CO2准干法压裂技术研究及应用

致密砂岩气藏普遍具有储层物性差、孔喉细、黏土矿物含量高的特征,水力压裂易导致储层产生水敏、水锁等液相伤害,影响增产效果。针对此问题,研究了CO₂准干法压裂技术,重点开展了准干法压裂工作液组成、携砂性能、耐温耐剪切性能等方面的研究,形成了一种液态CO₂中含有少量水基压裂液的均匀混合相体系,具有液相伤害小、造缝携砂性能好、现场操作性强等特点,可满足大砂量、高砂比压裂施工要求。该技术在冀东油田南堡5号构造深层致密砂岩气藏进行先导试验,压后单井日增油2.5倍,日增气8.6倍,增产效果理想。 

Research and application of quasi-dry CO2 fracturing technology

Tight sandstone gas reservoirs are generally characterized by poor reservoir physical properties, fine pore and throat volume, and high clay content. Conventional hydraulic fracturing may cause water-sensitive, water-lock and other liquid phase damage in tight sandstone reservoirs, which affects the stimulation effect. To solve this problem, research on quasi-dry CO₂ fracturing technology was carried out. The composition and sand-carrying capacity of quasi-dry CO₂ fracturing fluid were studied, temperature and shear resistance were tested. A highly viscous mixture system of emulsion was formed which contains liquid CO₂ and a small amount of water-based fracturing fluid. It has less formation damage, excellent fracture making ability and sand carrying capacity, strong field operability, which can meet the fracturing construction requirements of large scale sand addition and high sand concentration. Pilot test was conducted in a deep tight sandstone gas reservoir of Nanpu No.5 structure in Jidong oilfield. After fracturing, the pilot well achieved excellent stimulation effect with the daily oil and gas production increased 2.5 times and 8.6 times respectively.