孤岛潜山披覆构造浅层天然气成藏特点

Characteristics of shallow natural gas reservoir forming in drape structure of Gudao buried hill

由于孤岛潜山披覆构造浅层天然气较为丰富,因此从构造特征、圈闭类型及生储盖组合等方面入手,分析了浅层天然气的成藏特点。研究结果表明,该区古近纪早期拉张块断活动使得沿孤岛潜山的洼陷发育了以沙三段为主的多套烃源岩系,并继承性地发育了较大型的披覆背斜。在此基础上,该区高孔隙、高渗透性的砂岩储层,良好的区域性盖层,多类型输导层与洼陷中的烃源岩相贯通等地质成藏要素与地质作用在时空上相匹配,才得以形成孤岛潜山披覆构造浅层天然气藏。

The natural gas is rich in the shallow layers of the drape structure of the Gudao buried hill. The characteristics of the gas reservoir is analyzed from the aspects of the structure character,trap types and source-reservoir-seal combination. The extensional movement and block faulting in the early Palaeogene made multiple sets of hydrocarbon source rock series developed mainly in the Es3 along the sag area in Gudao buried hill. As a result, a large inherited drape anticline was developed. The key geological factors for the gas reservoir formation include high porosity and permeability sandstone reservoir,favorable regional caprock,and multiple types of transport layers connecting to the source rocks. These factors and their space-time matching with the geologic process caused shallow natural gas reservoirs in drape structure of Gudao buried hill developed.