CN106481332B - Method for determining area's dynamic holdup inside and outside shale gas multistage pressure break horizontal well - Google Patents
Method for determining area's dynamic holdup inside and outside shale gas multistage pressure break horizontal well Download PDFInfo
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Abstract
The invention discloses a kind of methods for determining area's dynamic holdup inside and outside shale gas multistage pressure break horizontal well, comprising: establishes gas well binomial potential curve and equation by gas testing data, calculates practical flowing bottomhole pressure (FBHP) by creation data and gas well structural parameters；Consider that adsorbed gas desorption and abnormal high pressure influence, establishes the matter balance equation in the fracturing reform area and non-fracturing reform area for multistage pressure break horizontal well respectively；The dynamic holdup in fracturing reform area and non-fracturing reform area is given respectively, and the expression formula in conjunction with the channelling between fracturing reform area and the matter balance equation and twoth area in non-fracturing reform area, binomial potential curve and equation adjust dynamic holdup to be fitted practical flowing bottomhole pressure (FBHP), so that it is determined that area's dynamic holdup inside and outside pressure break horizontal well.The present invention does not need closing well test mean reservoir pressure in use, and adsorbed gas desorption and the influence of abnormal high pressure and pressure break recombination region can be considered, and can determine fracturing reform area and peripheral non-fracturing reform area dynamic holdup respectively.
Description
Technical field
The invention belongs to shale gas exploration and development technical fields, specifically, being related to a kind of for determining shale gas multistage
The method of area's dynamic holdup inside and outside pressure break horizontal well.
Background technique
The evaluation method of shale Estimation of Gas Well Dynamic Reserves and conventional gas well are widely different, and be mainly reflected in: (1) gas reservoir geology is special
Sign and development technique are different.Shale gas reservoir is self-generation, self-reservoir gas reservoir, and permeability spy is low, needs through volume fracturing transformation come " people
Work makes hiding ", gas well yield and recoverable reserves are limited by pressure break, and individual well dynamic holdup is related with volume fracturing transformation.(2) seepage flow is special
Sign is different.Due to shale gas reservoir, matrix permeability spy is low, and gas reservoir is difficult to enter the boundary Control stream stage, and dynamic holdup evaluation is wanted
It asks and reaches the boundary Control stream stage, the dynamic holdup otherwise evaluated is only that pressure involves mining-employed reserves in range.(3) adsorbed gas
Desorption diffusion.Free gas and adsorbed gas all influence shale gas well deliverability, and dynamic holdup evaluation needs to consider that adsorbed gas desorption influences.
Shale gas well in North America is produced essentially according to production decline mode is bled off pressure at present, main to be divided using production rate decline curve
The ultimate recoverable reserves (EUR) of gassing well, mainly have improved Arps method, power law index method, diffusion index method and
Duong method etc..Be fitted yield data by adjusting coefficient in these decline curve models, then predict gas well yield and
Recoverable reserves.
It is little in the variation of production phase flowing bottomhole pressure (FBHP) that decline curve analysis method does not require nothing more than gas well, and requires pre-
Survey stage flowing bottomhole pressure (FBHP) remains unchanged.In addition, this method also requires gas well to reach the boundary Control stream stage, i.e. pressure wave reaches storage
Layer physical boundary or choked flow boundary, the yield and ultimate recoverable reserves otherwise predicted are higher.
Country's gas well generally requires the stable production period of 2-3 with the gas supply that guarantees to stabilize the market, later just according to level pressure at present
Production decline mode produces, such as the gas well stable production period of Fuling coke masonry dam shale gas field development program design is 2 years.It is possible thereby to
Find out, due to the difference of production method, domestic shale gas well is difficult to calculate in early stage using decline curve analysis method
Estimation of Gas Well Dynamic Reserves.
Material balance method is the common method for being used to determine Estimation of Gas Well Dynamic Reserves in normal gas pools, and this method needs fifty-fifty
Stressor layerWith tired gas production GPData.It is calculated by tired gas production and mean reservoir pressure valueValue, then in rectangular plots
It draws out a series ofWith GPData point, it is Estimation of Gas Well Dynamic Reserves that fitting a straight line, which is extrapolated to x-axis,.Wherein, mean reservoir pressure master
To restore well testing test interpretation by gas well shut-in pressure to obtain.
This method is applied to mainly have following problems when calculating shale Estimation of Gas Well Dynamic Reserves: first is that calculating gas well waterout storage
The influence of shale matrix adsorbed gas desorption diffusion can not be considered when amount；Second is that shale matrix permeability spy is low, it is difficult to pass through closing well
Pressure recovery transient well test is tested to explain mean reservoir pressure；Third is that fracturing reform area dynamic holdup and outer cannot be distinguished
Wei Wei fracturing reform area dynamic holdup.
From the point of view of comprehensive domestic and international shale gas well waterout Reserve Estimation Method, lack effectively accurate shale gas well waterout at present
Fracturing reform area dynamic holdup and non-fracturing reform area dynamic holdup cannot be distinguished in Reserve Estimation Method.
