薄差层水力压裂控缝高技术研究

Research on fracture height containment in thin and poor pay zones

对于低渗透薄差层的开发,水力压裂是非常有效的增产措施,而薄差层改造的最大技术难题是缝高的控制.本文归纳了影响缝高扩展的主要因素,针对这些因素,结合冀东油田的地质参数和施工参数设计了五水平七因素的正交方案,并利用FracproPT软件模拟了不同参数下裂缝的扩展情况,对影响缝高的各因素进行了敏感性分析和单因素分析.分析结果表明:影响缝高的各因素依次为隔/产层地应力差、施工规模、施工排量、压裂液粘度、隔/产层杨氏模量差、地层渗透率、断裂韧性差;隔/产层地应力差越大越有利于控制缝高,减小施工排量和压裂液粘度能减小缝内净压力而有利于控制缝高;油田实例表明,综合人工隔层、变排量和使用较小粘度压裂液能有效控制缝高.本研究对于薄差层的水力压裂优化设计和现场施工具有一定的指导作用.

For the development of thin and poor reservoir,hydraulic fracturing is an extremely effective measure to enhance production,but it is the key problem to get the fracture height under control when stimulating these types of pay zones.The paper firstly summarized the factors affecting fracture height,then an orthogonal design including seven factors of five levels was made according to the reservoir parameters and construction parameters of Jidong Oil-Field,and the fracture propagation under each situation was simulated with FracproPT.On the basis of the results,further sensitivity analysis and single factor analysis were conducted.The results turn out that factors impacting fracture height are sequentially：in-situ stress contrast between barrier layer and target layer,total amount of fracture fluid,pumping rate,fracture fluid viscosity,Young modulus contrast,reservoir permeability and fracture toughness contrast.The larger the stress difference between the barrier and target layer,the easier to control the fracture height;the smaller the pumping rate and fluid viscosity,the lower the net pressure in the fracture,and more benefit to limit height growth.Field case certified that using varies method of artificial barrier,changing pumping rate and low viscosity fluid can arrest the fracture height.The research can help to optimize the hydraulic fracturing design and guide the on-site treatment.