CN112709547A - Method for judging water plugging time of water producing gas well - Google Patents
Method for judging water plugging time of water producing gas well Download PDFInfo
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- E—FIXED CONSTRUCTIONS
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- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
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- E—FIXED CONSTRUCTIONS
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- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
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Abstract
The invention belongs to the technical field of oil-gas exploration and development, and particularly relates to a method for judging water plugging time of a water-producing gas well. The discrimination method of the present invention includes the steps of: 1) selecting at least two factors from the factors influencing the water plugging time as discrimination indexes, and determining the attribute weight of each factor selected as the discrimination indexes; normalizing each factor to obtain a normalization processing result of each factor; calculating a comprehensive evaluation value by using a weighted average type comprehensive evaluation model according to the attribute weight and the normalization processing result of each influence factor; 2) according to the obtained comprehensive evaluation value contrast evaluation set, the comprehensive evaluation value is less than or equal to 0.3: water is not blocked temporarily; 0.3 < comprehensive evaluation value < 0.6: water needs to be blocked; and the comprehensive evaluation value is more than or equal to 0.6, and immediately blocks water to judge the water blocking time. The method has high accuracy, and has important significance for guiding the water producing gas well to carry out timely water plugging and improving the success rate of water plugging and re-production.
Description
Technical Field
The invention belongs to the technical field of oil-gas exploration and development, and particularly relates to a method for judging water plugging time of a water-producing gas well.
Background
For a high-sulfur-content gas reservoir, after water breakthrough of a gas well, the method is limited by the underground working condition and safety requirement of the high-sulfur-content gas well, drainage and gas production process measures are difficult to develop, and water plugging becomes a main method for prolonging the production time of the gas well. For a water outlet gas well, if water plugging is too early, the reservoir is plugged, so that the loss of reserve capacity and productivity is caused, so that the water plugging is mainly performed after the gas well is flooded and laid down at present, but formation water after flooding is easily poured into an upper unproductive reservoir, so that the back dialysis of the unproductive reservoir is caused, the success rate of water plugging and production recovery is low, and the problem of too late water plugging exists. Therefore, the exploration and research on the reasonable water plugging time of the water producing gas well are of great significance for prolonging the production time of the water producing gas well, reducing the water yield, improving the final recovery ratio of the gas reservoir and ensuring the efficient and stable development of the gas field.
At present, a mature and complete method for judging the water plugging time of a gas well is not available at home and abroad. Therefore, under the current condition, a rapid and accurate method for plugging the water of the gas well is established, and the method has a guiding effect on prolonging the production time of the gas well and improving the development effect of the high-sulfur-content gas field.
Disclosure of Invention
The invention aims to provide a method for judging the water plugging time of a water producing gas well, which can avoid the difficulty in the production recovery of the water producing gas well caused by too late water plugging.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method for judging water plugging time of a water producing gas well comprises the following steps:
1) selecting at least two factors from the factors influencing the water plugging time as discrimination indexes, and determining the attribute weight of each factor selected as the discrimination indexes; normalizing each factor to obtain a normalization processing result of each factor; calculating a comprehensive evaluation value by using a weighted average type comprehensive evaluation model according to the attribute weight and the normalization processing result of each influence factor;
2) according to the obtained comprehensive evaluation value contrast evaluation set, the comprehensive evaluation value is less than or equal to 0.3: water is not blocked temporarily; 0.3 < comprehensive evaluation value < 0.6: water needs to be blocked; and the comprehensive evaluation value is more than or equal to 0.6, and immediately blocks water to judge the water blocking time.
The judging method comprehensively considers a plurality of influence factors influencing the water plugging time, and has high judging accuracy. The invention establishes a method for quickly and accurately judging the water plugging time of the gas production water well, can avoid the difficulty in the success of the water production gas well in the production of the gas well due to too late water plugging, and has important significance for guiding the water production gas well to carry out timely water plugging and improving the success rate of the water plugging and the production of the gas well. The discrimination method of the invention has guiding function for prolonging the production time of the gas reservoir, especially the gas well of the high-sulfur gas reservoir, and improving the development effect of the gas field.
Factors influencing the water plugging time comprise the rising rate of a liquid-gas ratio, the production liquid-gas ratio, the formation pressure, the productivity of a water-producing gas well, the shut-in frequency and the last shut-in time.
The factors used as the judgment indexes are the rising rate of the liquid-gas ratio, the produced liquid-gas ratio, the formation pressure, the productivity of the water-producing gas well, the shut-in times and the last shut-in time. The discrimination method of the invention can improve the accuracy of the discrimination method by taking various influence factors into consideration.
