极浅层稠油油藏油砂特征及潜力评价

油砂和浅层稠油是具有超低开发成本的两类非常规资源，非常规与历次油价下跌密切相关，使得这类资源成为了全球瞩目的焦点.春风油田兼具地表油砂和浅层稠油两类非常规，但岩心在地表会呈现极松散的不成型油砂，使得一些基础常规实验无法测定，影响到进一步分析评估.因此，需要针对这类非常规资源进行一系列新实验，即在常规实验的基础上，增加热物性、高温相渗、核磁共振等专项实验，并与常规实验结果进行比较.热物性实验发现，储层内部灰质、泥质夹层导热性良好，反映热波及效率会较高.相渗实验发现，油砂的油水相渗Kro和Krw的终点间距较大，两相覆盖范围宽，束缚水饱和度低，且孔隙越均匀，油相相对渗透率就越大.实验还发现，热物性、相渗、阵列感应实验得到的不同参数，相互之间存在一定相关性.利用新的核磁共振方法，可直接得到束缚水饱和度，获取原始含油饱和度，进而求取驱油效率，大大简化实验步骤和测试项目.最后，通过驱油效率计算和潜力评价发现，虽然经过多轮次吞吐，油砂目前的平均含油饱和度仍然很高，反映了稠油储量动用程度低，仍有很大的开发潜力.

FEATURES AND ASSESSMENT OF OIL SAND IN SHALLOW HEAVY OIL RESERVOIRS

Oil sand and shallow heavy oil are low-cost unconventional resources, which greatly impact the oil prices. In Chunfeng Oilfield, which is the combination of both kind resources, the rich oil sand in shallow reservoirs is loose due to weak compaction. Therefore, it is difficult to carry out some routine experiments, such as physical properties and oil saturation. Beside conventional tests, some new experiments are necessary for these unconventional resources, i.e. thermal properties, high-temperature permeability analysis, NMR saturation test, etc. Thermal experiments show that both muddy and limy interlayers in reservoirs are usually high thermal conductivity, indicating a high thermal efficiency during development. Phase permeability experiment, which reflects pore sizes and connectivity, shows great difference between the ending values of Kro and Krw, with a wide range of 2-phase covers and low irreducible water saturation. The evener the pore sizes are, the higher the oil phase relative permeability is. NMR can directly obtain the value of Swi and original oil saturation, and then calculate the oil displacement efficiency. The potential assessment result shows that after many rounds of steam stimulation, the inter-well oil saturation is still high, which reflects the low oil displacement efficiency, suggesting a great potential of the oil sand.