氮气泡沫调驱技术及其矿场应用

ADJUSTABLE DRIVING TECHNIQUE BY NITROGEN FOAM AND ITS FIELD APPLICATION

渤海油田储层非均质、原油黏度大,强注强采引起注入水层内绕流和层间窜流,水驱开发效果较差。采用室内实验和物理模拟方法研究了氮气泡沫调驱工艺技术,根据泡沫半衰期、阻力系数和采收率等指标优选出氮气泡沫体系并确定了注入方案,水驱阶段采收率分别为27.7%,26.8%和28.3%,相比水驱泡沫连续注入、2个段塞注入、3个段塞注入分别提高19.7%,23.5%和31.7%;泡沫采取小段塞分段注入效果更好。矿场应用表明:泡沫连续注入井组平均含水率下降5%,累计增油量1.86×10~4 m^3,有效期12个月;而泡沫分段塞间隔注入井组平均含水率下降7.6%,累计增油量3.58×10~4 m^3,有效期19个月。泡沫分段塞间隔注入好于连续注入,可有效解决气窜和吸液剖面反转问题,为改善水驱开发效果提供了新途径。

Due to the reservoir heterogeneity and rather serious oil viscosity of Bohai Oilfield, the strong water injection and oil production result in the flow around interlayer and the crossflow amoog the reservoirs, in the end the water flooded development effects are rather poorer. With the help of problem indoor experiment and physical simulation method, the adjustable driving technology of nitrogen foam is studied. According to the indexes of foam half- life, resistance coefficient and recovery and so on, the above technical system is optimized and the injection program is determined. Comparing with the continuous injection of foam in water flooding, two-slug and three-slug injections, the water-flooded stage recovery are 27.7% , 26.8% and 28.3% respectively, increased by 19.7% , 23.5% and 31.7% respectively, the effects of small slug step-by-step injection are more favorite. The field application shows that the average water cut drops 5% for the well group of continuous foam injection, the accumulated incremental oil is up to 1.86×10^4m^3, and the valid period reaches 12 months; while the corresponding water cut for the well group of interval plug injection decreases by 7.6% , the total increased oil is 3.58 ×10^4m^3 , lasting for 19 months. The latter injecting mode is better than the former： the problem of the gas cross and liquid-absorbing cross section inversion can be effectively solved, thus the new approach of improving water flooding effects has been provided.