CN107435528B - Volcanic gas reservoir gas well production allocation method - Google Patents
Volcanic gas reservoir gas well production allocation method Download PDFInfo
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Abstract
The invention provides a method for allocating production of a volcanic gas reservoir gas well, which comprises the steps of converting the wellhead pressure of the gas well into the bottom pressure of the gas well according to a flow pressure conversion formula and establishing a productivity equation of the gas well; determining stable flow pressure according to a gas testing system, and determining stable gas production rate of a gas well through the stable flow pressure and a productivity equation; establishing a development period model of the gas well according to the recoverable reserves and the development period of the gas well and the stable gas production rate, and determining the predicted stable production period yield of the gas well through the development period model; and performing trial production on the gas well according to the predicted steady production period yield, and adjusting the predicted steady production period yield by combining the trial production condition to determine the actual steady production period yield. The wellhead pressure of the gas well is converted into the bottom pressure of the gas well, the capacity equation of the gas well is established, and the yield in the stable production period is determined through the capacity equation and the development period model of the gas well, so that the predicted capacity of the gas well determined by the method is approximate to the actual yield, and the practicability and the reliability of the method are improved.
Description
Technical Field
The invention relates to the technical field of exploitation of gas reservoirs and gas wells, in particular to a volcanic rock gas reservoir gas well production allocation method.
Background
The new well generally adopts absolute unimpeded flow obtained by a gas testing test to carry out production allocation, but the absolute unimpeded flow of the single well with different lithologies has a large variation range which is generally between (10-150) × 104m3/d, while the absolute unimpeded flow of the single well with the same lithology, such as a flow line rock, is also between (20-60) × 104m 3/d.
At present, many researches are developed on how to accurately obtain the absolute unimpeded flow and how to establish a capacity prediction model by using geological static data, in the prior art, the capacity prediction model of an oil well is established by using oil deposit static data of a tested oil well for calculation, but the method is only limited to target determination of volcanic rock oil deposits in an exploration oil testing stage.
In the prior art, the development of gas testing technologies for different types of gas reservoirs is relatively mature, but most of productivity predictions are based on the premise of no resistance flow, and the production allocation error is large for complex volcanic gas reservoirs. The unobstructed flow is that the underground capacity of the gas well is converted into the ground capacity relative to the atmospheric pressure, so that the real underground situation of the gas well cannot be reflected, and the hypotonic volcanic gas reservoir mostly needs fracturing modification, so that the evaluation of reservoir parameters after the modification is more complex, a forward prediction model is difficult to accurately establish, and the predicted capacity and the actual yield are greatly different. Therefore, the problem of how to accurately predict the gas reservoir productivity suitable for the hypotonic volcanic rock on the basis of the existing mature gas testing and guide the actual production allocation needs to be solved urgently.
Disclosure of Invention
The invention mainly aims to provide a volcanic gas reservoir gas well production allocation method, which aims to solve the problem that the difference between the predicted capacity and the actual yield is large in the prior art.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method for allocating production of a volcanic gas reservoir gas well, comprising: converting the wellhead pressure of the gas well to the bottom pressure of the gas well according to a flowing pressure conversion formula and establishing a productivity equation of the gas well; determining stable flow pressure according to a gas testing system, and determining stable gas production rate of a gas well through the stable flow pressure and a productivity equation; establishing a development period model of the gas well according to the recoverable reserves and the development period of the gas well and the stable gas production rate, and determining the predicted stable production period yield of the gas well through the development period model; and performing trial production on the gas well according to the predicted steady production period yield, and adjusting the predicted steady production period yield by combining the trial production condition to determine the actual steady production period yield.
Further, in the trial production process, trial production stable time of the gas well is determined according to the stable gas production rate and the flow pressure decreasing rate in the trial production situation, and the predicted stable production period yield is adjusted according to an error coefficient between the trial production stable time and the stable production time in the development cycle model until the actual stable production period yield is equal to the adjusted predicted stable production period yield when the error coefficient meets a preset range.
Further, when the trial production steady production time is less than the steady production time, reducing the predicted steady production period yield until the error coefficient meets the preset range; and when the trial production stable time is longer than the stable production time, increasing the yield of the predicted stable production period until the error coefficient meets the preset range.