Summary of the invention
In order to solve the above problem, the present invention provides one kind for determining area's dynamic inside and outside shale gas multistage pressure break horizontal well
The method of reserves.
According to one embodiment of present invention, providing one kind, area is dynamic inside and outside shale gas multistage pressure break horizontal well for determining
The method of state reserves, comprising:
Shale gas pressure break horizontal well gas testing data, creation data and gas well structural parameters are obtained, and are provided by the gas testing
Material establishes gas well binomial potential curve and equation, calculates practical flowing bottomhole pressure (FBHP) by the creation data and gas well structural parameters；
Consider adsorbed gas desorption and abnormal high pressure influence, respectively establish for multistage pressure break horizontal well fracturing reform area and
The matter balance equation in non-fracturing reform area；
The dynamic holdup in the fracturing reform area and the non-fracturing reform area is given respectively, and in conjunction with the fracturing reform
The expression formula of channelling amount between area and the matter balance equation and twoth area in the non-fracturing reform area, the binomial production capacity side
Journey adjusts the dynamic holdup to be fitted the practical flowing bottomhole pressure (FBHP), so that it is determined that area's dynamic holdup inside and outside pressure break horizontal well.
According to one embodiment of present invention, fracturing reform area and the non-fracturing reform for multistage pressure break horizontal well are established
The step of matter balance equation in area, further comprises:
Consider that adsorbed gas desorption and abnormal high pressure influence, establishes shale gas reservoir matter balance equation；
Multistage pressure break horizontal well Area of a well is divided into fracturing reform area and non-fracturing reform according to well pattern spacing
Area；
The fracturing reform area and the non-fracturing reform area are established respectively based on the shale gas reservoir matter balance equation
Matter balance equation.
According to one embodiment of present invention, the step of establishing the shale gas reservoir matter balance equation further comprises:
Based on pore space compressibility of rock, since rock matrix compression and fluid expansion cause when calculating strata pressure variation
Underground pore volume reduction amount；
After calculating drop in formation pressure based on the underground pore volume reduction amount and Langmuir isothermal adsorpting equation
Shale gas reservoir residual free gas reserves and remaining adsorbed gas reserves；
According to the law of indestructibility of matter: original free gas reserves+original adsorbed gas reserves=residual free gas reserves+residue is inhaled
Attached gas yield+tired gas production, establishes the shale gas reservoir matter balance equation.
According to one embodiment of present invention, the shale gas reservoir matter balance equation are as follows:
Wherein, Za=Za(p),
Work as p=piWhen,P is strata pressure, piFor original formation pressure, GpFor cumulative production, G is that dynamic is stored up
Amount, cfFor pore space compressibility of rock, cwFor the water flooding compressed coefficient, SwiFor the original water saturation of gas reservoir, SgiFor gas reservoir original
Beginning gas saturation, φ are effecive porosity, ρBFor shale density, VLFor Langmuir volume, PLFor Lan Shi pressure, pscFor mark
Gas pressure under quasi- state, T are formation temperature, TscFor the temperature under standard state, z is the gas deviation factor under pressure p,
zscFor the gas deviation factor under standard state.
According to one embodiment of present invention, the matter balance equation in the fracturing reform area are as follows:
Wherein, p1For the mean reservoir pressure in fracturing reform area,G1For the dynamic holdup in fracturing reform area, Gp1
For gas well cumulative production, Gp2It is non-fracturing reform area to the accumulative channelling amount in fracturing reform area.
According to one embodiment of present invention, the matter balance equation in the non-fracturing reform area are as follows:
Wherein, p2For the mean reservoir pressure in non-fracturing reform area,Gp2Change for non-fracturing reform area to pressure break
Make the accumulative channelling amount in area, G2For the dynamic holdup in non-fracturing reform area.
According to one embodiment of present invention, the step of determining area's dynamic holdup inside and outside pressure break horizontal well further comprises:
The fracturing reform area dynamic holdup G of given shale gas well1, non-fracturing reform area dynamic holdup G2；
Based on fracturing reform area dynamic holdup G1, non-fracturing reform area dynamic holdup G2, fracturing reform area material balance side
The expression formula of channelling amount between journey, the matter balance equation in non-fracturing reform area, Gas Well Productivity and two-region, according to gas well
Daily output tolerance is iterated to calculate the mean reservoir pressure in fracturing reform area by fracturing reform area matter balance equation；
Mean reservoir pressure p based on the fracturing reform area1With the binomial potential curve and equation, predicted by daily output tolerance
Flowing bottomhole pressure (FBHP)；
The flowing bottomhole pressure (FBHP) predicted and the practical flowing bottomhole pressure (FBHP) are fitted to determine the dynamic in fracturing reform area described in horizontal well
The dynamic holdup of reserves and the non-fracturing reform area.
