鄂尔多斯盆地准连续型致密砂岩大气田成藏模式  

Q uasi-continuous accumulation model of large tight sandstone gas field in Ordos Basin

作　　者：赵靖舟[1] 付金华[2] 姚泾利[2] 刘新社[2] 王宏娥[2] 曹青[1] 王晓梅[1] 马艳萍[1] 凡元芳[1] 

机构地区：[1]西安石油大学地球科学与工程学院,陕西西安710065 [2]中国石油长庆油田公司,陕西西安710021

出　　处：《石油学报》2012年第A01期37-52,共16页Acta Petrolei Sinica

基　　金：国家重大科技专项"中国大型气田形成条件;富集规律及目标评价"(2011ZX05007-004)资助

摘　　要：鄂尔多斯盆地大气田主要赋存于上古生界致密砂岩储层中,且广泛分布于上古生界中下组合特别是二叠系山西组与下石盒子组。研究表明,鄂尔多斯盆地致密砂岩大气田既非典型的不连续型常规气藏,又非典型的连续型非常规气藏,而是介于常规与非常规或不连续型与连续型之间的一种过渡类型,称之为准连续型天然气聚集。其主要特点是:天然气大面积准连续分布,无明确气藏边界;圈闭介于常规圈闭与无圈闭之间,主要由非常规岩性圈闭和动力圈闭组成;气水分布复杂,无明显边、底水;天然气运移为非浮力驱动,近距离成藏。这种大气田的形成与分布主要受烃源岩和储层等因素控制,其中优质烃源岩的大面积分布是控制致密砂岩大气田形成和分布最重要的因素。由于为近距离运移成藏,加之致密储层本身同时可起到一定封盖作用,鄂尔多斯盆地上古生界致密砂岩大气田形成的生气强度下限可以低至10×108 m3/km2左右。准连续型致密砂岩天然气成藏模式的提出,预示着鄂尔多斯盆地上古生界天然气资源丰富,勘探潜力较大。但另一方面,准连续型成藏模式的确认,也意味着传统的常规油气地质学的研究思路及勘探理念在鄂尔多斯盆地并不完全适用。Large gas fields in Ordos Basin are mostly hosted in the tight sandstone reservoir of the Upper Paleozoic, and are widely distributed in the lower and middle formations of the Upper Paleozoic, especially in Shanxi Formation and Xiashihezi Formation of Permian. Studies have shown that tight sandstone gas fields in Ordos Basin are neither typical discontinuous conventional gas reser voir nor typical continuous unconventional gas reservoir, but a transitional type between the conventional and unconventional or be- tween the discontinuous and continuous, being known as quasi-continuous gas accumulation. This type of accumulations features that the natural gas is oceurred in large〉area and quasi-continuous in distribution without defined boundary; the trapping is between con ventional trapping and actually no trap and mainly composed of unconventional lithologic traps and dynamic traps; gas and water dis- tribution is complex and there is no obvious edge-bottom water; gas migration is subject to non-buoyancy driving and proximal accu- mulation. The formation and distribution of this large gas field is mainly controlled by factors such as hydrocarbon source rocks, res- ervoirs and so on, of which the distribution and quality of source rocks is predominant. Since it is subject to proximal migration and accumulation and the tight reservoir itself can play the role of seal-capping, the minimum gas generation intensity （GGI） of large tight sandstone gas fields of the Upper Paleozoic in Ordos Basin can be as low as about 10 × 108m3/km2. The proposal of quasi-con tinuous tight sandstone gas accumulation model implies that there are a greater natural gas resource endowment and exploration po- tential in the Upper Paleozoic of Ordos Basin. However, the confirmation of quasi-continuous accumulation model also means that the research ideas and exploration philosophy of conventional oil and gas geology are not fully applicable in Ordos Basin.

关 键 词：鄂尔多斯盆地 上古生界 大气田 致密气 准连续型聚集 

分 类 号：TE112.3[石油与天然气工程—油气勘探]