储气库不同类型砂岩储层压敏特征及其影响因素

Stress sensitivity characteristics and influencing factors of different types of sandstone reservoirs in gas storage

储气库库容和产能受多种因素影响,孔隙度和渗透率是其中的主要因素。为了揭示储气库不同类型砂岩储层在储气库工况下孔隙度和渗透率变化特征,针对渤海湾盆地辽河坳陷S储气库5块不同类型砂岩样品,开展应力敏感对比实验研究。结果表明,该储气库储层孔隙度与渗透率随有效应力的增加而减小,进而影响储气库的库容与产能,可以用孔隙度和渗透率的损害率来表征储气库库容和产能的损害程度。首次提出了表征库容与产能的损害因子,可用于定量评价交变载荷工况下储气库的库容和产能。S储气库储层孔隙度和渗透率损害率随有效应力的增加呈线性增加,泥质粉砂岩储层孔隙度应力损害率最大,中砂岩储层孔隙度应力损害率最小。该储气库泥质粉砂岩储层渗透率损害率同样也最大,且自身渗透率过低,应急保供时这类储层贡献较小;中砂岩储层渗透率损害率最小,对调峰保供能力影响不大。通过研究,明确了应力对储气库库容的定量化损害程度。依据不同类型储层的损害率合理优化储气库运行工况,可实现储气库库容和产能最大化。

The storage capacity and productivity of gas storage are affected by many factors,among which porosity and permeability are the main factors.To reveal the variation characteristics of porosity and permeability of different types of sandstone reservoirs in gas storage,five different types of sandstone samples were collected from the S gas storage in the Liaohe Depression,Bohai Bay Basin,and stress sensibility comparative experiments were carried out.The results show that the porosity and permeability decrease with the increase of effective stress,which affects the storage capacity and productivity of the gas storage.The porosity and permeability damage rate can be used to characterize the damage degree of the storage capacity and productivity.A damage factor characterizing storage capacity and productivity was proposed for the first time,which can be used to quantitatively evaluate storage capacity and productivity of gas storage under alternating load conditions.The porosity and permeability damage rate of the S gas storage increase linearly with the increase of effective stress.The porosity stress damage rate of the argillaceous siltstone reservoir is the largest,and the porosity stress damage rate of the medium-grained sandstone reservoir is the lowest.The argilla ceous siltstone reservoir also has the largest permeability damage rate and its own permeability is too low,so it contributes less during emergency supply assurance.The medium-grained sandstone reservoir has the smallest permeability damage rate,and it has little influence on the capacity of peak regulating and supply assurance.Through this study,the quantified damage degree of stress to gas storage capacity was determined.According to the damage rate of different types of reservoirs,the storage capacity and productivity of gas storage can be maximized by optimizing the operation condition of gas storage reasonably.