考虑岩矿非均质性的前置液酸压模拟研究
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摘要
前置液酸压工艺采用高黏非反应性前置压裂液压开储层形成水力裂缝,然后高压挤入酸液刻蚀裂缝表面,形成非均匀溶蚀缝面以此来增强裂缝的导流能力。为了给深部碳酸盐岩储层的前置液酸压改造提供理论依据,在建立多种矿物存在的裂缝酸化数学模型的基础上,结合裂缝拟三维延伸模型,构建了能够正确描述前置液酸压物理、化学过程的综合控制方程组;基于控制方程,模拟分析了岩矿层理、岩矿组分占比和排量等关键因素对前置液酸压改造效果的影响。结果表明:(1)岩矿层理对酸蚀裂缝形态起主导作用,且水平层理有助于提高酸液的有效作用距离;(2)石灰岩在碳酸盐岩矿物中所占比例越大,酸液有效作用距离越短;(3)在考虑岩矿非均质性的前置液酸压改造中,大排量能增加酸液的有效作用距离,但酸蚀缝宽相应变窄。结论认为:(1)与常规酸压模拟方法相比,该方法充分考虑了受地质沉积影响的岩矿分布特点,较真实地模拟了岩矿非均质性所引起的裂缝非均匀刻蚀形态;(2)该研究成果为碳酸盐岩储层前置液酸压改造优化设计提供了新的方法和手段,丰富了碳酸盐岩储层改造理论。
When the preflush acid fracturing technology is carried out, a high-viscosity nonreactive pad fracturing fluid is used to fracture the reservoirs and generate hydraulic fractures. Then, an acidizing fluid is injected at high pressures to etch the surface of the fractures, so that a nonuniform surface of dissolved fractures is formed to increase the flow conductivity of fractures. For providing the theoretical basis for the preflush acid fracturing of deep carbonate reservoirs, a mathematical model for fracture acidizing in the cases with multiple minerals was established. Then, based on the pseudo-three dimensional fracture propagation model, a comprehensive control equation set was prepared to accurately describe the physical and chemical courses of preflush acid fracturing. Based on the control equation, the influences of key factors(e.g. rock bedding, rock composition percentage and flow rate) on the stimulation effects of preflush acid fracturing were simulated and analyzed. And the following research results were obtained. First, the rock bedding plays a leading role for the morphologies of etched fractures and horizontal beddings is conducive to increase the effective distance of acidizing fluid. Second, the higher the content of limestone in carbonate minerals, the shorter the effective distance of acidizing fluid. Third, if the rock heterogeneity is considered in the preflush acid fracturing, a high flow rate can increase the effective distance of acidizing fluid, but the etched fractures become narrow correspondingly. It is concluded that different from conventional acid fracturing simulation methods, this method fully considers the rock distribution characteristics that are affected by geologic sedimentation and it can simulate authentically the nonuniform etch morphologies of fractures caused by rock heterogeneity. The research results provide a new method for the design optimization of the preflush acid fracturing in carbonate reservoirs and enrich the carbonate reservoir stimulation theories.
When the preflush acid fracturing technology is carried out, a high-viscosity nonreactive pad fracturing fluid is used to fracture the reservoirs and generate hydraulic fractures. Then, an acidizing fluid is injected at high pressures to etch the surface of the fractures, so that a nonuniform surface of dissolved fractures is formed to increase the flow conductivity of fractures. For providing the theoretical basis for the preflush acid fracturing of deep carbonate reservoirs, a mathematical model for fracture acidizing in the cases with multiple minerals was established. Then, based on the pseudo-three dimensional fracture propagation model, a comprehensive control equation set was prepared to accurately describe the physical and chemical courses of preflush acid fracturing. Based on the control equation, the influences of key factors(e.g. rock bedding, rock composition percentage and flow rate) on the stimulation effects of preflush acid fracturing were simulated and analyzed. And the following research results were obtained. First, the rock bedding plays a leading role for the morphologies of etched fractures and horizontal beddings is conducive to increase the effective distance of acidizing fluid. Second, the higher the content of limestone in carbonate minerals, the shorter the effective distance of acidizing fluid. Third, if the rock heterogeneity is considered in the preflush acid fracturing, a high flow rate can increase the effective distance of acidizing fluid, but the etched fractures become narrow correspondingly. It is concluded that different from conventional acid fracturing simulation methods, this method fully considers the rock distribution characteristics that are affected by geologic sedimentation and it can simulate authentically the nonuniform etch morphologies of fractures caused by rock heterogeneity. The research results provide a new method for the design optimization of the preflush acid fracturing in carbonate reservoirs and enrich the carbonate reservoir stimulation theories.
