塔里木盆地卡塔克隆起古生界油气运移体系与成藏演化

Hydrocarbon migration system and accumulation evolution in Paleozoic,Katake Uplift,Tarim Basin

塔里木盆地中部卡塔克隆起古生界油气资源丰富,但受多期构造叠加改造影响,具有混源供烃、早期充油、晚期注气、三期成藏、层楼式富集的成藏特征,油气运聚过程的复杂性制约了成藏规律的认识。该文从卡塔克隆起复式油气成藏主控因素入手,将油气运移体系划分成断裂型、不整合型、储集体型3大类,并讨论其4种空间组合模式。同时以油源断裂及区域不整合面演化为突破口,重点分析加里东晚期—海西早期、海西晚期和喜马拉雅期3个成藏关键时刻,油气运移体系演化及其与烃源岩生排烃的配置关系,指出塔中Ⅰ号、塔中Ⅱ号以及NE向走滑断裂等油源断裂是油气垂向运移的主要通道,而高隆—斜坡区T60,T70,T74复合—超覆不整合面与东河塘组骨架砂体叠置是油气侧向运移的关键因素,岩溶缝洞网络与继承性圈闭的空间展布决定了油气优势运移指向与富集部位。由断裂—溶蚀裂缝—不整合面以及骨架砂体组成的层楼式运移体系相互匹配,呈立体网状阶梯式多期充注、调整,是卡塔克隆起古生界油气成藏演化最显著标志。

Rich petroleum resources have been found in Paleozoic of the Katake Uplift, the Tarim Basin. Influenced by multiple stages of tectonic evolution, the study area is characterized by the following complicated accumulation features such as mixed hydrocarbon sources, early oil charging, late gas charging, 3 stages of accumulation, and multiple accumulations. The complicated accumulation processes restrict the studies of accumulation principles. Based on studies of the main controlling factors for hydrocarbon accumulations in the region, the hydrocarbon migration system has been divided into 3 big types： fracture, unconformity and reservoir body. 4 models for space combination are also discussed. From the aspect of source fracture and region unconformity evolution, the relationship between hydrocarbon migration system evolution and hydrocarbon generation and charging during the 3 key stages for accumulation （late Caledonian--early Hercynian, late Hercynian and Himalayan） are talked about. The regional hydrocarbon source faults such as Tazhong Ⅰ and Ⅱ as well as the NE oriented strike--slip faults work as the main pathways for vertical migration. In uplifting and slope regions, T06, T07, and T47 unconformities work together with matrix sandbodies of the Donghetang Formation, providing horizontal pathways for migration. The spatial distribution of karst network and inherited trap controls the favorable direction and accumulation position for hydrocarbon. In the Katake Uplift, the most outstanding feature for accumulation evolution is the cooperation of multiple migration systems composed of fracture, karst and unconformity, resulting in multiple stages of hydrocarbon charging and adjusting in 3 dimensions.