塔里木盆地西南部皮山北新1井白垩系油气成因

皮山北新1井位于塔里木盆地麦盖提斜坡皮山北1号背斜构造高部位,该井在白垩系获得油气,但油气源存在较大争议。原油轻烃特征表明,该井原油具有Ⅰ型母质类型来源的特征;原油饱和烃特征表明,生烃母质以泥质岩为主,但与塔河、玉北奥陶系原油有一定差异。原油二维色谱分析表明,该井原油与玉北、塔河、巴楚泥盆系原油均位于海相泥页岩的范畴;原油碳同位素特征表明,该井原油母质类型差于玉北奥陶系及巴楚巴什托石炭系原油。该井原油成熟度高于玉北奥陶系原油。通过该井白垩系油气与其周缘塔西南4套主力烃源岩生标特征的对比,认为皮山北新1井白垩系原油主要来源于塔西南海相石炭系烃源岩;天然气生源母质类型与塔西南柯克亚气田类似,有侏罗系腐殖型有机质来源天然气的贡献。皮山北新1井白垩系新层系油气成因研究将有助于拓展塔西南中新生界碎屑岩油气勘探领域。 

Cretaceous petroleum origin in well PSBX1 in the southwestern Tarim Basin

Well PSBX1 is located in the high part of anticlinal structure no. 1 on the Markit slope in the Tarim Basin, and has oil and gas in the Cretaceous. However, the hydrocarbon origin still remains under discussion. Light hydrocarbons from well PSBX1 indicated that the oils were mainly derived from type I source rocks. Saturated hydrocarbon features indicated that argillaceous materials were the dominant contributors to hydrocarbon generation, which was different from the Ordovician crude oils in the Tahe and Yubei areas. Two-dimensional chromatographic analyses showed that the Cretaceous crude oils from well PSBX1, the Ordovician crude oils from Yubei and Tahe areas, and the Devonian crude oils from Bachu area were sourced from marine mudstones. Carbon isotope characteristics of crude oils from well PSBX1 suggested poorer source quality compared with the Ordovician crude oils from Yubei area and the Carboniferous crude oils from Bachu area. Crude oils from well PSBX1 had higher maturity than those from Ordovician in the Yubei area. Analysis of the Cretaceous crude oils from well PSBX1 and four typical source rocks from adjacent areas in the southwestern Tarim Basin indicated that:(1) the Cretaceous crude oils from well PSBX1 mainly originated from the Cretaceous marine facies source rocks in the southwestern Tarim Basin; and (2) natural gas from the well was mainly sourced from Jurassic humic organic matter, which was similar to that in the Kekeya gas field. The study of the origin of Cretaceous petroleum in well PSBX1 would help oil and gas exploration in the Mesozoic and Cenozoic clastic rocks in the southwestern Tarim Basin.