Experimental investigation of various physical factors affecting the stability of water-in-oil emulsions in oil production
[Thesis]
A. K. M. Al-Jaziri
King Fahd University of Petroleum and Minerals (Saudi Arabia)
1995
90
M.S.
King Fahd University of Petroleum and Minerals (Saudi Arabia)
1995
Produced fluids from some wells in certain Saudi Arabian oil fields remain in the form of a stable emulsion before entering the Gas Oil Separation Plant (GOSP). This causes significant problems for the smooth operation of the GOSP as a result thousands of barrels of oil per day can not be produced. A laboratory system able to simulate various aspects of emulsion flow in the field was designed. Using this system we examined phase separation of field emulsions under dynamic conditions at temperatures and pressures similar to those existing at GOSPs in the oil fields under the influence of an electrostatic field. Also we examined the effectiveness of various demulsifying chemicals as well as the combined effects of temperature and demulsifier on breaking field emulsions. Finally an optimization study was done to find the optimum concentration of the best demulsifying chemicals. Based on the results obtained it is concluded that at reservoir temperatures of about 220F emulsions are unstable and are mostly formed after fluids enter the wellbore and during their flow into the GOSPs. The temperature plays a critical role on the stability of emulsions since heating these emulsions helps in breaking them into two phases, oil and water. Also addition of demulsifiers reduces emulsification tedency of produced oil extensively. It is found that, among the four commercially available demulsifiers used in this study, Champion demulsifier is the most effective one in resolving tight emulsions. The concentrations of this demulsifier needed to resolve tight emulsions from problem wells are over 10 folds greater than that of non-problem wells. It is important to study the demulsification process under dynamic condition which represents the condition that exists in the oil fields since the amount of demulsifier needed to resolve tight emulsions under dynamic condition is three to four times less than that needed under static condition.