引文
[1]Jeon J,Bashir MO,Liu JR&Wu XR.Fracturing carbonate reservoirs:Acidising fracturing or fracturing with proppants?[C]//SPE Asia Pacific Hydraulic Fracturing Conference,24-26 August2016,Beijing,China.DOI:http://dx.doi.org/10.2118/181821-MS.
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[3]韩慧芬,桑宇,杨建.四川盆地震旦系灯影组储层改造实验与应用[J].天然气工业,2016,36(1):81-88.Han Huifen,Sang Yu&Yang Jian.Experimental study and application of stimulation technologies for Sinian Dengying Formation reservoirs in the Sichuan Basin[J].Natural Gas Industry,2016,36(1):81-88.
[4]赵立强,牟媚,罗志锋,刘平礼,邹东篱.中国致密油储层改造理念及技术展望[J].西南石油大学学报(自然科学版),2016,38(6):111-118.Zhao Liqiang,Mu Mei,Luo Zhifeng,Liu Pingli&Zou Dongli.The outlook for China's tight oil reservoir stimulation concept and technology[J].Journal of Southwest Petroleum University(Science&Technology Edition),2016,38(6):111-118.
[5]韩慧芬.四川盆地上震旦统灯四段气藏提高单井产量的技术措施[J].天然气工业,2017,37(8):40-47.Han Huifen.Technological measures for improving single-well productivity of gas reservoirs of Upper Sinian Deng 4 Member in the Sichuan Basin[J].Natural Gas Industry,2017,37(8):40-47.
[6]郭建春,苟波,王坤杰,任冀川,曾冀.川西下二叠统超深气井网络裂缝酸化优化设计[J].天然气工业,2017,37(6):34-41.Guo Jianchun,Gou Bo,Wang Kunjie,Ren Jichuan&Zeng Ji.An optimal design of network-fracture acidification for ultra-deep gas wells in the Lower Permian strata of the western Sichuan Basin[J].Natural Gas Industry,2017,37(6):34-41.
[7]Liu PL,Zhao LQ,Luo ZF,Li NY&Xu M.Predicting productivity of hydraulic fracturing with pre-pad acid[C]//47th U.S.Rock Mechanics/Geomechanics Symposium.San Francisco,California:American Rock Mechanics Association,2013.
[8]刘飞,赵立强,孟向丽,马旭,赵振峰.前置缓速酸加砂压裂中酸岩反应模拟研究[J].石油天然气学报,2014,36(1):104-108.Liu Fei,Zhao Liqiang,Meng Xiangli,Ma Xu&Zhao Zhenfeng.Stimulation of acid-rock reaction in hydraulic fracturing with pre-pad retarded acid[J].Journal of Oil and Gas Technology,2014,36(1):104-108.
[9]Dong C,Zhu D&Hill AD.Modeling of the acidizing process in naturally fractured carbonates[J].SPE Journal,2002,7(4):400-408.
[10]Noiriel C,Gouze P&MadéB.3D analysis of geometry and flow changes in a limestone fracture during dissolution[J].Journal of Hydrology,2013,486:211-223.
