柴达木盆地昆北地区花岗岩储集性影响因素

Geological influential factors of bedrock reservoir in the North-Kunlun Faults Zone,Qaidam Basin

柴达木盆地昆北断阶带是以"花岗类基岩为主力产层"的典型区块。细化研究影响基岩储集性各个因素的作用机理以及影响程度,有利于进一步挖掘昆北基岩储集体的油气潜力。研究结果表明:断裂分布情况是基岩中孔缝发育程度的主控因素,古地形地貌差异和不同井区水岩反应的差异对储集性的影响次之。昆北西部井区基岩岩性为二长花岗岩,古地形较高顶部残积段多已被剥蚀储集体厚度较小,因此多见脆性颗粒因经受物理风化时间较长而形成的差异风化破裂缝。昆北东部井区的钾长花岗岩因古地形地貌较低厚度较大且保存齐全,因接受沉积时间较早上覆水岩反应产生的钙镁离子在基岩裂缝中浓度较大易发生沉淀,因此多见次生方解石脉贯入构造节理缝中。

Reservoir assemblage in the bed rocks constitutes the predominant oil reservoirs in the Kunbei Area,southwestern Qaidam Basin.This paper mainly focuses on the influential factors for the reservoir assemblage in the bed rocks in the Kunbei Area.These results can provide important insights into the oil exploration and productivity in the Kunbei Area.The results show that the fractures distribution is the main factor that control the development of pore fractures in bedrock.The difference between ancient landform and geomorphology and the difference of water and rock interaction in different wells affect the reservoir performance.The bedrock lithology of the western Kunbei belt is more obvious that the brittle particles are weathered and fractured due to the long term physical weathering process.In the eastern region of the Kunbei Area,due to the ancient landform is lower with the greater thickness and completely kept,secondary calcite fulfill the tectonic joint seam.