The formation pressure is determined according to the following equation:
in the formula PwsIs the bottom hole static pressure (MPa), PwhFor well-closing oil pressure (MPa), gammagIs gas density (kg/m)3)，
Is the average temperature (K) of the wellbore,
and H is the average deviation coefficient of the shaft, and H is the depth (m) of the gas well.
The productivity of the water producing gas well is determined by a productivity evaluation model established according to the geological characteristics of the blocky gas field of the gas reservoir where the water producing gas well is located, and the productivity evaluation model is as follows:
wherein q is the productivity (m) of the water-producing gas well3/d)，PeIs the formation pressure (MPa), PwfIs the bottom hole flow pressure (MPa), and k is the permeability (10)-3μm2) H is reservoir thickness (m), Z is natural gas bias coefficient, μ is gas phase viscosity (mPa · s), reIs the radius (m) of gas supply rwIs the wellbore radius (m).
The permeability k is the upper permeability k1And lower permeability k2Average value of (d); wherein the upper permeability k1For the permeability of the upper gas-phase single-phase flow, the upper and lower permeability k2The permeability of the gas-water two-phase flow at the lower part of the reservoir.
The liquid-gas ratio rising rate is determined by the relation between the liquid-gas ratio and the water breakthrough time established according to the production data of the water producing gas well after water breakthrough.
And the production liquid-gas ratio is determined according to the production data of the water-producing gas well.
In order to improve the accuracy of the normalization result, when the factor as the discrimination index is positively correlated with the water plugging time, the formula adopted by the normalization processing is xi＝(ai-L)/(H-L); if the factor as the judgment index is negatively correlated with the water plugging time, normalizingThe formula adopted is xi＝1-(ai-L)/(H-L); in the formula xiIs a factor normalized value ofiIs a factor value, L is a factor lower limit value, and H is a factor upper limit value. And the factor upper limit value and the factor lower limit value are determined according to the maximum variation range of the actual gas well production parameters.
Drawings
FIG. 1 is a flow chart of a discrimination method of the present invention;
FIG. 2 is the liquid-gas ratio variation of the Puguang 103-1 well of example 1 of the present invention;
FIG. 3 is the liquid-gas ratio variation of the Puguang 105-2 well of example 2 of the present invention;
FIG. 4 is a model of the layered seepage mechanism of the Puguang gas field;
FIG. 5 is a plot of water saturation versus relative permeability (core) for a Puguang gas field;
FIG. 6 is a graph of gas phase relative permeability versus production water-to-gas ratio;
FIG. 7 is a graph of the common light 103-1 well IPR curve in example 1 of the present invention;
FIG. 8 is a graphical representation of the common 105-2 well IPR profile of example 2 of the present invention.
Detailed Description
As shown in fig. 1, the method for judging the water plugging time of the water producing gas well comprises the following steps:
selecting at least two factors from factors influencing the water plugging time as discrimination indexes
Factors influencing the water plugging time comprise the rising rate of a liquid-gas ratio, the production liquid-gas ratio, the formation pressure, the productivity of a water-producing gas well, the shut-in frequency and the last shut-in time.
Factors selected as the judgment indexes are the rising rate of the liquid-gas ratio, the produced liquid-gas ratio, the formation pressure, the productivity of a water-producing gas well, the shut-in times and the last shut-in time.
The liquid-gas rising rate is determined by the relation between the liquid-gas ratio and the water breakthrough time established according to the production data of the water producing gas well after water breakthrough. And the production liquid-gas ratio is determined according to the production data of the water-producing gas well before shut-in or latest production data.
The formation pressure is determined according to a gas well shaft pressure conversion model and the shut-in oil pressure; the gas well shaft pressure reduction model is as shown in formula (1):
in the formula: pws-bottom hole static pressure, MPa;
Pwh-shut-in oil pressure, MPa;
γggas density, kg/m3；
h-gas well depth, m.