Further, the error coefficient is η ═ Pwf (stable) 2Wherein P iswf (stable)In order to stabilize the gas production.
Further, the predetermined range is greater than 0 and equal to or less than 0.5%.
Further, the stable gas production is Pwf (stable)The stable gas production is obtained by the following formula:
wherein,
γ＝0.132-0.32×log10Tr，
s＝0.03415×γgH/(TavZav)，
Pwhthe pressure of a wellhead of a gas well is expressed in MPa; t isrIs the comparison temperature; pr is a quasi-contrast pressure; z is a gas deviation factor; lambda is the oil pipe resistance coefficient; is a conversion coefficient; q. q.sgFor natural gas production, the unit is 104m3/d；TavThe average temperature of a gas column in a gas well is K; zavThe average deviation coefficient of the dynamic gas column in the gas well; d is the diameter in the oil pipe, and the unit is m; gamma raygIs the relative density of natural gas; h is the middle depth of a gas layer of natural gas, and the unit is m; pwf (stable)The stable flow pressure is the stable flow pressure of the gas well during stable production, and the unit is MPa.
Further, the capacity equation is obtained by the following formula:
wherein, PrIs a quasi-contrast pressure; pwfBottom hole pressure in MPa; q. q.sgFor natural gas production, the unit is 104m3D; a is a fitting coefficient of a productivity equation; and B is a fitting coefficient of the productivity equation.
Further, the stable gas production is q(Stable)Has a unit of 104m3And d, obtaining the stable gas production rate through the following formula:
wherein, Pwf (stable)The stable flow pressure is the stable flow pressure of the gas well during stable production, and the unit is MPa; prIs a quasi-contrast pressure; a is a fitting coefficient of a productivity equation; and B is a fitting coefficient of the productivity equation.
Further, the recoverable reserve is QpUnit is m3The recoverable reserve is obtained by the following formula:
wherein q isiThe unit is 10 for the natural gas production of a gas well in the i year4m3/d；tiThe steady production time, t, in the development period model corresponding to the steady gas production rate of the gas well in the steady production and pressure reduction process of the ith yeariIs more than 0, i belongs to a positive integer; t is taThe stable gas production time corresponding to the stable gas production rate of the gas well in the stable gas production and pressure reduction process of the gas well in the a year is t more than or equal to 7aLess than or equal to 10, a is a positive integer; dqThe method is used for the yield reduction rate of the gas well in the process of stabilizing pressure and reducing yield.
Further, yield reduction rate DqObtained by the following formula:
wherein q issIs the critical gas production of a gas well and has a unit of 104m3/d；qiThe unit is 10 for the natural gas production of a gas well in the i year4m3/d；tiThe stable yield time t corresponding to the stable gas production rate of the gas well in the stable yield and pressure reduction process in the ith yeariMore than 0, i is a positive integer; t is taThe stable yield time corresponding to the stable gas yield of the gas well in the stable yield and pressure reduction process of the year a is more than or equal to 7 and taIs less than or equal to 10, and a is a positive integer.
