Study On Emulsification And Viscosity Reduction Of Nitrogen - Assisted Heavy Oil

Viscosity reduction through emulsion formation of wellbore for G16 heavy oil block of Xiaoguai Oilfield have been carried out in the previous study, and conducted on-site construction applications, then achieved certain results to improve heavy oil recovery. But there are still some problems:one well with one formula increases the difficulty of construction; with the increasing exploitation of heavy oil, there will not be able to rely on the energy of formation to lift heavy oil from the ground to the wellbore to achieve viscosity reduction of wellbore. Therefore, it is necessary to carry out viscosity reduction through emulsion formation of stratum in the interior to solve the problem of heavy oil flowing in the formation and supplement formation energy, then, achieve continued exploitation of heavy oil.In this article, the degassing dehydrated crude oil of 7 wells (G1606, G1610, G306, G16, G1605, G1601, G1602) are mixed at first, then the basic physical parameters are measured, such as viscosity, density, acid of the mixing heavy oil, determine the rheology and the relationship between viscosity and temperature of the mixing heavy oil. At the following time the amount of emulsion viscosity reducer HD and stabilizer SH-1 are determined, and the affecting factors of viscosity reduction through emulsion formation are analyzed, such as volume ratio of oil/water, salinity, temperature, etc. Next, the actual reservoir conditions is simulated through physical simulation experiments, construction parameters are designed according to the actual situation, and then, the EOR effect of viscosity reduction is researched through emulsion formation and heavy oil emulsion viscosity reduction assisted by nitrogen, the effects of various parameters (the injection volume of nitrogen, the injection amount of viscosity reducer, the injection rate of viscosity reducer, the injection temperature of viscosity reducer, soak time, etc.) on the recovery situation are determined through the orthogonal test, eventually the process parameters of nitrogen assisted viscosity reduction through emulsion formation of heavy oil are ascertained. Then, we focus on the effects of nitrogen on the viscosity reduction through emulsion formation of heavy oil. Finally, the nitrogen-assisted heavy oil emulsification viscosity will be tested in oil field.The results show that:the formula of viscosity reduction system of G16 block is HD (0.35%)+SH-1 (300 mg/L), this system can make viscosity reduction rate reached 97.52%, stable time reached 48-56 h. The EOR effect of heavy oil emulsion viscosity reduction is not very good, its throughput cycle is short, so economical and effective exploitation of heavy oil can not be achieved, but the indoor simulation experiment of heavy oil emulsion viscosity reduction assisted by nitrogen achieved good results of EOR, the highest recovery improved 19.89% of G16 heavy oil block. Physical simulation experiments show that the influence of these parameters on recovery of heavy oil from largest to smallest are following that:the injection amount of viscosity reducer, the injection volume of nitrogen, soak time, the injection rate of viscosity reducer. The optimal level of each parameter is that:the injection amount of viscosity reducer is 135 mL, the injection volume of nitrogen is 637.2 mL, the injection rate of viscosity reducer is 0.67 mL/min, the soak time is 24 h. Nitrogen injection complements the formation energy, maintain reservoir pressure, and ultimately improve heavy oil recovery. In addition, the injection of nitrogen to some extent reduces the interfacial tension between oil and water, almost no effect on post-produced liquid emulsion break dehydration. The field test showed that the amount of daily fluid production of heavy oil well G1601 is up to 6.8 t/d and nissan oil is up to 4.4 t/d after measuring, the effect of oil increase is obvious, and the throughput cycle is long, the oil is increased 229.8 t within four months after the measure.