段塞蒸汽驱提高超稠油油藏采收率技术及其应用

EOR technology on ultra-heavy oil reservoir and its application with slug steam drive

目前超稠油开发以蒸汽吞吐为主,但单井吞吐的蒸汽波及范围较小,且随着注气吞吐周期轮次的增加,注入蒸汽对油井近井地带油层的冲刷溶蚀作用越来越明显,油层存水率逐渐升高,采出液也逐渐呈现高含水的特征,导致超稠油油藏开发效果逐渐变差。为了提高超稠油油藏的最终采收率,通过对开发方式的模拟研究,确定了段塞汽驱开发试验,实现了对地层能量的补充,扩大了蒸汽波及范围,有效提高了蒸汽利用率,同时针对汽窜影响,开展专项治理。针对单家寺油田单56块油藏特点,对蒸汽速度、段塞长度及注采比参数进行了优化,合理调整生产参数,采用高温泡沫剂和注氮气混合高温发泡剂与蒸汽混注,对高渗层采用有效封堵等技术,现场应用获得成功,使边底水中厚层砂岩超稠油油藏蒸汽采油速度、累积油气比和最终采收率得以提高。

At present, the development of ultra-heavy oil is mainly steam stimulation, but single well steam stimulation only sweeps a small area. Along with the increase of steam injection cycle rounds, the denudation of injected steam to the immediate vicinity of wellbore of oil well is more and more obvious, with the water storage rate of reservoir increased gradually and with the high water content presented in produced fluid, which results in a gradual deterioration of development effect in ultra-heavy oil reservoir. In order to improve the uhimate reeovery factor of ultra-heavy oil reservoir, the development test of slug steam drive is conducted and the supplement of producing energy is realized through the simulation of development mode. The area of steam sweeping is expanded, effectively improving the steam utilization ratio. At the same time, special treatments are carried out for the impact of steam channeling. Aiming at the reservoir features of Shan56 Block, steam velocity, slug length and the parameter of injection- production ratio are optimized and the production parameters are adjusted rationally. The techniques of mixing the high-temperature foaming agent and nitrogen with high-temperature foamer and steam and the effective plugging for high permeability reservoir are adopted to ensure the success of key technology in field application, which improves the oil production rate of ultra-heavy oil reservoir with edge-bottom water in medium-thick sandstone, and the cumulative oil-gas ratio and ultimate recovery factor.