CN115204504A - Failure type exploitation self-blowout oil well blowout stop prediction method - Google Patents
Failure type exploitation self-blowout oil well blowout stop prediction method Download PDFInfo
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Abstract
The invention provides a blowout stop prediction method for a failure type exploitation self-blowing oil well, which is characterized by comprising the following steps of: (1) Collecting high-pressure PVT data of the failure-type exploitation self-injection oil well, and calculating a crude oil volume correction coefficient and a dissolved gas-oil ratio correction coefficient; (2) Collecting a certain stratum pressure greater than the bubble point pressure and a corresponding liquid production index of single-phase seepage, calculating liquid production amounts corresponding to different pressures and drawing an inflow dynamic curve; (3) Combining the calculated data in the step (1), and calculating the pressure drop of the well shaft by using an iterative method; (4) Determining the corresponding relation between the future fluid production index and the fluid production index of the reference inflow dynamic curve, and predicting the inflow dynamic curve under the future formation pressure; (5) Drawing a spray stopping prediction curve, reading the intersection point liquid production capacity and the bottom hole flow pressure of inflow and outflow dynamics under different stratum pressures, if the intersection points show that the liquid production capacity is 0, and the stratum pressure, the bottom hole flow pressure and the liquid production capacity data corresponding to the intersection points are corresponding parameters for spray stopping, so that the aim of spray stopping prediction is fulfilled.
Description
Technical Field
The invention belongs to the technical field of oil and gas field development, and particularly relates to a failure type exploitation self-injection oil well blowout stop prediction method.
Technical Field
In the process of oil and gas field development and production, the formation pressure is gradually reduced, and more oil wells face the condition of blowout stoppage along with the production. The method can accurately predict the blowout stopping time of the oil well, and the bottom hole flowing pressure, the formation pressure, the yield and other flowing parameters are determined to be of great importance to the selection and design of the artificial lifting process. The prediction of the blowout stop time of the oil well relates to the comprehensive flow problem of stratum seepage and shaft multiphase pipe flow, the physical process is complex, and the accurate prediction difficulty is high. Typically, well blowout stoppage predictions only predict the blowout stoppage time. The time required for reaching the critical condition of spray stopping can be predicted according to the calculated flowing pressure or the actually measured formation static pressure change trend, and the time required for reducing the oil pressure to the minimum output pressure can also be predicted according to the oil pressure descending trend. However, the methods are empirical methods, lack theoretical support and have large prediction errors.
Therefore, the invention provides a blowout stop prediction method for the failure type exploitation self-blowing oil well. The method utilizes a node system analysis method to draw a stratum inflow dynamic curve (IPR) and a shaft oil pipe dynamic curve (TPC) according to the current stratum pressure and wellhead back pressure, and carries out prediction analysis on inflow dynamics under different stratum pressures, thereby realizing accurate prediction of the stop injection time.
Disclosure of Invention
The invention aims to solve the problem of accurately judging the blowout stop prediction of the failure type exploitation self-blowing oil well, and provides a method for judging the blowout stop prediction of the failure type exploitation self-blowing oil well.
A failure type exploitation self-injection oil well blowout stop prediction method comprises the following specific steps:
the method comprises the following steps: calculating a crude oil volume coefficient correction coefficient and a dissolved gas-oil ratio correction coefficient;
collecting high-pressure PVT data of the failure-type exploitation self-injection oil well, wherein the high-pressure PVT data comprises temperature, bubble point pressure, dissolved gas-oil ratio and crude oil volume coefficient under the original stratum condition; and calculating the high-pressure physical property of the crude oil under the original stratum condition by adopting a Vasquez-Beggs model, and calculating the volume coefficient of the crude oil by adopting an actual measurement value correction coefficient according to a formula I.
The first formula is as follows:
in the formula I, R S Is the dissolved gas-oil ratio of natural gas under the conditions of the original stratum, m 3 /m 3 ；T f Temperature at virgin formation conditions, deg.C; gamma ray API Is the relative density of the crude oil; gamma ray gc Is the relative density of natural gas.
