塔东古城地区鹰山组白云岩暴露标志识别及其油气地质意义

IDENTIFICATION OF THE DOLOMITE EXPOSURE MARKS IN EAGLE MOUNTAIN FORMATION AND ITS PETROLEUM GEOLOGICAL SIGNIFICANCE IN GUCHENG AREA OF EAST TARIM BASIN

塔东古城地区鹰山组内部是否存在短期暴露,对明确储层发育主控因素及勘探方向至关重要。通过三维地震、岩心、薄片、测井、录井以及相关地化实验数据等资料分析,识别出钻井的放空及漏失段、地震剖面上具削截反射特征、岩心存在溶蚀缝洞和渗流粉砂充填物、海退现象等4种暴露标志,这些暴露标志有助于层序界面识别和寻找储层发育带。研究认为:鹰山组内部存在一个海平面短暂下降期,鹰山组可划分出4个四级层序,多期次海平面升降旋回控制了"暴露滩体"的垂向格架,各层序高位域碳酸盐岩台地滩暴露地表并遭受大气淡水淋滤和溶蚀,形成优质储层。

Whether there is a short-term exposure in Eagle Mountain Formation or not is vital to make sure of the main controlling factors on the reservoir development and moreover the exploration direction. With the help of the analyses of the 3D seismic,core,thin section,well/mud logging and related geochemical data,four kinds of the exposure marks or signs were identified： drilling vented and missed intervals,truncated reflection characteristics in the seismic profiles,dissolved vug/fractures and seepage silt filling mass,regression phenomena and so on. These exposed signs are helpful to the identification of the sequence interface and finding out of the reservoir development belt. The researches show that there exists a decline period of the sea level in Eagle Mountain Formation,and furthermore 4 grades of the sequence can be divided in the formation,the vertical framework of ＂the exposed beach body＂is controlled by the multiple period-time sea-level rise-fall cycle,the high-stand carbonate plateaus of each sequence were exposed to the surface and leached by the atmospheric fresh water,and then dissolved. In the end,the high-quality reservoirs were developed.