According to one embodiment of present invention, the step of iterating to calculate the mean reservoir pressure in fracturing reform area is further wrapped
It includes:
By a upper time step ti-1Fracturing reform area mean reservoir pressure value p10As current tiTime step fracturing reform area is average
The iterative initial value p of strata pressure1If ti=0, then iterative initial value is original formation pressure value；
According to fracturing reform area mean reservoir pressure p1, do not pressed by the matter balance equation iterative calculation in non-fracturing reform area
Split transformation area's mean reservoir pressure p2；
According to fracturing reform area mean reservoir pressure p1, non-fracturing reform area mean reservoir pressure p2And between interior outskirt
Interporosity flow coefficient calculates current tiChannelling amount and accumulative channelling amount of the non-fracturing reform area of time step to fracturing reform area；
Based on fracturing reform area mean reservoir pressure value p1, original formation pressure pi, gas well cumulative gas Gp1And it is described
Accumulative channelling amount Gp2Calculate the matter balance equation residual error in current time step fracturing reform area:
When residual absolute value of the difference is less than assigned error, iteration convergence, iteration is exited；Otherwise with current fifty-fifty lamination
Force value p1As initial value, the mean reservoir pressure value for continuing to iterate to calculate new fracturing reform area according to Newton method is missed until meeting
Until difference requires.
According to one embodiment of present invention, the step of iterating to calculate the mean reservoir pressure in non-fracturing reform area is further
Include:
Take a time step ti-1Non- fracturing reform area mean reservoir pressure p20As this time step tiNon- fracturing reform area is average
Strata pressure initial value p2If ti=0, then it is taken as original formation pressure；
According to current tiThe current mean reservoir pressure value in time step fracturing reform area and non-fracturing reform areap1 and p2, calculate
Channelling amount q between the area Liang Ge2And accumulative channelling amount Gp2,
Channelling amount q between the current area time step Xia Liangge2It is calculate by the following formula:
Total accumulative channelling amount G between the area Liang Gep2It is calculate by the following formula:
Gp2=Gp20+ΔGp2,
Wherein, λ is interporosity flow coefficient, Δ Gp2Accumulative channelling amount between the area current step Nei Liangge,Δ t is time step step-length, q20For the channelling amount between the area last time step Liang Ge, Gp20For last time step
Total accumulative channelling amount between the area Liang Ge；
Based on current tiThe non-fracturing reform area mean reservoir pressure value p of time step2, original formation pressure piAdd up to alter with section
Miscarriage amount Gp2The matter balance equation residual error in non-fracturing reform area is calculated,
When residual absolute value of the difference is less than assigned error, iteration is exited, otherwise with current mean reservoir pressure value p2Make
For initial value, the mean reservoir pressure value for continuing to iterate to calculate non-fracturing reform area is until meeting error requirements.
According to one embodiment of present invention, flowing bottomhole pressure (FBHP) and the practical flowing bottomhole pressure (FBHP) for being fitted prediction are horizontal to determine
The step of dynamic holdup in fracturing reform area described in well and the dynamic holdup in the non-fracturing reform area, further comprises:
Mean reservoir pressure and the binomial potential curve and equation based on the fracturing reform area calculate flowing bottomhole pressure (FBHP)；
The dynamic holdup G in the fracturing reform area is adjusted by Optimizing Algorithm for Fitting1With moving for the non-fracturing reform area
State reserves G2, so that the error sum of squares value of the flowing bottomhole pressure (FBHP) being calculated and practical flowing bottomhole pressure (FBHP) is within the set range, from
And determine the dynamic holdup G in the fracturing reform area1With the dynamic holdup G in the non-fracturing reform area2。
Beneficial effects of the present invention:
The present invention does not need closing well test mean reservoir pressure in use, and it is contemplated that adsorbed gas desorption and exception are high
The influence of pressure and physical property recombination region can determine fracturing reform area and peripheral non-fracturing reform area dynamic holdup respectively.
Other features and advantages of the present invention will be illustrated in the following description, also, partly becomes from specification
It obtains it is clear that understand through the implementation of the invention.The objectives and other advantages of the invention can be by specification, right
Specifically noted structure is achieved and obtained in claim and attached drawing.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is required attached drawing in technical description to do simple introduction:
Fig. 1 is shale gas multistage pressure break horizontal well Area of a well schematic diagram；
Fig. 2 is method flow diagram according to an embodiment of the invention；
Fig. 3 is algorithm implementation flow chart according to an embodiment of the invention；
Fig. 4 is the flow chart of iterative solution inner region stratum average pressure according to an embodiment of the invention；
Fig. 5 is the flow chart of iterative solution outskirt stratum average pressure according to an embodiment of the invention；
Fig. 6 is the daily output tolerance and test flowing bottomhole pressure (FBHP) schematic diagram of well A according to an embodiment of the invention；
Fig. 7 is the binomial deliverability curve schematic diagram of well A according to an embodiment of the invention；
Fig. 8 be well A according to an embodiment of the invention history matching before calculate flowing bottomhole pressure (FBHP) and measured value and compare
Curve synoptic diagram；And
Fig. 9 be well A according to an embodiment of the invention history matching after calculate flowing bottomhole pressure (FBHP) and measured value and compare
Curve synoptic diagram.
