钙质含量旋回在卡拉沙依组小层对比中的应用

塔河油田卡拉沙依组河道相砂岩油层夹于卡三段和卡四段的泛滥平原泥岩中,小层对比时缺乏时间—岩性标志层。研究发现该地层中钙质含量变化似乎反映出与三级海平面变化有关的异旋回特点,因而具等时意义。根据钙质含量引起的电阻率和自然伽玛测井曲线变化和旋回特征将卡三段、四段自上而下分为5个小层。各小层厚度一般在80—100m之间,小层界线在连井地震剖面上均标定在同一个同相轴上,也反映了等时性。含油气砂岩较薄的单层厚度(2—5m)和河道微相类型决定了它们在横向上多为井间不连通的透镜状分布。

APPLICATION OF CALCAREOUS CONTENT ALLOCYCLES TO MINI-LAYER CORRELATION OF THE KALASHAYI FORMATION

The Carboniferous Kalashayi Formation in the Tahe Oilfield occurs as lenticular channel facies of sandstones interbedded between the overbank mudstones of Members K3 and K4. Minilayer correlation is difficult due to lack of isochronous lithologic mark. Based on cycles of resistivity and Gamma ray logs that change with calcareous contents in mudstones, Members K3 and K4 are subdivided into five minilayers, Ⅰ,Ⅱ,Ⅲ, Ⅳ, andⅤ in descending order. Each minilayer, 80—100m thick, situated on the same event when calibrated on a well-linked seismic section, suggesting isochronism of such stratigraphic correlation. The small thickness(2-5m) and channel type of the sandstones reservoir suggest their laterally limited distribution and disconnection between wells.