玛湖凹陷是准噶尔盆地重要的生烃凹陷,位于凹陷北部的玛页1井对二叠系风城组进行了全井段连续取心。通过系统描述和剖析岩心特征,结合高密度取样分析、电性及核磁共振分析,揭示出风城组常规和非常规储层并存,碱湖环境造就了这一特殊组合。常规储层以火山岩类、砂砾岩类和砂岩类为主,发育于低位期淡水或低盐度水体;非常规储层以泥岩类、云岩类和粉砂岩类为主,发育于弱水动力条件及强烈蒸发环境。根据四性关系,初步建立甜点评价标准,揭示了玛页1井风城组发育有一个常规“甜点段”和三个非常规“甜点段”,常规“甜点段”发育于风城组一段中部和下部,非常规“甜点段”发育于风城组三段下部、风城组二段,进一步证实了碱湖沉积盆地具有较好的油气勘探潜力。玛页1井风城组岩心剖析,进一步证实了碱湖沉积丰富的油气资源潜力,同时也为玛湖凹陷风城组“铁柱子”的建立奠定坚实基础。

Mahu sag is an important hydrocarbon-generating sag in Junggar Basin. The whole well section in Fengcheng Formation of Well-MY1, which is located in the north of the sag, has been continuously coring. Therefore, the coexisting characteristics of conventional and unconventional reservoirs in Fengcheng Formation are revealed by the combination of the systematic description and analysis of core characteristics with the analysis of high-density sampling and electrical/nuclear magnetic resonance. The main conventional reservoirs are volcanic rocks, glutenite and sandstone, which is developed in the low stage freshwater or low salinity water body. The main unconventional reservoirs are mud-stone, dolomite and siltstone, which is developed in the weak hydrodynamic conditions and strong evaporation environment. On this basis, with the comprehensive analysis of lithology, electrical properties, physical properties, oil content and other characteristics, it is further confirmed that there is one conventional “sweet spot” and three unconventional “sweet spot” in Fengcheng Formation of Well-MY1, and the conventional “sweet spot” is developed in the middle and lower part of 1st member of Fengcheng Formation, the unconventional “sweet spot” is developed in the lower part of 3rd member and the 2nd member of Fengcheng Formation. The core analysis and features of Fengcheng Formation in Well-MY1 further confirms the hydrocarbon resource potential of alkali lake deposit, and lays a foundation for the establishment of “Standard Lithology Profile” of Fengcheng Formation in Mahu sag.