大庆西部斜坡稠油地层流动性影响因素实验研究

Influencing Factor Analysis of Heavy-Oil Reservoir Mobility with Laboratory Test in Western Daqing Sploe

针对大庆西部斜坡稠油在开采过程中与地层水和注入水乳化生成高黏的油包水型乳状液降低地层流动性的问题,通过流变性实验和岩心流动实验,研究了乳化、温度及地层渗透率对稠油黏度和地层流动性的影响规律,明确了原油在地层中流动困难的原因及改善流动性的技术方向。结果表明:含水乳化和温度是影响其黏度的主要因素,温度由30℃上升至120℃,脱水稠油黏度降低了95.5%;当含水率低于70%时,原油与水形成油包水型乳状液,含水率越大黏度越大,含水率为70%的稠油的黏度是脱水黏度的30倍左右;地层渗透率、温度及含水乳化对原油地层流动性具有显著的影响,地层渗透率越低、温度越低、含水乳化越严重,原油流动性越差,不同温度和含水率下的采油指数相差可达10倍以上。因此,促使含水稠油乳状液转相是油田降黏增产的有效途径。研究成果对同类油藏开发具有重要的指导意义。

Rheological and core displacement experiments were conducted to clarify the reservoir mobility reduction results from the high-viscosity water-in-oil emulsion due to the emulsification between formation water and injection water in the heavy-oil reservoir of western Daqing slope.The effects of emulsification,temperature and formation permeability on heavy-oil viscosity and formation mobility were investigated to explore the causes of low oil mobility and technical orientation to improve mobility.Result indicates that the viscosity is greatly dependent on the water emulsification and temperature.The dehydrated heavy-oil viscosity can be reduced by 95.5%when the temperature is increased form 30℃to 120℃.The crude oil and water from a water-in-oil emulsion when the water-cut is below 70%,and the viscosity increases with the increase of water-cut.The viscosity of heavy-oil with a water-cut of 70%is about 30 times of that with dehydration.The formation oil mobility is greatly dependent on formation permeability,temperature and water emulsification.Low permeability and low temperature result in a strong emulsification and low oil mobility.The oil production index difference between different temperatures and water-cuts can reach more than 10 times.Therefore,phase inversion of water-bearing heavy-oil emulsion is an effective means to reduce viscosity and enhance production.This research could provide a significant guidance for the development of similar reservoirs.