葡北油田注水压力对套管损坏影响研究
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摘要
在进行了室内模拟实验,建立岩体失稳模型,对注水压力统计分析,以及对葡北油田原始地应力计算、岩石力学参数实验等综合分析基础上,计算得出葡北油田防止套管损坏注水压力。分析计算结果表明,葡北油田套管损坏的主要原因是不同岩性岩石的层间滑动。注水压力是使层间滑动的动力,注水地层以上泥岩层的水化是诱发地层层间滑动的重要原因。随着注水压力的增加,层间的滑移量随即增加,在某个注水压力值后,滑移量呈线性增加。滑移层不发生在注水层,而是发生在注水层以上的泥岩层。建议采取控制泥岩层浸水和水化措施来预防套损,断层附近应尽可能减小注水,防止断层浸水和断层滑动。对于注水压力较高的区域,建议将注水压力降低到临界压力以下;在未水化地层,地层压力控制在24MPa以下;已发生水化地层,地层压力应控制在22MPa以下。
Instability model of rock body is established and water injection pressure is analyzed through statistic data in a laboratory simulating experiment.Based on comprehensive analysis on original earth stress calculation and lithomechanics parameter experiment in Pubei oilfield,the water injection pressure for preventing casing failure is obtained in Pubei oilfield.Analysis results show that the main reason of casing damage in Pubei oilfield is the interlayer slipping between lays with different lithologic characters.Water injection pressure is the driving force that leads to interlayer slipping.The hydration of mudstone layer above water injection formation is the significant reason that induces interlayer slipping.Along with the increase of the water injection pressure,interlay slippage is increasing.The slippage linearly increases from certain water injection pressure.Slipping occurs in the mudstone layer not in the water injection formation.It is suggested that the retting and hydration of the mudstone layer should be controlled to prevent casing damage,and water injection near fault should be less as far as possible to prevent retting and slipping of the fault.The water injection pressure should be dropped below critical pressure in the area with high water injection pressure.Formation pressure should be controlled below 24MPa in the non hydrating formations;and the formation pressure should be controlled below 22MPa in the hydrated formations.
Instability model of rock body is established and water injection pressure is analyzed through statistic data in a laboratory simulating experiment.Based on comprehensive analysis on original earth stress calculation and lithomechanics parameter experiment in Pubei oilfield,the water injection pressure for preventing casing failure is obtained in Pubei oilfield.Analysis results show that the main reason of casing damage in Pubei oilfield is the interlayer slipping between lays with different lithologic characters.Water injection pressure is the driving force that leads to interlayer slipping.The hydration of mudstone layer above water injection formation is the significant reason that induces interlayer slipping.Along with the increase of the water injection pressure,interlay slippage is increasing.The slippage linearly increases from certain water injection pressure.Slipping occurs in the mudstone layer not in the water injection formation.It is suggested that the retting and hydration of the mudstone layer should be controlled to prevent casing damage,and water injection near fault should be less as far as possible to prevent retting and slipping of the fault.The water injection pressure should be dropped below critical pressure in the area with high water injection pressure.Formation pressure should be controlled below 24MPa in the non hydrating formations;and the formation pressure should be controlled below 22MPa in the hydrated formations.
引文
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[2]刁顺,杨春和,刘建军,等.渗流诱发套损机制与数值计算[J].岩土力学,2008,29(2):327-332.
[3]王立军,吕波,吴锋,等.注水井地层破裂压力预测方法及应用[J].大庆石油学院学报,2006,30(4):16-21.
[4]周延军,贾江鸿,李荣华.基于粗糙集理论和支持向量机的套管损坏动态预报方法[J].中国石油大学学报:自然科学版,2010,34(6):71-75.
[5]田杰,刘先贵,尚根华.基于流固耦合理论的套损力学机理分析[J].水动力学研究与进展:A辑,2005,20(2):221-225.
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