水文地质旋回在临清地区油气勘探中的应用

Application of the hydrogeologic cycles to hydrocarbon exploration in Linqing area

地下水文地质特征在油气藏形成与演化过程中起着重要的作用,受沉积环境及构造活动等因素的控制,不同的水文地质特征反映不同的地质环境。分析临清地区水文地质特征发现,该区沙四段地层水矿化度平均高于孔店组;前寒武系到中奥陶统地层水矿化度、水型出现明显变化;古近系地层水矿化度较低,表明该区地下水与渗入水的淡化作用有关。根据古水文地质旋回的概念,将研究区自下而上划分出6个水文地质旋回,结合构造和沉积特征分析表明,临清地区石炭系—二叠系烃源岩地层沉积前或沉积后的水文地质旋回对油气生成、运聚无影响,中生代的水文地质旋回和中生代与古近纪之间的水文地质旋回对油气的保存不利,新近纪是油气成藏的最好时期,钻井证实该期利于成藏。

Variation of hydrogeologic character is mainly controlled by sedimentary environment and tectonic movements,which plays important role on reservoir forming and evolution process. The salinity of formation water in the member 4 of Shahejie Formation is higher than the Kongdian Formation in Linqing area. Salinity and type of the formation water in Precambrian to Middle Ordovician changes obviously. Low salinity of the formation water in Paleogene shows that groundwater was related to infiltration of water desalination. According to the concept of hydrogeologic character,six hydrogeologic cycles were divided from bottom to top. Combined with the study of structural and sedimentary character of Linqing area,the hydrogeologic cycles before and after sedimentary period of Carboniferous-Permian source rocks had no effect on the hydrocarbon generation,migration and accumulation. The hydrogeological cycle of Mesozoic and between the Mesozoic to the Paleogene was unfavorable to the oil and gas preservation. Drilling confirmed that the deposition of Neogene period is the best period for oil and gas accumulation.