Specific embodiment
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings and examples, how to apply to the present invention whereby
Technological means solves technical problem, and the realization process for reaching technical effect can fully understand and implement.It needs to illustrate
As long as not constituting conflict, each feature in each embodiment and each embodiment in the present invention can be combined with each other,
It is within the scope of the present invention to be formed by technical solution.
It is (interior that shale gas multistage pressure break horizontal well Area of a well can be divided into fracturing reform area according to well pattern spacing
Area) and non-fracturing reform area (outskirt) two parts.It is as shown in Figure 1 a horizontal well Area of a well schematic diagram, control plane
Product includes fracturing reform area 100 and non-fracturing reform area 200, and the boundary in twoth area is fracturing reform area boundary, non-fracturing reform area
200 outer boundary choked flow boundary between well.Inner region be formed after the transformation of multistage volume fracturing by main fracturing fracture and
The complex fracture network area of dry composition, outskirt is between adjacent well not by the region of fracturing reform.
Shale gas pressure break horizontal well production phase early stage production gas is interior with inner region drop in formation pressure mainly from inner region
Pressure difference between outskirt gradually amplifies and forms section channelling.Channelling yield and interior outskirt strata pressure difference and section interporosity flow coefficient
It is related.After inner region drop in formation pressure is to critical desorption pressures, adsorbed gas starts desorption diffusion and generates shadow to gas well deliverability
It rings.
Therefore, the present invention provides a kind of for determining the side of area's dynamic holdup inside and outside shale gas multistage pressure break horizontal well
Method.There is interior outskirt according to shale gas pressure break horizontal well control area in the present invention, establish consideration respectively by the area Liang Ge and inhale
The shale gas reservoir matter balance equation that attached gas desorption, abnormal high pressure influence, and combine the binomial potential curve and equation and two of gas well
The expression formula of channelling amount between a area establishes a kind of shale gas well gas production, flowing bottomhole pressure (FBHP) computation model, by adjusting gas well
Interior outskirt Reserve Fitting flowing bottomhole pressure (FBHP), it is final to determine area's dynamic holdup inside and outside shale gas well.
It is illustrated in figure 2 method flow diagram according to an embodiment of the invention, is illustrated in figure 3 according to the present invention
The algorithm implementation flow chart of one embodiment, below with reference to Fig. 2 and Fig. 3, the present invention is described in detail.
Firstly, in step s 110, obtaining shale gas multistage pressure break horizontal well gas testing data, creation data and gas well structure
Parameter, and gas well binomial potential curve and equation is established by gas testing data, it is calculated by creation data and gas well structural parameters practical
Flowing bottomhole pressure (FBHP).
Specifically, the shale gas multistage pressure break horizontal well gas testing data, creation data and the gas well structural parameters such as table 1 that obtain
It is shown.According to People's Republic of China (PRC) oil and gas industry standard SY/T 5440-2000, established by fitting gas testing data
Gas well binomial potential curve and equation be expressed as follows:
Wherein, A is gas well binomial potential curve and equation Monomial coefficient；B is gas well binomial potential curve and equation two-term coefficient；
Q be gas well produce daily tolerance, 104m3/d；p1For fracturing reform area mean reservoir pressure, pwfFor gas well when yield is q corresponding well
Underflow pressure, MPa.By formula (1-1) as long as it is found that given fracturing reform area mean reservoir pressure p1After gas well daily gas amount,
The prediction flowing bottomhole pressure (FBHP) of gas well can be calculated according to the formula.Fracturing reform area mean reservoir pressure p1Below the present invention
The step of in can be calculated.
Next, in the step s 120, considering that adsorbed gas desorption and abnormal high pressure influence, establishing be directed to multistage pressure break respectively
The matter balance equation in the fracturing reform area of horizontal well and non-fracturing reform area.The step specifically includes several steps below.
In step S1201, considers that adsorbed gas desorption and abnormal high pressure influence, establish shale gas reservoir matter balance equation.
In this step, when establishing shale gas reservoir matter balance equation, need to comprehensively consider the shadow of free gas, adsorbed gas desorption diffusion
It rings.In addition, for abnormal high pressure shale gas reservoir, it is also necessary to consider that rock elasticity can influence.Because Abnormal High Pressure Gas Reservoirs are being developed
Initial stage pore space compressibility of rock is approximate with gas compressive coefficient in the same order of magnitude, and flexible drive can not ignore,
Otherwise the dynamic holdup evaluated is higher.Below by way of analysis abnormal high pressure and adsorbed gas desorption to shale gas reservoir matter balance equation
Influence establish and consider abnormal high pressure and the shale gas reservoir material balance side that adsorbed gas desorption influences according to the principle of mass conservation
Journey.
Assuming that gas reservoir original free gas reserves are Gf, when strata pressure is by PiWhen being reduced to P, due to rock matrix compression and
Pore volume reduction amount in underground caused by fluid expansion indicates are as follows:
Wherein, GfFor gas reservoir original free gas reserves, 104m3；BgiFor the natural-gas volume system under original formation pressure
Number；SgiFor the original gas saturation of gas reservoir；SwiFor the original water saturation of gas reservoir；cfFor the active porosity compressed coefficient, MPa-1；cw
For the water flooding compressed coefficient, MPa-1；ΔVeUnderground pore volume change caused by be declined by strata pressure, 104m3。
Due to as x → 0, ex≈ 1+x, formula (2-1) can simplify are as follows:
Then formula (2-2) indicates that Abnormal High Pressure Gas Reservoirs strata pressure declines caused underground pore volume variation.
