鄂尔多斯盆地延长组超低渗透油藏形成过程分析——以古峰庄—麻黄山地区为例

Accumulation Process of Ultra-low Permeability Reservoirs in Yanchang Formation Ordos Basin: A case from Gufengzhuang-Mahuangshan area

鄂尔多斯盆地古峰庄—麻黄山地区长6、长8超低渗透油藏具有典型性和代表性。通过流体包裹体均一温度与沉积埋藏史—热史综合分析表明,古峰庄—麻黄山地区长6、长8油藏为一期成藏,成藏时间为早白垩世。成藏过程中,长7油源成藏早期向长8单向充注,成藏中期向长6、长8双向充注,成藏后期则向长6单向充注。成藏过程的这种动态变化主要由源储距离及其垂向组合关系、油源岩生烃高峰、储层边致密边成藏等成藏要素联合作用控制。

Oil reservoirs in Chang 6 and Chang 8 members of Yanchang Formation in Gufengzhuang-Mahuangshan area of Ordos Basin are typical ultra-low permeability reservoirs. Comprehensive analysis of homogenous temperatures of fluid inclusions and geothermal and burial history shows that oil accumulation of Chang 6 and Chang 8 members happened in early Cretaceous. During the oil accumulation petroleum generating from Chang 7 source rock only charged into Chang 8 reservoir at the early stage,then charged up and down into Chang 6 and Chang 8 at the middle stage,and only filled into Chang 6 reservoir at the late stage. The difference of accumulation process was controlled by the relationship between source and reservoir,and the peak time of hydrocarbon generation,and the reservoir tightness prior to the accumulation.