安塞地区长7致密砂岩孔隙发育特征及其主控因素

孔隙发育特征及其影响因素对储层评价至关重要。为研究安塞地区长7致密油储层储集空间特征,明确储集空间发育的主控因素,通过采用X射线衍射、铸体薄片、扫描电镜和常规压汞等手段,对目的区孔隙发育特征及其影响因素进行研究,结果表明:①安塞地区长7致密砂岩主要发育粒间溶孔、粒内溶孔以及微孔隙等次生孔隙,其次发育原生粒间孔隙和原生剩余粒间孔隙;②储层孔喉半径分选性较差(0.025~0.250μm),孔喉峰位半径主要为细孔喉,储层主要的储集空间主要由较小孔喉贡献;③压实作用是造成孔隙度大量丧失的首要原因,胶结作用堵塞孔隙和喉道,使得储层的物性进一步变差。该研究结果为下一步深入挖掘长7致密油油气提供支撑资料。

Microscopic pore characteristics and main controlling factors of Chang 7 tight sandstone in Ansai oilfield

The characteristics of pore development and its influencing factors are very important for reservoir evaluation.In order to study the reservoir space characteristics of the Chang 7 tight oil reservoir in Ansai oilfield and to clarify the main controlling factors for the development of the reservoir space,this paper uses X-ray diffraction,cast thin films,scanning electron microscopy,and conventional mercury intrusion to measure the porosity of the target area.The development characteristics and their influencing factors are studied.The results show that:①The secondary pores,such as intergranular dissolved pores,intragranular dissolved pores,and micropores,mainly develop in Chang 7 tight sandstone in the Ansai area,followed by primary intergranular pores and primary residual intergranular pores.②The pore throat diameter of tight sandstone reservoirs in the study area is poorly sorted(0.025~0.250μm),the peak pore throat radius is mainly the pore throat,and the main reservoir space of the reservoir is mainly contributed by the smaller pore throat.③Compaction is the primary reasonforthe large loss of porosity,and cementation blocks the pores and throats,resulting in further physical deterioration of the reservoir.The above results will provide supporting data for the next step of deep exploration of C hang 7 tight oil and gas.