CN103821485A - Method for predicting water cut increasing rate of water-drive oil field - Google Patents

Abstract

The invention relates to a method for predicting the water cut increasing rate of a water-drive oil field. The method includes the following steps that cylindrical rock samples are taken from a natural rock core of the oil field, a rock core displacement experiment is performed, and a series of parameters such as water saturation Sw, oil phase relative permeability Kro and water phase relative permeability Krw are obtained; irreducible water saturation Swi and residual oil saturation Sor are obtained, and the oil and water viscosity ratio mur is obtained through measurement; the relations between the oil and water relative permeability ratio and the water saturation, the reflected relational expression between the water content and the recovery percentage, and the relational expression between the water cut increasing rate and the recovery percentage are obtained with a power method. According to the method, oil and water relative permeability materials are utilized, a power type mathematical processing method is adopted, the water content and the water cut increasing rate of the oil field are described, the development effect and the development degree of the oil field are analyzed and evaluated, development measures are planned according to the method, the yield of the oil field is reasonably planned and deployed, and more effective guidance can be provided for development of the oil field.

Description

The method that prediction water controlled field Water-Content Rise rate changes

Technical field

The present invention relates to the technical field of oil development reservoir engineering, more particularly, the present invention relates to a kind of method of predicting that water controlled field Water-Content Rise rate changes.

Background technology

Oil-water relative permeability is the significant data of the underground oil-water two-phase flow characteristic relation of reflection, is the important foundation data of reservoir engineering research, can be used for that oil reservoir prediction moisture content, moisture content change, the index such as the variation of Water-Content Rise rate and recovery ratio.Along with deepening continuously of development process, increasing middle and high infiltration sandstone oil reservoir will enter super-high water-cut stage (comprehensive water cut is greater than 90%), and the exploitation rule of this stage oil reservoir is different from the middle high water-cut development stage.At present, the method that characterizes permeability saturation curve is both at home and abroad all the conventional treatment based on relative permeability experiment, and it is early stage and consider under high waterflood flush multiple permeability saturation curve form or change the research characterizing to have no water filling, carrying out long-term injecting water, to wash away rear water drive oil theoretical research also little.In prior art, obtain on profit two-phase permeability and water saturation relation data basis in laboratory, calculate two-phase permeability ratio, adopt exponential processing method, adopt relational expression

prediction moisture content and moisture content change, and carry out lower step analytical work.But its result of calculation and real data will produce larger error near irreducible water saturation and two end points of residual oil saturation, in computational process, this error will be retained, and also, by by the oil pool analysis after substitution, reservoir performance analysis and programme establishment be brought to adverse effect.There is following shortcoming in especially above-mentioned permeability saturation curve characterizing method: 1. low water-cut stage oilfield development indexes variation is inconsistent with WATER FLOODING CHARACTERISTIC CURVE, oil-water relative permeability ratio value

with e ^-bSwnot in linear relation, in mining site production, water-cut increase is often faster; 2. the permeability saturation curve under higher amount of water injected has piecewise nonlinear feature, now oil-water relative permeability ratio value is less on the impact of moisture content in actual production, the sign required precision of this stage permeability saturation curve is not high, and oilfield development indexes variation meets WATER DISPLACEMENT CURVES feature; 3. flow through oil reservoir feature changes the ultra-high water-containing stage, and phenomenon appears upwarping in WATER FLOODING CHARACTERISTIC CURVE, oil-water relative permeability ratio value

with e ^-bSwno longer as completely in linear relation in routine, linear relation is only suitable for the interlude of permeability saturation curve, and can not characterize complete permeability saturation curve; 4. traditional oil displacement efficiency understanding contradicts with field pressure coring result: tradition (relative permeability experiment) thinks that oil-water displacement efficiency is generally lower than 60%, and field pressure coring thinks that oil-water displacement efficiency can exceed 70%, the seepage flow characteristics of conventional permeability saturation curve under can not the high amount of water injected of accurate description.

Summary of the invention

In order to solve above-mentioned technical problem of the prior art, the object of the present invention is to provide a kind of method of predicting that water controlled field Water-Content Rise rate changes.Method Application of oil-water relative permeability experimental data of the present invention is described Cut of Oilfield and Water-Content Rise rate, come oil reservoir prediction development effectiveness and exploitation degree, and carry out accordingly Planning and Development measure, the deployment field output of making rational planning for, more can effectively instruct oil field development.