By applying the technical scheme of the invention, the method for allocating the production of the volcanic gas reservoir gas well comprises the steps of converting the wellhead pressure of the gas well into the bottom pressure of the gas well according to a flow pressure conversion formula and establishing a productivity equation of the gas well. And determining stable flow pressure according to a gas testing system, and determining the stable gas production rate of the gas well through the stable flow pressure and a productivity equation. And establishing a development period model of the gas well according to the recoverable reserves and the development period of the gas well and the stable gas production rate, and determining the predicted stable production period yield of the gas well through the development period model. And performing trial production on the gas well according to the predicted steady production period yield, and adjusting the predicted steady production period yield by combining the trial production condition to determine the actual steady production period yield. The wellhead pressure of the gas well is converted into the bottom pressure of the gas well, the capacity equation of the gas well is established, and the yield in the stable production period is determined through the capacity equation and the development period model of the gas well, so that the predicted capacity of the gas well determined by the method is approximate to the actual yield, and the practicability and the reliability of the method are improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 illustrates the relationship between the unobstructed flow and the actual production of a sandstone reservoir in the prior art;
FIG. 2 illustrates a relationship between unobstructed flow and actual production for a hypotonic volcanic gas reservoir in the prior art;
FIG. 3 illustrates a flow chart of a method of allocating production to a volcanic gas reservoir gas well in accordance with the present invention;
FIG. 4 shows a steady production flow diagram for a gas well;
FIG. 5 shows a schematic of natural gas production over a production cycle of a gas well;
FIG. 6 shows a steady flow pressure schematic during a production cycle of a gas well;
FIG. 7 shows a steady-term production versus steady-flow chart diagram for a gas well; and
fig. 8 shows a comparison graph of the actual production allocation effect of the flow-stabilizing method of the gas well.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
As shown in fig. 3, according to one embodiment of the present invention, there is provided a method of allocating production from a volcanic gas reservoir gas well, the method comprising: converting the wellhead pressure of the gas well to the bottom pressure of the gas well according to a flowing pressure conversion formula and establishing a productivity equation of the gas well; determining stable flow pressure according to a gas testing system, and determining stable gas production rate of a gas well through the stable flow pressure and a productivity equation; establishing a development period model of the gas well according to the recoverable reserves and the development period of the gas well and the stable gas production rate, and determining the predicted stable production period yield of the gas well through the development period model; and performing trial production on the gas well according to the predicted steady production period yield, and adjusting the predicted steady production period yield by combining the trial production condition to determine the actual steady production period yield.
In the embodiment, the wellhead pressure of the gas well is converted into the bottom pressure of the gas well, the capacity equation of the gas well is established, and the yield at the steady production period is determined through the capacity equation and the development cycle model of the gas well, so that the predicted capacity of the gas well determined by the method is approximate to the actual yield, and the practicability and the reliability of the method are improved.
As shown in fig. 4, in the trial production process, the trial production steady production time of the gas well is determined according to the steady gas production rate and the flow pressure decreasing rate in the trial production situation, and the predicted steady production output is adjusted according to the error coefficient between the trial production steady production time and the steady production time in the development cycle model until the actual steady production output is equal to the adjusted predicted steady production output when the error coefficient satisfies the preset range.
The specific adjustment mode is as follows: and when the trial production stable time is less than the stable production time, reducing the yield of the predicted stable production period until the error coefficient meets the preset range. And when the trial production stable time is longer than the stable production time, increasing the yield of the predicted stable production period until the error coefficient meets the preset range.
The predetermined range is greater than 0 and less than or equal to 0.5%. The gas well is adjusted according to the preset range, so that the infinite approximation between the stable gas production predicted by using the method and the actual stable gas production can be further increased, and the reliability of the production allocation by using the method is increased.
The stable flow pressure of the gas well during stable gas production is obtained by the following formula:
wherein,
γ＝0.132-0.32×log10Tr，
s＝0.03415×γgH/(TavZav)，
Pwhthe pressure of the wellhead of the gas well is expressed in MPa. T isrIs the comparison temperature, Pr is the comparison pressure, Z is the gas deviation factor, and lambda is the resistance coefficient of the oil pipe, and is the conversionCoefficient qgFor natural gas production, the unit is 104m3/d。TavThe average temperature of the gas column in the gas well is expressed in K. ZavAnd d is the diameter in the oil pipe and has the unit of m. Gamma raygH is the depth of the middle of the gas bed of natural gas in m, which is the relative density of natural gas. Pwf (stable)The stable flow pressure is the stable flow pressure of the gas well during stable production, and the unit is MPa.
Further, the capacity equation is obtained by the following formula:
wherein, PrTo approximate pressure, PwfIs the bottom hole pressure in MPa. q. q.sgFor natural gas production, the unit is 104m3And d. A is the fitting coefficient of the productivity equation, and B is the fitting coefficient of the productivity equation.
Stable gas production of q(Stable)Has a unit of 104m3And d, obtaining the stable gas production rate through the following formula:
wherein, Pwf (stable)The stable flow pressure is the stable flow pressure of the gas well during stable production, and the unit is MPa. PrFor the simulation of the pressure, A is the fitting coefficient of the productivity equation, and B is the fitting coefficient of the productivity equation.
