砂岩中绿泥石包膜与岩石润湿性及岩电参数的关系研究

对复杂润湿性砂岩储层研究发现,绿泥石包膜的存在会导致岩石润湿性表现为亲油,并且这种润湿性不受洗油洗盐过程的影响。龙凤山地区营城组砂岩中广泛发育自生绿泥石包膜,岩电测量发现,在洗油洗盐后部分岩样的饱和度指数(n)值依然很高,最高达到14.57,同时胶结指数(m)值较低,m与n之间有较好的线性关系。研究认为这种m值偏低、n值偏高的原因是绿泥石包膜改变了岩石的润湿性,从而导致岩电参数的变化。对7块岩样进行了粘土和全岩分析,建立了绿泥石含量与m,n的关系,分析了绿泥石包膜对岩石导电性的影响机制,并从物源上对绿泥石及m,n的平面分布进行了解释。该研究为采用电测井方法评价复杂润湿性储层的含水饱和度提供了岩石物理基础,对岩石导电机制的进一步认识和提高此类砂岩的测井解释精度有一定的参考价值。

Previous studies on sandstone reservoirs with complex wettability characteristics demonstrated that the presence of a chlorite coating can make the rock more oil-wettable,and that this feature is not affected by the process of oil and salt washing.Authigenic chlorite coating is widespread in the sandstone layers of the Yingcheng formation in the Longfengshan area,China.It was shown that after oil washing and salt washing,the saturation index (n) of some rock samples remained very high (up to 14.57),while the cementation index (m) was low.Moreover,a good linear relationship between m and n was observed.Therefore,it was suggested that the low m and high n values could be attributed to a change in rock wettability caused by the chlorite coating,which also affected the electrical characteristics of the rock.In this study,7 rock samples were analyzed,both as a whole and with respect to their clay component.The relationships between the chlorite content and the values of m and n were evaluated,the mechanism underlying the influence of the chlorite coating on rock conductivity was analyzed,and the plane distribution of chlorite content and m and n were explained from the source object.This study provides a petrophysical basis for the evaluation of the water saturation of complex wettable reservoirs by means of electric logging,and provides a reference for the better understanding of the rock conductivity mechanism,and for improving the logging interpretation of complex sandstone layers.

中国博士后科学基金(2018T110245)特别资助。