GEOCHEMICAL CHARACTERISTICS OF SOURCE ROCKS AND ITS HYDROCARBON GENERATION POTENTIAL IN THE DUNHUA BASIN

The Dunhua Basin is a Mesozoic and Cenozoic rift basin with superimposed fault-depression in eastern China.Its exploration level is very low.To understand its geochemical characteristics and hydrocarbon generation potential,it has been done quantities of experiments by the method of systematic analysis and the simulation of seismic-geology hydrocarbon-generation based on seismic-geology integra-ted research.These investigations indicate that there are three sets of lacustrine source rocks which are developed in the Dunhua Basin:Lower Cretaceous,Paleogene and Neogene.The Lower Cretaceous and Paleogene are major source rocks.The Lower Neogene is only lower mature source rock.The Lower Cretaceous source rock covers an area of 342 km²,the average effective thickness is 300 m,the organic carbon is 2.11%～3.88%,the type is Ⅱ₂-Ⅲ,R_o is 0.8%～1.3%.The Paleogene source rocks cover an area of 430 km²,the average effective thickness is about 400 m,the organic carbon is 2.98%～4.18%,the type is Ⅱ₂-Ⅲ,R_o is 0.5%～1.2%.They are both matured hydrocarbons.The total resource of oil and gas is about 1.24×10⁸t.It shows that the area has the potential of forming a medium-sized oil-gas field and it has better prospection.