Recoverable reserve of QpUnit is m3The recoverable reserve is obtained by the following formula:
wherein q isiThe unit is 10 for the natural gas production of a gas well in the i year4m3/d。tiThe steady production time, t, in the development period model corresponding to the steady gas production rate of the gas well in the steady production and pressure reduction process of the ith yeari> 0, i is a positive integer. t is taThe stable gas production time corresponding to the stable gas production rate of the gas well in the stable gas production and pressure reduction process of the gas well in the a year is t more than or equal to 7aIs less than or equal to 10, and a is a positive integer. DqThe method is used for the yield reduction rate of the gas well in the process of stabilizing pressure and reducing yield.
Yield reduction rate DqObtained by the following formula:
wherein q issIs the critical gas production of a gas well and has a unit of 104m3/d。qiThe unit is 10 for the natural gas production of a gas well in the i year4m3/d。tiThe steady production time, t, in the development period model corresponding to the steady gas production rate of the gas well in the steady production and pressure reduction process of the ith yeariMore than 0, i is a positive integer; t is taThe stable yield time corresponding to the stable gas yield of the gas well in the stable yield and pressure reduction process of the year a is more than or equal to 7 and taIs less than or equal to 10, and a is a positive integer.
As shown in fig. 4, in this embodiment, first, a gas well productivity equation is established by using the productivity well testing data, and the wellhead pressure is converted to the bottom pressure of the gas well by using the flow pressure conversion formula. And then selecting the stable system flow pressure according to the unit pressure drop gas production rate under different gas testing systems, and substituting the stable flow pressure into a productivity equation to calculate the stable gas production rate.
As shown in fig. 5 and 6, a gas well development period model is established next, and the hypotonic gas reservoir is suitable for a development mode of stabilizing production and reducing pressure first and then stabilizing pressure and reducing production. The mode is beneficial to maintaining longer and reasonable stable production time of the gas reservoir and is also beneficial to pressurized exploitation after later-stage energy failure of the gas reservoir. And determining the recoverable reserve of a single well by using the gas testing and recompression data, calculating the stable yield time and the stable yield time according to the single well development period (generally 10-15 years) established by the geological characteristics of different gas reservoirs by combining a decreasing equation, selecting reasonable stable yield in the stable yield period according to the stable yield time standard of the gas reservoirs with different scales, and performing short-term test recovery according to the reasonable stable yield in the stable yield period.
And finally, adjusting the parturition in the stable production period by combining the trial production result, reversely calculating the stable production time according to the trial production flow pressure decrement rate, correspondingly reducing the parturition if the time is less than the previous calculation result, namely the trial production stable production time is less than the stable production time, and correspondingly increasing the parturition if the time is not less than the previous calculation result until the error is less than 0.5 percent. The trial run period is typically selected to be 60 days, with adjustment correction every 20 days. Wherein, the productivity well testing method is suitable to adopt a correction isochronous well testing method in the low-permeability gas reservoir. The stable flow pressure system adopts the maximum pressure drop gas production amount corresponding to the converted flow pressure as a standard, the converted flow pressure adopts a gas deviation factor calculation method suitable for correction, and a corrected vertical pipe flow method is introduced for flow pressure calculation. The development period model is an optimized development mode suitable for the low-permeability gas reservoir, namely a stable-production and pressure-reduction stage and a stable-pressure and pressure-reduction stage. The recoverable reserves of the gas well are obtained by adopting the conventional unstable well testing method and combining the critical production conditions. The gas well development cycle is determined according to different gas reservoir sizes and geological characteristics. The yield and pressure chart is used for drawing the variation curves of the yield and the pressure under different stable yield time under the premise of determining a development mode and a recoverable reserve. And the trial production period allocation is the initial selection allocation under different stable production modes, and after trial production is carried out for a certain time, the flowing pressure data is converted to the bottom of the well and then is subjected to descending fitting to obtain trial production stable production time. And the production allocation optimization is to compare the trial production stable time with the chart theoretical stable time, correspondingly reduce the production allocation if the trial production stable time is smaller than the chart theoretical stable time, and correspondingly improve the production allocation if the trial production stable time is smaller than the chart theoretical stable time until the error is less than 0.5 percent.
