特征元素比值在沉积物物源分析中的应用——以东营凹陷王58井区沙四上亚段研究为例

Application of the Ratio of Characteristic Elements in Provenance Analysis:a case study from the upper part of the fourth member of the Shahejie Fm. in the W58 area, Dongying Depression

利用Ni/Co、V/Co、Mg/Mn、Mn/Sr、Ba/Mn、Fe/K、Mg/Ca、Ba/Sr、Mg/Al、Al/Na十个特征元素比值,通过分布模式、物源指数、Q型聚类等方法,对东营凹陷王58井区沙四上亚段砂体物源进行了研究。沙四上亚段沉积时期,王58井区存在南北两大物源体系,王58井及其以北地区沉积物主要来自北部物源体系,王斜583和王126井及其以南地区主要为南部物源体系,中部牛114—斜1井一带具有南北混源特点。研究表明利用特征元素比值判别沉积物物源方向,能够有效地避免水动力及成岩作用的影响,更加准确地判断沉积物的物源方向。

Based on the ratios of Ni/Co, V/Co, Mg/Mn, Mn/Sr, Ba/Mn, Fe/K, Mg/Ca, Ba/Sr, A1/Mg and A1/ Na, the provenance of the sandbodies of the upper part of the fourth member of the Shahejie Formation in W58 area, Dongying depression was studied by distribution pattern, provenance index and Q-type cluster. During the period of the upper part of the fourth member of the Shahejie Formation, the south and north provenance systems co-exist in W58 area. The deposits in W58 well and its north area were provided by the north provenance system, and the deposits in WX583 and W126 wells and their south area were provided by the south provenance system, and the deposits in the vicinity of N114-X1 well have the characteristics both of the south and north provenance. This study shows that the direction of the provenance can be determined more accurately by the use of characteristic elements ratios because the influences of hydrodynamic force and diagenesis can be effectively avoided.