鄂尔多斯盆地隐性断裂识别及其控藏作用

所谓隐性断裂带,是指在断裂发育早期,主断面形成之前的裂缝发育带或一系列地质体定向律排列所反映的弱变形断裂趋势带.为了研究鄂尔多斯盆地隐性断裂带的形成机制及其对油气运聚成藏的控制作用,在重、磁、区域地质等分析的基础上,充分应用油气勘探、野外考查等资料,在鄂尔多斯盆地分别识别出了盆地级、坳陷级、凹陷级和圈闭级的隐性断裂带,按走向可分为东西向、北西向和北东向等.研究表明:按照从隐性到显性的顺序,可将隐性断裂带的演化分为盖层密集裂缝发育期、雁列式断裂线性展布期、断裂面断续形成期、断裂面陆续连通期以及断裂面连通且产生断距的显性断裂期5个基本阶段.隐性断裂带调节了盆地的构造格局、分割凹陷、隆起、加速烃源岩的发育程度、控制沉积体系的展布、改善储集层和输导体系,对油气的生成和运聚成藏都有着重要影响,隐性断裂带的发育区,往往是油气聚集靶区.

The Recognition of Potential Fault Zone in Ordos Basin and Its Reservoir Control

Potential fault zone refers to the weak deformation fault trend zone reflected by the fracture development zone or a series of geological body alignment before the formation of the main section in the early stage of fault development. In order to study the formation mechanism of potential fault zones in Ordos basin and their control on hydrocarbon migration and accumulation, basin-level, depression-level, sag-level and trap-level potential fault zones were identified in Ordos basin by fully utilizing the data of oil and gas exploration and field investigation on the basis of gravity, magnetism and regional geology analysis. These potential fault zones can be divided into east-west, north-west and north-east directions according to their strike. According to the sequence from recessive to dominant, the evolution of the potential fault zone can be divided into five basic stages: the development period of dense caprock fractures, the linear distribution period of echelon faults, the intermittent formation period of fracture surface, the successive connection period of fracture surface and the connection of fracture surfaces period. It is concluded that the potential fault zone has important impact on hydrocarbon generation and accumulation, regulating the structural pattern of basin, dividing depressions and uplifts, accelerating the development of source rocks, controlling the distribution of sedimentary systems, and improving reservoir and transport system. The development area of potential fault zone is often the target area for hydrocarbon accumulation.