温度、压力对莺-琼盆地储层岩石物性影响的实验研究

为探讨温度、压力的变化对储层岩石物性的影响,利用高温高压岩石物性参数测试系统对莺-琼盆地中深层砂岩储层岩样进行了气体介质的变温及高温变围压孔隙度和渗透率测试。实验结果表明,莺-琼盆地储层岩石在高温下的热膨胀会造成岩石的孔隙度和渗透率出现轻微下降,热膨胀效应对孔隙度影响很小(变化率3%),对渗透率的影响相对明显(平均变化率8%),且喉道越小,影响越大。在高温条件下(170℃),压力因素引起孔隙度和渗透率的下降幅度要大于单一温度的影响,岩石孔隙度的变化主要受初始孔隙空间大小及泥质含量的控制,而高温条件对岩石的渗透率降低有抑制作用。实验岩石表现出的温度及压力敏感特性主要受岩石刚性颗粒含量及胶结强度的控制。

Experimental study on effects of temperature and stress on properties of reservoir rocks in Yinggehai and Qiongdongnan basin,South China Sea

In order to study the effects of temperature and pressure on the properties of reservoir rocks,the authors use a testing system of rock physical parameters with high temperature and high pressure to measure the porosity and permeability of the sandstone reservoir rocks in the middle-deep formation of the Yinggehai and Qiongdongnan basin by nitrogen gas.The test results show that the thermal expansion of the reservoir rocks under high temperature will induce a slight decreasing of the porosity and permeability of the rocks.The thermal expansion effect is very small on the porosity (<3% in variation rate),but the effect is relatively large on the permeability (8% in average variation rate),and the smaller throats in rocks,the greater effect of the thermal expansion on the permeability.The decreasing extent of the porosity and permeability induced by confining pressure under high temperature (170℃)is larger than that induced only by temperature,and the porosity of rocks variation is controlled by the size of the original pore space and argillaceous content.There is a restraint effect on the permeability decreasing of rocks under high temperature.These special sensitive characteristics of pressure and temperature showed by the tested rock samples are mainly controlled by the stiff particle content and cementation intensity of rocks.