Oil/Water Separation Experience From a Large Oil Field
- Sunil L. Kokal (Saudi Aramco) | Abdulla Al Ghamdi (Saudi Aramco)
- Document ID
- Society of Petroleum Engineers
- SPE Production & Operations
- Publication Date
- August 2006
- Document Type
- Journal Paper
- 365 - 371
- 2006. Society of Petroleum Engineers
- 2.5.2 Fracturing Materials (Fluids, Proppant), 4.1.2 Separation and Treating, 4.3.3 Aspaltenes, 4.2.3 Materials and Corrosion, 4.2 Pipelines, Flowlines and Risers, 4.1.5 Processing Equipment, 4.3.4 Scale, 5.2 Reservoir Fluid Dynamics, 4.1.3 Dehydration
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This paper discusses challenges related to emulsions that have been encountered in a large Saudi Arabian field. The field produces from several different reservoirs with a range of fluid properties. These properties provide an interesting case of operational challenges in oil/water separation, including increased incidents of shorting in the separator, tripping of equipment, and increased demulsifier consumption.
This paper presents the results of a comprehensive study that was initiated to understand the main causes of emulsion formation in the field and ways to optimize oil/water separation. The effects of several recommendations that were implemented by operations engineering in the field were evaluated. These include the conversion of a two-phase separator into a three-phase separator, splitting of the demulsifier injection between offshore producing platforms and onshore wet-crude handling facilities, and field trials with promising chemicals. The demulsifier costs have been reduced by more than 50% by the implementation of retrofitting and proper demulsifier-injection strategies. The results presented in the paper provide invaluable operational experience, and many lessons learned are applicable to any crude-oil-treating facility.
Crude oil has to be separated from produced water at wet-crude handling facilities or gas/oil separation plants (GOSP). The GOSP typically produces dry crude, gas, and water. The incoming oil and water can form an emulsion and may be difficult to separate. When emulsions are tight, they can create a number of operational challenges such as tripping of equipment in a GOSP, plant instability, increased demulsifier consumption, production of off-spec crude, and high-pressure drops in flow lines. These emulsions have to be treated to meet crude specifications for transportation, storage, and export and to reduce corrosion and catalyst poisoning in downstream processing.
This paper presents the case history of a Saudi Arabian field that had been experiencing emulsion-related challenges (Kokal and Al-Juraid 1999). This field produces from seven different reservoirs including the more viscous crude from the "Arab?? reservoirs. These oils range in viscosity from 2 cp to more than 10 cp (at 22°C), and the American Petroleum Inst. (API) gravities range from 28 to 40. The n-pentane asphaltene content varies from 0.2% to more than 7%, and water cut for producing wells ranges from dry wells to more than 70%.
|File Size||1 MB||Number of Pages||7|
Kokal, S.L. 2005. Crude OilEmulsions: A State-Of-The-Art Review. SPEPF 20 (1):5-13. SPE-77497-PA.
Kokal, S.L. and Al-Juraid, J.I. 1998. Reducing Emulsion Problems ByControlling Asphaltene Solubility and Precipitation. Paper SPE 48995presented at the SPE Annual Technical Conference and Exhibition, New Orleans,27-30 September.
Kokal, S.L. and Al-Juraid, J.I. 1999. Quantification of Various FactorsAffecting Emulsion Stability: Watercut, Temperature, Shear, Asphaltene Content,Demulsifier Dosage, and Mixing Different Crudes. Paper SPE 56641 presentedat the SPE Annual Technical Conference and Exhibition, Houston, 3-6October.
Kokal, S.L. and Wingrove, M.D. 2000. Emulsion Separation Index: FromLaboratory to Field Case Studies. Paper SPE 63165 presented at the SPEAnnual Technical Conference and Exhibition, Dallas, 1-4 October.