致密火山岩气藏水相和油相圈闭损害实验评价——以南堡凹陷5号构造沙河街组为例

致密火山岩气藏通常与致密砂岩气藏呈互层分布，尽管储层岩石物性与致密砂岩气藏类似，但致密火山岩气藏水相圈闭和油相圈闭损害却未能引起关注。为了揭示致密火山岩气藏水相和油相圈闭损害潜力，选取南堡凹陷沙河街组致密火山岩气藏储层岩心，开展了水相和油相毛管自吸与液相返排实验评价，并与沙河街组致密砂岩气藏液相圈闭损害进行对比。结果表明：①致密火山岩气藏储层岩石水相和油相毛管自吸能力弱于致密砂岩，致密砂岩既亲水又亲油，致密火山岩亲油性更强；②沙河街组致密火山岩气藏液相圈闭损害呈现“三低”特点，即毛管自吸进液量低、液相返排率低和渗透率损害率低；③沙河街组致密火山岩气藏水相圈闭损害比油相圈闭损害更严重。孔喉呈多峰分布、裂缝发育、存在大量溶蚀孔等孔喉结构差异是造成致密火山岩气藏水相和油相圈闭损害显著区别于致密砂岩气藏的重要原因。致密火山岩气藏钻井过程中，需控制裂缝性漏失，避免水基或油基工作液滤液进入裂缝侧面储层深处；控制压裂等增产改造措施规模，以防沟通底水诱发水相圈闭损害；在开发生产过程中要制定合理工作制度，预防凝析油析出引起的油相圈闭损害。

Experimental evaluation of liquid phase trapping damage on tight volcanic gas reservoirs:Case study of Shahejie Formation in 5th structure,Nanpu Depression,Bohai Bay Basin

Tight volcanic rock gas reservoirs and tight sandstone gas reservoirs distribute alternately.Although the reservoir physical properties are similar to tight sandstone gas reservoirs,there is little research on the water and oil phase trapping damage in tight volcanic rock gas reservoirs.In order to investigate the damage degree of liquid phase trapping on natural gas reservoirs in Shahejie Formation,the liquid phase trapping damage experiment was carried out.The results showed that tight sandstones had a stronger liquid capillary imbibition behavior than tight volcanic rocks and caused more severe liquid phase trapping damage.Low liquid capillary imbibition,low liquid flowback rate and low permeability damage rate were the remarkable characteristics of tight volcanic rock gas reservoirs.The permeability damage rate caused by water phase trapping was higher than oil.According to the features of liquid phase trapping damage on gas reservoirs in Shahejie Formation,the operating time and operating pressure must be managed strictly to prevent liquid phase trapping damage on sandstone gas reservoirs,and reasonable application on working fluid of volcanic rock gas reservoirs will be considered.Beyond that,the gas production rate should be controlled to prevent oil phase trapping damage happening early.