CN110656923B - Method for predicting yield of production well of fractured-vuggy carbonate reservoir - Google Patents
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Abstract
The invention relates to a method for predicting the yield of a production well of a fractured-vuggy carbonate rock reservoir, which comprises the following steps of: step 1: according to the pressure reduction condition of the oil reservoir stratum, a fixed constant flow stage and an unsteady constant flow stage are divided; step 2: calculating the steady flow yield; and step 3: calculating the unsteady flow yield; and 4, step 4: calculating the yield of one eccentric well in the karst cave; and 5: the critical eccentricity is determined. The method aims at the problem of yield prediction difference caused by deviation of a drilling position from the karst cave center when a straight well of the fracture-cave oil reservoir encounters a single karst cave, develops different periods of oil field development, respectively deduces eccentric well yield calculation formulas under constant flow and unsteady flow conditions due to different correlations of formation pressure and time, establishes critical eccentricity calculation methods under two flow conditions, and has a good effect on correcting the yield of the fracture-cave oil reservoir.
Description
Technical Field
The invention belongs to the technical field of oil well yield prediction in fracture-cavity oil reservoir development, and particularly relates to a yield prediction method applied to a carbonate fracture-cavity type oil reservoir production well.
Background
The fracture-cave oil reservoir occupies an important position in the exploration and development of carbonate rock oil reservoirs in China, according to the current knowledge, according to statistics, by 2016 years, in 926 production units, one total 348 wells belong to a unit formed by controlling single-size karst cave bodies by a single well, 219 units for communicating a plurality of karst caves by the single well, and 359 units for controlling the plurality of karst caves by a plurality of wells. The fracture-cavity units can be divided into three types, namely a solution-cavity type (containing fracture-cavity type), a fracture type and a hole type according to the types of the storage spaces, wherein the solution-cavity type oil deposit is the main type of oil production, the accumulated oil production accounts for 68.3 percent of the whole oil field, the single-well yield of the solution-cavity type oil deposit is far higher than that of the fracture-cavity type and hole type oil deposits, and therefore the calculation of the single-well yield of the solution-cavity type oil deposit has very important significance. From these data, the production of the fracture-cavity reservoir can be stabilized only if the production condition of the karst-cavity reservoir is known.
In the production practice of fracture-cavity oil reservoirs, the well drilling position of an oil well is rarely consistent with the center of a karst cave. On the contrary, in order to improve the ultimate recovery rate, once the drill meets the karst cave, the drill is seldom continued after the loss occurs in the drilling process; for vertical wells that fail to drill a karst cave, communication is usually achieved by directional acid fracturing and sidetrack drilling techniques (see fig. 2). In the production process, 83.6 percent of oil well production data in the karst cave type oil reservoir has larger difference with a prediction result, which has great influence on yield prediction, scheme compilation, investment budget and project matching.
The oil and gas reservoir development capacity result is the basis of oil field capacity planning and investment budget, so that the yield and the change condition of an oil well are predicted as accurately as possible, the predicted content comprises yield, formation pressure, water content change rate, extraction degree and the like, and the core parameter is the yield of the oil well in different development stages.
Therefore, in order to better predict single well production, there is an urgent need to correct the prediction of single well production to better service the oilfield production.
The single well yield prediction method has three types: the first is a numerical simulation method, which needs to perform corresponding conceptual geological model modeling, takes long time, cannot be realized in a short time, and is relatively close to production practice. For more complex conditions, research can be carried out after geological modeling. The second is a physical simulation method, which requires a three-dimensional physical model to be manufactured according to geological modeling, has large workload, cannot be realized in a short time, and can be mostly used for mechanism analysis as a supplement to a numerical simulation method. The third method is a reservoir engineering calculation method, which can complete theoretical derivation and numerical solution in a short time without conceptual model geological modeling and three-dimensional physical model manufacturing and aims to obtain regularity understanding.