[11]Elkhoury JE,Ameli P&Detwiler RL.Dissolution and deformation in fractured carbonates caused by flow of CO2-rich brine under reservoir conditions[J].International Journal of Greenhouse Gas Control,2013,16(S1):S203-215.
[12]Deng H,Ellis BR,Peters CA,Fitts JP,Crandall D&Bromhal GS.Modifications of carbonate fracture hydrodynamic properties by CO2-acidified brine flow[J].Energy&Fuels,2013,27(8):4221-4231.
[13]王强.天然裂缝性碳酸盐岩储层酸化模拟研究[D].成都:西南石油大学,2006.Wang Qiang.The study on acidizing simulation of naturally-fractured carbonate formations[D].Chengdu:Southwest Petroleum University,2006.
[14]Mou JY.Modeling acid transport and non-uniform etching in a stochastic domain in acid fracturing[D].College Station:Texas A&M University,2009.
[15]Upadhyay VK,Szymczak P&Ladd AJC.Initial conditions or emergence:What determines dissolution patterns in rough fractures?[J].Journal of Geophysical Research Solid Earth,2015,120(9):6102-6121.
[16]Palmer ID&Luiskutty CT.A model of the hydraulic fracturing process for elongated vertical fractures and comparisons of results with other models[C]//SPE/DOE Low Permeability Gas Reservoirs Symposium,19-22 March 1985,Denver,Colorado,USA.DOI:http://dx.doi.org/10.2118/13864-MS.
[17]Clifton RJ&Abou-Sayed AS.A variational approach to the prediction of the three-dimensional geometry of hydraulic fractures[C]//SPE/DOE Low Permeability Gas Reservoirs Symposium,27-29 May 1981,Denver,Colorado,USA.DOI:http://dx.doi.org/10.2118/9879-MS.
[18]申颍浩,葛洪魁,程远方,夏雨梅,李娜,杨柳.水力压裂拟三维模型数值求解新方法[J].科学技术与工程,2014,14(26):219-223.Shen Yinghao,Ge Hongkui,Cheng Yuanfang,Xia Yumei,Li Na&Yang Liu.Algorithm renew study of hydraulic fracture pseudo-three dimensional model[J].Science Technology and Engineering,2014,14(26):219-223.
[19]李小刚,宋瑞,张汝生,杨兆中,林鑫.大尺寸可视化酸液指进模拟装置研制及应用[J].西南石油大学学报(自然科学版),2017,39(2):153-162.Li Xiaogang,Song Rui,Zhang Rusheng,Yang Zhaozhong&Lin Xin.Development and application of large scale visible physical simulation device for acid fingering[J].Journal of Southwest Petroleum University(Science&Technology Edition),2017,39(2):153-162.
[20]Liu PL,Xue H,Zhao LQ,Zhao XD&Cui MY.Simulation of 3Dmulti-scale wormhole propagation in carbonates considering correlation spatial distribution of petrophysical properties[J].Journal of Natural Gas Science and Engineering,2016,32:81-94.
[21]De Oliveira TJL,De Melo AR,Oliveira JAA&Pereira AZI.Numerical simulation of the acidizing process and PVBT extraction methodology including porosity/permeability and mineralogyheterogeneity[C]//SPE International Symposium and Exhibition on Formation Damage Control,15-17 February 2012,Lafayette,Louisiana,USA.DOI:http://dx.doi.org/10.2118/151823-MS.
[22]邝聃,郭建春,李勇明,曹军.酸液有效作用距离预测及影响因素分析[J].断块油气田,2009,16(5):97-100.Kuang Dan,Guo Jianchun,Li Yongming&Cao Jun.Predicting of effective distance of live acid for carbonate reservoir acid fracturing and its influence factors[J].Fault-Block Oil&Gas Field,2009,16(5):97-100.