In order to solve the described technical problem of invention and to realize goal of the invention, the present invention has adopted following technical scheme:

A kind of method of predicting that water controlled field Water-Content Rise rate changes, it is characterized in that comprising the following steps: oil field natural core is got to cylindric rock sample and carry out rock core displacement test, obtain a series of water saturation Sw, oil relative permeability Kro, water relative permeability Krw data; And obtain irreducible water saturation Swi and residual oil saturation Sor, measure and obtain viscosity ratio of oil and water μ _r; Based on power method, try to achieve a, b value according to relational expression (1) application least square method

$\frac{\mathrm{Kro}}{\mathrm{Krw}}=a\·{\left(\frac{\mathrm{Sw}-\mathrm{Swi}}{1-\mathrm{Sor}-\mathrm{Sw}}\right)}^{-b}---\left(1\right)$

(1) formula is updated to profit shunt volume equation and can obtains relational expression (2):

$\mathrm{fw}=\frac{1}{1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left(\frac{\mathrm{Sw}-\mathrm{Swi}}{1-\mathrm{Sor}-\mathrm{Sw}}\right)}^{-b}}---\left(2\right)$

Differentiated to Sw in relational expression (2) both sides, obtain relational expression (3):

$\frac{\∂\mathrm{fw}}{\∂\mathrm{Sw}}=\frac{(1-\mathrm{Sor}-\mathrm{Swi})\·\frac{a\·b}{{\mathrm{\μ}}_r}\·\frac{{(\mathrm{Sw}-\mathrm{Swi})}^{-b-1}}{{(1-\mathrm{Sor}-\mathrm{Sw})}^{-b+1}}}{{[1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left(\frac{\mathrm{Sw}-\mathrm{Swi}}{1-\mathrm{Sor}-\mathrm{Sw}}\right)}^{-b}]}^2}---\left(3\right)$

Water saturation Sw and recovery percent of reserves R available relationship formula (4) represent:

Sw＝Swi+(1-Swi)·R (4)

By relational expression (4) substitution relational expression (2) formula, obtain the moisture and recovery percent of reserves relational expression (5) of oil-water relative permeability data reflection:

$\mathrm{fw}=\frac{1}{1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left[\frac{(1-\mathrm{Swi})\·R}{1-\mathrm{Sor}-\mathrm{Swi}-(1-\mathrm{Swi})\·R}\right]}^{-b}}---\left(5\right)$

While can obtain Water-Content Rise rate and recovery percent of reserves is related to relational expression (6):

$\frac{\∂\mathrm{fw}}{\∂R}=\frac{(1-\mathrm{Swi})\·(1-\mathrm{Sor}-\mathrm{Swi})\·\frac{a\·b}{{\mathrm{\μ}}_r}\·\frac{{[(1-\mathrm{Swi})\·R]}^{-b-1}}{{[1-\mathrm{Sor}-\mathrm{Swi}-(1-\mathrm{Swi})\·R]}^{-b+1}}}{{[1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left[\frac{(1-\mathrm{Swi})\·R}{1-\mathrm{Sor}-\mathrm{Swi}-(1-\mathrm{Swi})\·R}\right]}^{-b}]}^2}---\left(6\right).$

Compared with immediate prior art, the method that prediction water controlled field Water-Content Rise rate of the present invention changes has following beneficial effect:

Method of the present invention adopts power method form relation formula to have higher index of correlation, has described the analytic relationship of oil-water relative permeability ratio value and water saturation, can truly reflect that subterranean oil water drive is for relation.The data that the present invention carries out rock core displacement test by oil field natural core is got to cylindric rock sample, adopt novel effective mathematical processing methods, moisture in dynamic analysis and Water-Content Rise rate change curve are obtained, reflect intuitively the relation of recovery percent of reserves and moisture content and Water-Content Rise rate, analyze, contrast oil reservoir and produce the relation of actual parameter and theoretical value with this, for oilfield development program is formulated and lower step measure and adjust programming more reliable reference frame is provided.

