大庆深层火山岩储层应力敏感性研究

大庆火山岩气藏储层埋藏深，岩石类型复杂，储集空间复杂多样且较为致密、物性差，属于低孔低渗储层。为了研究气藏开发过程中的储层物性变化规律，对大庆火山岩进行了应力敏感性实验和岩石力学实验分析，结果表明：大庆火山岩硬度大，抗压强度高，应力敏感性不强，当有效压力从5 MPa增大到60 MPa时，孔隙度下降率小于5％(相对值)；渗透率的变化较为复杂，孔隙型火山岩下降率较低，约为10％～20％，裂缝型火山岩在低压段受压后裂缝产生闭合，渗透率下降较快，高压段下降速率减缓，总的下降率约为40％～60％。对某一气藏的计算表明，当气藏由原始地层压力衰竭开采至后期低压时，储层的渗透率总体上下降不大，孔隙型储层仅下降约3.5％，裂缝型储层下降约17.1％。

STUDY ON STRESS SENSITIVITY OF DEEP VOLCANIC RESERVOIRS IN DAQING

The Daqing volcanic gas reservoir is deep, and the types of reservoir's rock andpore space are complex. The rock is tight and the properties are poor. It belongs to the low porosity and low permeability reservoir. The experiment of stress sensitivity and rock mechanics are done using Daqing volcanic samples to study the rule of the changes of reservoir physical properties in the process of development. The results show that the hardness of Daqing volcanic formation is strong, the compressive strength is high, and the stress sensitivity small. When effective pressure increases from 5 MPa to 60 MPa, the porosity decreases by less than 5% (relative value). But the change of permeability is complex. The decrease rate of porous volcanics is low, just about 10％～20％. The fractures of fractured volcanics will be closed under low pressures. Its permeability decreases quickly, but decreases slowly under high pressures. The total decrease rate of permeability is about 40％～60％. The calculation of one gas field shows that the rese rvoir's permeability decreases by a small amount when the depletion drive develo pment of the gas field from the initial pressure to the later low pressures. The decrease of porous reservoir is by about 3.5％, and the fractured reservoir by about 17.1％.