And the productivity of the water producing gas well is determined according to a productivity evaluation model which is established based on the gas-water two-phase seepage characteristics of the blocky gas reservoir and is based on the geological characteristics of the blocky gas field of the gas reservoir where the water producing gas well is located. The establishment of the productivity evaluation model comprises the following steps:
1) according to the production profile test result of the water-producing gas well, a layered seepage mechanism model of the integrally-packed blocky gas field is established, and the model has the characteristics of gas-producing water co-production at the lower part of a reservoir and gas production at the upper part of the reservoir as a whole, namely the upper part of the reservoir is a gas-phase single-phase flow, and the lower part of the reservoir is a gas-water two-phase flow;
2) and establishing a layered productivity calculation model according to the longitudinal difference of the seepage of the whole block gas reservoir. Wherein the relational expression of the formation coefficient and the upper part and the lower part of the reservoir is as follows: k is1h1+Krgk2h2Formula (2);
3) based on gas-water two-phase core experimental data, carrying out normalization processing on a gas reservoir phase permeability curve to obtain a normalized phase permeability curve, and adopting a polynomial to fit the normalized phase permeability data to determine KrgAnd fwThe relation of (1):
Krg＝-0.096ln(fw) +0.5218 formula (3);
4) according to the formation pressure and the relational expression, determining a productivity evaluation model relational expression as follows:
in the above relational expressions (2) to (4):
q-gas well productivity, m3/d；
Pe-formation pressure, MPa;
Pwf-bottom hole flow pressure, MPa;
k is the formation coefficient;
k-permeability, 10-3μm2，
h-reservoir thickness, m;
k1upper permeability, 10-3μm2；
h1-upper reservoir thickness, m;
k2lower permeability, 10-3μm2；
h2-lower reservoir thickness, m;
fwproduction liquid to gas ratio, m3/104m3；
Krg-gas phase relative permeability;
z-natural gas deviation coefficient;
μ -gas phase viscosity, mPas;
re-gas supply radius, m;
rwwellbore radius, m.
(II) normalization processing
According to the selected asJudging the relationship between the factors of the index and the water plugging time, and determining the factor value (liquid-gas ratio rising rate (a)) of each factor1) Production liquid to gas ratio (a)2) Formation pressure (a)3) Productivity of water producing gas wells (a)4) Number of shut-in times (a)5) And the last shut-in period (a)6) Normalized according to a normalization formula):
if the factor as the judgment index is positively correlated with the water plugging time, xi＝(ai-L)/(H-L); if the factor as the determination index is negatively correlated with the water shutoff timing, xi＝1-(ai-L)/(H-L); in the formula xiIs a factor normalized value ofiIs a factor value, L is a factor lower limit value, and H is a factor upper limit value.
Among the factors used as the discrimination index, the formation pressure (a)3) Productivity of gas well producing water (a)4) The water plugging time is in negative correlation, and other factors are in positive correlation.
Wherein the upper limit value and the lower limit value of each factor are determined according to the maximum variation range of the actual parameters of gas well production.
(III) evaluation matrix calculation
(1) Determining rating level
The interval [0, 1] is divided into three levels, as shown in Table 1.
TABLE 1 Water shutoff grade division example table
| Rank of | Temporary water blockage prevention | Need to block water | Immediately block water |
| Interval (Y, Z) | (0，0.3) | (0.3，0.6) | (0.6，1) |
(2) Calculating an evaluation level vector (V)
V＝[V1，V2，V3，……，Vm]T
In the formula: j is the number of evaluation levels, j is 1, 2, … …, and m is 3.
(3) Establishing a matrix, and correcting the factor normalization value:
in the matrix: r isijIs an item to be evaluated as a factor to the discrimination index, wherein rij＝1-|xi-vjL, representing the likelihood that the item belongs to level j; i is the number of indexes, i is 1, 2, 3, …, n is 6; j is the number of evaluation levels, j is 1, 2, … …, and m is 3.
(IV) determining a weight vector W
And determining the weight vector W of each factor according to the fitting condition of the model and the actual production data of the water-producing gas well and the sensitivity analysis result.
(V) calculating a comprehensive evaluation value
And multiplying the weight vector W by the evaluation matrix R to obtain an evaluation vector S.
S＝W×R＝[s1，s2，s3，……，sm]T
Multiplying the evaluation level vector V by the evaluation vector S by a formula
The result B of the comprehensive evaluation was obtained.
And (5) evaluating the water plugging time according to the result B: comprehensive evaluation value is less than or equal to 0.3: water is not blocked temporarily; 0.3 < comprehensive evaluation value < 0.6: water needs to be blocked; and (5) the comprehensive evaluation value is more than or equal to 0.6, and water is immediately blocked.
