\mathrm{\Δq}=\frac{\underset{X}{\∫}\frac{k}{\mathrm{\μ}}(\mathrm{dp}-\mathrm{\λd\ξ})}{\underset{X}{\∫}\frac{\mathrm{d\ξ}}{A\left(\mathrm{\ξ}\right)}}=\frac{\frac{k}{\mathrm{\μ}}(P_i-P_w-\underset{X}{\∫}\mathrm{\λd\ξ})}{\underset{X}{\∫}\frac{\mathrm{d\ξ}}{A\left(\mathrm{\ξ}\right)}}---\left(3\right)$

Formula (3) is launched and substitutes into (2):

$\mathrm{\Δq}=\frac{\frac{k}{\mathrm{\μ}}(P_i-P_w-\underset{X}{\∫}\mathrm{\λd\ξ})}{\underset{X}{\∫}\frac{\mathrm{d\ξ}}{A\left(\mathrm{\ξ}\right)}}=\frac{\frac{k}{\mathrm{\μ}}(P_i-P_w-\mathrm{\λ}\left(\right))}{\underset{X}{\∫}\frac{\mathrm{d\ξ}}{A\left(\mathrm{\ξ}\right)}}---\left(4\right)$

For all angles relation, easily draw:

$\mathrm{\Δ\β}=\frac{{\mathrm{\β}}_m}{{\mathrm{\α}}_m}\mathrm{\Δ\α},\mathrm{\β}=\frac{{\mathrm{\β}}_m}{{\mathrm{\α}}_m}\mathrm{\α}---\left(5\right)$

Formula (5) is substituted into formula (4):

$\mathrm{\Δq}=\frac{\frac{k}{\mathrm{\μ}}(P_i-P_w-\mathrm{\λ}(X_1+X_2-2r_w))}{\frac{1}{2\mathrm{htg}\frac{\mathrm{\Δ\α}}{2}}{\∫}_{r_w}^{X_1}\frac{\mathrm{d\ξ}}{{\mathrm{\ξ}}_1}+\frac{1}{2\mathrm{htg}\frac{\mathrm{\Δ\β}}{2}}{\∫}_{r_w}^{X_2}\frac{\mathrm{d\ξ}}{{\mathrm{\ξ}}_2}}---\left(6\right)$

Carry out abbreviationization to above formula to lead to, and after crossing finding limit and integration:

$q={\∫}_0^{{\mathrm{\α}}_1}\frac{\frac{\mathrm{kh}}{\mathrm{\μ}}(P_i-P_w-\mathrm{\λ}(\frac{\mathrm{\ωd}(\sin \mathrm{\α}+\sin )}{\sin (\mathrm{\α}+\mathrm{\β})}-2r_w))}{\ln \left(\frac{\mathrm{\ω}d\sin \mathrm{\β}}{r_w\sin \left(\text{\α+\β}\right)}\right)+\frac{{\mathrm{\α}}_m}{{\mathrm{\β}}_m}\ln \left(\frac{\mathrm{\ω}d\sin \mathrm{\α}}{r_w\sin (\mathrm{\α}+\mathrm{\β})}\right)}\mathrm{d\α}---\left(7\right)$

Formula (7) is exactly that a note one adopts unit well yield formula.

In formula: q is flow, cm ³/ s; K is reservoir permeability, 10 ^-3μm ²; H is effective thickness, m; μ is FFV, mPas; P _ifor water injection well bottomhole injection pressure, MPa; Pw is extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m; α is Injection Well angle, (°); β is oil well angle, (°), r _wfor well radius; α _mand β _mfor the angle of computing unit, (°), ω is length factor; α ₁for the maximum angle of computing unit, (°).Flow process enters into step 102.

In a step 102, propose the computational methods of water drive sweep efficiency according to the production formula that step 101 is set up, and establish different well pattern Water Under and drive sweep efficiency design formulas.

In formula (7), the denominator perseverance on the right is greater than zero, when molecule is zero, the well yield caused by injection production pressure difference is zero, therefore the concept that non-darcy Water Under drives sweep efficiency is defined: in low-permeability oil deposit, due to the existence of free-boundary problem, under certain injection production pressure difference, within the scope of effective displacement, not that whole unit can be employed, when seepage flow is reached stable state, the displacement of water filling energy to area be defined as water drive sweep efficiency with the ratio of whole cellar area, be the index weighing reservoir water-flooding performance.

The design formulas of water drive sweep efficiency:

The angle [alpha] of maximum Injection Well and the producing well can employed when well yield is zero can be obtained according to formula (7) ₀, β ₀, see following formula, thus determine water drive sweep efficiency.

