古龙南凹陷葡萄花油层致密油成藏机理研究

古龙南凹陷葡萄花油层油水关系复杂,由凹陷中心向四周表现为致密油藏-油水过渡带-常规油藏的特点。通过沉积微相、储层微观孔隙特征、成岩作用、恒速压汞实验、相渗实验研究可知,凹陷中心区以三角州前缘席状砂为主,北部和西部物源交互沉积,形成了条带状或透镜状砂体。砂体泥质含量较高,成岩作用较强,储层岩石亲油。凹陷内储层喉道半径大于构造高部位区储层喉道半径,且分选性较差;凹陷区储层孔隙半径小于高部位区储层孔隙半径,且分选性较好。凹陷区储油空间以喉道为主,凹陷区内储层孔隙、喉道数量较少,孔喉半径比相对较小,孔隙连通性较差;构造高部位区储油空间以孔隙为主,储层孔隙、喉道数量较多,孔喉半径比较大,孔隙连通性较好;石油成藏动力以喉道毛管力与下伏地层生烃压力为主。

Tight oil reservoir mechanism study of Putaohua oil reservoirs in south Gulong sag

South Gulong sag possesses a complicated oil- water relationship,from the sag center to the surrounding it presents the characteristic of tight oil reservoir- oil and water transition zone- conventional reservoirs.Through studies on sedimentary microfacies,reservoir microscopic pore characteristics,diagenesis,constant-rate mercury injection experiment and relative permeability experiment,the sag center is mainly composed of delta front sheet sand.The interactive deposition from the north and the west leads to banded or lenticular sand bodies.The shale content of the sag center is high,showing the diagenesis occurs late,and the reservoir rock is lipophilic.At the sag center,the throat radius is greater than that of the structural high areas,but its sorting is poor.The pore radius there is smaller than that of the high areas,but with better sorting.Furthermore,oil reservoirs of the depression center are mainly characterized by big throat radius,the pores,number of throats and the porethroat radius ratios are generally smaller with poor pore connectivity.While in the structural high areas,oil reservoirs are characterized by pores,the numbers of pores and throats are bigger with big throat number-radius ratios and good connectivity.At the sag center,the dynamics of petroleum accumulation mainly comes from throat capillary force and hydrocarbon generation pressure of underlying strata.