If the gas production well is in the stage of 'temporary water blockage prevention', the water blockage is not considered at present; the stage of needing water plugging indicates that the related design of water plugging needs to be made at present, the water plugging operation is carried out according to the operation steps, and the success rate of water plugging is higher at the stage; the method is in the stage of 'immediate water shutoff', which indicates that the water shutoff and the production recovery tend to be difficult at present, and the water shutoff operation should be carried out as soon as possible to improve the success rate of the water shutoff and the production recovery.
The invention will be further explained by combining the water gas well of the high sulfur-containing gas field-Puguang gas field in northeast China and the attached drawings.
A gas field stratified seepage mechanism model shown in figure 4 is established according to gas field production data, and a gas reservoir phase seepage curve (shown in figure 5) and a gas phase relative permeability-production water-gas ratio change curve (shown in figure 6) are obtained based on gas-water two-phase core experiment data.
Example 1
In this embodiment, the method for determining the water shutoff time of the well with the general light 103-1 as an example comprises the following steps:
(1) according to production data after water breakthrough of the ordinary light 103-1 well, establishing a relation between a liquid-gas ratio and water breakthrough time (as shown in figure 2); as can be seen from FIG. 2, the change law of the liquid-gas ratio is generally proportional to the water breakthrough time, and the liquid-gas ratio rising rate of the well is 0.019m3/(104m3D) (from the rise in the phase liquid-gas ratio divided by the time);
(2) according to production data, determining the gas-liquid ratio of the production liquid before flooding to be 15.1m3/104m3；
(3) Oil pressure P to close wellwh23MPa, average temperature of a shaft of 328K, average coefficient of the shaft of 1.2, gammagIs 0.7kg/m3Substituting the well depth H into 6000m
Calculating to obtain a bottom hole static pressure of 40.2MPa, and determining the formation pressure of the ordinary light 103-1 well to be 40.2MPa (the formation pressure is the bottom hole static pressure);
(4) determining the gas phase relative permeability K of the gas-water layer of the well according to the measured water saturation and the figures 5 and 6rgIs 0.26, and the formation coefficient K is 304.5 multiplied by 10-3μm2·m；
(5) Determining the bottom hole flowing pressure to be 38MPa according to the figure 7, substituting parameters such as formation pressure, permeability and the like into a productivity calculation formula:
determining the productivity of the common light 103-1 well to be 120 multiplied by 104m3/d。
(6) And (4) counting the times of opening and closing the well after the stop of the general beam 103-1 and the well closing time in the water plugging operation according to the production data of the gas well. The well is opened and closed for 4 times for 103-1 wells under general lighting, and the well is closed for 160 days before water plugging;
(7) evaluating the time of water plugging operation of a common light 103-1 well according to the comprehensive model for evaluating the time of water plugging:
normalization processing was performed based on the factor data in table 2, and the normalized values of the factors are shown in table 2.
TABLE 2 correlation data for various factors of the Puguang 103-1 well
And calculating the water plugging coefficient of the common light 103-1 well according to the determined weight of each factor (shown in the table 2) and the normalization result.
(8) Determining rating level
The interval [0, 1] is divided into three levels as shown in Table 3
TABLE 3 Water shutoff grade division example table
| Rank of | Temporary water blockage prevention | Need to block water | Immediately block water |
| Interval (Y, Z) | (0，0.3) | (0.3，0.6) | (0.6，1) |
(9) Calculating an evaluation level vector (V)
V＝[V1，V2，V3，……，Vm]T
Calculated V ═ 0.15, 0.45, 0.80]T
In the formula: j is the number of evaluation levels, j is 1, 2, … …, and m is 3.
(10) Establishing a matrix, and correcting the factor normalization value:
in the matrix: r isijIs an item to be evaluated as a factor to the discrimination index, wherein rij＝1-|xi-vjL, representing the likelihood that the item belongs to level j; i is the number of indexes, i is 1, 2, 3, …, n is 6; j is the number of evaluation levels, j is 1, 2, … …, and m is 3.
When calculating R, x1The content of the organic acid was 0.95,x2is 0.75, x3Is 0.33, x4Is 0.72, x5Is 0.80, x6Is 0.80; v. of1Is 0.15, v2Is 0.45, v3Is 0.80, and the result of R calculation is:
(11) determining a weight vector W
According to the fitting condition of the model and the actual production data of the water-producing gas well, determining the weight of each factor according to the sensitivity analysis result, wherein the weight of each factor is shown in a table 4:
TABLE 4 weight of each factor
(12) Calculating a comprehensive evaluation value
And multiplying the weight vector W by the evaluation matrix R to obtain an evaluation vector S.
