Characteristics of Paleogene source kitchen and its control on hydrocarbon accumulation in Qikou Sag, Bohai Bay Basin

Abstract

Source kitchen is an important factor to control the distribution of oil and gas. In this paper, the characteristics of Paleogene source kitchen of Qikou Sag in Bohai Bay Basin and its relationship with hydrocarbon accumulation were analyzed using data from structure, geochemistry and thermal history. The results show that Qikou sag was a large continental fault–depression basin with long-term continuous subsidence, and multiple lacustrine source rocks were developed with the 1st and 3rd section in the Shahejie Formation of the Paleogene (hereafter referred to as Es1 and Es3, respectively) as the main source rocks. The tectonic evolution of Qikou sag was controlled by basement subsidence and fault growth that leaded to the formation of multiple depressions in local subsidence centers. As a result, multiple source kitchens were developed in Es1 and Es3 with different oil and gas characteristics. Oil and gas fields were mainly distributed in the uplifts and slopes around the source kitchen which showed that source kitchen acted as an important factor in the process of oil and gas accumulation.