考虑启动压力梯度的弹性采收率计算方法及影响因素
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摘要
低渗透油藏流体渗流存在启动压力梯度,应用非达西渗流理论,对不同渗流形态下考虑启动压力梯度的弹性采收率计算方法进行了分析,给出了考虑启动压力梯度的直井、直井压裂、水平井和水平井压裂4种开发方式的弹性采收率计算公式,并通过实例分析不同参数对弹性采收率的影响。研究结果表明:随着启动压力梯度的增加,4种开发方式的弹性采收率均呈线性下降,其中直井降幅最大,水平井次之,水平井压裂降幅最小;4种开发方式的弹性采收率和单位压差弹性采收率均随压差的增加而增加,前者呈线性增加,后者增幅逐渐变缓;直井压裂开发的弹性采收率随压裂裂缝半缝长的增加而增加,但增幅逐渐变缓;对于水平井压裂开发,压裂裂缝半缝长较裂缝间距对弹性采收率的影响更大,且存在最优的压裂裂缝半缝长;对于启动压力梯度较大且弹性开发的低渗透油藏,宜采用压裂的方式来提高弹性采收率。
There is a threshold pressure gradient in the flow of fluid in low-permeability reservoirs. Based on the non-Darcy flow theory,a new computing method of natural depletion oil recovery considering the threshold pressure gradient in different flow forms was analyzed. The calculating formulas for depletion oil recovery of the vertical well,fractured vertical well,horizontal well,and fractured horizontal well in the low-permeability reservoir were developed. The effect of each parameter on the depletion oil recovery was discussed while applying the formulas to real cases. The results show that the depletion oil recovery decreased linearly with the increase of threshold pressure gradient. The oil recovery of the vertical wells is very sensitive to the threshold pressure gradient,the horizontal well is less sensitive,and the effect for the fractured horizontal wells is the weakest. The depletion oil recovery and the one per unit pressure drawdown increases with pressure drawdown linearly and in a gradually slower manner respectively. The depletion oil recovery of the fractured vertical well increases with the half fracture length,but the effect decreases gradually. Half fracture length is more sensitive than fracture space to the depletion oil recovery in the fractured horizontal wells. There is optimized half fracture length. It is recommended that the low-permeability reservoir with large threshold pressure gradient under depletion development should be developed with hydraulic fracturing.
There is a threshold pressure gradient in the flow of fluid in low-permeability reservoirs. Based on the non-Darcy flow theory,a new computing method of natural depletion oil recovery considering the threshold pressure gradient in different flow forms was analyzed. The calculating formulas for depletion oil recovery of the vertical well,fractured vertical well,horizontal well,and fractured horizontal well in the low-permeability reservoir were developed. The effect of each parameter on the depletion oil recovery was discussed while applying the formulas to real cases. The results show that the depletion oil recovery decreased linearly with the increase of threshold pressure gradient. The oil recovery of the vertical wells is very sensitive to the threshold pressure gradient,the horizontal well is less sensitive,and the effect for the fractured horizontal wells is the weakest. The depletion oil recovery and the one per unit pressure drawdown increases with pressure drawdown linearly and in a gradually slower manner respectively. The depletion oil recovery of the fractured vertical well increases with the half fracture length,but the effect decreases gradually. Half fracture length is more sensitive than fracture space to the depletion oil recovery in the fractured horizontal wells. There is optimized half fracture length. It is recommended that the low-permeability reservoir with large threshold pressure gradient under depletion development should be developed with hydraulic fracturing.
引文
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[12]时佃海.低渗透砂岩油藏平面径向渗流流态分布[J].石油勘探与开发,2006,33(4):491-494.Shi Dianhai.Flow state distribution of areal radial flow in low permeability sandstone reservoir[J].Petroleum Exploration and Development,2006,33(4):491-494.
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[14]姜瑞忠,张晓亮.低渗透油藏弹性采收率计算方法研究[J].特种油气藏,2008,15(4):70-72.Jiang Ruizhong,Zhang Xiaoliang.Calculation method of natural depletion oil recovery of low-permeability reservoirs[J].Special Oil&Gas Reservoirs,2008,15(4):70-72.
[15]陈明强,张明禄,蒲春生,等.变形介质低渗透油藏水平井产能特征[J].石油学报,2007,28(1):107-110.Chen Mingqiang,Zhang Minglu,Pu Chunsheng,et al.Productivity of horizontal well in deformation medium of low-permeability reservoirs[J].Acta Petrolei Sinica,2007,28(1):107-110.
[16]张学文,方宏长,裘怿楠,等.低渗透率油藏压裂水平井产能影响因素[J].石油学报,1999,20(4):51-55.Zhang Xuewen,Fang Hongchang,Qiu Yinan,et al.A study on factors affecting the performance of hydraulically fractured horizontal well in low permeability reservoirs[J].Acta Petrolei Sinica,1999,20(4):51-55.
[17]郝明强,胡永乐,李凡华.特低渗透油藏压裂水平井产量递减规律[J].石油学报,2012,33(2):269-273.Hao Mingqiang,Hu Yongle,Li Fanhua.Production decline laws of fractured horizontal wells in ultra-low permeability reservoirs[J].Acta Petrolei Sinica,2012,33(2):269-273.
[2]张江华,刘传虎,朱桂林,等.莫西庄油田低渗透储层特征与成因[J].特种油气藏,2014,21(3):58-61.Zhang Jianghua,Liu Chuanhu,Zhu Guilin,et al.Characteristics and genesis of low permeability reservoirs in the Moxizhuang oilfield[J].Special Oil&Gas Reservoirs,2014,21(3):58-61.
