CN106777847A - Low-permeability oil deposit staged fracturing horizontal well unstable state productivity model - Google Patents

Low-permeability oil deposit staged fracturing horizontal well unstable state productivity model Download PDF

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CN106777847A
CN106777847A CN201710194495.XA CN201710194495A CN106777847A CN 106777847 A CN106777847 A CN 106777847A CN 201710194495 A CN201710194495 A CN 201710194495A CN 106777847 A CN106777847 A CN 106777847A
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crack
horizontal well
low
model
staged fracturing
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白远
田丰
谢旭强
云彦舒
黄兴
高庭
袁家宝
王维波
景成
白海涛
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Abstract

The invention discloses a kind of low-permeability oil deposit staged fracturing horizontal well unstable state productivity model, the present invention is by taking the low-permeability oil deposit of natural energy elasticity exploitation as an example, establish unstable state productivity model, to extend based on the low-permeability oil deposit data of oil field, demonstrate the validity of model, using method for numerical simulation, different artificial Number of Fractures, the influence relation of seam position and fracture half-length to horizontal productivity are have studied, carry out the preferred of different cloth seam modes.Result of study shows：With the increase of Number of Fractures, the tired yield of staged fracturing horizontal well is consequently increased, but there is the optimal value that seam bar number is 6, should try one's best so that fracturing fracture is uniformly distributed along horizontal wellbore and forms " short in foreign minister " type crack in the case where technique is allowed, the research provides effective foundation for similar oil reservoir pressing crack construction is designed.