The single-hole production process can be divided into a steady flow stage and an unsteady flow stage, wherein pressure is not conducted to a karst-cave boundary, the calculation of yield needs to be considered in a segmented mode, before the pressure reaches the boundary, the relation between eccentricity and yield can be obtained by using a mirror image reflection method, and the yield is the maximum value of the oil well yield and is used for reference in oil reservoir production allocation. And then after pressure is transmitted to the karst cave boundary, establishing the relation between the eccentricity and the yield by adopting a boundary element and Green function method, and analyzing to obtain the relation between the yield change multiple and the eccentricity, so that the sectional equation is obviously more in line with the oil reservoir production practice. And finally, the correctness of the method is verified, and the development and production of the oil field are guided.
Disclosure of Invention
In order to solve the problems, the invention provides a method for predicting the production well yield of the fractured-vuggy carbonate rock reservoir, which can correct the yield calculation error caused by deviation of the well position of a drilling well from the center of a karst cave.
The invention provides a method for predicting the yield of a production well of a fractured-vuggy carbonate reservoir, which is characterized by comprising the following steps of:
step 1: dividing a steady flow stage and an unsteady flow stage according to the pressure reduction condition of the oil reservoir stratum;
and 2, step: calculating the steady flow yield;
and step 3: calculating the unsteady flow yield;
and 4, step 4: calculating the yield of one eccentric well in the karst cave;
and 5: the critical eccentricity is determined.
In an embodiment, the step 2 further specifically includes the following steps:
at the initial stage of oil field development, the change degree of reservoir formation pressure is small, and the pressure and the yield do not change along with time, namely the flowing process belongs to steady flow;
then, by using a mirror image reflection principle and a multi-well interference theory in classical seepage mechanics, an influence calculation formula of a distance d between the center of one vertical well and the center of the karst cave on the yield q of the karst cave stratum is obtained as follows:
where k represents reservoir permeability, 10 -3 μm 2 (ii) a h represents reservoir thickness, m; p is a radical of e Indicating that the original pressure in the karst cave is also the original pressure value at the boundary of the karst cave, namely Mpa; p is a radical of w Represents the bottom hole pressure of the production well, Mpa; μ represents formation crude oil viscosity, mpa.s; r is e Represents the karst cave boundary radius, m; r is w Represents the well bore internal radius, m.
In an embodiment, the step 3 further specifically includes the following steps:
step 3.1: in the middle and later stages of oil field development, the oil-water movement speed is related to the reservoir formation pressure, namely the flow process belongs to unsteady flow, and then the reservoir formation pressure change equation is obtained:
the solution conditions are as follows:
initial condition p (r,0) ═ p i
The outer boundary condition p (∞, t) ═ p i
Inner boundary condition
Wherein p represents the reservoir internal pressure at the moment of calculation, Mpa; r represents the distance from any point of the stratum to the center of the oil well, m; μ represents formation crude oil viscosity, mpa.s; c t Is the compression coefficient of crude oil, Mpa -1 (ii) a t represents time; b represents a crude oil volume coefficient; p is a radical of formula i The original reservoir pressure, Mpa.
In one embodiment, said step 3.1 is followed by a step 3.2: solving the relation between pressure and yield by adopting a boundary element method;
step 3.2: the method also comprises the following specific steps:
step 3.2.1: dividing the boundary into boundary units with finite sizes according to the boundary element calculation principle;
step 3.2.2: dispersing the integral equation into an algebraic equation, so that the problem of solving the differential equation is converted into the problem of solving the algebraic equation;
step 3.2.3: the boundary element method can realize the prediction of the yield of the eccentric well only by changing the well coordinates on the basis of closing one vertical well model in the boundary oil reservoir.
In an embodiment, in step 3.2.3, the method further includes:
differential equation of seepage:
the solution conditions are as follows:
inner boundary conditions:
initial conditions: p is a radical of D (r D ,0)＝0
And (3) sealing external boundary conditions:
wherein p is D Representing dimensionless pressure; r is D Represents a dimensionless radius; q. q of D Indicates dimensionless yield; t is t D Representing a dimensionless time; r is eD Indicating a dimensionless radius of the cavern boundary.
In one embodiment, the seepage differential equation in step 3.2.3 is subjected to dimensionless processing to obtain a vertical well model in the closed boundary reservoir, and the dimensionless calculation process is as follows:
dimensionless pressure p D Calculating the formula:
dimensionless yield q D Calculating the formula:
dimensionless radius r D Calculating the formula:
dimensionless time t D Calculating the formula:
where φ is the reservoir effective porosity.
