敦化盆地烃源岩地球化学特征及其生烃潜力

敦化盆地为一中新生代断坳叠合型裂谷盆地,至今勘探程度极低,为搞清其烃源岩地球化学特征及其生烃潜力,在地震地质综合研究基础上,通过系统分析化验法及地震地质生烃模拟法研究表明:盆地发育下白垩统、古近系、新近系3套湖相烃源岩,前两者为主力烃源岩,新近系下段仅为低成熟烃源岩;其中,下白垩统烃源岩分布面积342 km2,平均有效厚度约300 m,有机碳含量为2.11%～3.88%,类型为Ⅱ₂—Ⅲ型,R_o值0.8%～1.3%;古近系烃源岩在北部凹陷分布面积430 km2,平均有效厚度约400 m,有机碳含量为2.98%～4.18%,类型为Ⅱ₂—Ⅲ型,R_o值0.5%～1.2%,二者均为成熟优质烃源岩。盆地油气总资源量约1.24×108 t,表明本区具备形成中小型油气田的物质条件,具有较好的油气勘探前景。 

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.