塔河油田12区奥陶系油藏溶洞普遍发育,但受暗河沉积物和后期剥蚀改造作用的影响,溶洞充填比例高达33%,对完井段的选取和完井方式的制定带来极大的困难.为提高充填溶洞预测水平、深化充填机理认识、明确充填溶洞挖潜方向,以12区36口井的钻井、测井和录井资料为基础,综合应用岩溶地质识别、地震属性提取、地震反射特征对比、古地貌恢复等方法,对充填溶洞展开全面研究.结果表明:12区奥陶系发育暗河沉积型、地表河凸岸堆积型、敞口充填型和垮塌充填型等4种溶洞充填类型;存在粉砂岩、泥岩、垮塌角砾岩和方解石等4种溶洞充填物.同时,建立了3种充填溶洞地震预测方法:地震反射特征对比法、奥陶系中—下统顶面形态对比法、古地貌恢复法,并提出了3个挖潜方向:充填溶洞段内挖潜、充填溶洞段间挖潜和充填溶洞井间挖潜.%Karst caves are widely developed in Ordovician reservoirs in block-12 of Tahe Oilfield,but affected by filling of the underground river sediments and later denudation,the filled cave drilling rate of Upper Ordovi-cian in denuded area is as high as 33%,which brings great difficulties such as well completion selection and comple-tion method requirements.In order to improve the prediction level of filling cave,deepen the understanding of filling mechanism and clear the potential tapping direction of filling cave,based on drilling and logging data of 36 drilled wells,the filling caves were studied by using the methods of karst geology,seismic attributes,seismic reflection features and ancient landform restoration.The results show that the Ordovician in block-12 developed four types of karst cave filling,including underground river sediment,river lateral stacking,unconfined and collapse. The karst cave fillings can be divided into four types:siltstone,mudstone,collapse breccia and calcite.At the same time,three geophysical prediction methods for filling karst cave were established:seismic reflection contrast method,Middle and Lower Ordovician top surface shape comparison method and ancient landform restoration method.Three potential tapping directions were pointed out:intraformational potential,interlamination potential and interwell potential.
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