Due to the natural gas in shale gas reservoir in a manner of free gas and adsorbed gas preservation, wherein adsorbed gas accounting reach 20~
85%.Shale adsorbed gas air content can be described with following Langmuir isothermal adsorpting equation:
Wherein, V (p) indicates that shale is saturated adsorbed gas air content, m when pressure is p3/t；VLFor Langmuir volume, indicate
The maximum saturation adsorbed gas air content of shale, m when strata pressure tends to infinity3/t；PLFor Lan Shi pressure, Lan Shi etc. is indicated
50%V in warm adsorption curveLCorresponding pressure, MPa.Lan Shi pressure is lower, then adsorbed gas is less susceptible to solve in recovery process
It inhales.
Based on formula (2-3), the total absorption tolerance of shale gas reservoir can be indicated under any pressure are as follows:
Wherein, ρBFor shale density, t/m3；VBFor shale total volume, m3。
Based on formula (2-4), original formation pressure piWhen free gas and adsorbed gas gross reserves may be expressed as:
When strata pressure is by piTired gas production when being reduced to p is Gp, shale gas reservoir pore volume reduction amount can pass through formula
(2-6) is calculated:
Residual free gas reserves can be calculate by the following formula to obtain:
Remaining adsorbed gas reserves:
According to the law of indestructibility of matter: original free gas reserves+original adsorbed gas reserves=residual free gas reserves+residue is inhaled
Attached gas yield+tired gas production, available:
By the B in formula (2-9)gIt is converted, then formula (2-9) can be arranged with compressibility factor z are as follows:
As enabled:
Then formula (2-10) can arrange are as follows:
Formula (2-12) is the shale gas reservoir matter balance equation for considering adsorbed gas desorption and abnormal high pressure and influencing.
In step S1202, the Area of a well of multistage pressure break horizontal well is divided by pressure break according to well pattern spacing and is changed
Area and non-fracturing reform area are made, subregion is as shown in Figure 1.
In step S1203, established respectively based on shale gas reservoir matter balance equation for fracturing reform area and non-pressure break
The matter balance equation in area is transformed.Specifically, the material balance based on the fracturing reform area established matter balance equation (2-12)
Equation are as follows:
Wherein, p1For the mean reservoir pressure in fracturing reform area, G1For the dynamic holdup in fracturing reform area, Gp1It is tired for gas well
Count yield, Gp2It is non-fracturing reform area to the accumulative channelling amount in fracturing reform area.
Matter balance equation based on the non-fracturing reform area established matter balance equation (2-12) are as follows:
Wherein, p2For the mean reservoir pressure in non-fracturing reform area, G2For the dynamic holdup in non-fracturing reform area.
Finally, in step s 130, giving the dynamic holdup in fracturing reform area and non-fracturing reform area respectively, and combine pressure
Split expression formula, the binomial potential curve and equation of the channelling amount between transformation area and the matter balance equation and twoth area in non-fracturing reform area
Dynamic holdup is adjusted to be fitted practical flowing bottomhole pressure (FBHP), so that it is determined that area's dynamic holdup inside and outside pressure break horizontal well.
In this step, determine that outskirt dynamic holdup specifically includes several steps below in horizontal well.Firstly, in step
In S1301, the estimated value for giving shale gas fractured horizontal well transformation area's dynamic holdup is G10, non-fracturing reform area dynamic holdup
Estimated value is G20, it is not end value that the two dynamic holdups, which are estimated value,.
In step S1302, the estimated value G based on fracturing reform area dynamic holdup10, non-fracturing reform area dynamic holdup
Estimated value G20, the matter balance equation in fracturing reform area, the matter balance equation in non-fracturing reform area, Gas Well Productivity and double
The expression formula of channelling amount between area produces the mean reservoir pressure in tolerance iterative calculation fracturing reform area daily according to gas well.
Specifically, the mean reservoir pressure in iterative calculation fracturing reform area can be realized by several steps shown in Fig. 4.
