东非裂谷Kerio盆地石油地质特征与勘探潜力

东非裂谷东支的South Lokichar盆地于2012年获得勘探突破,成为研究和勘探的热点地区。但近年来周边盆地勘探效果不佳,有待深入分析。Kerio盆地紧邻South Lokichar盆地,勘探程度低,国内在此地的研究处于空白区。基于最新地震地质综合研究成果,阐述其石油地质特征和勘探潜力。结果表明: Kerio盆地为主动裂谷,呈西陡东缓的半地堑结构; 发育渐新世以来的5套沉积地层,最大沉积厚度可达6 500 m; 存在一套被证实的烃源岩,生烃指标好,但厚度仅20 m; 发育河流和三角洲相砂岩,孔渗物性好。盆地可划分为4个凹陷和5个构造圈闭带。中部缓坡带和东部反转构造带为盆地的有利勘探区带,可能存在2种成藏模式。盆地具有一定勘探潜力,烃源岩是最主要的地质风险。

Petroleum geological characteristics and exploration potential of Kerio Basin in East African Rift System

Since the oil and gas exploration breakthrough has been made in South Lokichar Basin of eastern East African Rift System (EARS) in 2012, the EARS has become a hot spot for research and exploration. However, there were barely good exploration results in peripheral basins, which is worthy to be analyzed deeply. Kerio Basin is adjacent to South Lokichar Basin with lower exploration degree, and there were few domestic researches and achievements in this area. Based on the latest seismic and geological integrated achievements, the petroleum geological characteristics and exploration potential of the basin were expounded. The results show that Kerio Basin is an active rift and half graben with steep slope in the west and gentle slope in the east. Five sedimentary sequences in the basin from Oligocene were developed and the maximum thickness of total deposit is about 6 500 meters. A good source rock was confirmed, but the thickness is about 20 meters. Fluvial and deltaic sandstones with good porosity and permeability were also developed in the basin. The basin can be divided into four sags and five structure zones. The central gentle slope zone and the eastern structural inversion zone are the favorable zones for oil and gas prospecting with two possible hydrocarbon accumulation models. The basin is confirmed to have certain exploration potential, while source rock is the main geological risk in the exploration.