$P_i-P_w-\mathrm{\λ}\frac{\mathrm{\ωd}(\sin {\mathrm{\α}}_0+\sin {\mathrm{\β}}_0)}{\sin ({\mathrm{\α}}_0+{\mathrm{\β}}_0)}=0$

For square Five-point method pattern, derivation water drive sweep efficiency design formulas is as follows:

Water drive sweep efficiency=tan α

Wherein, in above formula, parameter is obtained by Solving Equations below:

$(P_i-P_w-\mathrm{\λ}\frac{d}{\cos \mathrm{\α}})=0$

In formula: Pi is water injection well bottomhole injection pressure, MPa; Pw is extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m; α is Injection Well angle, (°).

For rectangular pattern, derivation water drive sweep efficiency design formulas is:

Wherein, in above formula, parameter is obtained by Solving Equations below:

(1) $\begin{array}{c}\mathrm{tg}{\mathrm{\α}}_1=\frac{L-L_2}{d},{\mathrm{\α}}_1=\mathrm{arctg}\frac{L-L_2}{d},{\mathrm{\β}}_1=\frac{\mathrm{\π}}{2}-{\mathrm{\α}}_1,d_1=\sqrt{d^2+{(L-L_2)}^2}\\ (P_i-P_w-\mathrm{\λ}\left(\frac{d_1(\sin \mathrm{\α}+\sin )}{\sin (\mathrm{\α}+\mathrm{\β})}\right))=0,\mathrm{\β}=\frac{{\mathrm{\β}}_1}{{\mathrm{\α}}_1}\mathrm{\α}\end{array}$

(2) $\begin{array}{c}\mathrm{tg}{\mathrm{\α}}_2=\frac{d}{L-L_1},{\mathrm{\α}}_2=\mathrm{arctg}\frac{d}{L-L_1},{\mathrm{\β}}_2=\frac{\mathrm{\π}}{2}-{\mathrm{\α}}_2,d_2=\sqrt{d^2+{(L-L_1)}^2}\\ (P_i-P_w-\mathrm{\λ}\left(\frac{d_2(\sin \mathrm{\α}+\sin )}{\sin (\mathrm{\α}+\mathrm{\β})}\right))=0,\mathrm{\β}=\frac{{\mathrm{\β}}_2}{{\mathrm{\α}}_2}\mathrm{\α}\end{array}$

(3) $\begin{array}{c}{L}_2=m{L}_1,m\≠1,d_1=\sqrt{{d_1}^2+{(1-m)}^2{l}^2-2d_1(1-m)l\cos {\mathrm{\α}}_l},{\mathrm{\α}}_l=\frac{\mathrm{\π}}{2}-{\mathrm{\α}}_1\\ \frac{\mathrm{kh}}{\mathrm{\μ}}(P_i-P_w-\mathrm{\λ}{d}_1)=0\end{array}$

In formula: P _ifor water injection well bottomhole injection pressure, MPa; P _wfor extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m; α is Injection Well angle, (°); β is oil well angle, (°); α _mand β _mfor the angle of computing unit, (°); r _wfor well radius, m; d ₁for well is to the distance of oil well crack end, m; d ₂for oil well is to the distance of well crack end, m; △ t is the width that arbitrary stream pipe sewed on by well, m; M is that oil well seam length stitches the ratio of length with well, zero dimension; d _lfor well crack is to the distance in oil well crack, m; α ₁, β ₁, β ₂, α ₁for the maximum angle of computing unit, (°).

As shown in Figure 4, left figure is rectangular pattern, and wherein dash area is 1/4th rectangular patterns; Right figure is 1/4th rectangular pattern specific features, and the real circle of band arrow represents well; The real circle of arrow is not with to represent oil well; Heavy line represents the long L of well artificial fracturing dummy joint ₁with the long L of oil well artificial fracturing dummy joint ₂, m is that oil well seam length stitches the ratio of length with well, L ₁/ L ₂; Black fine dotted line represents the streamline of well to oil well.Flow process enters into step 103.

In step 103, obtain target reservoir underlying parameter, need get parms and comprise target reservoir permeability, md; Oil reservoir free-boundary problem, MPa/m; Water injection well injection pressure, Mpa; Extraction well flowing bottomhole pressure (FBHP), MPa.Main method is: the well testing of evaluating objects block, well logging or core analyzing data calculate target reservoir permeability; Evaluating objects block rock core free-boundary problem testing experiment, obtains oil reservoir free-boundary problem; In conjunction with oil reservoir and site technique determination target block Reasonable Injection well injection pressure and extraction well flowing bottomhole pressure (FBHP).Flow process enters into step 104.

In step 104, utilize water drive sweep efficiency formula, the different well spacing of drafting target reservoir, array pitch mate plate with fracturing fracture.In this embodiment, as shown in Fig. 5 to Fig. 7, by utilizing water drive sweep efficiency formula, draw permeability 5 × 10 ^-3μm ², in starting pressure 0.05MPa/m, injection production pressure difference 15MPa situation, different well spacing, array pitch mate plate with fracturing fracture.Flow process enters into step 105.

