长庆超低渗砂岩储层可动流体实验

 评价超低渗砂岩储层渗流能力及开发潜力时，可动流体及其赋存特征是重要参考因素之一。利用核磁共振测试实验及离心实验，对长庆油田的6块超低渗砂岩储层岩样进行离心标定，定量分析了不同尺寸喉道控制的可流动孔隙空间大小，结果表明，对于长庆超低渗储层砂岩，以往低渗储层砂岩离心法所用的经验值1.38MPa已不再适用，最佳离心力应为2.07MPa；有效喉道半径下限为0.07μm，T2截止值为12.47ms。将实验结果与长庆油田的另外3块特低渗砂岩、6块致密砂岩岩样的实验结果进行对比，结果表明，长庆超低渗砂岩岩样大喉道控制的可动流体百分数小于长庆特低渗砂岩岩样，而大于长庆致密砂岩岩样。

Experimental Study of the Movable Fluid of Super-low Permeability Sandstone Reservoirs in Changqing

For the evaluation of the seepage capacity and the development potential of super-low permeability sandstone reservoirs, the percentage of the movable fluid and its distribution are key factors to be considered. To obtain the percentage of the movable fluid, one has to determine T2 cutoff value T2cutoff accurately. With Nuclear Magnetic Resonance (NMR) technology, centrifuged laboratory experiments were carried out for the centrifugal calibration with 6 samples from super-low permeability sandstone reservoirs of Changqing, together with quantitative calculations of the movable pore space controlled by various throats with different sizes in these samples. The experiment results of these 6 samples are compared with those of 3 ultra-low permeability ones and 6 tight ones also from Changqing. The following conclusions are drawn. For the sandstones of super-low permeability reservoirs in Changqing, the empirical value of 1.38MPa for centrifuging sandstones of low permeability reservoirs is no longer applicable. The optimal centrifugal force is 2.07MPa, which is used to estimate the lower limit of the effective throat radius, which is 0.07μm. The T2cutoff of super-low permeability sandstones in Changqing is suggested to be 12.47ms. The percentage of the movable fluid controlled by large throats in super-low permeability sandstone samples from Changqing is less than that in ultra-low permeability ones from Changqing and more than that in tight ones also from Changqing.