S＝W×R＝[s1，s2，s3，……，sm]T
Multiplying the evaluation level vector V by the evaluation vector S by a formula
The result B of the comprehensive evaluation was obtained.
Determining the comprehensive evaluation value of the common light 103-1 to be 0.55, combining an evaluation set that the comprehensive evaluation value is less than or equal to 0.3: water is not blocked temporarily; 0.3 < comprehensive evaluation value < 0.6: water needs to be blocked; and (4) the comprehensive evaluation value is more than or equal to 0.6, water is blocked immediately, and the common light 103-1 well is determined to be in the stage of needing water blocking.
Example 2
In this embodiment, taking a common 105-2 well as an example, the method for determining the water shutoff time includes the following steps:
(1) according to production data after water breakthrough of the common 105-2 well, establishing a relation between a liquid-gas ratio and water breakthrough time (as shown in figure 3); as can be seen from FIG. 3, the change rule of liquid-gas ratio is generally consistent with the water breakthroughTime proportional, the liquid-gas ratio rise rate of the well is 0.011m3/(104m3·d)；
(2) According to production data, determining the liquid-gas ratio before flooding to be 19.0m3/104m3；
(3) Oil pressure P to close wellwh20MPa, average temperature of a shaft is 329K, average coefficient of the shaft is 1.2, gammagIs 0.76kg/m3Substituting well depth H into 5890m
Calculating to obtain a bottom hole static pressure of 30MPa, and determining the formation pressure of a common 105-2 well to be 30 MPa;
(4) according to the measured water saturation, the gas phase relative permeability K of the same layer of the well gas and waterrgIs 0.27, and the formation coefficient K is 240.3 multiplied by 10-3μm2·m；
(5) Determining the bottom hole flowing pressure to be 27.9MPa according to the graph 8, substituting parameters such as formation pressure, permeability and the like into a productivity calculation formula:
determining the productivity of the common 105-2 well to be 80 multiplied by 104m3/d。
(6) And (4) counting the times of opening and closing the well after the blowout of the common 105-2 well is stopped and the well closing time length during water plugging operation according to the production data of the gas well. Opening and closing the well for 5 times by using a common 105-2 well, and closing the well for 200 days before water plugging;
(7) according to the comprehensive model for evaluating the water plugging time, evaluating the time of water plugging operation of a common 105-2 well:
normalization processing was performed based on the data associated with each factor in table 5.
TABLE 5 correlation data for factors of Puguang 105-2 well
(8) Determining rating level
The interval [0, 1] is divided into three levels
TABLE 6 Water shutoff grade division example table
| Rank of | Temporary water blockage prevention | Need to block water | Immediately block water |
| Interval (Y, Z) | (0，0.3) | (0.3，0.6) | (0.6，1) |
(9) Calculating an evaluation level vector (V)
V＝[V1，V2，V3，……，Vm]T
Calculated V ═ 0.15, 0.45, 0.80]T
In the formula: j is the number of evaluation levels, j is 1, 2, 3, … …, m, m is 3.
(10) Establishing a matrix, and correcting the factor normalization value:
in the matrix: r isijIs an item evaluated as a factor to a discrimination index, whereinrij＝1-|xi-vjL, representing the likelihood that the item belongs to level j; i is the number of indexes, i is 1, 2, 3, …, n is 6; j is the number of evaluation levels, j is 1, 2, … …, and m is 3.
When calculating R, x1Is 0.95, x2Is 0.95, x3Is 0.67, x4Is 0.88, x5Is 1.00, x6Is 1.00; v. of1Is 0.15, v2Is 0.45, v3Is 0.80, and the result of R calculation is:
(11) determining a weight vector W
According to the fitting condition of the model and the actual production data of the water-producing gas well, the weight of each factor is determined according to the sensitivity analysis result, and is shown in the table 7:
TABLE 7 weight of each factor
(12) Calculating a comprehensive evaluation value
And multiplying the weight vector W by the evaluation matrix R to obtain an evaluation vector S.
S＝W×R＝[s1，s2，s3，……，sm]T
Multiplying the evaluation level vector V by the evaluation vector S by a formula
The result B of the comprehensive evaluation was obtained.
Determining the comprehensive evaluation value of the common light 105-2 to be 0.61, and combining an evaluation set that the comprehensive evaluation value is less than or equal to 0.3: water is not blocked temporarily; 0.3 < comprehensive evaluation value < 0.6: water needs to be blocked; and the comprehensive evaluation value is more than or equal to 0.6, and water is immediately blocked, and the stage that the common 105-2 well needs to be immediately blocked is determined.
