致密油藏碳化水驱提高采收率方法

目前,国内尚无碳化水驱研究报道,国际上碳化水驱研究仅针对中高渗、低渗油藏。为此针对致密油藏,首次研究碳化水和碳化水+表面活性剂驱提高采收率的可行性。基于长庆油田M区致密储层,开展了碳化水驱、CO_2水气交替注入、表面活性剂驱、碳化水+表面活性剂驱室内实验,明确碳化水驱的增油潜力,证明碳化水驱提高致密油藏采收率的可行性。实验结果表明,碳化水驱比水驱增加7%的采收率,比CO_2水气交替注入增加3%的采收率;碳化水+表面活性剂驱开发效果最好,比水驱增加10%的采收率。针对表面活性剂驱、碳化水驱、碳化水+表面活性剂驱进行数值模拟研究,并与室内实验结果进行对比,结果表明,常规组分模型普遍高估碳化水驱开发效果,通过引入亨利定律和表面活性剂驱模型,能够较为准确地预测碳化水驱的开发效果,与实验结果相比误差低于1.2%。

EOR method by the carbonated water injection (CWI) for tight oil reservoirs

At present, there is no report about carbonated water injection (CWI) in China, and there exist the studies of the CWI abroad only focusing on the middle-high and low permeability oil reservoirs. In the light of tight oil reservoirs, the feasibility of the CWI for enhancing the oil recoveries by CWI and CWI+surfactant (CWI adding surfactant, ACWI) flooding was researched for the first time. Based on the reservoir condition of Block M in Changqing Oilfield, the following indoor experiments were conducted: CWI, water alternating CO 2 injection, surfactant flooding and ACWI flooding to make sure of the oil incremental potentials of the CWI and moreover to ensure the feasibility of CWI'EOR in the tight oil reservoir. The experimental results demonstrate that CWI recovery is 7% more than that of the water flooding, and 3% more than the degree of the CO 2/water alternating injection;ACWI achieves the best performance with 10% oil recovery than that of the water flooding. In the light of the surfactant, CWI and ACWI floodings, their numerical simulations were studied, and furthermore the contrast was engaged with the results of the indoor experiments, the results show that the conventional compositional model generally overestimates CWI’s development effects, with the help of inducing Henry’s law and surfactant model, the effects stated above can be more accurately predicted, comparing with the experimental result, the error is lower than 1.2%.