Firstly, by a upper time step ti-1The mean reservoir pressure value p in interior fracturing reform area10As current time step tiInterior fracturing reform area
Mean reservoir pressure p1Iterative initial value.If ti=0, iterative initial value is then original formation pressure value pi。
Then, according to fracturing reform area mean reservoir pressure p1, by the matter balance equation iteration meter in non-fracturing reform area
Suan Wei fracturing reform area mean reservoir pressure p2。
Iterate to calculate non-fracturing reform area mean reservoir pressure p2When include several steps shown in fig. 5.Firstly, taking one
A time step ti-1Nei Wei fracturing reform area mean reservoir pressure p20As this time step tiAt the beginning of Nei Wei fracturing reform area mean reservoir pressure
Value p2If ti=0, iterative initial value is then taken as original formation pressure pi。
Then, it is based on current tiThe current mean reservoir pressure value p in fracturing reform area and non-fracturing reform area in time step1
And p2, the channelling amount q between the area current time step Xia Liangge is calculated according to the following formula2And accumulative channelling amount Gp2.Wherein, when calculating current
Channelling amount q between the area Bu Xialiangge2Expression formula:
Calculate total accumulative channelling amount G between the area Liang Gep2Expression formula are as follows:
Gp2=Gp20+ΔGp2, (2-16)
Wherein,λ is interporosity flow coefficient, and Δ t is time step step-length, q20Between the area last time step Liang Ge
Channelling amount, Gp20Total accumulative channelling amount between the area Liang Ge of last time step, Δ Gp2Between the area current step Nei Liangge
Accumulative channelling amount.
Then, it is based on current tiTime step Nei Wei fracturing reform area mean reservoir pressure value p2, original formation pressure piThe section and
Accumulative channelling yield Gp2Calculate the matter balance equation residual error in non-fracturing reform area.The residual error are as follows:
When residual absolute value of the difference is less than assigned error, iteration is exited；Otherwise, with current mean reservoir pressure value p2Make
For iterative initial value, continue the mean reservoir pressure value for iterating to calculate non-fracturing reform area, until the mean reservoir pressure value meets
Until error requirements.
Based on the mean reservoir pressure value p for calculating available non-fracturing reform area above2.Next, being changed according to pressure break
Make area mean reservoir pressure p1, non-fracturing reform area mean reservoir pressure p2And section interporosity flow coefficient calculate non-fracturing reform area to
The current time step channelling amount and accumulative channelling amount in fracturing reform area.Current time step channelling amount and accumulative channelling amount can use herein
The value being calculated when the mean reservoir pressure value in non-fracturing reform area is sought above.
Next, being based on fracturing reform area mean reservoir pressure value p1, original formation pressure pi, gas well cumulative gas Gp1
With accumulative channelling amount Gp2Calculate the matter balance equation residual error in fracturing reform area in current time step.The residual error are as follows:
When residual absolute value of the difference is less than assigned error, iteration convergence, iteration is exited；Otherwise, with current average stratum
Pressure value p1As iterative initial value, continue the mean reservoir pressure value for iterating to calculate new fracturing reform area according to Newton method, directly
Until the mean reservoir pressure value meets error requirements.
In step S1303, the mean reservoir pressure value p based on the fracturing reform area obtained above1With binomial production capacity
Equation predicts flowing bottomhole pressure (FBHP) by daily output tolerance.Specifically, under other parameters known case, as long as given fracturing reform area is dynamic
The estimated value G of state reserves10The estimated value G of non-fracturing reform area dynamic holdup20, so that it may gas well is obtained by creation data
It produces tolerance daily, produces tolerance daily further according to gas well and deliverability equation calculates corresponding flowing bottomhole pressure (FBHP).
In step S1304, the flowing bottomhole pressure (FBHP) and practical flowing bottomhole pressure (FBHP) for being fitted prediction are to determine that area is transformed in fractured horizontal well
Dynamic holdup and non-fracturing reform area dynamic holdup.Specifically, in this step, the average stratum based on fracturing reform area
Pressure and binomial potential curve and equation formula (1-1) calculate flowing bottomhole pressure (FBHP), and the dynamic in fracturing reform area is adjusted by Optimizing Algorithm for Fitting
Reserves G1The dynamic holdup G in non-fracturing reform area2, so that the error of the flowing bottomhole pressure (FBHP) being calculated and practical flowing bottomhole pressure (FBHP)
Quadratic sum value within the set range, so that it is determined that the dynamic holdup G in fracturing reform area1The dynamic holdup G in non-fracturing reform area2。
Table 1
Below by way of a specific embodiment, the present invention will be described.This sentences Sichuan Basin Lower Silurian Series Longma
For small stream group shale gas well A, which is shown in Table 1.
The well after the gas testing in December, 2012 using 5 cun half-covering tube pilot production 9 months, then 2 cun of half oil pipe of tripping in is raw
It produces, during which adds up to carry out 9 bottom pressures and temperature gradient test altogether.Fig. 6 produces tolerance and survey daily during being the well gas testing pilot production
Try flowing bottomhole pressure (FBHP).
Before dynamic holdup calculating, first according to the gas testing data evaluation well binomial potential curve and equation.It is total according to the Chinese people
With state oil and gas industry standard SY/T 5440-2000, gas well binomial potential curve and equation is established by being fitted gas testing data,
As a result as shown in Figure 7.Wherein, well A binomial potential curve and equation coefficient is respectively A=21.107, B=2.9494.
Method according to the present invention, establishes algorithm routine, inputs the production such as above-mentioned 1 parameter of table and Fig. 6 daily output tolerance
Data, and the estimated value G of inside and outside dynamic holdup is given respectively10、G20, G10=2.5 hundred million sides, G20=3 hundred million sides.It flows in the shaft bottom of calculating
Pressure is as shown in Figure 8.Dynamic holdup G is adjusted by Optimizing Algorithm for Fitting1And G2, the flowing bottomhole pressure (FBHP) of the Fitting Calculation and real well underflow
Pressure, final fitting result are as shown in Figure 9.The dynamic holdup of the current inner region of the well A of fitting is 1.83 hundred million sides, and outskirt employs storage
Amount is 0.4 hundred million sides, then the development degree of outskirt is low.
