川东北地区须家河组砂岩储层特征

Characteristics of Xujiahe Fm sandstone reservoir in Northeast region of Sichuan basin

根据铸体薄片、扫描电镜、物性、孔隙结构和声发射等分析资料,对川东北地区须家河组储层特征进行了研究,结果表明:该套储层储集空间以次生孔隙为主;储层物性较差,微裂缝对改善储层孔渗性有一定贡献;排驱压力和饱和度中值压力不高,但孔喉半径小且分选性较差,孔隙结构参数总体较差。储层质量受沉积微相和成岩作用的综合影响,其中由河控三角洲和扇三角洲形成的中粒分流河道砂体为最有利储层发育的微相,成岩早期环边绿泥石胶结作用对于部分原生孔隙和吼道的保存起到一定作用,溶蚀作用对改善吼道连通性效果不佳。利用储层物性和孔隙结构参数,将须家河组砂岩评价为4类储层,其中I、II类储层在目前的工艺技术条件下为可动用储层,是增储上产的首选储层。

The characterists of Xujiahe Fm sandstone reservoir in Northeast region of Sichuan basin were investigated by the data of core analysis,scanning electron microscope,porosity and permeability analysis and acoustic emission test.The pore space of reservoir mainly includes the secondary pores.The microfractures can limitedly improve the petrophysical property of reservoir of Xujiahe Fm sandstone reservoir with low permeability and porosity,not high displacement and saturation median point pressure,small pore throat radius,poor pores throat sorting and fine skewness.The quality of reservoir was affected by sedimentary microfacies and dia-genesis.Distributary channel mesograin sandstone of delta plain was the best microfacies for the reservoir development.The agglutination of authigenic chlorite in the early stage of diagenesis were favorable for protection of primary pores and throats,but the dissolution only limitedly improve the connectivity of pore throat of Xujiahe Fm sandstone reser-voir.According to the pet rophysical properties of reservoir and pore structure parameters,Xujiahe Fm sandstone reservoir was classified into four types.The type I and type Ⅱ reservoirs are the available reservoirs under the current process conditions and can be taken as the major target zones for increasing reserves.