泥饼承压及抗冲刷能力是压力衰竭储层砾石充填作业成功的关键因素.南海西部A气田压力衰竭储层长水平井砾石充填具有充填窗口小、充填压差高、充填时间长等特点.前期使用的无固相钻井液(PRD)形成的泥饼承压能力低,无法满足长时间砾石充填冲刷.针对PRD钻井液泥饼面临的问题,室内对PRD钻井液进行了改良,增强了泥饼承压能力,并对改良型PRD钻井液防漏能力、泥饼抗砾石充填液冲刷能力及泥饼破胶后储层保护能力进行研究.实验结果表明改良型PRD钻井液具有较强的堵漏性能;充填速度、砂比对泥饼影响较小;充填压差对泥饼影响较大;泥饼容易破胶,不会对储层油气通道造成堵塞,储层保护效果好.现场使用改良型PRD钻井液,A气田三口长水平井砾石充填作业均顺利完成,无漏失发生,三口井测试产量整体超配产要求.%The pressure bearing capacity and scour resistance of mud cake is key successful factor of ravel pack operations in depleted reservoir.Horizontal wells of A Gas Field with highly depleted reservoir in Western South China Sea has small window,high packing pressure difference and long packing time for gravel pack operation.The pressure bearing capacity of mud cake that solid-free drilling fluid (PRD) formed is low,and it cannot satisfy gravel pack fluid scouring for a long time.For problems faced by PRD drilling fluid filter cake,PRD drilling is improved and its mud cake bearing capacity is enhanced.Lost circulation prevention ability of improved PRD drilling fluid,mud cake scour resistance and comprehensive reservoir protection after the mud cake gel breaking are studied.Test results show that improved PRD drilling fluid has strong ability of plugging,and improved PRD drilling fluid mud cake can meet the gravel pack operation requirements.Packing velocity and gravel pack sand ratio is less effect on mud cake washing.However effect of gravel pack liquid packing pressure differential on mud cake erosion is larger.Mud cake is easy to break,not affecting the channel plugging of oil and gas reservoir,and reservoir protection effect is good.Gravel pack operations of three long horizontal wells are completed successfully with using improved PRD drilling fluid in the flied,and no lost circulation occurring.The test production of three wells overall is far more than reservoir proration.
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