摘要
对原油烃类化学组成的剖析表明,东营凹陷南部缓坡带王家岗油田第三系沙河街组原油与邻区八面河油田沙河街组特征相似,都具有较高含量的甾烷、伽马蜡烷和脱羟基维生素E,C27、C28、C29ααα甾烷呈“V”字型分布,Pr/Ph<1,甾烷异构化程度不高等咸水湖相油特征,表明两区沙河街组原油成因相同及具有共同的油源。处于牛庄洼陷与其南斜坡过渡带的王家岗油田原油成因及成熟度与八面河油田原油的相同或相近,暗示后者主要来自牛庄洼陷而非仅局限于南斜坡未熟—低熟烃源岩。王家岗地区丁家屋子孔店组原油既有沙河街组原油的某些特征(如高含量伽马蜡烷),也有其不具备而第三系孔店组烃源岩可能具备的某些特征(如明显的C29甾烷优势、较高含量的氧芴系列等)。孔店组原油的双重特征及其相对较高的成熟度,说明孔店组油气的深层来源及其油源的混合性。相同成因、不同成熟度原油及不同油源原油的混合可能是叠合盆地的普遍现象。王家岗-八面河地区孔店组较高成熟度油气的发现表明该区具有广泛的深源油气前景。
Detail investigation of the chemical compositions for the oils from Shahejie Formation of Tertiary in the Wangjiagang Oilfield in the lower position of the South Slope of the Niuzhuang Sag, the Bohai Bay Basin show similarity of the oils with those of the oils in the Bamianhe Oilfield in the higher position of the slope. The oils bear common characteristics of Tertiary brackish lacustrine oils in eastern China, including high concentration of steranes, gammacerane and methyltrimethyl tridecylchromans （MTTCs）, Pr/Ph 〈 1, “V” shape of C27, C28,C29-αααsterane and low isomerization of steroids （the levels of C29 sterane ααα20S/（S ＋R） ranging in 0. 30 ～0. 35）, etc. The similar characteristics of the oils in the two oilfields suggest that their genetic kinetics are coincident and they originated from the same set of source rock. Particularly, the results suggest that it is likely possible that the oils of the Bamianhe oilfield are mostly derived from the Niuzhuang Sag rather than only contributed by the immature source rock in the South Slope of the Niuzhaung Sag. Oils of Kongdian Formation in Dingjiawuzi of the Wangjiagang region have features of both Es4 rock extracts and related Shahejie oils, i.e. high content of gammacerane and Ek rocks extracts such as obvious predominance of C29-regular sterane among C27, C28, C29 regular steranes and high content of dibenzofurane, suggesting mixed resources of Kongdian oils. Much higher mature maturity of Kongdian oils than Shahejie ones shows the former originated from deep Es4 and Ek and are of good petroleum potential in deep position in the area studied. It is suggested that mixing of oils with different maturity and/or different source rocks during oil migration and accumulation is probably a common phenomenon in composite basins.
出处
《地球化学》
CAS
CSCD
北大核心
2005年第5期515-524,共10页
Geochimica
基金
国家重点基础研究发展计划项目(G1999043310)~~
