川西地区低渗透气藏水平井完井优化设计技术

水平井完井技术对低渗透致密气藏产能发挥和开采动态的影响很大。通过完井方案优化,可以提高水平井完善程度、延缓边底水锥进、提高开发效果。针对川西地区低渗透致密气藏自然产能低、气水关系复杂、裂缝非均质性强、储层改造难度大等问题,在水平井渗流机理分析、井壁稳定性预测、产能评价等研究的基础上,结合现场试验,对气藏完井方案进行了优化并对施工关键技术进行了深入研究和总结。现场实践表明:①中浅层裂缝不发育的储层,采用衬管完井或者射孔完井,结合压裂改造能获得较好的开采效果;②中深层裂缝孔隙型储层,采用衬管完井结合酸化解堵,能最大限度地发挥裂缝对产能的贡献,川西地区中深层首口水平井新21-1H井衬管完井获得无阻流量203.415×104m3。

An optimal design of horizontal well completion in low-permeability gas reservoirs of west Sichuan Basin

The technology of horizontal well completion plays an important role in improving the productivity and controlling the dynamic recovery of low permeability tight gas reservoirs. An optimal design of horizontal well completion can help enhance the degree of well completion, delay the edge and bottom water coning, thus, achieving good results of exploitation. Based on the analysis of percolation mechanism, forecast of borehole stability, and productivity assessment, a systematic study was made on the optimal design of well completion from two aspects of modes and parameters. Thus, a series of technology was formed on the optimal design of horizontal well completion in low permeability tight gas reservoirs of the western Sichuan Basin, which are characterized by low natural production capacity, complicated gas/water relationship, strong heterogeneity of fractures, and great difficulty in reservoir reconstruction. Then through analysis of the key techniques adopted in this optimal design, we concluded from the field practice that ①as for the medium and shallow reservoirs with undeveloped fractures, favorable gas deliverability could be achieved by liner or perforation completion in combination with fracturing treatment, and ②as for deep fracture pore type reservoirs, liner completion with acidizing plugging removal could help tap the potential of fractures in making contribution to gas productivity. The well Xin21-1H, the first horizontal well in deep reservoirs of the western Sichuan Basin, obtained the open flow capacity of 203.415×104m3 after liner completion.