Wherein when the relative density of crude oil is gamma API Constant a > 0.8762 1 、a 2 、a 3 Respectively takes the values of 4.677 multiplied by 10 -4 ,1.751×10 -5 ，-1.811×10 -8 (ii) a When relative density of crude oil is gamma API Constant a is less than or equal to 0.8762 1 、a 2 、a 3 Respectively taking the value of 4.670 multiplied by 10 -4 ,1.100×10 -5 ，1.377×10 -9 。
The volume coefficient of the crude oil under the original stratum condition is subjected to quotient with the volume coefficient of the crude oil calculated by the model, so that a volume coefficient correction coefficient of the crude oil can be obtained, and the volume coefficient correction coefficient of the crude oil is calculated by a formula II;
the second formula is:
in the formula two, C Bo The volume coefficient correction coefficient of the crude oil is obtained; b o,m For measuring volume coefficient of crude oil under original formation conditions, m 3 /m 3 。
The dissolved gas-oil ratio is calculated by formula three.
The third formula is:
wherein, P b Bubble point pressure, MPa; when the relative density of crude oil is gamma API Constant b > 30 1 、b 2 、b 3 The values are respectively 0.0178,1.1870 and 23.9310; when the relative density of crude oil is gamma API When the constant is less than or equal to 30, the constant b 1 、b 2 、b 3 The values are respectively 0.0362,1.0937 and 25.7240.
The dissolved gas-oil ratio under the original stratum condition is subjected to quotient drawing with the dissolved gas-oil ratio calculated by the model to obtain a crude oil dissolved gas-oil ratio correction coefficient, and the crude oil dissolved gas-oil ratio correction coefficient is calculated by a formula IV;
the fourth formula is:
in the fourth formula, C Rs The gas-oil ratio correction coefficient is used for crude oil dissolution; r is s,m For measuring the dissolved gas-oil ratio of crude oil under the original formation conditions, m 3 /m 3 。
Step two: drawing a reference inflow dynamic curve;
collecting any formation pressure greater than the bubble point pressure and the corresponding fluid production index during single-phase seepage;
calculating the liquid production amount corresponding to different bottom hole flow pressure conditions, wherein the method comprises the following steps:
when the bottom hole flowing pressure is greater than or equal to the bubble point pressure, single-phase flow is formed in the oil reservoir, and the liquid production amount of the oil well is calculated by a formula V;
the formula five is as follows: q. q of o ＝J o (p r -p wf ) (5)
In the formula five, q o For well production, m 3 /d；J o Is the liquid production index m at the time of bottom hole flowing pressure high pressure bubble point pressure 3 /(d·MPa)；p r Is the average formation pressure, MPa; p is a radical of formula wf Is the bottom hole flowing pressure, MPa;
when the bottom hole flowing pressure is lower than the crude oil bubble point pressure, the vertical well liquid production amount is calculated by a formula six;
the sixth formula is:
the inflow dynamic of the horizontal well is calculated by a formula seven;
the seventh formula is:
drawing an inflow dynamic curve on a bottom hole flowing pressure-liquid yield coordinate axis according to different bottom hole flowing pressures and the calculated liquid yield;
when the bottom hole flowing pressure is 0, the oil well unobstructed flow q of the stratum pressure corresponding to the reference inflow dynamic curve can be calculated omax 。
Step three: drawing an outflow dynamic curve;
collecting parameters of the oil well such as pipe conveying pressure, ground temperature, ground gas-oil ratio, water content, oil pipe size, well depth and the like, and calculating the pressure drop of the shaft by adopting an iterative method by combining the crude oil volume coefficient, the solution gas-oil ratio prediction model and the correction coefficient thereof in the first step. The method comprises the following steps:
(1) Dividing the liquid production into N portions, respectively making them equal to
Segmenting the shaft according to the well depth, and dividing the number of iteration segments into N I ；
(2) Sequentially setting a liquid production amount according to the liquid production amount in the step (1) from small to large;
(3) Given the boundary conditions: well head condition p 0 ＝p t ，
(4) Calculating p i (j＝1)：
(5) Let p =0.5[ p ] i-1 +p i (j)]；
The bubble point pressure is calculated by a formula eight;
the formula eight is:
wherein Rs is dissolved gas-oil ratio, m 3 /m 3 ；γ gs Is the relative density of the gas.
In this equation eight, the coefficient d is calculated by equation nine.
