黔中隆起下组合古油藏和残余油气藏

FOSSIL OIL POOLS AND RESIDUAL OIL AND GAS POOLS IN THE LOWER ASSEMBLAGE OF QIANZHONG UPLIFT

通过对黔中隆起及其周缘地区典型古油藏和残余油气藏的石油地质主要特征、埋藏史、热史与成藏条件等进行分析研究,明确了古油藏和残余油气藏的含义,探讨了古油藏和残余油气藏的油气成藏模式和油气成藏规律。进而指出:①该区油气成藏期以加里东期为主,加里东期古隆起是控制油气成藏的首要因素;②抬升剥蚀作用是早期油气藏被改造和破坏的控制因素,燕山—喜山期构造运动是造成该区早期油气全面被破坏的主导因素;③加里东期存在和油气演化有着良好配置关系的古圈闭和储盖组合,从而形成了众多大型加里东期古油气藏;印支—燕山期缺乏与油气演化有着良好配置关系的构造圈闭(古隆起)和储盖组合,使该区晚期成藏条件相对较为不利;④埋藏差异造成该区油气演化程度差异较大,但目前仍存在寻找油气的客观条件。

Based on the study of the main petroleum geologic features, burial history, thermal history and pooling conditions of the typical fossil oil reservoirs and residual oil and gas pools in the Qianzhong uplift and the adjacent areas, this paper gives clear definitions of fossil oil pool and residual oil and gas pools, and discusses their modes and patterns of hydrocarbon pooling. The following understandings are obtained. (1) Hydrocarbon pooling mainly occurred in the Caledonian epoch and the Caledonian paleouplift was the primary factor controlling hydrocarbon pooling. (2) Uplifting and erosion were the controlling factors of reformation and destruction of the early oil and gas pools and the Yanshanian-Himalayan tectonic movement was the dominant factor leading to the overall destruction of the early oil and gas pools in the study area. (3) Plaeotraps and reservoir-cap rock combinations that had favorable timing with the evolution of oil and gas existed in the Caledonian epoch, leading to the formation of numerous Caledonian fossil oil and gas pools. In contrast, no structural traps (paleouplifts) and reservoir-cap rock combinations that had favorable timing with the evolution of oil and gas existed in the Indo-Chinese-Yanshanian epochs, thus the conditions for late hydrocarbon pooling in the study area were relatively poor. (4) Differential burial resulted in the large difference of evolution of oil and gas, but conditions for obtaining discoveries still exist in the study area at present.