基于测井-录井资料评价变质岩风化壳结构——以渤海南部渤中X构造为例

Comprehensive Evaluation of Weathering Crust Structure of Metamorphic Rocks Based on Log Data:A Case from Bozhong X Structure in the Southern Bohai Sea

渤海地区变质岩潜山油气藏相继获得较大的发现,但前人对于变质岩风化壳研究多沿用其他岩类的方法,缺乏针对性。以渤海海域渤中X构造变质岩风化壳为研究对象,通过对大量岩心薄片观察、测井资料及元素录井数据的趋势背景值计算、特征元素提取和聚类分析,建立了一套风化壳定量综合评价方法,其能够清晰地识别和划分变质岩垂向风化壳结构。将该方法在新钻井B井进行了应用,自上而下识别和划分出风化破碎带、强风化裂缝带、弱风化裂缝带和未风化裂缝带4个分带,有利地指导了该区的勘探。

Great discoveries have been achieved successively in the buried-hill reservoirs of metamorphic rocks in Bohai area, but there are lack of targeted methods to study weathering crust of metamorphic rocks. Taking the weathering crust of metamorphic rocks in Bozhong X structure in the Bohai Sea as the study object, and based on thin section observation, logging data, element mud log data, characteristic element extraction and clustering analysis, a set of quantitatively comprehensive evaluation methods is established for weathering crust,which can clearly identify and classify vertical structures of metamorphic rock weathering crust. The method has been applied in the newly drilled Well B and 4 zones are classified from top to bottom, i.e., weathering crush zone, strongly weathering fracture zone, weak weathering fracture zone and unweathering fracture zone, which provides references for the exploration in the area.