The ninth formula is:
wherein when the relative density of the crude oil is gamma API Constant c is more than or equal to 0.8762 1 、c 2 、c 3 The values are 27.62,0.914328 and 11.172 respectively; when relative density of crude oilγ API Constant c < 0.8762 1 、c 2 、c 3 The values are 56.18,0.84246 and 10.393 respectively.
In the formula eight, γ gs Calculated by the formula ten.
The formula ten is:
if p is b >p, then let p b ＝p；
Calculating the dissolved gas-oil ratio Rs and c when the bubble point pressure is p by using a formula III, further calculating the real gas quantity of the shaft, and calculating by using a formula eleven;
the formula eleven shown is: q g ＝Q s -Q o R s，c C Rs (11)
Wherein Qs is total gas production amount, x 10 4 m 3 /d；Q o For the amount of gas evolved,. Times.10 4 m 3 /d。
The superficial gas flow rate is calculated by formula twelve;
the formula twelve shown is:
wherein, B g Is the gas volume coefficient, m 3 /m 3 (ii) a A is the area of oil pipe, m 2 ；
Calculating the real fluid flow rate of the well by using the p value, and calculating by using a formula thirteen;
the formula thirteen shown is:
calculating dp/dz (j + 1) using the p value, which is calculated by equation fourteen;
the formula fourteen shown is:
in the fourteenth equation, p is a pressure,pa; theta is a well oblique angle (an included angle between a well axis and the horizontal direction); v. of m Flow rate of the two-phase mixture, m/s; d is the inner diameter of the oil pipe, m; f. of m The coefficient of friction resistance of the two phases; ρ is a unit of a gradient m Is the average density of the gas-liquid mixture on any section Z.
Wherein the coefficient of friction resistance f of the two phases m Calculated by the Mukherjee-Brill model method.
Average density of gas-liquid mixture ρ m Calculated by the equation fifteen.
The formula fifteen is: ρ is a unit of a gradient m ＝ρ L H L +ρ G (1-H L ) (15)
In the formula fifteen, H L For the liquid holdup, it was calculated from a formula sixteen, which was established based on experimental data fitting.
The formula sixteen is:
wherein, c 1 ＝-1.089，c 2 ＝1.319，c 3 ＝-0.961，c 4 ＝0.362，c 5 ＝0.061；
Sigma is the gas-water interfacial tension, N/m;
(6) Calculating p i (j+1)：
(7) And (3) judging convergence: if | p i (j+1)-p i (j)∣/p i (j+1)>Epsilon, then let p i (j)＝p i (j + 1), and repeating the steps (5) to (7); otherwise let p i+1 ＝p i (j + 1), i = i +1, repeating steps (4) - (7) until i = N I To obtain the bottom hole pressure p at a given liquid production rate wf ；
(8) Changing the liquid production amount according to the requirement of the step (2), and repeating the steps (2) to (8).
Step four: predicting a formation inflow dynamic curve under different formation pressures in the future;
(1) Given a range of formation pressures p r1 、p r2 、……p rM If the local pressure is above the bubble point pressure, it can be determined that the future fluid production index corresponds to the fluid production index of the baseline inflow profile as calculated by equation seventeen.
The seventeenth formula is: j is a unit of f ＝J p (μ o B o ) f /(μ o B o ) p (17)
Wherein J represents the fluid production index, m 3 V (d.MPa); subscript f denotes a time in the future; subscript p denotes the current conditions; mu.s 0 Crude oil viscosity, mPa · s; b 0 Is the volume coefficient of crude oil, m 3 /m 3 。
(2) When the formation pressure is lower than the bubble point pressure, the corresponding relation of the non-resistance flow and the reservoir pressure which is the bubble point pressure is calculated by a formula eighteen;
the formula eighteen is: q. q.s omaxF ＝q omaxb (p rF /p rb ) 3 (18)
Wherein q is omaxF For formation pressure p rF Corresponding unobstructed flow, m 3 /d；q omaxb For formation pressure of p rb Corresponding unobstructed flow, m 3 /d；p rb Bubble point pressure, MPa; p is a radical of rF For future formation pressure, MPa;
(3) According to the obtained result, an inflow dynamic curve under the condition of predicting the future formation pressure can be obtained, and the inflow dynamic curve is obtained by calculation of a formula from seventeen to eighteen;
step five: drawing a spray stopping prediction curve;
reading intersection point liquid production capacity and bottom hole liquid production capacity of inflow dynamic and outflow dynamic under different stratum pressure conditions, if the intersection points do not intersect, indicating that the liquid production capacity is 0, and finally, the formation pressure, bottom hole liquid production capacity and liquid production capacity data corresponding to the intersection points are corresponding parameters for stopping the injection, so that the purpose of predicting the stop of the injection of the self-injection well of the oil field is achieved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Drawings
FIG. 1 is a schematic diagram of stall prediction for sensitively differentiating formation pressure into IPR curves and outflow dynamics curves;
FIG. 2 is a schematic diagram of measured shut-in formation pressure versus production.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings by way of examples.
