Abstract:

During the fracturing of oil and gas reservoirs with low porosity,low and ultra-low permeability,it is very difficult to get an expected post-fracturing performance because of low seepage capacity of oil and gas flowing from reservoir matrix to the hydraulic fracture,though the fracture is longer enough and conductivity is high enough under the condition of single fracture.Therefore,a new concept of "fracture network" fracturing technique was put forward for the reservoirs with low porosity,low permeability and without natural fractures in this paper.The adaptable conditions,technical guidelines and applicable method of this technique were discussed.The relationship between the difference of two horizontal stresses and the net pressure for fracture extension was applied to ensure creation of multiple fractures far from well-bore region(including near well-bore region)and enhance the seepage flowing capacity from reservoir matrix to the hydraulic fractures and further to improve post-fracturing performance.The other new methods including multiple transverse fractures in horizontal wells and "liquid explosion within the formation" techniques were studied in details.The "fracture network" fracturing technique enlarges the technical connotation of hydraulic fracturing and provides a good reference in theory and field application.

Key words: low and ultra-low permeability reservoir, sandstone hydrocarbon reservoir, reservoir reconstruction, hydraulic fracturing, "fracture network", fracturing technique

摘要：

在对低孔隙度、低渗透-特低渗透砂岩油气藏压裂中,由于储层基质向裂缝的供油气能力较差,仅靠单一的压裂主缝(不管缝有多长、导流能力有多高)很难取得预期的增产效果。因此,提出了适合低孔隙度、低渗透、不含天然裂缝储层的"缝网压裂"技术。其核心思想是利用储层两个水平主应力差值与裂缝延伸净压力的关系,实现远井地带(而不仅仅局限于近井筒区域)的"缝网"效果,增加储层基质向人工裂缝供油气能力,提高压裂增产改造效果。论述了"缝网压裂"技术的适用条件、工艺设计思路及应用方法。在此基础上,对"缝网压裂"的实现途径进行了探索,包括水平井及应用"层内液体爆炸"技术等。缝网压裂技术对理论和现场施工有重要的参考价值。

关键词: 低渗透-特低渗透油藏, 砂岩油气藏, 油气藏改造, 水力压裂, 缝网压裂技术