Influence of Resin/Asphaltene Influence of Resin/Asphaltene Ration on Paraffin Wax Deposition in Crude Oils from Barrackpore Oilfield in Trinidad
- Celia Josefina Garcia-james (Petroleum Co-Trinidad & Tobago) | Fernando Pino (Universidad de Oriente) | Tomas Marin (Universidad de Oriente) | Utam S. Maharaj (Strategic Global Technologies)
- Document ID
- Society of Petroleum Engineers
- SPETT 2012 Energy Conference and Exhibition, 11-13 June, Port-of-Spain, Trinidad
- Publication Date
- Document Type
- Conference Paper
- 2012. Society of Petroleum Engineers
- 4.1.5 Processing Equipment, 4.3.3 Aspaltenes, 5.8.5 Oil Sand, Oil Shale, Bitumen, 2.4.3 Sand/Solids Control, 4.1.9 Tanks and storage systems, 4.1.2 Separation and Treating, 5.1.2 Faults and Fracture Characterisation, 4.6 Natural Gas
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The precipitation and deposition of paraffin wax during production, transportation and storage of crude oil are common problems encountered by the majority of oil producers around the world. During the last decade, the Barrackpore oilfield in Trinidad has reported wax deposition on nineteen (19) of its wells. This condition has been exacerbated due to the reduction of temperature, pressures and losses of gas which have allowed wax to separate from the crude oil, precipitate and deposit in the walls of tubings, thereby reducing their diameter and restricting the flow of oil through the system. The situation represented a serious problem for Petroleum Company of Trinidad & Tobago (Petrotrin), because it caused a reduction in the production levels and significant economic losses. This study was based on the necessity to find feasible solutions to minimize this problem. The research was focused to determine if there was influence of the resin/asphaltene ratio on wax deposition under laboratory conditions, to start an understanding process of the causative factors of these depositions. In addition, the influence of two (2) different wax inhibitors were studied for comparison, since it is understood they may behave as resins peptizing the asphaltene particles and keeping them in solution. To ensure the validity of this investigation, extensive bibliographical reviews were undertaken, followed by numerous laboratory tests such as SARA analysis, Cloud Point Tests and Wax Content Tests as methods to evaluate the crude oil and its behaviour under various conditions. The results showed that wax and asphaltene content are the controlling factors in the precipitation and depositions processes respectively.
Paraffin deposition related problems have manifested itself in oil production processes around the world; from formation deposition, down hole equipments to flow lines, separators and storage tanks. Paraffin deposition generally consists of wax, asphaltene, resins and sands; the main component being wax, which is a solid state non-cyclic alkane of high molecular weight (320-560 atomic mass units) , with 15 to 80 carbon atoms. Under the oil formation conditions, the wax is dissolved in crude oil; however, in the course of the crude oil flowing up to the surface, due to a decrease of pressure and temperature and the release of gas dissolved, the wax separates out to form crystals which will grow, aggregate and then precipitate on the walls of oil tubing causing reduction of its diameter and requiring more power to force the same amount of crude oil through the system. Most investigators focus on separation studies of each solid component and the opinions about the influence of asphaltenes on wax deposition are divided. Some authors have inferred that asphaltenes aid in nucleation of wax particles thereby promoting wax deposition (Stout, 1979) while others have inferred that they act as natural inhibitors and hence help to retard deposition (Patton and Jessen, 1965; Bucaram, 1967; Bilderback and McDougall, 1969).
In Trinidad, more specifically Petrotrin began wax deposition studies in 1982 and have been related to applicability of mitigation methods while the main causes of wax deposition have not been completely understood. To date wax deposition continues to be a serious problem that generates a large cost increase to the Petroleum Company of Trinidad and Tobago due to cleaning operations, chemical treatments and lost of production.
The main objective of the present work is the evaluation of the influence of the resin/asphaltene ratio in the deposition of wax under laboratory conditions, to start an understanding of the processes involved leading to a possible solution.
The crude oil exploitation industry in Trinidad has been plagued with chronic wax deposition problems. As the onshore and offshore fields become more mature, the problem has exasperated by the need to produce every barrel of oil available.
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