塔北奥陶系露头古溶洞充填特征及其油气储层意义

塔河油田是中国储量规模最大的碳酸盐岩岩溶缝洞型油藏,是1种极为特殊且复杂的油藏类型。塔北柯坪—巴楚地区与塔河油区具有相似的地质演化过程,奥陶系露头广泛发育古岩溶,溶洞被不同程度充填,充填物包括洞穴沉积物、垮塌角砾岩和化学充填物3种类型,同一溶洞中可以出现2种或3种充填物组合,形成复合充填物。文中对该区溶洞砂泥质沉积充填、垮塌角砾充填及化学充填特征进行分析,探讨溶洞的成因模式,从而指导塔河油田缝洞型储层的充填物识别和充填过程研究,有助于查明该类储层的形成机制。

Paleo-cavern filling characteristics and hydrocarbon reservoir implication in the Ordovician outcrops in northern Tarim Basin

The Tahe oilfield has the largest reserve in carbonate paleokarst fracture-cavern reservoirs in China.This type of reservoirs is very special and complex.The Keping-Bachu area in northern Tarim Basin has similar geological evolution process with the Tahe oilfield.Paleokarst was developed widely in the Ordovician outcrops,the caverns were filled to various degrees with fillings including cavern deposits,collapsed breccia and chemical fillings.There may be two or three types of fillings in a same cave,forming composite fillings.This paper analyzes the characteristics of arenaceous-pelitic deposits,collapsed breccia filling and chemical filling,and discusses the genetic model of caverns,thus guiding the identification of fillings and the study of filling process for fracture-cavern reservoirs in Tahe oilfield and is helpful to work out the formation mechanism of such reservoirs.