太古宇变质岩潜山优势岩性评价新方法

A New Method for Evaluating Dominant Lithology of Archean Metamorphic Buried Hill

渤海海域太古宇变质岩分布面积广,整体以长英质含量较高的片麻岩和混合岩为主,具有发育规模性优质储层的岩性基础。文章通过分析渤中19-6气田17口探井的岩性、矿物、元素与储层物性的关系,建立了基于太古宇变质岩三大主要造岩矿物石英、长石、暗色矿物代表元素Si、Na+K、Fe+Mg的浅色矿物发育指数。结果表明,浅色矿物发育指数可以快速、定量评价变质岩优势岩性。评价方法在渤中19-6气田开发井中应用,对变质岩优势岩性评价效果良好。此评价方法充分利用元素录井数据,在随钻阶段即可识别优势岩性,对变质岩潜山储层快速评价具有重要意义。

The Archean metamorphic rocks in the Bohai Sea area are widely distributed and mainly composed of gneiss and migmatite with high felsic content,which have a lithological basis for developing large-scale high-quality reservoirs.Based on the analysis of the relationship among lithology,minerals,and elements of 17 exploration wells in Bozhong 19-6 Gas Field and the development of reservoir physical properties,this study establishes a light-colored mineral development index based on the three main rock-forming minerals of Archean metamorphic rocks:quartz,feldspar,and dark mineral representative elements:Si,Na+K,and Fe+Mg.The results show that the light-colored mineral development index can quickly and quantitatively evaluate the dominant lithology of metamorphic rocks.The evaluation method has been applied in the development wells of Bozhong 19-6 Gas Field,and the evaluation results for the dominant lithology of metamorphic rocks are good.This evaluation method fully utilizes element logging data and can identify the dominant lithology during drilling,which is of great significance for rapid evaluation of metamorphic buried hill reservoirs.