Fig. 1 is a schematic diagram of a sensitive and differential formation pressure making IPR curve and outflow dynamic curve, wherein a spray stopping prediction curve is drawn by the following method:
the method comprises the following steps: calculating a crude oil volume coefficient correction coefficient and a dissolved gas-oil ratio correction coefficient;
collecting high-pressure PVT data of the depletion type exploitation self-injection oil well, wherein the high-pressure PVT data comprises temperature, bubble point pressure, dissolved gas-oil ratio and crude oil volume coefficient under the original stratum condition; and calculating the high-pressure physical property of the crude oil under the original stratum condition by adopting a Vasquez-Beggs model, and calculating the volume coefficient of the crude oil by adopting an actual measurement value correction coefficient according to a formula I.
The first formula is as follows:
in the formula I, R S Is the dissolved gas-oil ratio of natural gas under the conditions of the original stratum, m 3 /m 3 ；T f Temperature at the original formation conditions; gamma ray API Is the relative density of the crude oil; gamma ray gc Is the relative density of natural gas.
Wherein when the relative density of the crude oil is gamma API Constant a > 0.8762 1 、a 2 、a 3 Respectively taking values of 4.677 and a10 -4 ,1.751×10 -5 ，-1.811×10 -8 (ii) a When relative density of crude oil is gamma API When the constant is less than or equal to 0.8762, the constant a 1 、a 2 、a 3 Respectively taking the value of 4.670 multiplied by 10 -4 ,1.100×10 -5 ，1.377×10 -9 。
The crude oil volume coefficient under the original stratum condition is subjected to quotient with the crude oil volume coefficient calculated by the model, so that a crude oil volume coefficient correction coefficient can be obtained, and the coefficient is calculated by a formula II;
the second formula is:
in the second formula, C Bo The volume coefficient correction coefficient of the crude oil is obtained; b o,m For measuring volume coefficient of crude oil under original formation conditions, m 3 /m 3 。
The dissolved gas-oil ratio is calculated by formula three.
The third formula is:
wherein, P b Bubble point pressure, MPa; when relative density of crude oil is gamma API Constant b > 30 1 、b 2 、b 3 The values are respectively 0.0178,1.1870 and 23.9310; when the relative density of crude oil is gamma API Constant b is less than or equal to 30 1 、b 2 、b 3 The values are respectively 0.0362,1.0937 and 25.7240.
The dissolved gas-oil ratio under the original stratum condition is subjected to quotient drawing with the dissolved gas-oil ratio calculated by the model to obtain a crude oil dissolved gas-oil ratio correction coefficient, and the crude oil dissolved gas-oil ratio correction coefficient is calculated by a formula IV;
the fourth formula is:
in the formula four, C Rs The gas-oil ratio correction coefficient is used for crude oil dissolution; r s,m For measuring the dissolved gas-oil ratio of crude oil under the conditions of the original stratum, m 3 /m 3 。
Step two: drawing a reference inflow dynamic curve;
collecting any formation pressure greater than the bubble point pressure and the corresponding liquid production index during single-phase seepage;
calculating the liquid production amounts corresponding to different bottom hole flowing pressure conditions, wherein the method comprises the following steps:
when the bottom hole flow pressure is greater than or equal to the bubble point pressure, single-phase flow exists in the oil reservoir, and the liquid production amount of the oil well is calculated by a formula five;
the formula five is as follows: q. q.s o ＝J o (p r -p wf ) (5)
In the formula five, q o For well production, m 3 /d；J o Is the liquid production index m at the time of bottom hole flowing pressure high pressure bubble point pressure 3 /(d·MPa)；p r Is the average formation pressure, MPa; p is a radical of wf Is bottom hole flowing pressure, MPa;