[3]曲占庆,何利敏,窦小康,等.低渗透油藏水平井流入动态分析及举升方式优选[J].油气地质与采收率,2013,20(6):54-60.Qu Zhanqing,He Limin,Dou Xiaokang,et al.Inflow performance analysis and optimization of artificial lifting for horizontal wells in low permeability reservoir[J].Petroleum Geology and Recovery Efficiency,2013,20(6):54-60.
[4]王锋,刘慧卿,吕广忠.低渗透油藏长缝压裂直井稳态产能预测模型[J].油气地质与采收率,2014,21(1):84-86,91.Wang Feng,Liu Huiqing,LüGuangzhong.Steady-state productivity prediction model for long-length fractured vertical well in low permeability oil reservoirs[J].Petroleum Geology and Recovery Efficiency,2014,21(1):84-86,91.
[5]徐亮.低渗透油藏差异开发技术研究与实践——以济阳坳陷博兴洼陷为例[J].油气地质与采收率,2014,21(4):107-110.Xu Liang.Research and practice of differencial development technologies in low permeability oil reservoirs:case study of Boxing sag,Jiyang depression[J].Petroleum Geology and Recovery Efficiency,2014,21(4):107-110.
[6]许建红,程林松,周颖,等.一种求解低渗透油藏启动压力梯度的新方法[J].石油勘探与开发,2007,34(5):594-597.Xu Jianhong,Cheng Linsong,Zhou Ying,et al.A new method for calculating kickoff pressure gradient in low permeability reservoirs[J].Petroleum Exploration and Development,2007,34(5):594-597.
[7]熊伟,雷群,刘先贵,等.低渗透油藏拟启动压力梯度[J].石油勘探与开发,2009,36(2):232-235.Xiong Wei,Lei Qun,Liu Xiangui,et al.Pseudo threshold pressure gradient to flow for low permeability reservoirs[J].Petroleum Exploration and Development,2009,36(2):232-235.
[8]赵益忠,程远方,刘钰川,等.启动压力梯度对低渗透油藏微观渗流及开发动态的影响[J].油气地质与采收率,2013,20(1):67-69,73.Zhao Yizhong,Cheng Yuanfang,Liu Yuchuan,et al.Study on influence of start-up pressure gradient to micro-seepage in low permeability reservoirs and development trends[J].Petroleum Geology and Recovery Efficiency,2013,20(1):67-69,73.
[9]田冷,顾永华,何顺利.低渗透油藏非线性渗流产能计算模型及参数敏感性分析[J].水动力学研究与进展A辑,2011,26(1):108-115.Tian Leng,Gu Yonghua,He Shunli.Study on the nonlinear radial stable flow model in the low permeable reservoir[J].Chinese Journal of Hydrodynamics,2011,26(1):108-115.
[10]姜瑞忠,杨仁锋,马勇新,等.低渗透油藏非线性渗流理论及数值模拟方法[J].水动力学研究与进展A辑,2011,26(4):445-452.Jiang Ruizhong,Yang Renfeng,Ma Yongxin,et al.Nonlinear percolation theory and numerical simulation in low permeability reservoirs[J].Chinese Journal of Hydrodynamics,2011,26(4):445-452.
[11]王晓冬,郝明强,韩永新.启动压力梯度的含义与应用[J].石油学报,2013,34(1):188-191.Wang Xiaodong,Hao Mingqiang,Han Yongxin.Implication of the threshold pressure gradient and its application[J].Acta Petrolei Sinica,2013,34(1):188-191.
[12]时佃海.低渗透砂岩油藏平面径向渗流流态分布[J].石油勘探与开发,2006,33(4):491-494.Shi Dianhai.Flow state distribution of areal radial flow in low permeability sandstone reservoir[J].Petroleum Exploration and Development,2006,33(4):491-494.
[13]陈光梅,车雄伟.弹性驱低渗透油气藏的分区物质平衡方法[J].新疆石油地质,2011,32(2):157-159.Chen Guangmei,Che Xiongwei.Domain material balance method for low permeability gas-oil reservoir by depletion drive process[J].Xinjiang Petroleum Geology,2011,32(2):157-159.
[14]姜瑞忠,张晓亮.低渗透油藏弹性采收率计算方法研究[J].特种油气藏,2008,15(4):70-72.Jiang Ruizhong,Zhang Xiaoliang.Calculation method of natural depletion oil recovery of low-permeability reservoirs[J].Special Oil&Gas Reservoirs,2008,15(4):70-72.
[15]陈明强,张明禄,蒲春生,等.变形介质低渗透油藏水平井产能特征[J].石油学报,2007,28(1):107-110.Chen Mingqiang,Zhang Minglu,Pu Chunsheng,et al.Productivity of horizontal well in deformation medium of low-permeability reservoirs[J].Acta Petrolei Sinica,2007,28(1):107-110.
[16]张学文,方宏长,裘怿楠,等.低渗透率油藏压裂水平井产能影响因素[J].石油学报,1999,20(4):51-55.Zhang Xuewen,Fang Hongchang,Qiu Yinan,et al.A study on factors affecting the performance of hydraulically fractured horizontal well in low permeability reservoirs[J].Acta Petrolei Sinica,1999,20(4):51-55.
[17]郝明强,胡永乐,李凡华.特低渗透油藏压裂水平井产量递减规律[J].石油学报,2012,33(2):269-273.Hao Mingqiang,Hu Yongle,Li Fanhua.Production decline laws of fractured horizontal wells in ultra-low permeability reservoirs[J].Acta Petrolei Sinica,2012,33(2):269-273.