In one embodiment, the formula for calculating the production of one eccentric well in the karst cave in step 4 is as follows:
wherein, the Q point is any point in the region and on the boundary Gamma; p' is any point on the boundary; n represents a unit vector of normal risk of a karst cave boundary;
moving the point Q to the boundary f, the integral equation is used to calculate p D (p', t) and
unknown boundary variables, increased unknowns q D Increase the counterpart by moving the point Q to the point WSolving the process;
the function G represents the basic solution of the laplace diffusion equation, which is of the form:
wherein, K 0 Is a zero order Bessel function of the second kind.
In an embodiment, the step 5 further specifically includes the following steps:
step 5.1: basis of determination
Firstly, determining eccentricity as a factor influencing yield;
secondly, the eccentricity D of 20% affecting the yield is defined as the critical eccentricity D c ；
Finally, when the eccentricity D is less than D c Directly adopting a karst cave central vertical well yield calculation formula;
and obtaining an analytic solution or a numerical solution from the closed outside of the homogeneous oil reservoir model, and performing calculation programming by using Matlab to obtain the output of the central vertical well of one karst cave at different moments.
In one embodiment, said step 5.1 is followed by a step 5.2: the critical eccentricity determining method under the condition of constant flow comprises the following steps:
when the eccentricity D is greater than D c The influence of eccentricity must be considered; the cutoff for considering the off-center effect is determined as 20% change in raw yield in units of m:
D c ＝0.85R e -1.71
wherein R is e The radius of the equivalent karst cave is expressed, and the calculation method is obtained according to the principle that the internal volume of the karst cave is equal to the volume of a sphere, so that the karst cave with any shape is equivalently calculated into the spherical karst cave, and the critical eccentricity is calculated;
critical eccentricity D at steady flow c The size of the cavern is related to other parameters such as reservoir thickness and permeability.
In one embodiment, said step 5.2 is followed by a step 5.3: the critical eccentricity determining method under unsteady flow conditions comprises the following steps:
in the middle and later stages of oilfield development, the oil-water movement speed is related to pressure and belongs to unsteady flow, the influence of the drilling position of a vertical well in the karst cave on the yield of the vertical well is greater than that in the initial stage of development, the yield is reduced along with the increase of the eccentricity, and the influence degree of the eccentricity reaching 20% of the radius of the karst cave on the yield must be considered;
equivalent karst cave radius R e The viscosity mu of the crude oil of the stratum and the permeability k of the reservoir have certain influence on the yield of the eccentric well, and variables are defined
By utilizing a multivariate nonlinear fitting method, according to the yield change of 20%, the critical eccentricity relationship is determined as follows: d c ＝-15.47ln(T c )+14.76；
Wherein a variable T is calculated c The units of each parameter are as follows:
reservoir permeability k, 10 -3 um 2 ；
Equivalent karst cave radius R e ，m；
Formation crude oil viscosity μ, mpa.s.
The method aims at the problem of yield prediction difference caused by deviation of a drilling position from the karst cave center when a straight well of the fracture-cave oil reservoir encounters a single karst cave, develops different periods of oil field development, respectively deduces eccentric well yield calculation formulas under constant flow and unsteady flow conditions due to different correlations of formation pressure and time, establishes critical eccentricity calculation methods under two flow conditions, and has a good effect on correcting the yield of the fracture-cave oil reservoir.
Drawings
The invention will be described in more detail hereinafter on the basis of embodiments and with reference to the accompanying drawings. Wherein:
FIG. 1 is a flow chart of a method for production prediction for a production well of a fractured-vuggy carbonate reservoir in accordance with the present invention;
FIG. 2 is a diagram of a communication method implemented by the prior art of directional acid fracturing and sidetracking;
FIG. 3 is a graph of production predictions for a Tahe S74 cell SXX well;
FIG. 4 shows the predicted production from TK7-XXX wells in Tahe S80 unit.
In the drawings like parts are provided with the same reference numerals. The figures are not drawn to scale.
