页岩气网络压裂设计方法研究

Study on Network Fracturing Design Method in Shale Gas

页岩气能否有效产出,很大程度上取决于压裂裂缝和压裂过程中诱导天然裂缝开启而形成的相互交错的网络裂缝面积大小,其与页岩气井生产指数具有一定的相关性,因此,页岩气压裂设计的根本出发点在于如何形成有效的网络裂缝。在借鉴国外海相页岩气压裂成功经验的基础上,针对国内陆相页岩气的特殊性,进行了网络压裂的探索性研究。确立了页岩气网络压裂设计原则及相关理论基础,阐述了网络压裂设计的基本思路及优化方法,包括射孔方案、小型测试方案、压裂材料优选、施工参数及压后返排参数优化等,并围绕页岩气网络裂缝的主控因素(页岩可压性、诱导应力场、主裂缝净压力优化及控制等)进行了系统的模拟分析。基于所提出的优化设计方法,对河南油田某页岩气井实施了小型测试压裂和主压裂施工,获得成功并取得了很好的效果。

Shale gas recovery mainly depends on fracture network created by hydraulic and induced fractures during hydraulic fracturing. The fracture network is correlated with shale gas productivity index. Therefore the fundamental starting point of shale gas fracturing design is how to create effective fracture network. Based foreign successful experiences in marine shale gas fracturing,exploratory study on network fracturing were conducted according to the specialty of domestic terrestrial shale gas. The design principles and related theory were established. This paper described basic idea of fracture network design and optimization method, including perforation scheme, minifrac tests, fracturing materials selection, fracturing and flowback parameters etc. The factors influencing fracture network were analyzed systematically,including shale frac-ability, induced stress field, main fracture net pressure optimization and controlling. The proposed design method was applied in a well for mini-frae treatment and major fracturing treatment in Henan Oilfield. Good results were achieved. The fracturing success in this well provides reference and guidance for future shale gas fracturing design.