Accompanying drawing explanation

Fig. 1 is oil-water relative permeability curve datagram described in embodiment 1.

Fig. 2 is the oil-water relative permeability ratio value matched curve figure that adopts power method and index method to obtain described in embodiment 1.

Fig. 3 is moisture content and Water-Content Rise rate change curve described in embodiment 1.

The specific embodiment

Method prediction water controlled field Water-Content Rise rate of the present invention being changed below with reference to specific embodiment is further elaborated, to help those skilled in the art to have more complete, accurate and deep understanding to inventive concept of the present invention, technical scheme; What need statement is to be all exemplary in the description of specific embodiment, and does not mean limiting the scope of the invention, and interest field of the present invention is as the criterion with the claim limiting.

Embodiment 1

Carry out rock core displacement test by certain oil field natural core is got to cylindric rock sample below, describe the method that prediction water controlled field Water-Content Rise rate of the present invention changes, described method mainly comprises the following steps:

1. carry out rock core displacement test, gather and ooze mutually experimental data

Certain oil field natural core is got to cylindric rock sample and carry out rock core displacement test.In experimentation, the injection-production method of selecting is that one end note, the other end are adopted, and in order to determine, liquid injects experiment control condition, level pressure output; Obtain a series of water saturation Sw, oil relative permeability Kro, water relative permeability Krw data; And obtain irreducible water saturation Swi and residual oil saturation Sor, measure and obtain viscosity ratio of oil and water μ _r; Wherein, the oil-water relative permeability curve data that obtain as shown in Figure 1.

2. set up least square method object function

Based on power method and index method, according to Least Square in Processing oil-water relative permeability data as shown in Figure 1, can find out and adopt the only middle straightway of matched curve of index method by accompanying drawing 2, there is higher index of correlation, but can not matching for two ends, adopt power multiplication of the present invention can realize the omnidistance matching of curve, index of correlation reaches more than 0.99, greatly improve fitting precision, reduced analytical error.

3. set up water saturation and recovery percent of reserves, and Water-Content Rise rate and recovery percent of reserves relational expression:

$\mathrm{fw}=\frac{1}{1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left(\frac{\mathrm{Sw}-\mathrm{Swi}}{1-\mathrm{Sor}-\mathrm{Sw}}\right)}^{-b}}---\left(2\right)$

Partial derivative is asked to Sw in relational expression (2) both sides, obtains relational expression (3):

$\frac{\∂\mathrm{fw}}{\∂\mathrm{Sw}}=\frac{(1-\mathrm{Sor}-\mathrm{Swi})\·\frac{a\·b}{{\mathrm{\μ}}_r}\·\frac{{(\mathrm{Sw}-\mathrm{Swi})}^{-b-1}}{{(1-\mathrm{Sor}-\mathrm{Sw})}^{-b+1}}}{{[1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left(\frac{\mathrm{Sw}-\mathrm{Swi}}{1-\mathrm{Sor}-\mathrm{Sw}}\right)}^{-b}]}^2}---\left(3\right)$

Water saturation Sw and recovery percent of reserves R available relationship formula (4) represent:

Sw＝Swi+(1-Swi)·R (4)

By relational expression (4) substitution relational expression (2) formula, obtain the moisture and recovery percent of reserves relational expression (5) of oil-water relative permeability data reflection:

$\mathrm{fw}=\frac{1}{1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left[\frac{(1-\mathrm{Swi})\·R}{1-\mathrm{Sor}-\mathrm{Swi}-(1-\mathrm{Swi})\·R}\right]}^{-b}}---\left(5\right)$

While can obtain Water-Content Rise rate and recovery percent of reserves is related to relational expression (6):

$\frac{\∂\mathrm{fw}}{\∂R}=\frac{(1-\mathrm{Swi})\·(1-\mathrm{Sor}-\mathrm{Swi})\·\frac{a\·b}{{\mathrm{\μ}}_r}\·\frac{{[(1-\mathrm{Swi})\·R]}^{-b-1}}{{[1-\mathrm{Sor}-\mathrm{Swi}-(1-\mathrm{Swi})\·R]}^{-b+1}}}{{[1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left[\frac{(1-\mathrm{Swi})\·R}{1-\mathrm{Sor}-\mathrm{Swi}-(1-\mathrm{Swi})\·R}\right]}^{-b}]}^2}---\left(6\right).$

Result as shown in Figure 3, the moisture content that method derivation described in employing the present embodiment produces and Water-Content Rise rate and recovery percent of reserves relational expression more can truly reflect the displacement characteristics of underground fluid seepage flow, thus can be for analyzing, contrast oil reservoir produce the relation of actual index parameter and theoretical value, for oilfield development program is formulated and lower step measure and adjust programming more reliable reference guide foundation is provided.