Detailed Description
The invention will be further explained with reference to the drawings. Therefore, the realization process of how to apply the technical means to solve the technical problems and achieve the technical effect can be fully understood and implemented. It should be noted that the technical features mentioned in the embodiments can be combined in any way as long as no conflict exists. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
The single well control single hole condition existing in the fracture-cavity type oil reservoir development is more, the flow change degree of the condition caused by pressure reduction is far higher than that of the clastic rock, when the pressure is reduced to a certain degree, the pressure is difficult to maintain, the yield and the pressure of an oil well are related to time, and the oil well belongs to unsteady flow. The unsteady flow condition is rarely considered in the original calculation of the yield of the vertical well, the result of the unsteady flow condition is not seen in an eccentricity yield calculation formula, the eccentricity yield calculation formula is inconsistent with the actual production of an oil field, and the critical eccentricity calculation is not carried out, so that the production decision is not facilitated.
The invention provides a method for predicting the yield of a production well of a fractured-vuggy carbonate rock reservoir, which is characterized by comprising the following steps of:
step 1: dividing a steady flow stage and an unsteady flow stage according to the pressure reduction condition of the oil reservoir stratum;
step 2: calculating the steady flow yield;
and step 3: calculating the unsteady flow yield;
and 4, step 4: calculating the yield of one eccentric well in the karst cave;
and 5: the critical eccentricity is determined.
The step 2 further comprises the following steps:
at the initial stage of oil field development, the change degree of reservoir formation pressure is small, and the pressure and the yield do not change along with time, namely the flowing process belongs to steady flow;
then, by using a mirror image reflection principle and a multi-well interference theory in classical seepage mechanics, an influence calculation formula of a distance d between the center of one vertical well and the center of the karst cave on the yield q in the karst cave stratum is obtained as follows:
where k represents reservoir permeability, 10 -3 μm 2 (ii) a h represents reservoir thickness, m; p is a radical of e Indicating that the original pressure in the karst cave is also the original pressure value at the boundary of the karst cave, namely Mpa; p is a radical of w Represents the bottom hole pressure of the production well, Mpa; μ represents formation crude oil viscosity, mpa.s; r is e Represents the karst cave boundary radius, m; r is w Represents the well internal radius, m.
The step 3 further comprises the following steps:
step 3.1: in the middle and later stages of oil field development, the oil-water movement speed is related to the reservoir formation pressure, namely the flow process belongs to unsteady flow, and then the reservoir formation pressure change equation is obtained:
the solution conditions are as follows:
initial condition p (r,0) ═ p i
The outer boundary condition p (∞, t) ═ p i
Inner boundary condition
Wherein p represents the reservoir internal pressure at the moment of calculation, Mpa; r represents the distance from any point of the stratum to the center of the oil well, m; μ represents formation crude oil viscosity, mpa.s; c t Is the compression coefficient of crude oil, Mpa -1 (ii) a t represents time; b represents a crude oil volume coefficient; p is a radical of i Is original toInitial reservoir pressure, Mpa.
Step 3.2 is also followed by step 3.1: solving the relation between pressure and yield by adopting a boundary element method;
step 3.2: the method also comprises the following specific steps:
step 3.2.1: dividing the boundary into boundary units with limited size according to the boundary element calculation principle;
step 3.2.2: dispersing the integral equation into an algebraic equation, so that the problem of solving the differential equation is converted into the problem of solving the algebraic equation;
step 3.2.3: the boundary element method can realize the prediction of the yield of the eccentric well only by changing the well coordinates on the basis of closing one vertical well model in the boundary oil reservoir.
In the step 3.2.3, the method further includes:
differential equation of seepage:
the solution conditions are as follows:
inner boundary conditions:
initial conditions: p is a radical of D (r D ,0)＝0
And (3) sealing external boundary conditions:
wherein p is D Representing dimensionless pressure; r is D Represents a dimensionless radius; q. q.s D Indicates dimensionless yield; t is t D Representing a dimensionless time; r is a radical of hydrogen eD Indicating a dimensionless radius of the cavern boundary.
And 3, carrying out dimensionless processing on the seepage differential equation in the step 3.2.3 to obtain a vertical well model in the closed boundary oil reservoir, wherein the dimensionless calculation process comprises the following steps:
dimensionless pressure p D Computing deviceFormula (II):
dimensionless yield q D Calculating the formula:
dimensionless radius r D Calculating the formula:
dimensionless time t D Calculating the formula:
where φ is the reservoir effective porosity.
