石油与天然气地质 ›› 2010, Vol. 31 ›› Issue (6): 770-778,837.doi: 10.11743/ogg20100610

• 石油与天然气地质 • 上一篇    下一篇

鄂尔多斯盆地陇东地区长81段低渗油藏成藏过程

  

  • 出版日期:2010-12-28 发布日期:2011-02-09

Oil accumulation process in the low-perm eability Chang-81 member of Longdong area，the Ordos Basin

  • Online:2010-12-28 Published:2011-02-09

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摘要：

鄂尔多斯盆地陇东地区延长组长81段低渗储层油藏具有典型性和代表性。通过对长81段低渗储层成岩过程、沥青赋存状态的细致观察，分析了古流体的活动特征，总结出西峰油田长81段储层经历了多期成岩过程，其间至少发生了3期油充注。在前人及作者先前工作的基础上，分析了西峰油田低渗储层的特征，结合对各种可能的油气成藏模式的动力学条件分析，提出研究区较为可信的成藏模式:在侏罗纪晚期，储层孔渗性良好，长7 3 段优质烃源岩生成的油气进入长81段输导体系，在浮力作用下发生侧向运移，并第一次成藏;以后随盆地发生翘倾构造活动，已聚集的油发生散失，而持续的压实、胶结等成岩作用使得储层变为低渗;早白垩世以来的油气运聚成藏过程中，油气利用先前与油长期接触而具亲油性的残留路径网络，沿优势输导通道侧向运移、聚集成藏。

关键词: 成岩过程, 输导体系, 成藏模式, 低渗油藏, 西峰油田, 陇东地区, 鄂尔多斯盆地

Abstract:

Oil reservoirs in the Chang-81 member of the Yanchang Formation of the Longdong area in Erdos Basin are typical low-permeability reservoirs.An observation of their diagenesis and bitumen occurrence and an analysis of the paleo-fluid indicate a multistage diagenesiswith at least three times ofoil charge in the reservoirs of the member.The previous study results were employed in the analysis of the reservoir features.Based on an analysis of dynam ic conditions，a reliable oil accumulation pattern is proposed.During the late Jurassic when the reservoirs still had favorable porosity and permeability，hydrocarbons generated by the quality source rocks of the Chang-7 3 member entered the carrier system of the Chang-8 3 member.The hydrocarbonsm igrated laterally due to buoyancy and accumulated for the first time.Later，with the tilting of the basin，the accumulated oil and gas escaped.At the same time，the continuous compaction and cementation lowered the permeability of the reservoirs.Since the early Cretaceous，the hydrocarbons mainly m igrate and accumulate laterally along the residual pathways that are oil-wet due to long-term contactwith oil.

Key words: diagenetic process, carrier system, reservoiring pattern, low-permeability reservoir, Xifeng oilfield, Longdong area, Ordos Basin