延长致密气储层微观孔隙结构及流体分布特征

Micropore structure and fluid distribution characteristics of Yanchang tight gas reservoir

微观孔隙结构及流体分布的研究,对评价及合理有效开发致密气储层具有重要意义。文中利用低温液氮吸附和核磁共振实验,对延长致密气储层的微观孔隙结构、流体分布及孔喉分形特征进行了评价和研究,表明了孔隙结构参数间的关系,并探究了微观孔隙结构参数对储层流体分布的影响。结果表明:延长致密气山西组和石盒子组储层的孔隙类型有开放型的槽状孔、细颈孔或墨水瓶状孔以及一侧近似封闭的不透气孔等3种;延长致密气储层中介孔、宏孔最为发育,且储层非均质性较严重;岩石比表面积随着微孔孔容增加而增加,随着平均孔径的增大而减小,此外还受到储层非均质性的影响;岩石比表面积、微孔孔容、平均孔径及分形维数皆是影响致密气储层流体分布的主要因素。

The study of micropore structure and fluid distribution was of great significance to evaluate and develop tight gas reservoir reasonably and effectively.In this paper,low-temperature nitrogen adsorption and NMR were used as the main experimental methods to study and evaluate the micropore structure and fluid distribution in the Yanchang tight gas reservoir.The fractal of pore throat in tight gas reservoir was studied.The relationship between pore structure parameters and the influence of micropore structure parameters on reservoir fluid distribution were explored.The results show that there were three types of pores in the Shanxi formation and the Shihezi formation of the Yanchang tight gas reservoir,included open grooved pores,fine neck pores or ink bottle pores and nearly closed impermeable pores on one side.Mesopores and Macropores were the most developed in the reservoir,and the heterogeneity was serious.The specific surface of rock increased with the increase of pore volume,decreased with the increase of average pore diameter,and was affected by heterogeneity.The specific surface of rock,micropore volume,average pore diameter and fractal dimension were the main factors in fluid distribution of the tight gas reservoir.