塔河油田奥陶系岩溶古暗河岩溶期机械充填特征

Mechanical filling characteristics of Ordovician Karst paleo-subterranean rivers in Karst stage of Tahe oilfield

塔河油田岩溶古暗河的结构类型呈多样性,几何特征存在较大差异,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,建立古暗河岩溶期机械充填的识别标志,然后分析裂缝、断裂、表层落水洞+断裂、深部落水洞四种不同的古暗河入水口结构类型,阐明其运动特征、对岩溶水的作用、水流流动方向以及对砂泥质等充填物的携带能力。在机械充填物识别和入水口结构研究的基础上,总结出落水洞–断裂–管道、断裂–厅堂、裂缝–管道三种不同岩溶组合形态,并分析了其机械充填原因、地震和测井识别方法、生产特征,指出断裂–厅堂型是有利的岩溶组合形态,是后期开发的重点对象。

The structural types of karst paleo-subterranean rivers in Tahe oilfield are diversified,and there are great differences in geometric characteristics,which has restricted the development of oil reservoirs in paleosubterranean rivers.Based on the comprehensive analysis of core,conventional logging,imaging logging and drilling logging data,the identification marks of mechanical filling in Karst period of paleo-subterranean rivers are established,and then four different structural types of intake structures are analyzed,namely,crack,fracture,surface sinkhole+fracture and deep sinkhole.Their movement characteristics,action on karst water,flow direction and carrying capacity of sand and argillaceous filling materials have been clarified.Based on the identification of mechanical filling and the study of intake structure,three different karst combination forms are summarized,namely sinkhole-fracture-pipeline,fracture-hall and crack-pipeline.And then their mechanical filling causes,seismic and logging identification methods and production characteristics are analyzed.It is pointed out that the fracture-hall type is a favorable karst combination form,which is the key target of later development.