when the bottom hole flowing pressure is lower than the bubble point pressure of the crude oil, the liquid production amount of the vertical well is calculated by a formula six;
the sixth formula is:
the inflow dynamic of the horizontal well is calculated by a formula seven;
the seventh formula is:
drawing an inflow dynamic curve on a bottom hole flowing pressure-liquid yield coordinate axis according to different bottom hole flowing pressures and the calculated liquid yield;
when the bottom hole flowing pressure is 0, the oil well unobstructed flow q of the stratum pressure corresponding to the reference inflow dynamic curve can be calculated omax 。
Step three: drawing an outflow dynamic curve;
collecting parameters of the oil well such as pipe pressure, surface temperature, surface gas-oil ratio, water content, oil pipe size, well depth and the like, and calculating the pressure drop of the shaft by adopting an iterative method by combining the crude oil volume coefficient, the dissolved gas-oil ratio prediction model and the correction coefficient thereof in the first step. The method comprises the following steps:
(1) Dividing the liquid production into N parts, respectively making them equal to
Segmenting the shaft according to the well depth, and dividing the number N of iteration segments I ；
(2) Sequentially setting a liquid production amount according to the liquid production amount in the step (1) from small to large;
(3) Given the boundary conditions: well head condition p 0 ＝p t ，
(4) Calculating p i (j＝1)：
(5) Let p =0.5[ 2 ] p i-1 +p i (j)]；
The bubble point pressure is calculated by a formula eight;
the formula eight is:
wherein Rs is dissolved gas-oil ratio, m 3 /m 3 ；γ gs Is the relative density of the gas.
In this equation eight, the coefficient d is calculated by equation nine.
The ninth formula is:
in the formula eight, γ gs Calculated by the formula ten.
The formula ten is:
if p is b >p, thenLet p be b ＝p；
Calculating the dissolved gas-oil ratio Rs and c when the bubble point pressure is p by using a formula III, further calculating the real gas quantity of the shaft, and calculating by using a formula eleven;
the formula eleven shown is: q g ＝Q s -Q o R s，c C Rs (11)
Wherein Qs is total gas production amount, x 10 4 m 3 /d；Q o Amount of gas evolved,. Times.10 4 m 3 /d。
The superficial gas flow rate is calculated by the formula twelve;
the formula twelve shown is:
wherein, B g Is the gas volume coefficient, m 3 /m 3 (ii) a A is the area of oil pipe, m 2 ；
Calculating the real fluid flow rate of the well by using the p value, and calculating by using a formula thirteen;
the formula thirteen shown is:
calculating dp/dz (j + 1) using the p value, which is calculated by equation fourteen;
the formula shown is fourteen:
in the fourteenth equation, p is pressure, pa; theta is a well inclination angle (an included angle between a well axis and the horizontal direction); v. of m Flow rate of the two-phase mixture, m/s; d is the inner diameter of the oil pipe, m; f. of m The coefficient of friction resistance of the two phases; ρ is a unit of a gradient m Is the average density of the gas-liquid mixture on any section Z.
Wherein the coefficient of friction resistance f of the two phases m Calculated by the Mukherjee-Brill model method.
Average density of gas-liquid mixture ρ m Calculated by the equation fifteen.
The formula fifteen is: rho m ＝ρ L H L +ρ G (1-H L ) (15)
In the formula fifteen, H L For the liquid holdup, it was calculated from a formula sixteen, which was established based on experimental data fitting.
The formula sixteen is:
wherein, c 1 ＝-1.089，c 2 ＝1.319，c 3 ＝-0.961，c 4 ＝0.362，c 5 ＝0.061；
Sigma is gas-water interfacial tension, N/m;
(6) Calculating p i (j+1)：
(7) And (3) judging convergence: if | p i (j+1)-p i (j)∣/p i (j+1)>ε, then let p i (j)＝p i (j + 1), and repeating the steps (5) to (7); otherwise let p i+1 ＝p i (j + 1), i = i +1, repeating steps (4) - (7) until i = N I To obtain the bottom hole pressure p at a given liquid production rate wf ；
(8) Changing the liquid production amount according to the requirement of the step (2), and repeating the steps (2) to (8).
