Evolution and Movement of Source Kitchens and Their Control of Oil and Gas in the Tarim Cratonic Basin, China

Abstract

The cratonic region of the Tarim Basin contains two main Lower Paleozoic source rocks–the Middle-Upper Ordovician and Lower-Middle Cambrian. However, few research focus on the relation between the evolution of hydrocarbon kitchens and its role in controlling oil and gas. Based on previous research results, this paper applies geochemical parameters of rock pyrolysis, hydrocarbon expulsion threshold theory and hydrocarbon-generated potential methods to identify the effectiveness of source rocks from the Lower Paleozoic while quantitatively calculating the hydrocarbon expulsion intensities and amounts for the two sets of source rocks. The above result is used to analysis the distribution of the effective hydrocarbon kitchen in each primary history stage and the controls on oil and gas. This study shows multiple phases of oil and gas generation and expulsion from the Cambrian-Ordovician source rocks with four oil-generating peaks with large-scale oil migration and accumulation. According to the changes in hydrocarbon expulsion intensity within different stages, we can elucidate the evolution of the source kitchens, because the hydrocarbon kitchens from the two sets of source rocks migrated in time and space, and there are multiple hydrocarbon expulsion centers. Based on the concept of the oil/gas threshold distribution model, the relation between the quantitative characterization of the hydrocarbon kitchen controlling function, and quantitative prediction of reservoir formation probability is studied, and the result shows that oil and gas reservoirs are located in more than 50% probability of controlling area. However, different periods and different layers of stacked hydrocarbon kitchen is complex and causing the main mixing of oil and gas. All these hydrocarbon expulsion centers had control over the distribution of oil and gas in the basin. From a macro and quantitative point of view, this discovery will provide certain guide for oil and gas exploration.