The fitting mode of the capacity equation comprises the following steps:
(1) solving a productivity equation on the basis of productivity well testing, and correcting the isochronous well testing productivity equation according to a formula (1):
Pwf 2＝Pwh 2e2s+1.3243×10-10λqg 2Tav 2Zav 2(e2s-1)/d5(2)
wherein,
γ＝0.132-0.32×log10Tr
s＝0.03415×γgH/(TavZav)
(2) considering the phenomenon that the flow pressure is easy to fluctuate in the gas testing process, the flow pressure is converted by using a formula (2), the converted flow pressure gradient is compared with the actually measured flow pressure gradient, and the error is within 0.2% and meets the condition.
(3) Selecting stable point flow pressure according to a formula (3) by taking the maximum unit pressure drop gas production rate as a standard, and calculating the reasonable yield of the stable production period according to the stable flow pressure according to a formula (4):
wherein α, β and gamma are deviation factor calculation coefficients, non-dimensional Tr is quasi-contrast temperature, non-dimensional Pr is quasi-contrast pressure, non-dimensional Z is gas deviation factor, non-dimensional PwfBottom hole pressure, MPa. PwhThe pressure of the wellhead of the oil pipe is MPa. s is the epidermal coefficient, dimensionless. And lambda is the oil pipe resistance coefficient. Is a conversion coefficient and has no dimension. q. q.sgFor natural gas production, 104m3/d。TavThe average temperature of the gas column in the shaft, K. ZavThe average deviation coefficient of the pneumatic column in the shaft is zero dimension. d is the inner diameter of the oil pipe, m. Gamma raygIs natural gas relative density without dimension. H is the depth of the middle of the gas layer, m.
(4) Calculating dynamic reserve of single well by using unstable well testing analysis and according to threshold pressure PwfsReckoning recoverable reserve Qp。
(5) Solving the stable yield time t corresponding to the stable yield in the stable yield pressure reduction process by using the formula (5) and the formula (6)iAnd the yield reduction rate Dq in the process of stabilizing voltage and reducing yield:
wherein t is more than 0 and less than ti,ti＜t＜ta。
(6) Calculating the initial flow pressure P in the stable production pressure reduction stage by using the capacity equation obtained in the capacity well testingwfiCan be based on the initial flow pressure PwfiAnd a threshold flow pressure PwfsAnd performing exponential decreasing fitting, and drawing a yield and pressure change chart.
(7) And correcting whether the prior stable production period is suitable for parturition according to the actual production and the flow pressure data in the trial production period. Firstly, converting the flowing pressure to the bottom of the well according to a formula (2), then calculating the decreasing rate of the flowing pressure, and calculating the stable production time in the trial production period by taking the production critical pressure as the end condition of the stable production period. And comparing the trial production steady production time with the steady production time to determine the final production allocation yield of the gas well.
The method is used for gas reservoir gas well production allocation, and has strong operability for field operators. The method overcomes the defects that the bottom pressure of the gas well is difficult to test or the test result has large fluctuation on site, and lays a foundation for reasonable production allocation. The method can give full play to the yield stabilizing potential of the gas well to the maximum extent, can effectively improve the production allocation precision by combining with the verification of the pilot production result, and provides a powerful guarantee for the dynamic monitoring and adjustment of actual production.
Referring to fig. 3 again, the method includes data acquisition, test gas analysis, mode selection, production allocation plate, flow pressure calculation, test gas analysis, data processing, production allocation optimization, and data storage module. The data acquisition module collects parameters such as gas well string parameters, test gas pressure, temperature, yield and gas component characteristics. The test gas analysis module is used for processing and analyzing test gas results of different production capacities, and comprises the steps of processing abnormal test points, solving productivity equation coefficients and calculating the yield under different flow pressures. The mode selection module is used for defining a development mode and comprises stable output voltage reduction, stable voltage output reduction, voltage output reduction and a combination mode of any two of the stable output voltage reduction, the stable voltage output reduction and the voltage output reduction. The production allocation plate module comprises the determination of stable production time, a pressure decreasing rule and a yield decreasing rule under different development modes. The trial production analysis module comprises the determination of the steady production time and the pressure decreasing rule in the trial production period. The flow pressure calculation module comprises basic parameter input, deviation factor calculation and flow pressure iterative calculation. And the flow pressure in the test gas analysis module and the test production analysis module utilizes the function in the flow pressure calculation module. The allocation and production optimization module comprises a combined allocation and production chart and a trial production analysis module, and the allocation and production is adjusted until the error of the allocation and production chart and the trial production analysis module is smaller than a specified range.
