杭锦旗区块致密气藏混合水体积压裂技术

Volumetric Fracturing with Mixed Water in Tight Gas Reservoirs in the Hangjinqi Block

鄂尔多斯盆地杭锦旗区块存在致密气藏储层物性较差、单一裂缝无法有效扩大储层改造体积和压裂后初期产量低等问题,为解决这些问题,结合杭锦旗区块下石盒子组储层地质特征,按照'体积压裂'理念,分析了影响混合水体积压裂工艺效果的关键因素,优选了压裂液体系,并进行了施工排量及施工规模优化,形成了适用于杭锦旗区块致密气藏的混合水体积压裂技术.该技术采用滑溜水、线性胶和交联液等不同类型的液体进行交替压裂施工,在开启储层天然裂缝的同时形成了高导流主缝及复杂支缝,实现对储层的立体改造.该技术在杭锦旗区块现场应用了5口井,压裂后平均无阻流量为13.2×104 m3/d,增产效果明显.研究结果表明,致密气藏混合水体积压裂技术解决了杭锦旗区块单一裂缝无法扩大储层改造体积和压裂后产量低的问题,具有较好的推广应用价值.

The goal of the study was to develop best practices for hydraulic fracturing in the complicated mixed water conditions in the tight gas reservoirs of the Hangjinqi Block.The study was necessary due to challenges such as poor physical properties,limited fracture length to cover reservoir stimulation volume,and low initial post-frac production in the tight gas reservoirs of Hangjinqi Block in the Ordos Basin.In viewing of those challenges and combining with reservoir geological characteristics of the lower Shihezi Formation within the block,key factors affecting volumetric fracturing with mixed water were analyzed,fracturing fluid system selected,and the optimization on the pumping flow rate and operation scale carried out to establish volumetric fracturing technology suitable for the tight gas reservoirs in Hangjinqi Block.In this technology,different types of fluids such as slick water,linear gel and cross-linker for the alternative fracturing are adopted,and forms high-conductive main fractures and complex branched fractures while opening the natural fractures in the reservoir to realize 3D stimulation.This technology has been applied in 5 wells in the block with average open flow capacity 13.2×104m3/d.The research showed that this technology can help in solving the problems of non-sufficient reservoir stimulation volume from limited single fracture length and low post-fracturing production,and it demonstrates a good potential for further development of standard application practices.