姬塬地区长6 油层组储层特征及形成机理

鄂尔多斯盆地储层形成机理复杂，对其储层特征及形成机理进行研究，是寻找优质储层、认识油气分布规律的有效途径。 利用铸体薄片、压汞曲线和测井资料，对姬塬地区长 6 油层组储层物性、微观孔隙结构及压汞系数等特征进行了研究。 在特低渗透储层评价中，引入了压汞系数，它综合考虑了孔隙度、最大进汞饱和度、中值半径、排驱压力和分选系数共 5 个因素。 对研究区长 6 油层组的 136 块岩石样品进行了压汞实验，根据压汞系数及压汞曲线特征，将储层划分为优质、好、中等和差共 4 种类型。 实验结果表明，压汞系数越大，相应层段的试油产量越高，说明利用压汞系数评价低渗透储层具有一定的合理性。 研究表明，姬塬地区长 6 油层组储层形成的主控因素有沉积作用、次生溶蚀作用及异常高压作用；三角洲前缘亚相水下分流河道中的绿泥石膜胶结带、次生溶蚀孔隙发育带和异常高压带，是研究区优质储层发育的有利区带。

Characteristics and formation mechanism of Chang6 reservoir in Jiyuanarea

The formation mechanism of reservoir in Ordos Basin is very complex. The study on reservoir characteristics and formation mechanism is an effective way to find high-quality reservoirs and cognize oil and gas distribution rule.Based on the analyses of casting sections, intrusive mercury curve and logging data, the features of physical properties,microscopic pore structure and intrusive mercury coefficient of Chang 6 reservoir in Jiyuan area were studied. In term of the evaluation of extra-low permeability reservoir, microscopic pore structure can reflect the reservoir quality more effectively. The intrusive mercury coefficient was introduced, which takes into account five factors, including porosity,maximum intake mercury saturation, median radius, displacement pressure and sorting coefficient. 136 rock samples of Chang 6 reservoir were selected to carry out the mercury injection experiment. According to the characteristics of intrusive mercury coefficient and intrusive mercury curve, the reservoirs are divided into four types which are highquality, good, moderate and poor reservoir. The experiment result shows that the larger the intrusive mercury coefficient is, the higher the well test yield in the corresponding zone will be, indicating a certain rationality of intrusive mercury coefficient for reservoir evaluation. The main controlling factors of Chang 6 reservoir in Jiyuan area include sedimentation, secondary dissolution and overpressure. It is suggested that the chlorite cementation zones, secondary pore zones and overpressure zones of subaqueous distributary sand bodies in delta front are the favorable belts for the development of high-quality reservoirs.