The matter balance equation established in the present invention considers that adsorbed gas desorption and pore space compressibility of rock influence, and
The dynamic holdup evaluation side of matter balance equation and gas well deliverability establishing equation based on Production development data is integrated on the basis of this
Method.The desorption of shale gas adsorbed gas and pore space compressibility of rock can be considered when calculating to shale gas reservoir material balance for this method
The influence of equation, and do not need in calculating the mean reservoir pressure of shut-in pressure restoration evaluation.What calculated result was suitable for
A variety of applications such as shale gas well rational proration, developing value and development plan optimization.
While it is disclosed that embodiment content as above but described only to facilitate understanding the present invention and adopting
Embodiment is not intended to limit the invention.Any those skilled in the art to which this invention pertains are not departing from this
Under the premise of the disclosed spirit and scope of invention, any modification and change can be made in the implementing form and in details,
But scope of patent protection of the invention, still should be subject to the scope of the claims as defined in the appended claims.
Claims (10)
1. a kind of method for determining area's dynamic holdup inside and outside shale gas multistage pressure break horizontal well, comprising:
Shale gas multistage pressure break horizontal well gas testing data, creation data and gas well structural parameters are obtained, and are provided by the gas testing
Material establishes gas well binomial potential curve and equation, calculates practical flowing bottomhole pressure (FBHP) by the creation data and gas well structural parameters；
Consider that adsorbed gas desorption and abnormal high pressure influence, establishes the fracturing reform area for multistage pressure break horizontal well respectively and do not press
Split the matter balance equation in transformation area；
The estimated value of the dynamic holdup in the fracturing reform area and the non-fracturing reform area is given respectively, and in conjunction with the pressure break
The expression formula of the channelling amount between area and the matter balance equation and twoth area in the non-fracturing reform area is transformed, the binomial produces
Can equation adjust the estimated value of the dynamic holdup to be fitted the practical flowing bottomhole pressure (FBHP), so that it is determined that the fracturing reform area with
The dynamic holdup in the non-fracturing reform area, as area's dynamic holdup inside and outside pressure break horizontal well；
Wherein, the expression formula of channelling amount is as follows:
Wherein, q2Channelling amount between the area Liang Ge, λ are interporosity flow coefficient, p1For the mean reservoir pressure value in fracturing reform area, p2
For the mean reservoir pressure value in non-fracturing reform area.
2. the method according to claim 1, wherein establish for multistage pressure break horizontal well fracturing reform area and
The step of matter balance equation in non-fracturing reform area, further comprises:
Consider that adsorbed gas desorption and abnormal high pressure influence, establishes shale gas reservoir matter balance equation；
Multistage pressure break horizontal well Area of a well is divided into fracturing reform area and non-fracturing reform area according to well pattern spacing；
Establish the object in the fracturing reform area and the non-fracturing reform area respectively based on the shale gas reservoir matter balance equation
Matter equilibrium equation.
3. according to the method described in claim 2, it is characterized in that, the step of establishing the shale gas reservoir matter balance equation into
One step includes:
Based on pore space compressibility of rock, when calculating strata pressure variation as caused by rock matrix compression and fluid expansion
Lower hole volume reduction；
Shale after calculating drop in formation pressure based on the underground pore volume reduction amount and Langmuir isothermal adsorpting equation
Gas reservoir residual free gas reserves and remaining adsorbed gas reserves；
According to the law of indestructibility of matter: original free gas reserves+original adsorbed gas reserves=residual free gas reserves+residue adsorbed gas
Yield+tired gas production, establishes the shale gas reservoir matter balance equation.
4. according to the method in claim 2 or 3, which is characterized in that the shale gas reservoir matter balance equation are as follows:
Wherein, Za=Za(p),
Work as p=piWhen,P is strata pressure, piFor original formation pressure, GpFor cumulative production, G is dynamic holdup, cf
For pore space compressibility of rock, cwFor the water flooding compressed coefficient, SwiFor the original water saturation of gas reservoir, SgiFor the original gassiness of gas reservoir
Saturation degree, φ are effecive porosity, ρBFor shale density, VLFor Langmuir volume, PLFor Lan Shi pressure, pscFor standard state
Lower gas pressure, T are formation temperature, TscFor the temperature under standard state, z is the gas deviation factor under pressure p, zscFor
Gas deviation factor under standard state.
5. according to the method described in claim 4, it is characterized in that, the matter balance equation in the fracturing reform area are as follows:
Wherein, p1For the mean reservoir pressure in fracturing reform area,G1For the dynamic holdup in fracturing reform area, Gp1For gas
Well cumulative production, Gp2It is non-fracturing reform area to the accumulative channelling amount in fracturing reform area.
