徐家围子断陷北部玄武岩储层分布及有利区预测

Distribution of basalt reservoirs and prediction of favorable exploration zones in northern Xujiaweizi fault depression

通过分析松辽盆地徐家围子断陷玄武岩测井响应、地震反射特征和储层孔隙微观结构,研究储层特征及其与岩性岩相之间的关系,确定储层发育的主控因素;利用反演手段预测储层发育特征,基于反演结果将储层分为3类,以预测有利油气聚集区。研究表明玄武岩储集空间主要有原生孔隙、次生孔隙和构造-溶蚀缝,储层孔隙度为6%～12%,渗透率为0. 01～1 m D;玄武岩地层在测井曲线上自然伽马值较低,在地震反射剖面上具有振幅强、连续性较好的特征。玄武质火山角砾岩和玄武质角砾凝灰岩储层物性最好,玄武岩次之;火口相储层物性最好,近火口相次之。在断陷北部整个凹陷,Ⅱ类区玄武岩分布广泛、物性较好、资源潜力大,为玄武岩下一步勘探的有利方向。

Through the study of logging response,seismic reflection and pore microstructure of basalt in Xujiaweizi fault depression of Songliao Basin,the reservoirs’ characteristics in relation to lithology and facies are analyzed. The main controlling factors on basalt reservoirs are revealed. Distribution of reservoirs is studied by inversion and the reservoirs are grouped into three types based on the inversion results to predict favorable exploration zones. It is revealed that pores in basalt reservoirs comprise primary pore,secondary pore and structure-eroding fissure,with porosity of 6% ~ 12% and permeability of 0. 01 ~ 1 m D. Basalt shows low gamma ray on well log and is represented by high amplitude continuous reflectors on seismic. The most effective reservoir types are basaltic volcanic breccia and basaltic breccia tuff,followed by basalt. The best reservoirs are usually found in crater facies,followed by near crater facies. Type II is the favorable zone for exploration in the northern Xujiaweizi fault depression,with extensive basalt distribution,better physical properties and more potential resources.