Design of a Solar Parabolic Trough Capable of Producing Steam for Enhanced Oil Recovery in Trinidad and Tobago

Enhanced oil recovery by steam injection requires the burning of natural gas, a finite and expensive resource for steam production. However, solar energy can be harnessed for steam production via solar parabolic troughs. In this study, the design and application of a solar parabolic trough, in tandem with a heat exchanger for producing steam for Enhanced Oil Recovery (EOR) in Trinidad and Tobago is presented. Excel spreadsheets were developed to perform the calculations and to optimize the size and design of the parabolic trough collector for maximum heating efficiency. The parabolic trough designed was 36 m in length and consisted of a parabolic aluminum reflector, stainless steel receiver tube, and a glass envelope that surrounded the receiver tube. The heat transfer fluid used was Therminol VP-1, a synthetic oil, which was heated up to 403 °C. Once heated, the heat transfer fluid was then transferred to a heat exchanger whereby steam was produced at 300°C. Overall, 4 of the parabolic trough collector systems were required to heat enough fluid to fill the calculated 343 tubes of the heat exchanger, which were 0.091 m in diameter and 4.9m in length. The total cost of the parabolic troughs and the heat exchanger tubes was calculated to be USD 119,562. By having a mass flow rate of 46 kg/s for the water within the heat exchanger, approximately 1630 barrels of oil were economically produced at a maximum steam oil ratio of 4.5 after one day of steam injection. A cash flow projection was completed using both operational and capital expenditure of the parabolic trough collector. From this study, the parabolic trough system was shown to generate a profit of USD 1.8 MM after six months of steam injection. Profit calculation considered both capital and operating expenditure as well as the income gained from oil recovery due to the parabolic trough collector. The spreadsheet developed can be used to design similar systems of steam generation for enhanced oil recovery projects of different scales.