6. according to the method described in claim 4, it is characterized in that, the matter balance equation in the non-fracturing reform area are as follows:
Wherein, p2For the mean reservoir pressure in non-fracturing reform area,Gp2It is non-fracturing reform area to fracturing reform area
Accumulative channelling amount, G2For the dynamic holdup in non-fracturing reform area.
7. method according to claim 5 or 6, which is characterized in that determine the step of area's dynamic holdup inside and outside pressure break horizontal well
Suddenly further comprise:
The estimated value G of the fracturing reform area dynamic holdup of given shale gas multistage pressure break horizontal well10, non-fracturing reform area dynamic stores up
The estimated value G of amount20；
Estimated value G based on fracturing reform area dynamic holdup10, non-fracturing reform area dynamic holdup estimated value G20, fracturing reform
Channelling amount between the matter balance equation in area, the matter balance equation in non-fracturing reform area, Gas Well Productivity and two-region
Expression formula is iterated to calculate the fifty-fifty lamination in fracturing reform area according to gas well daily output tolerance by fracturing reform area matter balance equation
Power；
Mean reservoir pressure p based on the fracturing reform area1With the binomial potential curve and equation, shaft bottom is predicted by daily output tolerance
Stream pressure；
The flowing bottomhole pressure (FBHP) predicted and the practical flowing bottomhole pressure (FBHP) are fitted to determine the dynamic holdup in fracturing reform area described in horizontal well
With the dynamic holdup in the non-fracturing reform area.
8. the method according to the description of claim 7 is characterized in that the step of the mean reservoir pressure in iterative calculation fracturing reform area
Suddenly further comprise:
By a upper time step ti-1Fracturing reform area mean reservoir pressure value p10As current tiTime step fracturing reform area is averaged stratum
The iterative initial value p of pressure1If ti=0, then iterative initial value is original formation pressure value；
According to fracturing reform area mean reservoir pressure p1, non-pressure break is iterated to calculate by the matter balance equation in non-fracturing reform area and is changed
Make area mean reservoir pressure p2；
According to fracturing reform area mean reservoir pressure p1, non-fracturing reform area mean reservoir pressure p2And interior outskirt interporosity flow coefficient meter
Calculate current tiChannelling amount and accumulative channelling amount of the non-fracturing reform area of time step to fracturing reform area；
Based on fracturing reform area mean reservoir pressure value p1, original formation pressure pi, gas well cumulative gas Gp1And it is described accumulative
Channelling amount Gp2Calculate the matter balance equation residual error in current time step fracturing reform area:
When residual absolute value of the difference is less than assigned error, iteration convergence, iteration is exited, otherwise with current mean reservoir pressure value
p1As initial value, wanted according to the mean reservoir pressure value that Newton method continues to iterate to calculate new fracturing reform area until meeting error
Until asking.
9. according to the method described in claim 8, it is characterized in that, iterating to calculate the mean reservoir pressure in non-fracturing reform area
Step further comprises:
Take a time step ti-1Non- fracturing reform area mean reservoir pressure p20As this time step tiNon- fracturing reform area is averaged stratum
Pressure initial value p2If ti=0, then it is taken as original formation pressure；
According to current tiTime step fracturing reform area and the current mean reservoir pressure value p in non-fracturing reform area1And p2, inside and outside calculating
Channelling amount q between area2And accumulative channelling amount Gp2,
Total accumulative channelling amount G between interior outskirtp2It is calculate by the following formula:
Gp2=Gp20+ΔGp2,
Wherein, Δ Gp2Accumulative channelling amount between outskirt interior in current step,When Δ t is step by step
It is long, q20For the channelling amount between outskirt in last time step, Gp20Total accumulative channelling amount between the interior outskirt of last time step；
Based on current tiThe non-fracturing reform area mean reservoir pressure value p of time step2, original formation pressure piAdd up to alter with inside and outside section
Miscarriage amount Gp2Calculate the matter balance equation residual error in non-fracturing reform area:
When residual absolute value of the difference is less than assigned error, iteration is exited, otherwise with current mean reservoir pressure value p2As first
Value, the mean reservoir pressure value for continuing to iterate to calculate non-fracturing reform area is until meeting error requirements.
10. according to the method described in claim 9, it is characterized in that, flowing bottomhole pressure (FBHP) and the real well underflow of fitting prediction
The step of pressing dynamic holdup to determine the dynamic holdup in fracturing reform area described in horizontal well and the non-fracturing reform area is into one
Step includes:
Mean reservoir pressure and the binomial potential curve and equation based on the fracturing reform area calculate flowing bottomhole pressure (FBHP)；
The estimated value G of the dynamic holdup in the fracturing reform area is adjusted by Optimizing Algorithm for Fitting10With the non-fracturing reform area
Dynamic holdup estimated value G20, so that the error sum of squares value of the flowing bottomhole pressure (FBHP) being calculated and practical flowing bottomhole pressure (FBHP) is being set
Determine in range, so that it is determined that the dynamic holdup G in the fracturing reform area1With the dynamic holdup G in the non-fracturing reform area2。
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