For the ordinary skill in the art; specific embodiment is just exemplarily described the present invention by reference to the accompanying drawings; obviously specific implementation of the present invention is not subject to the restrictions described above; as long as adopted the improvement of the various unsubstantialities that method of the present invention design and technical scheme carry out; or without improving, design of the present invention and technical scheme are directly applied to other occasion, all within protection scope of the present invention.

Claims (1)

1. a method of predicting that water controlled field Water-Content Rise rate changes, it is characterized in that comprising the following steps: oil field natural core is got to cylindric rock sample and carry out rock core displacement test, obtain a series of water saturation Sw, oil relative permeability Kro, water relative permeability Krw data; And obtain irreducible water saturation Swi and residual oil saturation Sor, measure and obtain viscosity ratio of oil and water μ _r; Based on power method, try to achieve a, b value according to relational expression (1) application least square method

$\frac{\mathrm{Kro}}{\mathrm{Krw}}=a\·{\left(\frac{\mathrm{Sw}-\mathrm{Swi}}{1-\mathrm{Sor}-\mathrm{Sw}}\right)}^{-b}---\left(1\right)$

(1) formula is updated to profit shunt volume equation and can obtains relational expression (2):

$\mathrm{fw}=\frac{1}{1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left(\frac{\mathrm{Sw}-\mathrm{Swi}}{1-\mathrm{Sor}-\mathrm{Sw}}\right)}^{-b}}---\left(2\right)$

Differentiated to Sw in relational expression (2) both sides, obtain relational expression (3):

$\frac{\∂\mathrm{fw}}{\∂\mathrm{Sw}}=\frac{(1-\mathrm{Sor}-\mathrm{Swi})\·\frac{a\·b}{{\mathrm{\μ}}_r}\·\frac{{(\mathrm{Sw}-\mathrm{Swi})}^{-b-1}}{{(1-\mathrm{Sor}-\mathrm{Sw})}^{-b+1}}}{{[1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left(\frac{\mathrm{Sw}-\mathrm{Swi}}{1-\mathrm{Sor}-\mathrm{Sw}}\right)}^{-b}]}^2}---\left(3\right)$

Water saturation Sw and recovery percent of reserves R available relationship formula (4) represent:

Sw＝Swi+(1-Swi)·R (4)

By relational expression (4) substitution relational expression (2) formula, obtain the moisture and recovery percent of reserves relational expression (5) of oil-water relative permeability data reflection:

$\mathrm{fw}=\frac{1}{1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left[\frac{(1-\mathrm{Swi})\·R}{1-\mathrm{Sor}-\mathrm{Swi}-(1-\mathrm{Swi})\·R}\right]}^{-b}}---\left(5\right)$

While can obtain Water-Content Rise rate and recovery percent of reserves is related to relational expression (6):

$\frac{\∂\mathrm{fw}}{\∂R}=\frac{(1-\mathrm{Swi})\·(1-\mathrm{Sor}-\mathrm{Swi})\·\frac{a\·b}{{\mathrm{\μ}}_r}\·\frac{{[(1-\mathrm{Swi})\·R]}^{-b-1}}{{[1-\mathrm{Sor}-\mathrm{Swi}-(1-\mathrm{Swi})\·R]}^{-b+1}}}{{[1+\frac{1}{{\mathrm{\μ}}_r}\·a\·{\left[\frac{(1-\mathrm{Swi})\·R}{1-\mathrm{Sor}-\mathrm{Swi}-(1-\mathrm{Swi})\·R}\right]}^{-b}]}^2}---\left(6\right).$

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