Step four: predicting a future formation inflow dynamic curve under different formation pressures;
(1) Given a range of formation pressures p r1 、p r2 、……p rM If the local pressure is above the bubble point pressure, it can be determined that the future fluid production index corresponds to the fluid production index of the baseline inflow profile as calculated by equation seventeen.
The formula seventeen is: j. the design is a square f ＝J p (μ o B o ) f /(μ o B o ) p (17)
Wherein J represents the fluid production index, m 3 V (d.MPa); subscript f indicates a time in the future; subscript p indicates the current conditions; mu.s 0 Crude oil viscosity, mPa · s; b is 0 Is the volume coefficient of crude oil, m 3 /m 3 。
(2) When the formation pressure is lower than the bubble point pressure, the corresponding relation of the non-resistance flow and the reservoir pressure which is the bubble point pressure is calculated by a formula eighteen;
the formula eighteen is: q. q of omaxF ＝q omaxb (p rF /p rb ) 3 (18)
Wherein q is omaxF For formation pressure of p rF Corresponding unobstructed flow, m 3 /d；q omaxb For formation pressure p rb Corresponding unobstructed flow, m 3 /d；p rb Bubble point pressure, MPa; p is a radical of formula rF For future formation pressure, MPa;
(3) According to the obtained result, an inflow dynamic curve under the condition of predicting the future formation pressure can be obtained, and the inflow dynamic curve is obtained by calculation of a formula from seventeen to eighteen;
step five: drawing a spray stopping prediction curve;
reading intersection point liquid production capacity and bottom hole flow pressure of inflow dynamics and outflow dynamics under different stratum pressure conditions, if the intersection points show that the liquid production capacity is 0, and the stratum pressure, the bottom hole flow pressure and the liquid production capacity data corresponding to the last intersection point are corresponding parameters for stopping the spraying, so that the aim of predicting the stopping of the spraying of the automatic spraying well in the oil field is fulfilled. The predicted shut-off parameters may be compared to, for example, the static formation pressure in the actual shut-off formation pressure and production map of fig. 2, and the prediction error of the method may be obtained.
Claims (3)
1. The failure type exploitation self-injection oil well blowout stop prediction method is characterized by mainly comprising the following steps of:
the method comprises the following steps: collecting high-pressure PVT data of the failure type exploitation self-blowing oil well, including temperature, bubble point pressure, dissolved gas-oil ratio and crude oil volume coefficient under the original stratum condition, and calculating a crude oil volume coefficient correction coefficient and a dissolved gas-oil ratio correction coefficient;
step two: collecting a certain stratum pressure greater than the bubble point pressure and a corresponding liquid production index during single-phase seepage, calculating liquid production amounts corresponding to different bottom hole flow pressure conditions, and drawing an inflow dynamic curve on a bottom hole flow pressure-liquid production amount coordinate axis according to different bottom hole flow pressures and the calculated liquid production amounts;
step three: combining the crude oil volume coefficient, the solution gas-oil ratio prediction model and the correction coefficient thereof in the step one, and calculating the pressure drop of the shaft by adopting an iterative method;
step four: determining the corresponding relation between the future fluid production index and the fluid production index of the reference inflow dynamic curve, and predicting the inflow dynamic curve under the condition of future formation pressure;
step five: drawing a spray stopping prediction curve, reading intersection point liquid production capacity and bottom hole flow pressure of inflow dynamics and outflow dynamics under different stratum pressure conditions, indicating that the liquid production capacity is 0 if the intersection points do not exist, and finally obtaining stratum pressure, bottom hole flow pressure and liquid production capacity data corresponding to the intersection points as corresponding parameters for spray stopping, thereby achieving the aim of predicting the spray stopping of the self-blowing well of the oil field.
2. The depletion mode production self-blowing oil well blowout stop prediction method of claim 1, wherein the iterative calculation method of the wellbore pressure drop in the third step is as follows: comprises eight steps:
the method comprises the following steps: dividing the liquid production into N portions, respectively making them equal to
Segmenting the shaft according to the well depth, and dividing the number N of iteration segments I ；
Step two: sequentially setting a liquid production amount according to the liquid production amount in the last step from small to large;
step three: to giveDetermining boundary conditions: well head condition p 0 ＝p t ，
Step four: calculating p i (j＝1)：
Step five: let p =0.5 (p) i-1 +p i (j))；
The bubble point pressure is calculated by the following method:
wherein Rs is dissolved gas-oil ratio, m 3 /m 3 ；γ gs Is the relative density of the gas.
