渝东南地区茅口组气藏大石1HF井酸压工艺技术研究

Acid fracturing technology of Maokou Formation in well-Dashi-1HF,southeastern Chongqing

渝东南地区在深层气藏,特别是深层页岩气勘探开发方面取得了重大的进展,但在浅层气勘探方面一直无较大进展,特别是浅层的茅口组气藏,为裂缝—基质型灰岩气藏,其储层孔隙度、渗透率、储层温度、压力系数均较低,裂缝发育一般,酸压过程中,酸液破胶困难、返排难、效果差,难以实现突破。以大石1HF井茅口组碳酸盐储层为例,分析其改造过程中的难点,合成了清洁胶凝酸稠化剂,并阐述了其自破胶的降解机理,优化了酸液体系配方,优选水平井分段酸压管柱,形成了清洁胶凝酸和多级封隔器的酸压工艺体系,同时优化了茅口组分段酸压工艺参数。大石1HF井累计完成4段酸压,酸液总用量为2 129.2 m3,压后测试工业气流产量为22.6×104m3/d。结果表明:渝东南浅层灰岩气藏采用清洁胶凝酸和水平井分段酸压工艺技术具有较好的效果,为今后类似层位的酸压改造提供了借鉴。

Significant advances has been made in the exploration and development of deep gas reservoirs in the southeastern Chongqing,especially the deep shale gas.While the shallow gas exploration is on the contrary,especially the shallow fracturematrix limestone gas reservoir,Maokou Formation,with low porosity,low permeability,low fracture development,low reservoir temperature,low pressure coefficient,and mediocre fracture development.During the acid fracturing process,as the gel is hard to break by acid and the flow back is difficult,then the effect is poor,and it is difficult to make breakthrough.Taking the characteristics of carbonate reservoir,Maokou Formation in well-Dashi-1HF,as the example,the difficulties in reservoir acid fracturing have been analyzed,the self-degradation gelling acid has been synthesized,the mechanism of degradation has been introduced,and the optimization of the acid-liquid system has been carried out.The horizontal well acid fracturing pipe string has been optimized to form acid fracturing technology of self-degradation gelling acid and multilevel packer,at the same time,the segmented acid fracturing parameters have been optimized.4 stages acid fracturing of well-Dashi-1HF has been completed,and the total acid dosage is 2129.2 m3.The test gas production after acid fracturing is 22.6×104 m3/d.The results show that this new technology has a good effect in the shallow limestone of southeastern Chongqing,and provides useful reference for the acid fracturing of similar layers in the future.