阿联酋地区古生界碳酸盐岩油气成藏与勘探潜力

古生界是波斯湾盆地天然气的主要产出层位,阿联酋地区古生界天然气主要富集于上二叠统胡夫组碳酸盐岩储层。在构造、沉积演化研究的基础上,分析了阿联酋地区古生界碳酸盐岩油气藏的成藏主控因素,优选了2类有利勘探区带,指明了该区古生界下一步勘探方向。结果显示:阿联酋古生代可划分为4个构造演化阶段,构造演化对油气成藏具有重要影响,古生界已发现油气主要分布于被动大陆边缘。该区古生界古赛巴段热页岩烃源灶分布及规模控制着油气分布范围与资源规模;胡夫组层内膏盐层为古生界油气藏的主要盖层,控制油气纵向与平面分布;同时油气在平面上的富集带明显受胡夫组岩相分布控制,已发现油气主要位于碳酸盐岩陆架颗粒灰岩—泥粒灰岩相带内;热页岩生烃灶周围的古构造高是古生界油气运聚的有利指向区。阿联酋古生界胡夫组仍有较大的勘探潜力,膏盐盖层发育区与优质储层岩相带的叠合部位,且邻近热页岩生烃灶的地区,油气成藏条件最好,该区域内的背斜构造和岩性—地层型构造是古生界油气勘探的重点。

HYDROCARBON ACCUMULATION AND EXPLORATION POTENTIAL OF PALEOZOIC CARBONATE IN THE UNITED ARAB EMIRATES

The Palaeozoic is the major gas producing strata of the Persian Gulf Basin. The gas of Paleozoic in the United Arab Emirates (UAE) is accumulated in the carbonate reservoir of Khuff Formation of the Upper Permian. In this paper, the main controlling factors of carbonate reservoir over petroleum accumulation are analyzed on the basis of tectonic and sedimentary evolution. Two types of favorable exploration zone are optimized, and the exploration direction of Palaeozoic in this region is indicated. The results show that the Paleozoic in the UAE can be subdivided into four tectonic evolutionary stages. Tectonic evolution has important impacts on hydrocarbon accumulation, and the oil and gas found in the Paleozoic is mainly distributed in the deposits formed in the passive continental margin stage. The distribution and the size of hydrocarbon source kitchen of the Qusaiba hot shale are the factors which control the oil and gas distribution and scale of resources. The halite in the Khuff Formation is the main cap of Paleozoic reservoirs, and controls the vertical and spatial distribution of oil and gas. The rich zone of oil and gas is apparently controlled by the lithofacies distribution of the Khuff Formation, and hydrocarbon discoveries mainly occur in the carbonate shelf grain limestone -packstone facies belt. The surrounding basement high of the hot shale hydrocarbon generation kitchen is the favorable migration and accumulation area of oil and gas. The Khuff Formation of the United Arab Emirates still has large exploration potential. The overlapping areas of halite cap and high quality reservoir facies belt, and adjacent hot shale hydrocarbon generation kitchen, provide excellent conditions for hydrocarbon accumulation. The anticline structures and lithology-stratigraphic type of traps in this area are critical for oil and gas exploration in the Paleozoic.