高压致密气藏压裂技术研究与应用

Study on Technique of Fracturing and Its Application in High Pressure and Tight Gas Reservoir

巴喀油田柯柯亚区块气藏埋深3100～3900m,为特低孔、特低渗储层。该区块储层常规试油资料表明,储层钻井污染较重。常规试油求产天然气产量均较低,通过酸化解堵后产气量也达不到工业油气流标准,必须进行压裂改造。由于气藏地层属高温高压地层,进行水力压裂很容易发生砂堵,极大限制了气藏的有效开发。针对吐哈油田深层致密气藏储层增产改造的技术难点,开展了醇酸酸化处理技术、低浓度陶粒段塞技术、不同粒径陶粒组合技术、分层压裂改造技术、施工排量优化技术、裂缝缝长优化技术、高温延迟压裂液体系、快速返排技术并进行了现场试验,成功实施6口井,取得了较好的应用效果,为深层高压致密气藏的压裂改造提供了技术思路。

Kekeya Block of Baka Gas Reservoir was characterized by extra-low porosity and low permeability,its depth was from 3100 to 3900m,rock porosity was 1.9%~8.4%( 4.09% in average) and permeability was (0.05~10.0)×10-3μm2 (0.23×10-3μm2 in average).It was a reservoir with extra-low porosity and permeability reservoir The conventional testing data showed that the reservoir was polluted seriously by the drilling fluid,gas production was generally low,between 0.1×104m3/d and 1×104m3/d,after acidizing the production was (0.3~3)×104m3/d. The production could not meet the industry standard,therefore it should be fractured and reconstructed. As the gas reservoir had a temperature of 88.4~102℃,pressure coefficient was 0.98~1.17,it belonged to high temperature and pressure reservoir. It was easy to be sand blocked when hydraulic fracturing was deployed,which would greatly limit the effective development of gas reservoirs.In allusion to the the alkyd acid process,low concentration of ceramic slug technology,different size ceramic combinatorial technology,the hierarchical fracturing technology,construction emissions optimization techniques,optimization of fracture lengths,high temperature delaying fracturing fluid system and fast flowing back technology are used. These measures are successfully applied in six wells,and good application effect is obtained,it provides technical ideas for stimulation in the deep high-pressure and tight gas reservoirs.