The formula for calculating the yield of one eccentric well in the karst cave in the step 4 is as follows:
wherein, the Q point is any point in the region and on the boundary Gamma; p' is any point on the boundary; n represents a unit vector of normal risk of a karst cave boundary;
moving the Q point to the boundary f, the integral equation is used to calculate p D (p', t) and
unknown boundary variables, increased unknowns q D Moving the point Q to the well point W to increase a corresponding equation for solving;
the function G represents the basic solution of the laplace diffusion equation, which is of the form:
wherein, K 0 Is a zero-order shell of the second kindThe Sehr function.
In the step 5, the method further comprises the following steps:
step 5.1: basis of determination
Firstly, determining eccentricity as a factor influencing yield;
secondly, the eccentricity D of 20% affecting the yield is defined as the critical eccentricity D c ；
Finally, when the eccentricity D is less than D c Directly adopting a karst cave central vertical well yield calculation formula;
and obtaining an analytic solution or a numerical solution from the closed outside of the homogeneous oil reservoir model, and performing calculation programming by using Matlab to obtain the output of the central vertical well of one karst cave at different moments.
Step 5.2 is also followed by step 5.1: the critical eccentricity determining method under the condition of constant flow comprises the following steps:
when the eccentricity D is greater than D c The influence of eccentricity must be considered; the cutoff for considering the off-center effect is determined as 20% change in raw yield in units of m:
D c ＝0.85R e -1.71
wherein R is e The radius of the equivalent karst cave is expressed, and the calculation method is obtained according to the principle that the internal volume of the karst cave is equal to the volume of a sphere, so that the karst cave with any shape is equivalently calculated into the spherical karst cave, and the critical eccentricity is calculated;
critical eccentricity D at steady flow c The size of the cavern is related to other parameters such as reservoir thickness and permeability.
Step 5.3 is also followed by step 5.2: the critical eccentricity determining method under unsteady flow conditions comprises the following steps:
in the middle and later stages of oil field development, the oil-water movement speed is related to pressure and belongs to unsteady flow, the influence of the drilling position of a vertical well in the karst cave on the yield of the vertical well is greater than that in the initial stage of development, the yield is reduced along with the increase of the eccentricity, and the influence degree of the eccentricity reaching 20 percent of the radius of the karst cave on the yield must be considered;
equivalent karst cave radius R e Formation crude oil viscosity mu and reservoir permeability k vs. eccentricityWell production has a certain impact, defining variables
By utilizing a multivariate nonlinear fitting method, according to the yield change of 20%, determining that the critical eccentricity relationship is as follows: d c ＝-15.47ln(T c )+14.76；
Wherein a variable T is calculated c The units of the parameters are as follows:
reservoir permeability k, 10 -3 um 2 ；
Equivalent karst cave radius R e ，m；
Formation crude oil viscosity μ, mpa.s.
Example one
The yield of several oil wells in different blocks of the Tahe oil field is calculated according to the yield calculation formula obtained in the invention, and the eccentric distance is calculated according to the seismic interpretation result
The yield prediction result of the Tahe oil field S74 unit SXX well is as follows: the SXX well is located in a Tahe oilfield main force area S74 development unit, the self-injection production is started from 2001, the original formation pressure is 58.9Mpa, the yield of the well is calculated by utilizing the constant flow and the unsteady flow respectively, the comparison is carried out on the yield of the well and the actual yield of the well, the result is shown in figure 3, the calculation result shows that the critical eccentricity is 35.9m, the actual eccentricity is 58.2m and is larger than the critical eccentricity, and therefore when the yield of the well is predicted, the influence of the eccentricity on the yield of the well needs to be considered.
Example two
The yield prediction result of the TK7-XXX well of the S80 unit is that the TK7-XXX well is located in one straight well at the north of the S80 unit of the Tahe oil field main power area, the drilling is completed in 4 months in 2006, the predicted formation pressure of the adjacent well is 58.63Mpa when the drilling is completed, the self-injection time of the well is from 5 months in 2006 to 11 months in 2009, the yield of the well is predicted according to the method, and the result is shown in figure 4. The well critical eccentricity is predicted to be 30.2m, the eccentricity is predicted to be 19.5m and is smaller than the critical eccentricity by seismic interpretation, and the influence of the eccentricity can not be considered when the well yield is predicted.