Description

Low-permeability oil deposit staged fracturing horizontal well unstable state productivity model
Technical field
The present invention relates to oil reservoir detection field, and in particular to a kind of low-permeability oil deposit staged fracturing horizontal well unstable state production capacity Model.
Background technology
Ordos Basin extension oil field belongs to low-permeability oil deposit, big with filtrational resistance, the features such as fluid continuity difference, For relatively conventional oil well, staged fracturing horizontal well has the clear superiority to few well high yield, has promoted the use of at present many The exploitation of individual oil-bearing series, is limited by landform and water resources problem, and what is mainly taken is that natural energy without water filling is developed, can be with Say that staged fracturing of horizontal well provides strong technical support for the effective exploitation of low-permeability oil deposit.But for AOF calculation The basic research such as model and fracturing parameter aspect is also weaker.
The content of the invention
To solve the above problems, the invention provides a kind of low-permeability oil deposit staged fracturing horizontal well unstable state production capacity mould Type.
To achieve the above object, the technical scheme taken of the present invention is：
Low-permeability oil deposit staged fracturing horizontal well unstable state productivity model
Assuming that：(1) fluid flows category isothermal unsteady state flow through porous medium in matrix and crack, and gravity, capillary force effect are not considered Influence；(2) fluid is single-phase flow in oil reservoir and crack；(3) fluid first uniformly flows into crack along crack wall, then is flowed by crack Enter horizontal wellbore, do not consider to flow directly into the flow event of horizontal wellbore by matrix；(4) rectangular vertical crack completely penetrates through product Layer；
Horizontal well is divided into N sections by the model for N bar hydraulic fracturings square crack from horizontal well heel end to end, A crack is arranged in every section of centre position, for parallel to X-axis, being centrally located at yfiCrack, its source function is by both direction Source function draw, X-direction be infinity plane in a width of 2XfBand source, y directions be infinite space in line source, The source function in whole space is the product of both direction source function：
For with qfT the crack of () production, by Duhamel principles, it is in the drop of pressure that space causes：
Then in NfThe pressure drop at any point can be expressed as in the earth formation under crack collective effect：
The then pressure drop at j-th strip crack can be expressed as by formula：
By 2 formulas and 4 formulas, draw
In formula, XfFor the dummy joint in crack is long, m；NfIt is Number of Fractures；qiThe yield of the i-th crack, m3/s；Hole Degree, %；C is system compressibility, MPa -1, h is seam height, m；P is pressure, MPa。
In for the calculating of formula (5), j gets N from 1f, respectively obtain NfIndividual equation, wherein NfCrack, per crack Yield is unknown, has NfIndividual unknown number, solves the yield that this equation group just can obtain each crack.
The invention has the advantages that：
By taking the low-permeability oil deposit of natural energy elasticity exploitation as an example, unstable state productivity model is established, it is low to extend oil field Based on infiltration Reservoir Data, the validity of model is demonstrated, using method for numerical simulation, have studied different man-made fracture bars The influence relation of number, seam position and fracture half-length to horizontal productivity, carries out the preferred of different cloth seam modes.
Brief description of the drawings
Fig. 1 is pressure break horizontal well physical model schematic diagram in the embodiment of the present invention.
Fig. 2 is pressure break horizontal well physical model top view in the embodiment of the present invention.
Fig. 3 is that model is calculated and software digital-to-analogue comparative result figure.
Fig. 4 is that the tired yield of horizontal well changes over time curve under different Number of Fractures.
Fig. 5 is different crack locations distribution cloth seam scheme schematic diagram.
Fig. 6 is horizontal well daily output and to tire out product and change over time curve under different crack location schemes；
In figure, (a) daily output is changed over time；B () tired product is changed over time.
Fig. 7 is different crack dummy joints cloth seam scheme schematic diagram long.
Horizontal well is produced daily and tires out product and changes over time curve under the dummy joint scheme long of Fig. 8 differences crack；
In figure, (a) daily output is changed over time；B () tired product is changed over time.
Horizontal well pressure distribution map under Fig. 9 difference producing days；
In figure, (a) producing days t=0.03d；(b) producing days t=0.3d；(c) producing days t=3d；D () produces Number of days t=30d.
Specific embodiment
In order that objects and advantages of the present invention become more apparent, the present invention is carried out further with reference to embodiments Describe in detail.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to limit this hair It is bright.
Low-permeability oil deposit staged fracturing horizontal well unstable state productivity model, it is characterised in that：
Assuming that：(1) fluid flows category isothermal unsteady state flow through porous medium in matrix and crack, and gravity, capillary force effect are not considered Influence；(2) fluid is single-phase flow in oil reservoir and crack；(3) fluid first uniformly flows into crack along crack wall, then is flowed by crack Enter horizontal wellbore, do not consider to flow directly into the flow event of horizontal wellbore by matrix；(4) rectangular vertical crack completely penetrates through product Layer；
As Figure 1-Figure 2, the model is for N bar hydraulic fracturings square crack, from horizontal well heel end to end Jiang Shui Horizontal well is divided into N sections, and a crack is arranged in every section of centre position, for parallel to X-axis, being centrally located at yfiCrack, its source Function is shown that X-direction is a width of 2X in infinity plane by the source function of both directionfBand source, y directions are infinitely great empty Between in line source, the source function in whole space is the product of both direction source function：
For with qfT the crack of () production, by Duhamel principles, it is in the drop of pressure that space causes：
Then in NfThe pressure drop at any point can be expressed as in the earth formation under crack collective effect：
The then pressure drop at j-th strip crack can be expressed as by formula：
By 2 formulas and 4 formulas, draw
In formula, XfFor the dummy joint in crack is long, m；NfIt is Number of Fractures；qiThe yield of the i-th crack, m3/s；Hole Degree, %；C is system compressibility, MPa -1, h is seam height, m；P is pressure, MPa。
In for the calculating of formula (5), j gets N from 1f, respectively obtain NfIndividual equation, wherein NfCrack, per crack Yield is unknown, has NfIndividual unknown number, solves the yield that this equation group just can obtain each crack.
