朱寨子油区低压低渗储层钻井液保护技术研究

朱寨子油区的油气藏具有压力系数低、物性差、渗流能力低、孔喉微细、比表面积大和泥质含量高等特点,容易受到固相、液相、聚合物吸附、矿物敏感等伤害。分析了朱寨子油区储层伤害机理,提出了朱寨子油区储层钻井液保护技术,在钻井液中加入一定量的聚合物抑制剂和无机盐抑制剂,可有效防止储层中的敏感矿物因滤液入侵而引起的敏感性伤害;经粒径优化的架桥粒子和可软化变形的ST-3按一定比例复配而成的复合暂堵剂,可以形成致密的泥饼以减少钻井液的侵入量和侵入深度;由两种表面活性剂复配组成的HFR可有效降低油/水界面张力而显著降低储层水锁损害的程度。有助于将侵入储层的液相返排出来,提高油相饱和度和渗透率,改善储层的渗流能力,最终提出两套钻井液保护技术。

Protection Technology of Zhu-Zhaizi Oilfield Drilling Fluid Reservoir with Low Pressure and Low Permeability

The Zhu-Zhaizi oilfield reservoir has the characteristics of low pressure coefficient,poor physical property,low permeability,micro-pore and micro-throat,large specific surface and high sand concentration.It is easily damaged by the solid phase matter,liquid phase matter,polymer adsorption and sensitive mineral content.On the base of analyses about Zhu-Zhaizi oilfield formation damage mechanism,this paper introduces a method of drilling fluid reservoir protection technology.That is filtrate invasion sensitive damage can be slightly inhibited caused by sensitive mineral content through adding some polymer inhibition and inorganic salts inhibition into drilling fluid.The temporary plugging agent is made by size optimized bridging particle and soften deformable ST-3 ,and it can reduce the amount of drilling fluid intrusion and invasion depth by forming a dense cake.HFR which is compounded by two kinds of surfactants can efficiently reduce oil-water interfacial tension and significantly reduce the damage degree of water block.It also can help to flow back the filtrate invasion liquid phrase,enhance the oil saturation and relative permeability,and improve the formation permeability.So,two methods of drilling fluid reservoir formation technologies are finally given.