While the present invention has been described with reference to the preferred embodiments as above, the description is only for the convenience of understanding of the embodiments of the present invention and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (1)
1. A method for predicting the yield of a production well of a fractured-vuggy carbonate reservoir is characterized by comprising the following steps of:
step 1: according to the pressure reduction condition of the oil reservoir stratum, a fixed constant flow stage and an unsteady constant flow stage are divided;
step 2: calculating the steady flow yield;
and 3, step 3: calculating the unsteady flow yield;
and 4, step 4: calculating the yield of one eccentric well in the karst cave;
and 5: determining a critical eccentricity;
the step 2 further comprises the following steps:
at the initial stage of oil field development, the change degree of reservoir formation pressure is small, and the pressure and the yield do not change along with time, namely the flowing process belongs to steady flow;
then, by using a mirror image reflection principle and a multi-well interference theory in classical seepage mechanics, an influence calculation formula of a distance d between the center of one vertical well and the center of the karst cave on the yield q of the karst cave stratum is obtained as follows:
wherein k represents reservoir permeability, 10 -3 μm 2 (ii) a h represents reservoir thickness, m; p is a radical of e Indicating that the original pressure in the karst cave is also the original pressure value at the boundary of the karst cave, namely Mpa; p is a radical of w Represents the bottom hole pressure of the production well, Mpa; μ represents formation crude oil viscosity, mpa.s; r is e Represents the karst cave boundary radius, m; r is w Indicating in the wellA section radius, m;
the step 3 further comprises the following steps:
step 3.1: in the middle and later stages of oilfield development, the oil-water movement speed is related to the reservoir stratum pressure, namely the flow process belongs to unsteady flow, and then the reservoir stratum pressure change equation is obtained:
the solution conditions are as follows:
initial condition p (r,0) ═ p i
The outer boundary condition p (∞, t) ═ p i
Inner boundary condition
Wherein p represents the reservoir internal pressure at the moment of calculation, Mpa; r represents the distance from any point of the stratum to the center of the oil well, m; μ represents formation crude oil viscosity, mpa.s; c t Is the compression coefficient of crude oil, Mpa -1 (ii) a t represents time; b represents a volume coefficient of crude oil; p is a radical of i Original reservoir pressure, Mpa;
said step 3.1 is followed by a step 3.2: solving the relation between pressure and yield by adopting a boundary element method;
step 3.2: the method also comprises the following specific steps:
step 3.2.1: dividing the boundary into boundary units with limited size according to the boundary element calculation principle;
step 3.2.2: dispersing the integral equation into an algebraic equation, so that the problem of solving the differential equation is converted into the problem of solving the algebraic equation;
step 3.2.3: the boundary element method can realize the prediction of the yield of the eccentric well only by changing the well coordinates on the basis of closing one vertical well model in the boundary oil reservoir;
in step 3.2.3, the method further includes:
differential equation of seepage:
the solution conditions are as follows:
inner boundary conditions:
initial conditions: p is a radical of formula D (r D ,0)＝0
And (3) sealing external boundary conditions:
wherein p is D Representing dimensionless pressure; r is D Represents a dimensionless radius; q. q.s D Indicates dimensionless yield; t is t D Representing a dimensionless time; r is eD Representing a karst cave boundary dimensionless radius;
and 3, carrying out dimensionless processing on the seepage differential equation in the step 3.2.3 to obtain a vertical well model in the closed boundary oil reservoir, wherein the dimensionless calculation process comprises the following steps:
dimensionless pressure p D Calculating the formula:
dimensionless yield q D Calculating the formula:
dimensionless radius r D Calculating the formula:
dimensionless time t D Calculating the formula:
wherein phi is the effective porosity of the reservoir;
the formula for calculating the yield of one eccentric well in the karst cave in the step 4 is as follows:
wherein, the Q point is any point in the region and on the boundary Gamma; p' is any point on the boundary; n represents a unit vector of normal risk of a karst cave boundary;
moving the Q point to the boundary f, the integral equation is used to calculate p D (p', t) and
unknown boundary variables, increased unknowns q D Moving the point Q to the well point W to increase a corresponding equation to solve;
the function G represents the basic solution of the laplace diffusion equation, which is of the form:
wherein, K 0 A zero-order Bessel function of a second type;
in the step 5, the method further comprises the following steps:
step 5.1: basis of determination
Firstly, determining eccentricity as a factor influencing yield;
secondly, the eccentricity D of 20% affecting the yield is defined as the critical eccentricity D c ；
Finally, when the eccentricity D is less than D c Directly adopting a karst cave central vertical well yield calculation formula;
obtaining an analytic solution or a numerical solution from the closed outside of the homogeneous oil reservoir model, and performing calculation programming by using Matlab to obtain the output of the central vertical well of one karst cave at different moments;
step 5.2 is also followed by step 5.1: the critical eccentricity determining method under the condition of constant flow comprises the following steps:
when the eccentricity D is greater than D c The influence of eccentricity must be considered; the cutoff for considering the off-center effect is determined as 20% change in raw yield in units of m:
D c ＝0.85R e -1.71
wherein R is e The radius of the equivalent karst cave is expressed, the calculation method is obtained according to the principle that the internal volume of the karst cave is equal to the volume of a sphere, the karst cave with any shape is equivalently calculated into the spherical karst cave, and the critical eccentricity is calculated;
critical eccentricity D at steady flow c The size of the karst cave is related, and the size of the karst cave is not related to other parameters;
said step 5.2 is followed by a step 5.3: the critical eccentricity determining method under unsteady flow conditions comprises the following steps:
in the middle and later stages of oilfield development, the oil-water movement speed is related to pressure and belongs to unsteady flow, the influence of the drilling position of a vertical well in the karst cave on the yield of the vertical well is greater than that in the initial stage of development, the yield is reduced along with the increase of the eccentricity, and the influence degree of the eccentricity reaching 20% of the radius of the karst cave on the yield must be considered;
equivalent karst cave radius R e The viscosity mu of the crude oil of the stratum and the permeability k of the reservoir have certain influence on the yield of the eccentric well, and variables are defined
By utilizing a multivariate nonlinear fitting method, according to the yield change of 20%, determining that the critical eccentricity relationship is as follows: d c ＝-15.47ln(T c )+14.76；
Wherein the variable T is calculated c The units of the parameters are as follows:
reservoir Permeability k, 10 -3 um 2 ；
Equivalent karst cave radius R e ，m；
Formation crude oil viscosity μ, mpa.s.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103413030A (en) * | 2013-07-24 | 2013-11-27 | 中国石油天然气股份有限公司 | Fracture-cavity type carbonate rock gas reservoir dynamic analysis method and system |
| CN106640021A (en) * | 2016-12-01 | 2017-05-10 | 中国石油天然气股份有限公司 | Calculation method and device of post-pressure blowout parameters |
| CN107563027A (en) * | 2017-08-21 | 2018-01-09 | 西南石油大学 | For analyzing the WELL TEST INTERPRETATION MODEL and method of more fracture-cavity units cascaded structures |
-
2018
- 2018-06-28 CN CN201810690612.6A patent/CN110656923B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103413030A (en) * | 2013-07-24 | 2013-11-27 | 中国石油天然气股份有限公司 | Fracture-cavity type carbonate rock gas reservoir dynamic analysis method and system |
| CN106640021A (en) * | 2016-12-01 | 2017-05-10 | 中国石油天然气股份有限公司 | Calculation method and device of post-pressure blowout parameters |
| CN107563027A (en) * | 2017-08-21 | 2018-01-09 | 西南石油大学 | For analyzing the WELL TEST INTERPRETATION MODEL and method of more fracture-cavity units cascaded structures |
Non-Patent Citations (2)
| Title |
|---|
| 变形介质油藏中的不稳定渗流;宋付权等;《水动力学研究与进展A辑》;20070228(第01期);全文 * |
| 碳酸盐岩油藏缝洞单元离散数值模型及压力响应曲线特征;陈方方等;《科技导报》;20170728(第14期);全文 * |
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