To verify the application effect of model, take underlying parameter as shown in table 1 below and calculated.Each parameter is substituted into model Calculate, the production decline data that pressure break horizontal well total output is changed over time can be obtained.It is checking model, in ECLIPSE Numerical-Modes Intend Modeling Calculation staged fracturing horizontal well production under software.What is calculated in view of this unsteady Model is level in infinitely great stratum Well capacity, thus modeling when be eliminate border influence.180d is calculated in numerical simulation software Imitating, yield is obtained at any time Between the data (Fig. 3) that change, contrast model result of calculation and ECLIPSE numerical simulation calculation results, the calculating data of model with Field Production Data coincide property preferably, illustrates the reliability of model.
The staged fracturing horizontal well underlying parameter list of table 1
Cloth seam mode is studied
Influence of the Number of Fractures to production capacity
To study influence of the different Number of Fractures to production capacity, Number of Fractures N=1,2,3 ... 9, the parameter of reference table 1, generation are taken Enter the tired yield of staged fracturing horizontal well under model calculates different Number of Fractures to change with time, as shown in Figure 4.Understand with splitting The increase of bar number is stitched, the tired yield of staged fracturing horizontal well is consequently increased, but after Number of Fractures N=6 bars, yield occurs viscous Stagnant growth, amplification is not obvious.N=6 is optimal Number of Fractures under the conditions of example.For the actual staged fracturing water gone into operation Horizontal well, there is optimal crack between oil reservoir and match bar number in it, needed during FRACTURING DESIGN the optimal pressure break hop count of optimization with Obtain optimal economic benefit.
Crack location is distributed the influence to production capacity
Influence for research crack location distribution to total output, by taking six cracks as an example, three kinds of cloth seam schemes of design.Scheme Six cracks are uniformly distributed along horizontal well axis in one.Crack is two section of three cluster in scheme two, and its two ends is in horizontal borehole axis Vertical line, is close type scheme in outer dredging.Crack is also two section of three cluster in scheme three, and its two ends, near horizontal well two ends, is outer close interior The type of dredging scheme, cloth seam schematic diagram is as shown in Figure 5.
Underlying parameter substitution model calculates staged fracturing under three kinds of different fractue spacing position cloth seam schemes respectively in taking table 1 The horizontal well daily output and tired yield change with time situation, and its comparative analysis result is as shown in Figure 6.
By Fig. 6 a, under the given production time, the uniform cloth seam daily output in scheme one (uniform cloth seam) is higher than scheme Non-homogeneous cloth seam yield in two (close in dredging outward)；In producing initial stage, the yield of scheme one also above scheme three (outward close interior dredge), The yield of two schemes remains basically stable after a period of time.The yield of scheme three is located at level higher than the yield in scheme two, i.e. crack Yield during well end is located at yield when in the middle of horizontal well higher than it.From Fig. 6 b, the staged fracturing horizontal well of scheme one Tired yield is maximum, and scheme three is taken second place, and scheme two is minimum.Therefore, should be tried one's best so that fracturing fracture edge in the case where technique is allowed Horizontal wellbore to be uniformly distributed.
The dummy joint influence to production capacity long
To study influence of the different fracture half-lengths to total output, so that six are uniformly distributed crack as an example, three kinds of dummy joints are designed Scheme long.As shown in table 2, six cracks are isometric in scheme one, scheme two (short in foreign minister) and scheme three (short interior length outward) every Seam dummy joint is long, and with Length discrepancy, why such dummy joint cloth seam scheme long ensure that the total crack length under three kinds of schemes is identical, Eliminate the influence for involving scope to production capacity.
Fracture half-length's tables of data under the different cloth seam schemes of table 1
Different crack dummy joint cloth seam scheme schematic diagrames long are as shown in Figure 7.
Underlying parameter substitution model calculates staged fracturing horizontal well under three kinds of different dummy joints cloth seam schemes long respectively in taking table 1 The daily output and tired yield change with time situation, its comparative analysis result as shown in Figure 8 a, the certain feelings of overall length in crack Under condition, the daily output of scheme two is higher than scheme one and the yield of scheme three within the given production time；From Fig. 8 b, scheme two The tired yield of staged fracturing horizontal well it is maximum, scheme one is taken second place, and scheme three is minimum.
In sum, in the case of example, optimal cloth stitches scheme for Number of Fractures N=6, along horizontal wellbore axis It is uniformly distributed, forms " short in foreign minister " type crack.Production time t=0.03,0.3,3,30d, the optimal cloth seam side of research are taken respectively Under case, horizontal well pressure change, as shown in Figure 9.
In producing initial stage, the flowing in space is occurred mainly in around crack.Horizontal well production is main by nearly crack area Fluid is to flow in fracture.With the carrying out of flowing, there is crack interference phenomenon, " region of bypassed oil " occur between each crack, when reaching After certain production time, horizontal well region is monolithically fabricated one " pressure release system ", and stratum is to this region radial direction feed flow.
This specific implementation establishes low-permeability oil deposit staged fracturing horizontal well unstable state productivity model, and demonstrates model Validity, for research low-permeability oil deposit staged fracturing horizontal well Production development provides effective predicting means；Low-permeability oil deposit In 700m, it is 6 that should use Number of Fractures to staged fracturing horizontal well horizontal segment, is uniformly distributed along horizontal wellbore axis, is formed " outward It is short in long " the cloth seam mode in type crack, under this cloth seam mode, the nearly shaft bottom band of horizontal well forms " pressure release a body for entirety System ", fluid is to horizontal segment Radial Flow.
The above is only the preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art For member, under the premise without departing from the principles of the invention, some improvements and modifications can also be made, these improvements and modifications also should It is considered as protection scope of the present invention.

