塔河奥陶系岩溶古暗河充填特征研究

塔河油田岩溶古暗河系统形成于古风化壳的内幕,受古潜水面控制,是潜流带形成演化的结果。岩溶古暗河的结构类型呈多样性,几何特征存在较大差异。在后续海侵掩覆和埋藏下,容易被晚期沉积物填实,或陆续发生塌陷,很少能完整保存下来。充填物类型和结构不清楚等问题的存在,造成古暗河的储集体分布特征认识不清,一直制约着古暗河油藏的开发。在岩心、常规测井、成像测井和钻录井资料综合分析的基础上,将奥陶系洞穴充填物可以分为4种充填相:搬运型岩相、垮塌型岩相、化学充填相及渗流充填相四种充填相。在单井充填相识别的基础上,共识别出顶部未充填型、多期方解石充填型和多期砂泥质充填型等3种纵向充填结构,指出响应的潜力储层段,为后续的精细开发提供地质依据。

DESCRIPTION OF FILLING CHARACTERISTICS OF KARST ANCIENT RIVER IN TAHE OILFIELD

The karst paleo-dark river system in tahe oilfield was formed in the inner part of the paleo-weathering crust and controlled by the paleo-submersible surface.The structure of the ancient karst underground river types diverse;there are large differences between geometric features.Under the subsequent transgression cover and burial,it is easy to be filled up by late sediments,or collapse occurs gradually,and it is rarely completely preserved.The type and structure of the filling materials are not clear,which leads to the unclear understanding of the characteristics of the collective distribution of the reservoir and restricts the development of the reservoir.On the basis of comprehensive analysis of core,conventional logging,imaging logging and drilling and logging data,the filling materials in ordovician caves can be divided into four filling phases:porter-type rock facies,collapsed rock facies,chemical filling facies and seepage filling facies.On the basis of single well filling knowledge,three kinds of longitudinal filling structures,including unfilled top type,multi-stage calcite filling type and multistage sandy and argillaceous filling type,were identified.Point out that the three kinds of longitudinal filling structure of potential reservoir section,and provide geological basis for subsequent fine development.