As shown in fig. 4, the rational production allocation of the gas well is gradually determined from the gas test of the gas well, the production allocation steps are introduced by taking the development modes of correcting the isochronous gas test, the binomial capacity equation, exponential decreasing fitting and first stabilizing and reducing pressure and then reducing the production and stabilizing the production as examples, the binomial capacity equation of the gas well is determined by using a formula (1), the flow pressure conversion is performed by using a formula (2), the converted flow pressure gradient is compared with the actually measured flow pressure gradient, the error meets the condition within 0.2%, and the stable production corresponding to the maximum unit pressure reduction gas production is determined by using a formula (3) and a formula (4). Calculating dynamic reserve of single well by using unstable well testing analysis and according to threshold pressure PwfsReckoning recoverable reserve Qp. As shown in FIG. 4, assume that the gas well development to failure time is taCorresponding to a critical gas production of qsThe formula (5) and the formula (6) are transformed into the formula (7), so that the formula (8) is used for solving the stable yield time t corresponding to the stable yield in the stable yield pressure reduction processiAnd a yield reduction rate Dq in the process of stabilizing voltage and reducing yield.
As shown in fig. 6, the pressure and production changes are plotted in the same coordinate system, the flow pressure is converted to the bottom of the well according to the formula (2) according to the actual production and flow pressure data in the pilot production period, the actual flow pressure decreasing rate is calculated, and the stable production time is calculated by taking the threshold pressure as the stable production period end condition. Contrast trial production steady production time tsAnd the stable yield time t of the modeliIf t issLess than tiThe production allocation should be correspondingly reduced if tsGreater than tiAnd correspondingly increasing the production allocation until the error is less than 0.5 percent. The trial run period is typically selected to be 60 days, with adjustment correction every 20 days.
In this embodiment, table 1 is a modified isochronous well test data table:
TABLE 1
Table 2 is a table of gas well data for a section of a block:
TABLE 2
The table 1 is a corrected isochronous well testing data table, and the table 2 is a comparison of the production allocation effect of the gas well steady flow method of a part of a certain block. Comparing the effects of the non-resistance flow method and the stable-production flow method (i.e., the method for allocating the production of the volcanic gas reservoir gas well), it shows that the gas well with the stable-production flow method has a production allocation time of 55% or more, the error between the production allocation and the actual production is below 5%, and the effect of allocating the production according to the stable-production flow method is shown in fig. 7.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A volcanic gas reservoir gas well production allocation method is characterized by comprising the following steps:
converting the wellhead pressure of the gas well to the bottom pressure of the gas well according to a flowing pressure conversion formula and establishing a productivity equation of the gas well;
determining stable flow pressure according to a test gas system, and determining the stable gas production rate of the gas well through the stable flow pressure and the capacity equation;
establishing a development cycle model of the gas well according to the recoverable reserves and the development cycle of the gas well and the stable gas production rate, and determining the predicted steady-production-period yield of the gas well through the development cycle model;
and performing trial production on the gas well according to the predicted steady-production-period yield, and adjusting the predicted steady-production-period yield by combining the trial production condition to determine the actual steady-production-period yield.
2. The method of claim 1, wherein in the pilot production process, pilot production steady-state time of the gas well is determined according to the steady gas production rate and a flow pressure decreasing rate in the pilot production situation, and the predicted steady-state production is adjusted according to an error coefficient between the pilot production steady-state time and the steady-state production in the development cycle model until the actual steady-state production is equal to the adjusted predicted steady-state production when the error coefficient meets a preset range.
3. The method of claim 2, wherein when the trial production steady-state time is less than the steady-state time in the development cycle model, decreasing the predicted steady-state production until the error coefficient satisfies the preset range; and when the trial production steady production time is longer than the steady production time in the development cycle model, increasing the predicted steady production period yield until the error coefficient meets the preset range.
4. The method according to claim 2 or 3, wherein the predetermined range is greater than 0 and equal to or less than 0.5%.
