北美典型致密油地质特征对比及分类

Comparison of geological characteristics and types of typical tight oil in North America

为全面认识致密油,汲取国外成功的开发经验,从而推动我国致密油发展,通过详细对比北美地区巴肯组、鹰滩组和卡尔蒂姆组的地质特征,从方便储量计算的角度,提出了更为完善的致密油定义,并系统划分了致密油的类型.结果表明：致密油主要是指以吸附或游离状态赋存于未纳入常规油田产区的低渗储层（卡尔蒂姆组）或地层深部致密沉积岩（巴肯组、鹰滩组）中,且必须通过水平井或多级压裂等开发技术才能实现经济采出的轻质非常规石油聚集,可以划分为2个大类、5个亚类,其中,巴肯组致密油资源量最大,具有“大而肥”的特点,主要赋存在渗透率为0.01～1.00 mD的致密砂岩中,卡尔蒂姆组致密油资源量次之,主要赋存在渗透率为0.1～10.0 mD的砂质泥岩中,而鹰滩组致密油资源量最低,主要赋存在渗透率为0.000 001～0.000 100 mD的致密灰岩中.

In order to understand tight oil comprehensively, learn the successful development experiences and then promote the development of tight oil in our country, this paper analyzed and compared the geological characteristics of Bakken Formation, Eagleford Formation and Cardium Formation in North America. From the aspect of the convenient reserve calculation, more reasonable tight oil definition was put forward, and the types were divided systematically. The study results show that tight oil is an unconventional light petroleum accumulation in tight sedimentary rocks, including tight source rocks （mudstones） in place in a free or adsorbed state and tight sandstones and carbonates interbedded with or adjacent to source rocks （Bakken Formation and Eagleford Formation）, as well as the reservoirs which have not been developed with conventional technology （Cardium Formation）. The reservoir permeability is extremely low and the reservoir oil can＇t achieve economic recovery unless using horizontal well and multistage fracturing techniques. Among the three tight oil reservoirs, tight oil resource of Bakken Formation is the largest and mainly occurs in the tight sandstone, of which the permeability is between 0.01 mD and 1.00 mD. Tight oil resource of Cardium Formation comes the second, and the lithology is mainly sandy mudstone and the permeability is between 0. 1 mD and 10.0 mD. Eagleford Formation has the minimum amount of tight oil, and this kind of tight oil mainly occurs in the tight limestone and the range of permeability is 0.000 001 mD to 0.000 100 mD.