During west testing,there exists large difference in single-well productivity and poor effect in stable production for gas reservoirs of the fifth member of Xujiahe Formation(Xujiahe 5 Member)in Dongfengchang area.So,the main con-trols on the productivity and reasons on production decline were discussed in the light of geological,dynamic monitoring and experimental data.And some countermeasures were made for stabilizing production.Results show that(i)the productiv-ity is principally affected by both types of gas wells and extensional degree of quality reservoirs.The productivity in hori-zontal wells is significantly higher than that in vertical ones.The more developed the quality reservoirs,the higher the pro-ductivity;(ii)for these wells,the stabilizing effect is poor with the average stable period of 10 months,and the production decline index of 0.0017 per day on average,creating low effective permeability and finite gas supply;(iii)induced from big production pressure difference caused by high proration in the early days of development,the reservoirs feature strong stress sensitivity.Moreover,small dew-point pressure difference results that condensate oil is easy to be precipitated to cause anti condensation damage,to bringing about permeability loss,and finally the rapid productivity decline;(iv)fractur-ing sand's backflow results in the decrease of the conductivity in induced fractures and these fractures accumulated near wellbore area.And it's hard for fracturing liquid to flow back,resulting in liquid accumulation or even water flooding and well shutdown;and(v)the managed-pressure production can effectively reduce the permeability loss.And liquid nitro-gen cleanup and production-string optimization are conducive to liquid drainage.As a result,the productivity decline may be put off.All results may provide important reference on technical measures made for the development of tight sandstone gas reservoirs in similar areas.
关键词
四川盆地/东峰场地区/上三叠统须家河组五段气藏/产能变化/递减因素/稳产对策
Key words
Sichuan Basin/Dongfengchang area/Upper Triassic Xujiahe 5 gas reservoirs/Productivity change/Decline fac-tor/Countermeasures for stabilize production
维普
万方数据