苏里格气藏岩石应力敏感性研究

在气藏的生产过程中,随着流体的产出,净上覆岩层压力不断升高,储层孔隙结构因受到压缩而发生改变,导致渗流速度降低,使油气井的产能下降。在模拟地层温度及应力条件下,分析了苏里格气藏小岩心和全直径岩心渗透率与净上覆岩层压力之间的关系,研究了小岩心与全直径岩心的应力敏感性。结果表明:岩心渗透率均随上覆岩层压力的升高而逐渐降低,且随净上覆岩层压力的增大,渗透率下降的幅度逐渐变小,并表现出明显的渗透率滞后效应;苏里格气藏岩石的渗透率损害程度或应力敏感性属于中等;全直径岩心的应力敏感性较小岩心弱。

Study on the Stress-sensitivity of the Reservoir Rock in Sulige Gas Field

In producing the gas well, the net overburden pressure is increasing as the fluid flow out of the formation. The pore structure of the reservoir is deformed because of the compression resulted from the o verburden pressures, leading to a reduced gas flow rate and production rate. In stimulating the formation temperature and stress conditions, the relationship between the formation permeability and the net overburden pressure was investigated, using the small cores and full-sized cores from Sulige gas field. Also studied was the stress sensitivity of the small cores and full-sized cores. The results showed that the core permeability decreased with the increase in overburden pressures, and the magnitude of the permeability decrease would be reduced as the net overburden pressure increases, showing a remarkable "hysteresis effect" in formation permeability. The study also showed that the rock permeability losses or stress-sensitivity in Sulige gas field were moderate. The stress-sensitivity of the full-sized cores was weaker than that of the small cores.