东濮凹陷文南地区未成熟原油特征研究及勘探意义

ON GEOCHEMICAL CHARACTERISTIC OF IMMATURE CRUDE OIL AND EXPLORATION SIGNIFICANCE IN WENNAN, DONGPU SAG, HENAN

本文分析了东濮凹陷文南地区沙一段原油及生油岩地球化学特征。沙一段原油具有族组成以低饱和烃和高芳烃及高非烃+沥青质含量为特征,气相色谱特征表现为异构烷烃、环烷烃含量丰富,具明显的植烷优势,Ph/nC18>3。生物标志化合物分布谱图缺乏低碳数化合物,甾烷以反映生物构型的ααα-20RC27、C28、C29胆甾烷为主,萜烷以αβ-C30藿烷、C29—C30莫烷及γ—蜡烷占绝对优势;成熟度参数ααα-C2920S/20(S+R)和C29ββ/(αα+ββ)值分别为0.20和0.21。综合盆地沙一段原油和烃源岩地质、地球化学特征认为砂一段原油是自生自储的未成熟原油。该研究成果对于东濮凹陷广大的未成熟、低热变史地区的油气勘探具有指导意义。

By analyzing the geochemical characteristics of the crude oil and the source rock of Sha-1 in Wennan, Dongpu sag, the of crude oil components in Sha-1 is usually associated with lower n-alkanes and higher aromatics and asphalt, th e distribution of hydrocarbon on the gas chromatograms shows that the abundance of iso-alkanes and cyclic-alkanes and phytane predominance, Ph/nC_ 18 >3.The bioma rker on GC/MS shows that ααα-20RC_ 27 ,C_ 28 ,C_ 29 cho lestanes is more a bundant and αβ-C_ 30 hopane and C_ 29 ,C_ 30 moranes and gammacera nes is predominant. The mature parameters of ααα-C_ 29 20S/20(S+R) and C_ 29 ββ/(αα+β β ) are resp ectively 0.20 and 0.21. Synthetic analytic result of the geological and geochemi cal characteristic of crude oil and source rock shows that the crude oil of Sha- 1 is immature crude oil which self-generation and self-bearing. For immature and lower thermal historic oil and gas exploration areas in Dongpu sag, this result s have their significance.