A study on hydrocarbon generation conditions in the North Yellow Sea basin

North Korea has drilled 15 wells in the North Yellow Sea basin by the end of 1997 and tested oil and gas flows in the Mesozoic reservoirs,indicating large oil and gas potential in this area. The hydrocarbon generation conditions of this basin are studied and the following understandings are achieved:a. the North Yellow Sea basin is a small multicycle basin formed by a superimposition of the Paleozoic,Mesozoic and Cenozoic prototype basins; b. the evolutionary process of the basin can be divided into four major stages,including formation of the basement in the Sinian-Permian,fault subsidence in the Mesozoic,superimposed fault subsidence in Paleogene,and down warping in Neogene; c. the basin is mainly composed of three depressions and many small fault depressions in an uplift setting,and its post-Paleozoic sedimentary cover of marine-transitional facies and fluvial-lacustrine -delta facies with a maximum thickness over 8000 m contains several sets of well-developed source rocks with favorable hydrocarbon generation conditions; d. the Mesozoic and Paleogene were the most favorable periods for the development of source rocks in the study area,with two sets of source rocks deposited; e. the basin is capable of generating hydrocarbons and the eastern and central depressions are the most favorable hydrocarbon kitchens.