改进的PICKETT法在Y油田低阻油层识别中的应用

Application of improved PICKETT method to identification of low-resistivity pays in Y Oilfield

对Y油田低阻油层岩心资料(孔隙度,渗透率,颗粒密度,毛管压力曲线,电性参数,相对渗透率实验,薄片分析,X衍射,扫描电镜,粘土矿物)、录井、测井以及试油资料的分析结果表明,低阻油层的主要影响因素包括:①复杂的孔隙结构,尤其是微孔隙较发育,导致了高的束缚水饱和度;②粘土含量高,粘土矿物(高岭石,伊利石)吸附了大量的束缚水,导致了含水饱和度的增高;③粘土矿物的附加导电性(高Qv值);④咸水钻井泥浆条件下泥浆滤液的侵入。PICKETT法可用于储层评价,主要是根据测井资料和岩心资料建立深探测电阻率与孔隙度的交会图。将改进的PICKETT法用于识别Y油田低阻油层,是在原方法的基础上,通过毛细管压力曲线将自由水界面之上的高度集成到PICKETT图中,取得了满意的效果。

The analyses of core data (such as porosity, permeability, capillary pressure curve, electrical parameters, relative permeability, thin section, clay mineral), logging, well logs and well testing for low-resistivity pays in Y Oilfield show that the low-resistivity pays are mainly caused by some factors including (1) complicated porous structure, especially high irreducible water saturation in micro-porosity system; (2) high volume clay minerals (kaolinite and illite) adsorbing abundance of irreducible water; (3) high cation exchange capacity; (4) deeper invasion of saline mud filtrate. PICKETT method is mainly based on cross-plot of deep laterolog and porosity from well logs and core data. The height of free water level of pay was introduced into the initial PICKETT method to improve the PICKETT method. The improved method has been successively applied to identify the low-resistivity pay in Y Oilfield.