低渗气藏储层孔隙中水的赋存模式及对气藏开发的影响

Experimental Study on Occurrence Models of Water in Pores and the Influencing to the Development of Tight Gas Reservoir

水在低渗气藏储层孔隙中普遍存在,影响储层供气能力。根据储层孔隙结构形态建立孔隙结构模型,研究了水在不同孔隙类型中的赋存模式及影响气相渗流的机理,在此基础上,采用仿真物理模拟实验技术,研究气藏发生水侵的条件及其对低渗储层供气能力的影响。研究结果表明:气藏储层孔隙中水主要以可动水和残余水2种方式赋存,两者是与储层物性、气驱压力直接相关的变量参数。可动水主要赋存于大孔隙及裂缝中,残余水在不同孔隙形态中有不同的赋存模式,对气相渗流的影响也存在差异。当气藏中水体大于6.0PV时易发生水侵,经过润湿作用形成部分残余水,滞留孔隙喉道中,占据甚至堵塞气相渗流通道,使气井外围储层储量动用滞后甚至难以动用,从而影响低渗气藏有效开发。

It is normal to see that some water occurs in low permeability gas reservoir which influences the gas supply ability.The paper builds a model according to the pore structure,studies the occurrence models of water in different pores and the mechanism that influences the gas flows.The paper also studies the water breakthrough condition in the gas reservoir and the influence to the gas supply ability by physical simulation method.The result shows that there are two types of water in pores,movable water and residual water,which are both determined by reservoir physical properties and gas drive pressure.Movable water mainly occurrs in the fracture and big pores,and the residual water has many occurrence models in differential pores.The result also shows that when the water body is bigger than 6.0PV in gas reservoir,it′s easy to break into the formation.After wetting,some water is remained in the pore just as residual water occupying part or whole flow path.This will make the reserves far from the well and difficult to be employed,so it will influence development of the low permeability gas reservoir.