In step 105, mate plate according to the different well spacings obtained in step 104, array pitch with fracturing fracture, the reservoir evaluating such reservoir is employed situation and is carried out the optimization of well spacing array pitch and the long coupling of pressure-break preferably.Flow process terminates.

In an application specific embodiment of the present invention, effectively employ coefficient by setting up this is theoretical, propose man-made fracture and well spacing array pitch adaptation method under different well pattern condition.Utilize the method can carry out the preferred of low-permeability oil deposit man-made fracture and well spacing array pitch fast.This technology is applied dam, Dongying Nan Po beach sand emphasis Productivity Construction block Fan 151 pieces, plate is mated with fracturing fracture according to the different well spacings obtained in step 104, array pitch, at the determination economic and reasonable well spacing 350m of target block, when target water drive sweep efficiency is 0.85, under pressure break scale (requiring the long 160m of dummy joint) condition, calculating array pitch is 120m, sees Fig. 6, and Fig. 6 is pressure break dummy joint long 160m rectangular pattern well spacing array pitch plate; The horizontal fine dotted line of black represents target reservoir water drive sweep efficiency, and black is indulged fine dotted line and represented economic and reasonable well spacing, and black filled circle is calculated array pitch by two line intersection points represent.Object block petroleum-in-place 204 × 10 is employed after plan implementation ⁴t, disposes oil well 11 mouthfuls, 6 mouthfuls, well, optimizes optimum Match fracture length 110m, annual mean year oil productive capacity 2.5 × 10 ⁴t, newly increased recoverable reserves 52.2 × 10 ⁴t, oil well takes effect rate more than 80%, achieves the breakthrough of dam, beach sand low-permeability oil deposit water filling.Meanwhile, the method also directs Fan 144 pieces, dam, the beach sand block waterflooding program establishments such as high 890.

Claims (7)

1. low-permeability oil deposit man-made fracture pressure-break length and well array are apart from defining method, it is characterized in that, this low-permeability oil deposit man-made fracture pressure-break is long to be comprised with well array distance defining method:

Step 1, sets up the formula of well yield under non-darcy flow condition;

Step 2, the water drive sweep efficiency design formulas of different well pattern form under setting up non-darcy flow condition;

Step 3, utilizes water drive sweep efficiency design formulas, and the different well spacing of drafting target reservoir, array pitch mate plate with fracturing fracture; And

Step 4, mates plate according to the different well spacings obtained in step 3, array pitch with fracturing fracture, and the reservoir evaluating such reservoir is employed situation and carried out the optimization of well spacing array pitch and the long coupling of pressure-break preferably.

2. low-permeability oil deposit man-made fracture pressure-break length according to claim 1 is with well array apart from defining method, and it is characterized in that, in step 1, a note one is adopted unit well yield formula and is:

$q={\∫}_0^{{\mathrm{\α}}_1}\frac{\frac{\mathrm{kh}}{\mathrm{\μ}}(P_i-P_w-\mathrm{\λ}(\frac{\mathrm{\ωd}(\sin \mathrm{\α}+\sin )}{\sin (\mathrm{\α}+\mathrm{\β})}-2r_w))}{\ln \left(\frac{\mathrm{\ω}d\sin \mathrm{\β}}{r_w\sin \left(\text{\α+\β}\right)}\right)+\frac{{\mathrm{\α}}_m}{{\mathrm{\β}}_m}\ln \left(\frac{\mathrm{\ω}d\sin \mathrm{\α}}{r_w\sin (\mathrm{\α}+\mathrm{\β})}\right)}\mathrm{d\α}$

In formula: q is flow, cm ³/ s; K is reservoir permeability, 10 ^-3μm ²; H is effective thickness, m; μ is FFV, mPas; P _ifor water injection well bottomhole injection pressure, MPa; Pw is extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m; α is Injection Well angle, (°); β is oil well angle, (°), r _wfor well radius; α _mand β _mfor the angle of computing unit, (°), ω is length factor, α ₁for the maximum angle of computing unit, (°).

3. low-permeability oil deposit man-made fracture pressure-break length according to claim 2 and well array distance defining method, it is characterized in that, in step 2, water drive sweep efficiency is the area that arrives of water filling energy displacement and the ratio of whole cellar area, adopts according to a note one angle [alpha] that unit well yield formula obtains maximum Injection Well and the producing well can employed when well yield is zero ₀, β ₀, as shown in the formula:

$P_i-P_w-\mathrm{\λ}\frac{\mathrm{\ωd}(\sin {\mathrm{\α}}_0+\sin {\mathrm{\β}}_0)}{\sin ({\mathrm{\α}}_0+{\mathrm{\β}}_0)}=0$

Thus determining water drive sweep efficiency, in formula: Pi is water injection well bottomhole injection pressure, MPa; Pw is extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m.

