关键词: 低渗, 疏松砂岩气藏, 低效井, 伤害机理, PRD 钻井液, 水锁, 有机固相堵塞

Abstract:

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 completion，
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 mechanisms
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.

Key words: low permeability, loose sandstone gas reservoir, low efficiency wells, PRD drilling fluid, water blocking, organic
solid plugging