In the calculation formula of the bubble point pressure, the calculation method of the coefficient d is as follows:
wherein when the relative density of crude oil is gamma API Constant c is more than or equal to 0.8762 1 、c 2 、c 3 The values are respectively 27.62,0.914328 and 11.172; when the relative density of crude oil is gamma API < 0.8762, constant c 1 、c 2 、c 3 The values are 56.18,0.84246 and 10.393 respectively.
In the calculation of the bubble point pressure, γ gs The calculation method comprises the following steps:
if p is b >p, then let p b ＝p；
And calculating the real gas volume of the well bore by using the p value, wherein the calculation method comprises the following steps:
Q g ＝Q s -Q o R s,c C Rs
the apparent airflow velocity is calculated by the following method:
wherein, B g Is the gas volume coefficient, m 3 /m 3 (ii) a A is the area of oil pipe, m 2 ；
And calculating the real fluid flow rate of the well bore by using the p value, wherein the calculation method comprises the following steps:
and (3) calculating dp/dz (j + 1) by using the p value, wherein the calculation method of the value is as follows:
in this formula, p is the pressure, pa; theta is a well inclination angle (an included angle between a well axis and the horizontal direction); v. of m Flow rate of the two-phase mixture, m/s; d is the inner diameter of the oil pipe, m; f. of m The coefficient of friction of the two phases; rho m The average density of the gas-liquid mixture on any section Z;
wherein the coefficient of friction resistance f of the two phases m Calculating by a Mukherjee-Brill model method;
average density of gas-liquid mixture ρ m The calculation method comprises the following steps:
ρ m ＝ρ L H L +ρ G (1-H L )
in the above formula, H L For the liquid holdup, it was calculated from a formula established based on experimental data fitting:
wherein, c 1 ＝-1.089，c 2 ＝1.319，c 3 ＝-0.961，c 4 ＝0.362，c 5 ＝0.061；
Sigma is the gas-water interfacial tension, N/m;
step six: calculating p i (j+1)：
Step seven: and (3) judging convergence: if | p i (j+1)-p i (j)∣/p i (j+1)>Epsilon, then let p i (j)＝p i (j + 1), repeating the fifth to seventh steps; otherwise let p i+1 ＝p i (j + 1), i = i +1, repeating steps four to seven until i = N I To obtain the bottom hole pressure p at a given liquid production rate wf ；
Step eight: and (5) changing the liquid production amount according to the requirement of the step two, and repeating the step two to the step eight.
3. The depletion mode production jet well shut-off prediction method of claim 1, wherein the step four of predicting the inflow dynamic curve under future formation pressure conditions comprises three steps:
the method comprises the following steps: given a range of formation pressures p r1 、p r2 、……p rM When the local pressure is higher than the bubble point pressure, the calculation method for determining the corresponding relation between the future liquid production index and the liquid production index of the reference inflow dynamic curve comprises the following steps:
J f ＝J p (μ o B o ) f /(μ o B o ) p
wherein J represents the fluid production index, m 3 /(d.MPa); subscript f denotes a time in the future; lower partThe index p indicates the current condition; mu.s 0 Crude oil viscosity, mPa · s; b is 0 Is the volume coefficient of crude oil, m 3 /m 3 ；
Step two: when the formation pressure is lower than the bubble point pressure, the calculation method of the corresponding relation of the non-resistance flow when the reservoir pressure is the bubble point pressure comprises the following steps:
q omaxF ＝q omaxb (p rF /p rb ) 3
wherein q is omaxF For formation pressure of p rF Corresponding unobstructed flow, m 3 /d；q omaxb For formation pressure p rb Corresponding unobstructed flow, m 3 /d；p rb Bubble point pressure, MPa; p is a radical of rF For future formation pressure, MPa;
step three: according to the obtained result, an inflow dynamic curve under the condition of predicting the future formation pressure can be obtained, and the inflow dynamic curve is obtained through calculation according to the formulas in the first step and the second step.
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| CN116933407B (en) * | 2023-06-01 | 2024-04-02 | 中国石油天然气股份有限公司 | Method for determining conversion limit of CCUS machine extraction and self-injection production |
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