In order to test the accuracy of the discrimination method, the common light 103-1 well is blocked at the stage of needing water blocking, and the re-production is successful; the common 105-2 well carries out water plugging operation after entering the 'immediate water plugging' stage for one year, and the re-production is not successful. The water plugging operation result accords with the expected water plugging time model judgment, the success rate of water plugging and production recovery is higher in the stage of 'needing water plugging' of the water producing gas well, the difficulty of water plugging and production recovery is higher in the stage of 'immediately plugging', and the model accuracy is high.
Claims (10)
1. A method for judging water plugging time of a water producing gas well is characterized by comprising the following steps:
1) selecting at least two factors from the factors influencing the water plugging time as discrimination indexes, and determining the attribute weight of each factor selected as the discrimination indexes; normalizing each factor to obtain a normalization processing result of each factor; calculating a comprehensive evaluation value by using a weighted average type comprehensive evaluation model according to the attribute weight and the normalization processing result of each influence factor;
2) according to the obtained comprehensive evaluation value contrast evaluation set, the comprehensive evaluation value is less than or equal to 0.3: water is not blocked temporarily; 0.3 < comprehensive evaluation value < 0.6: water needs to be blocked; and the comprehensive evaluation value is more than or equal to 0.6, and immediately blocks water to judge the water blocking time.
2. The method for judging the water plugging time of the water producing gas well as claimed in claim 1, wherein the factors influencing the water plugging time comprise the rising rate of a liquid-gas ratio, the production liquid-gas ratio, the formation pressure, the productivity of the water producing gas well, the shut-in times and the last shut-in time.
3. The method for judging the water plugging time of the water producing gas well as claimed in claim 1, wherein the factors used as the judgment indexes are the rising rate of the liquid-gas ratio, the production liquid-gas ratio, the formation pressure, the productivity of the water producing gas well, the shut-in times and the latest shut-in time.
4. The method for judging the water plugging time of the water producing gas well as claimed in claim 2 or 3, wherein the formation pressure is determined according to the following formula:
in the formula PwsIs the bottom hole static pressure (MPa), PwhFor well-closing oil pressure (MPa), gammagIs gas density (kg/m)3)，
Is the average temperature (K) of the wellbore,
and H is the average deviation coefficient of the shaft, and H is the depth (m) of the gas well.
5. The method for judging the water plugging opportunity of the water producing gas well as claimed in claim 2 or 3, wherein the productivity of the water producing gas well is determined by a productivity evaluation model established according to geological characteristics of a blocky gas field of a gas reservoir where the water producing gas well is located, and the productivity evaluation model is as follows:
wherein q is the productivity (m) of the water-producing gas well3/d)，PeIs the formation pressure (MPa), PwfIs the bottom hole flow pressure (MPa), and k is the permeability (10)-3μm2) H is reservoir thickness (m), Z is natural gas bias coefficient, μ is gas phase viscosity (mPa · s), reIs the radius (m) of gas supply rwIs the wellbore radius (m).
6. The method for judging the water plugging time of the water producing gas well as recited in claim 5, wherein the permeability k is an upper permeability k1And lower permeability k2Average value of (d); wherein the upper permeability k1For the permeability of the upper gas-phase single-phase flow, the upper and lower permeability k2For gas-water two-phase flow in the lower part of the reservoirAnd (3) permeability.
7. The method for judging the water plugging time of the water producing gas well as claimed in claim 2 or 3, wherein the rising rate of the liquid-gas ratio is determined by the relationship between the liquid-gas ratio and the water breakthrough time established according to the production data of the water producing gas well after water breakthrough.
8. The method for judging the water plugging time of the water producing gas well is characterized in that the production liquid-gas ratio is determined according to the production data of the water producing gas well.
9. The method for judging the water plugging time of the water producing gas well as claimed in any one of claims 1 to 3, wherein when the factor as the judgment index is positively correlated with the water plugging time, the normalization treatment adopts the formula xi＝(ai-L)/(H-L); if the factor as the judgment index is negatively correlated with the water plugging time, the formula adopted by the normalization processing is xi＝1-(ai-L)/(H-L); in the formula xiIs a factor normalized value ofiIs a factor value, L is a factor lower limit value, and H is a factor upper limit value.
10. The method for judging the water plugging time of the water producing gas well as the water plugging time of the water producing gas well is characterized in that the factor upper limit value and the factor lower limit value are determined according to the maximum variation range of actual parameters of the gas well production.
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