4. low-permeability oil deposit man-made fracture pressure-break length according to claim 3 is with well array apart from defining method, and it is characterized in that, in step 2, for square Five-point method pattern, water drive sweep efficiency design formulas is as follows:

Water drive sweep efficiency=tan α

Wherein, in above formula, parameter is obtained by Solving Equations below:

$(P_i-P_w-\mathrm{\λ}\frac{d}{\cos \mathrm{\α}})=0$

In formula: Pi is water injection well bottomhole injection pressure, MPa; Pw is extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m; α is Injection Well angle, (°).

5. low-permeability oil deposit man-made fracture pressure-break length according to claim 3 is with well array apart from defining method, and it is characterized in that, in step 2, for rectangular pattern, water drive sweep efficiency design formulas is:

Wherein, in above formula, parameter is obtained by Solving Equations below:

(1) $\begin{array}{c}\mathrm{tg}{\mathrm{\α}}_1=\frac{L-L_2}{d},{\mathrm{\α}}_1=\mathrm{arctg}\frac{L-L_2}{d},{\mathrm{\β}}_1=\frac{\mathrm{\π}}{2}-{\mathrm{\α}}_1,d_1=\sqrt{d^2+{(L-L_2)}^2}\\ (P_i-P_w-\mathrm{\λ}\left(\frac{d_1(\sin \mathrm{\α}+\sin )}{\sin (\mathrm{\α}+\mathrm{\β})}\right))=0,\mathrm{\β}=\frac{{\mathrm{\β}}_1}{{\mathrm{\α}}_1}\mathrm{\α}\end{array}$

(2) $\begin{array}{c}\mathrm{tg}{\mathrm{\α}}_2=\frac{d}{L-L_1},{\mathrm{\α}}_2=\mathrm{arctg}\frac{d}{L-L_1},{\mathrm{\β}}_2=\frac{\mathrm{\π}}{2}-{\mathrm{\α}}_2,d_2=\sqrt{d^2+{(L-L_1)}^2}\\ (P_i-P_w-\mathrm{\λ}\left(\frac{d_2(\sin \mathrm{\α}+\sin )}{\sin (\mathrm{\α}+\mathrm{\β})}\right))=0,\mathrm{\β}=\frac{{\mathrm{\β}}_2}{{\mathrm{\α}}_2}\mathrm{\α}\end{array}$

(3) $\begin{array}{c}{L}_2=m{L}_1,m\≠1,d_1=\sqrt{{d_1}^2+{(1-m)}^2{l}^2-2d_1(1-m)l\cos {\mathrm{\α}}_l},{\mathrm{\α}}_l=\frac{\mathrm{\π}}{2}-{\mathrm{\α}}_1\\ \frac{\mathrm{kh}}{\mathrm{\μ}}(P_i-P_w-\mathrm{\λ}{d}_1)=0\end{array}$

In formula: P _ifor water injection well bottomhole injection pressure, MPa; P _wfor extraction well flowing bottomhole pressure (FBHP), MPa; λ is free-boundary problem, MPa/m; D is well spacing, m; α is Injection Well angle, (°); β is oil well angle, (°); α _mand β _mfor the angle of computing unit, (°); r _wfor well radius, m; d ₁for well is to the distance of oil well crack end, m; d ₂for oil well is to the distance of well crack end, m; △ t is the width that arbitrary stream pipe sewed on by well, m; M is that oil well seam length stitches the ratio of length with well, zero dimension; d _lfor well crack is to the distance in oil well crack, m; α ₁, β ₁, β ₂, α ₁for the maximum angle of computing unit, (°).

6. low-permeability oil deposit man-made fracture pressure-break length according to claim 1 and well array distance defining method, it is characterized in that, this low-permeability oil deposit man-made fracture pressure-break is long also to be comprised apart from defining method with well array, after step 2, obtain target reservoir known parameters, needing gets parms comprises target reservoir permeability, md; Oil reservoir free-boundary problem, MPa/m; Water injection well injection pressure, Mpa; Extraction well flowing bottomhole pressure (FBHP), MPa.

7. low-permeability oil deposit man-made fracture pressure-break length according to claim 6 and well array distance defining method, it is characterized in that, in the step obtaining target reservoir known parameters, the well testing of evaluating objects block, well logging or core analyzing data calculate target reservoir permeability; Evaluating objects block rock core free-boundary problem testing experiment, obtains oil reservoir free-boundary problem; In conjunction with oil reservoir and site technique determination target block Reasonable Injection well injection pressure and extraction well flowing bottomhole pressure (FBHP).