5. The method of claim 1, wherein the stable gas production has a stable gas flow pressure of Pwf (stable)The stable flow pressure is obtained by the following formula:
wherein,
s＝0.03415×γgH/(TavZav)，
the P iswhThe pressure of the wellhead of the gas well is expressed in MPa;
the lambda is the resistance coefficient of the oil pipe;
the above is the conversion coefficient;
q is a number ofgFor natural gas production, the unit is 104m3/d；
The T isavThe average temperature of the gas column in the gas well is K;
z isavThe average deviation coefficient of the dynamic gas column in the gas well is obtained;
d is the diameter in the oil pipe and has the unit of m;
the gamma isgIs the relative density of natural gas;
and H is the depth of the middle part of a gas layer of the natural gas, and the unit is m.
6. The method of claim 1, wherein the capacity equation is obtained by the following formula:
wherein,
the P isrIs a quasi-contrast pressure;
the P iswfBottom hole pressure in MPa;
q is a number ofgFor natural gas production, the unit is 104m3/d；
A is a fitting coefficient of the productivity equation;
and B is a fitting coefficient of the productivity equation.
7. The method of claim 1, wherein the steady gas production is q(Stable)Has a unit of 104m3The stable gas production is obtained by the following formula:
wherein,
the P iswf (stable)The stable flow pressure of the gas well during stable production is expressed in MPa;
the P isrIs a quasi-contrast pressure;
a is a fitting coefficient of the productivity equation;
and B is a fitting coefficient of the productivity equation.
8. The method of claim 1, wherein the recoverable reserve is QpUnit is m3The recoverable reserve is obtained by the following formula:
wherein,
q is a number ofiThe natural gas production of the gas well in the i year is 104m3/d；
Said t isiThe stable yield time in the development cycle model corresponding to the stable gas yield of the gas well in the stable yield and pressure reduction process of the ith year，tiIs more than 0, i belongs to a positive integer;
said t isaThe gas well stabilizes the yield stabilizing time corresponding to the gas production rate in the process of stabilizing the yield and reducing the pressure in the year a, and t is more than or equal to 7aLess than or equal to 10, a is a positive integer;
said DqAnd the yield reduction rate of the gas well in the process of stabilizing the pressure and reducing the yield is obtained.
9. The method of claim 8, wherein the yield reduction rate DqObtained by the following formula:
wherein,
q is a number ofsIs the critical gas production of the gas well, and has a unit of 104m3/d；
Q is a number ofiThe natural gas production of the gas well in the i year is 104m3/d；
Said t isiThe stable yield time, t, in the development cycle model corresponding to the stable gas yield of the gas well in the stable yield and pressure reduction process of the ith yeariMore than 0, i is a positive integer;
said t isaThe stable yield time corresponding to the stable gas production rate of the gas well in the stable yield and pressure reduction process of the year a is more than or equal to 7 and taIs less than or equal to 10, and a is a positive integer.
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| CN111852463B (en) * | 2019-04-30 | 2023-08-25 | 中国石油天然气股份有限公司 | Gas well productivity evaluation method and equipment |
| CN113222204B (en) * | 2020-02-06 | 2024-03-05 | 中国石油天然气股份有限公司 | Fracture-cavity type oil reservoir stable production well yield prediction method, device, equipment and storage medium |
| CN113323648B (en) * | 2020-02-12 | 2023-07-25 | 中国石油天然气股份有限公司 | Method and device for determining unimpeded flow of gas well |
| CN114382465B (en) * | 2020-10-21 | 2024-04-30 | 中国石油天然气股份有限公司 | Method, device, terminal and storage medium for determining stable production age of gas well |
| CN113047815B (en) * | 2021-04-02 | 2022-02-15 | 西南石油大学 | Reasonable production allocation method for gas well |
| CN115247548A (en) * | 2021-04-26 | 2022-10-28 | 中国石油化工股份有限公司 | Differential production allocation method for water-containing compact gas reservoir gas well |
| CN113236207B (en) * | 2021-07-13 | 2021-09-10 | 西南石油大学 | Fixed yield decreasing prediction method for water producing gas well in strong heterogeneity reservoir |
| CN117386334B (en) * | 2023-12-13 | 2024-03-08 | 中国石油集团川庆钻探工程有限公司 | Reasonable production allocation method for fracture-cavity type high-yield gas well |
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