[23]王洋,袁清芸.超高温高压气藏酸液有效作用距离定量研究[J].钻采工艺,2016,39(6):31-33.Wang Yang&Yuan Qingyun.The research of acid effective distance for super high temperature and high pressure gas reservoir[J].Drilling&Production Technology,2016,39(6):31-33.
[24]Maheshwari P,Ratnakar RR,Kalia N&Balakotaiah V.3-D simulation and analysis of reactive dissolution and wormhole formation in carbonate rocks[J].Chemical Engineering Science,2013,90:258-274.
[2]Kalfayan LJ.Fracture acidizing:History,present state,and future[C]//SPE Hydraulic Fracturing Technology Conference,29-31 January 2007,College Station,Texas,USA.DOI:http://dx.doi.org/10.2118/106371-MS.
[3]韩慧芬,桑宇,杨建.四川盆地震旦系灯影组储层改造实验与应用[J].天然气工业,2016,36(1):81-88.Han Huifen,Sang Yu&Yang Jian.Experimental study and application of stimulation technologies for Sinian Dengying Formation reservoirs in the Sichuan Basin[J].Natural Gas Industry,2016,36(1):81-88.
[4]赵立强,牟媚,罗志锋,刘平礼,邹东篱.中国致密油储层改造理念及技术展望[J].西南石油大学学报(自然科学版),2016,38(6):111-118.Zhao Liqiang,Mu Mei,Luo Zhifeng,Liu Pingli&Zou Dongli.The outlook for China's tight oil reservoir stimulation concept and technology[J].Journal of Southwest Petroleum University(Science&Technology Edition),2016,38(6):111-118.
[5]韩慧芬.四川盆地上震旦统灯四段气藏提高单井产量的技术措施[J].天然气工业,2017,37(8):40-47.Han Huifen.Technological measures for improving single-well productivity of gas reservoirs of Upper Sinian Deng 4 Member in the Sichuan Basin[J].Natural Gas Industry,2017,37(8):40-47.
[6]郭建春,苟波,王坤杰,任冀川,曾冀.川西下二叠统超深气井网络裂缝酸化优化设计[J].天然气工业,2017,37(6):34-41.Guo Jianchun,Gou Bo,Wang Kunjie,Ren Jichuan&Zeng Ji.An optimal design of network-fracture acidification for ultra-deep gas wells in the Lower Permian strata of the western Sichuan Basin[J].Natural Gas Industry,2017,37(6):34-41.
[7]Liu PL,Zhao LQ,Luo ZF,Li NY&Xu M.Predicting productivity of hydraulic fracturing with pre-pad acid[C]//47th U.S.Rock Mechanics/Geomechanics Symposium.San Francisco,California:American Rock Mechanics Association,2013.
[8]刘飞,赵立强,孟向丽,马旭,赵振峰.前置缓速酸加砂压裂中酸岩反应模拟研究[J].石油天然气学报,2014,36(1):104-108.Liu Fei,Zhao Liqiang,Meng Xiangli,Ma Xu&Zhao Zhenfeng.Stimulation of acid-rock reaction in hydraulic fracturing with pre-pad retarded acid[J].Journal of Oil and Gas Technology,2014,36(1):104-108.
[9]Dong C,Zhu D&Hill AD.Modeling of the acidizing process in naturally fractured carbonates[J].SPE Journal,2002,7(4):400-408.
[10]Noiriel C,Gouze P&MadéB.3D analysis of geometry and flow changes in a limestone fracture during dissolution[J].Journal of Hydrology,2013,486:211-223.
[11]Elkhoury JE,Ameli P&Detwiler RL.Dissolution and deformation in fractured carbonates caused by flow of CO2-rich brine under reservoir conditions[J].International Journal of Greenhouse Gas Control,2013,16(S1):S203-215.
[12]Deng H,Ellis BR,Peters CA,Fitts JP,Crandall D&Bromhal GS.Modifications of carbonate fracture hydrodynamic properties by CO2-acidified brine flow[J].Energy&Fuels,2013,27(8):4221-4231.
