特低渗储层可动流体饱和度研究——以甘谷驿油田长6储层为例

Study on movable fluid saturation in ultra low permeability reservoir:taking Chang 6 reservoir in Ganguyi oil field as an example

特低渗储层油水分布关系复杂、微观孔喉网络分布模式及油水微观渗流机理复杂多变、水驱效率低、开发矛盾突出.可动流体饱和度是精细评价特低渗储层的关键因素,因此,利用铸体薄片、扫描电镜、X衍射、常规压汞、恒速压汞、核磁共振等实验手段,研究分析甘谷驿油田长6储层可动流体饱和度的分布特征及主控因素.结果表明:研究区长6储层的可动流体饱和度偏小,平均值为37.42%.微观孔隙结构是控制可动流体饱和度大小的主要因素,粘土矿物次之,储层物性的影响最弱.渗透率对可动流体饱和度的敏感性显著强于孔隙度.孔隙连通性好,孔喉比小,喉道半径粗、残余粒间孔保存较好、次生孔隙发育,粘土矿物含量小,可动流体饱和度相对较高.粒间孔的剩余程度、溶孔及喉道的发育程度等对储层的好坏及可动流体饱和度的大小具有至关重要的作用.孔隙特征参数中,喉道半径,孔隙半径,孔喉比、单位体积总有效孔喉体积与可动流体饱和度的关系更为密切.

Development contradictions in extra low permeability reservoir have occurred at its complexity on the distribution of oil and water, micro pore-throat net distribution, flow principles and poor displacement efficiency. The movable fluid saturation is the key factors in extra low permeability reservoir evaluation. The distribution characteristics and main factor of controlling reservoir movable fluid saturation of chang 6 reservoir in Ganguyi oil field are analyzed by using casting thin-sections, scanning electron micrograph observations, X-ray diffractions, conventional mercury injection technology, constant-rate mercury injection technology, nuclear magnetic resonance and so on. Movable fluid saturation of chang 6 reservoir is 37.42%, which is small. Movable fluid saturation is mainly controlled by microscopic pore structure. Clay minerals and reservoir physical property have less effect on movable fluid saturation than microscopic pore structure. The sensitivity of permeability to movable fluids is significantly stronger than that of the porosity. Movable fluid saturation of the reservoir that good pore connectivity, small pore throat radius ratio, big throat radius, a lot of residual intergranular pore and secondary pore, and low clay mineral content is high. The quality of the reservoir and the size of the movable fluid saturation are determined by the size of residual intergranular pore and dissolved pore and development of throat. The throat radius, pore radius, pore throat radius ratio and unit volume total effective pore volume in pore characteristic parameters has more important influence on movable fluid saturation.