Claims (2)

1. low-permeability oil deposit staged fracturing horizontal well unstable state productivity model, it is characterised in that：
Assuming that：(1) fluid flows category isothermal unsteady state flow through porous medium in matrix and crack, and gravity, capillary force function influence are not considered； (2) fluid is single-phase flow in oil reservoir and crack；(3) fluid first uniformly flows into crack along crack wall, then flows into water by crack Horizontal well cylinder, does not consider to flow directly into the flow event of horizontal wellbore by matrix；(4) rectangular vertical crack completely penetrates through payzone；
Horizontal well is divided into N sections, every section by the model for N bar hydraulic fracturings square crack from horizontal well heel end to end Centre position arrange a crack, for parallel to X-axis, being centrally located at yfiCrack, its source function by both direction source Function show that X-direction is a width of 2X in infinity planefBand source, y directions be infinite space in line source, entirely The source function in space is the product of both direction source function：
s ( x , y , t ) = s ( x , t ) · s ( y , t ) = 1 4 πη y t [ e r f ( x f + x 2 η x t ) + e r f ( x f - x 2 η x t ) ] × exp ( - ( y - y f i ) 2 2 η y t ) - - - ( 1 )
For with qfT the crack of () production, by Duhamel principles, it is in the drop of pressure that space causes：
Then in NfThe pressure drop at any point can be expressed as in the earth formation under crack collective effect：
The then pressure drop at j-th strip crack can be expressed as by formula：
By 2 formulas and 4 formulas, draw
F ( i , j , t ) = Σ i = 1 N f ∫ 0 t q i x f s i ( x w , y w j , t - τ ) d τ - - - ( 5 )
In formula, XfFor the dummy joint in crack is long, m；NfIt is Number of Fractures；qiThe yield of the i-th crack, m3/s；Porosity, %；C is System compressibility, MPa -1, h is seam height, m；P is pressure, MPa。
2. low-permeability oil deposit staged fracturing horizontal well unstable state productivity model as claimed in claim 1, it is characterised in that：For In the calculating of formula (5), j gets N from 1f, respectively obtain NfIndividual equation, wherein NfCrack, per crack yield be it is unknown, Total NfIndividual unknown number, solves the yield that this equation group just can obtain each crack.
CN201710194495.XA 2017-03-29 2017-03-29 Low-permeability oil deposit staged fracturing horizontal well unstable state productivity model Pending CN106777847A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111400853A (en) * 2019-01-03 2020-07-10 中国石油天然气股份有限公司 Method and device for predicting unsteady state capacity of closed boundary fractured horizontal well
CN111612747A (en) * 2020-04-30 2020-09-01 重庆见芒信息技术咨询服务有限公司 Method and system for rapidly detecting surface cracks of product

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
廉培庆: "垂直压裂水平井非稳态条件下的产能分析", 《中国石油大学学报(自然科学版)》 *
朱大伟: "低渗/致密油藏分段压裂水平井产能及渗流规律研究", 《中国优秀硕士学位论文全文数据库 基础科学辑》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111400853A (en) * 2019-01-03 2020-07-10 中国石油天然气股份有限公司 Method and device for predicting unsteady state capacity of closed boundary fractured horizontal well
CN111612747A (en) * 2020-04-30 2020-09-01 重庆见芒信息技术咨询服务有限公司 Method and system for rapidly detecting surface cracks of product
CN111612747B (en) * 2020-04-30 2023-10-20 湖北煌朝智能自动化装备有限公司 Rapid detection method and detection system for product surface cracks

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