摘要
明确低渗透储层孔隙分布及不同尺度孔隙中石油微观赋存状态是认识致密油特征的关键。应用核磁共振测试技术对鄂尔多斯盆地延长组低渗透致密砂岩储层进行研究,发现了鄂尔多斯盆地延长组低渗透致密砂岩储层普遍发育纳米孔隙,具大孔、中孔、小孔、微孔及纳米孔多尺度孔隙发育特征。通过对近源与远源油藏储层多尺度孔隙中石油的微观赋存状态分析,明确了近源油藏储层具从大孔到纳米孔隙连续性赋存石油特征,且微孔至纳米孔隙含油饱满;远源油藏储层石油有选择性地赋存在大至中孔隙中,纳米孔隙不含油。延长组7段(长7)生烃增压产生的异常压力,控制石油在具多尺度孔隙的低渗透致密砂岩储层中差异性赋存,这为认识盆地致密油分布规律提供了理论依据。由此指出长7烃源岩分布区的长8油层组上部、长7油层组和长6油层组下部致密砂岩是今后致密油研究和勘探开发的主要目标。
Identifying pore distribution of tight reservoirs and the microscopic occurrence of oil in pores of different scales is critical to understand the characteristics of tight oil.In this study,tight sandstone samples from Yanchang Formation,Ordos Basin,were investigated through Nuclear Magnetic Resonance（NMR） experiment.Nano-scale pores are common in the tight sand of Yanchang Fm and macro-scale,medium-scale,small-scale,micro-scale and nano-scale pores co-exist in the samples.The microscopic occurrence of oil in multiple-scale pores are compared between near-source reservoir and far-source reservoir.In near-source reservoirs,oil exists in all kinds of pores and the micro-pores and nano-pores are saturated with oil.In contrast,in far-source reservoirs,oil selectively occur in macro-scale and medium-scale pores and nanopores contains no oil.The abnormal pressure caused by hydrocarbon-generation in Chang 7 layer is believed to be the main controlling factor for different occurrences of oil in multi-scale pores in tight reservoir.This provides a theoretical basis for understanding the distribution of tight oil reservoir.It is concluded that the upper Chang 8,the Chang 7 and lower Chang 6 reservoirs within the distribution area of Chang 7 source rock are the main potential targets for tight oil exploration in the future.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2013年第3期288-293,共6页
Oil & Gas Geology
基金
中国石油天然气股份公司重大科技专项(2011E-2602)
鄂尔多斯盆地大型岩性地层油气藏勘探开发示范工程(2008ZX05044)
关键词
核磁共振技术
多尺度孔隙
微观赋存状态
致密油
低渗透储层
鄂尔多斯盆地
Nuclear Magnetic Resonance
multi-scale pore
microscopic occurrence
tight oil
low permeability reservoir
Ordos Basin
