致密砂岩气藏可动水层早期判识方法及矿场应用

随着致密砂岩气藏开发时间延长,产水问题越来越明显,对产能和采收率影响也愈加显著。气藏开发早期的可动水层判识,对于优化气藏"控水增气"开发具有重要意义。以鄂尔多斯盆地某气田区块为研究目标,通过高压压汞、铸体薄片、核磁共振与逐级增压气驱水等多种实验,测试了气、水在砂岩微观孔喉中渗流特征。结果表明:不同渗透率储层中水相流动性取决于含水饱和度与流体赋存空间类型所占比例;当储层含水饱和度大于毛管力作用空间与束缚流体空间所占比例之和时,水相极易流动,储层打开后易产出水,划分为可动水层,反之为不可动水层。利用典型区块气井资料与试气结果进行了对比,结果吻合度良好。

EARLY IDENTIFYING METHODS OF THE MOVABLE AQUIFER IN TIGHT SANDSTONE GAS RESERVOIRS AND THEIR FIELD APPLICATIONS

With the time extend of the tight sandstone gas reservoir development,the problem of the water production becomes more and more obvious,and moreover its influences on the productivity and recovery are rather significant.Therefore,it is of great significance to identify the movable aquifer in the early stage of the development for optimizing by “controlling water and increasing gas production”.Taking one gas field block of Ordos Basin as the research target,with the help of high-pressure mercury injection,casting thin section,nuclear magnetic resonance and step-wise pressurized gas driving for the water etc.,the seepage characteristics were tested for the gas and water in the microscopic pore and throat of the sandstone.The results show that the water phase mobility in the reservoirs with different permeabilities depends on the water saturation and the proportion of the fluid occurrence space;when the water saturation is larger than the sum of the proportions of the capillary action space and the bound fluid space,the water phase is extremely easy to flow,and it will be easy to produce water when opening the reservoir,i.e the layer can be classified into the movable aquifer,on the contrary,it belongs to the immovable aquifer.The contrast between the gas well data and gas tested results for the typical block shows that the coincidence is much better.