大庆油田北一二排西部分质聚合物驱试验效果

FIELD TEST RESULTS OF THE SPLIT-QUALITY POLYMER FLOODING IN WEST N1-2-P OF DAQING OILFIELD

北一二排西部T组油层聚合物驱试验区是大庆油田第一个将注采井距缩小到175m的上返试验区，试验区射开了所有油层，目的是确定二类油层技术界限。试验过程中暴露出的主要问题是河道砂及有效厚度大于1m油层在175m井距、1600万相对分子质量注入条件下油层动用程度可达到80％以上，而有效厚度小于1m油层连续动用比例仅为30％，表外层不能连续。为改善试验区层内、层间矛盾，挖掘各类油层潜力，针对试验区不同性质油层开展了不同相对分子质量的分质聚合物驱试验。结果表明，对不同性质油层采用匹配的聚合物相对分子质量和注入质量浓度，可提高注入能力，扩大聚合物波及体积。分质聚合物驱可提高聚合物驱效率，进一步提高采收率。

The polymer-flooding pilot-test area in T Formation oil reservoirs of West N1-2-P is the first upwards-going experiment whose injector spacing reduced to 175 m. All the oil layers of the area are perforated so as to determine technical limits of the Class II oil reservoirs. The exposed main problems in the course of the test are that for the channel sands and oil layers whose effective thickness more than l m, under the conditions of 115 m well spacing and 16 million molecular weight, the developed degrees of the oil reservoirs are all up to 80% ; on the contrary, the oil layers whose thickness less than lm, the continuously developed proportion is only 30%, and further more the non-tabulated reservoirs can not be produced successively. In order to solve the contradictions within and between layers and furthermore tap the potentials of various types of oil layers in the pilot area, the split-quality experiments of polymer flooding with different molecular weights are caught out according to the different properties of oil reservoirs. The results show that the matched molecular weights and injection concentrations according to the above features can enhance the injection capacity and enlarge the swept volume of the polymer. The polymer flooding can improve oil-displaced efficiency and furthermore enhanced oil recovery.