[13]王强.天然裂缝性碳酸盐岩储层酸化模拟研究[D].成都:西南石油大学,2006.Wang Qiang.The study on acidizing simulation of naturally-fractured carbonate formations[D].Chengdu:Southwest Petroleum University,2006.
[14]Mou JY.Modeling acid transport and non-uniform etching in a stochastic domain in acid fracturing[D].College Station:Texas A&M University,2009.
[15]Upadhyay VK,Szymczak P&Ladd AJC.Initial conditions or emergence:What determines dissolution patterns in rough fractures?[J].Journal of Geophysical Research Solid Earth,2015,120(9):6102-6121.
[16]Palmer ID&Luiskutty CT.A model of the hydraulic fracturing process for elongated vertical fractures and comparisons of results with other models[C]//SPE/DOE Low Permeability Gas Reservoirs Symposium,19-22 March 1985,Denver,Colorado,USA.DOI:http://dx.doi.org/10.2118/13864-MS.
[17]Clifton RJ&Abou-Sayed AS.A variational approach to the prediction of the three-dimensional geometry of hydraulic fractures[C]//SPE/DOE Low Permeability Gas Reservoirs Symposium,27-29 May 1981,Denver,Colorado,USA.DOI:http://dx.doi.org/10.2118/9879-MS.
[18]申颍浩,葛洪魁,程远方,夏雨梅,李娜,杨柳.水力压裂拟三维模型数值求解新方法[J].科学技术与工程,2014,14(26):219-223.Shen Yinghao,Ge Hongkui,Cheng Yuanfang,Xia Yumei,Li Na&Yang Liu.Algorithm renew study of hydraulic fracture pseudo-three dimensional model[J].Science Technology and Engineering,2014,14(26):219-223.
[19]李小刚,宋瑞,张汝生,杨兆中,林鑫.大尺寸可视化酸液指进模拟装置研制及应用[J].西南石油大学学报(自然科学版),2017,39(2):153-162.Li Xiaogang,Song Rui,Zhang Rusheng,Yang Zhaozhong&Lin Xin.Development and application of large scale visible physical simulation device for acid fingering[J].Journal of Southwest Petroleum University(Science&Technology Edition),2017,39(2):153-162.
[20]Liu PL,Xue H,Zhao LQ,Zhao XD&Cui MY.Simulation of 3Dmulti-scale wormhole propagation in carbonates considering correlation spatial distribution of petrophysical properties[J].Journal of Natural Gas Science and Engineering,2016,32:81-94.
[21]De Oliveira TJL,De Melo AR,Oliveira JAA&Pereira AZI.Numerical simulation of the acidizing process and PVBT extraction methodology including porosity/permeability and mineralogyheterogeneity[C]//SPE International Symposium and Exhibition on Formation Damage Control,15-17 February 2012,Lafayette,Louisiana,USA.DOI:http://dx.doi.org/10.2118/151823-MS.
[22]邝聃,郭建春,李勇明,曹军.酸液有效作用距离预测及影响因素分析[J].断块油气田,2009,16(5):97-100.Kuang Dan,Guo Jianchun,Li Yongming&Cao Jun.Predicting of effective distance of live acid for carbonate reservoir acid fracturing and its influence factors[J].Fault-Block Oil&Gas Field,2009,16(5):97-100.
[23]王洋,袁清芸.超高温高压气藏酸液有效作用距离定量研究[J].钻采工艺,2016,39(6):31-33.Wang Yang&Yuan Qingyun.The research of acid effective distance for super high temperature and high pressure gas reservoir[J].Drilling&Production Technology,2016,39(6):31-33.
[24]Maheshwari P,Ratnakar RR,Kalia N&Balakotaiah V.3-D simulation and analysis of reactive dissolution and wormhole formation in carbonate rocks[J].Chemical Engineering Science,2013,90:258-274.