中文摘要：

低渗疏松砂岩气藏不仅具有常规低渗气层孔喉细小、敏感性矿物含量高、毛细管压力大的特点，同时储层胶结疏松，在钻完井、开发过程中易受到损害。以南海DF11气田低渗疏松砂岩气藏为研究对象，针对气藏自身特点并结合现场施工工艺，改进了石油天然气行业标准对工作液伤害的评价方法，并系统评价了气藏的伤害机理。研究结果表明：PRD钻完井液体系对气层主要损害机理为有机固相堵塞和水锁；生产过程中微粒运移伤害程度弱。改进后方法的评价结果更加符合现场生产实际。建议在后期开发井钻完井设计中优化PRD钻井液体系配方，加入5%粗粒刚性封堵颗粒，有效降低有机固相、液相侵入程度；增加完井液中破胶剂用量至6%，提高破胶效率。

英文摘要：

Low permeability loose sandstone gas reservoir is characteristic of such as small pore throat size,high sensitive mineral content,high capillary pressure,loose reservoir cementing at the same time. In the process of drilling and comple-tion,the formation damage is easy to occur. In this paper,taking the second sequence of Yinggehai formation which is low permeability loose sandstone gas reservoir of DF1 1 gas field in the south China sea as the research object,according to the characteristics of gas reservoir and combining the field construction technological process,we improved the working fluids damage evaluating methods of the oil and nature gas industrial standard,and systematically evaluated the main damage mech-anisms of low permeability loose sandstone gas reservoir. The research results indicate that during drilling and completion, the organic solid plugging and water blocking are the main damage mechanisms of the PRD drilling and completion fluids;the damage degree of fine particles migration during production is weak. The results gotten from the improved evaluating methods conform to the field practice better. 5 percent of big size rigid plugging particle is suggested to mix into the PRD drilling fluid, to reduce the invasion degree into gas reservoir of the organic solid phase,and liquid phase. Adding 6%of gel breaker amount in the completion fluid,the efficiency of gel breaking will be improved.