Abstract
The recovery of hydrocarbons has gone into deep and ultra-deep waters. Typically, operations from such an environment make the system susceptible to flow assurance challenges. Operations with long subsea flowlines need special attention with respect to flow assurance problems, especially with respect to wax deposition and risk of hydrate formation. As a result, during such operations, it becomes very crucial to evaluate the flowline sizes, flow rates and subsea flowline lengths to minimize flow assurance problems. For the wax deposition control, the operating temperature must be maintained above wax appearance temperature (WAT) by either insulation or electrical heating depending on the cost and energy efficiency factors. In this study, several multiphase simulations were carried out using PIPESIM software to investigate the effects of flowline sizes, flow rates, insulation material, type and configuration on flow assurance of waxy crude over 10.2 km between the wellhead and the first stage separator on the platform. Considering the implications of these factors for flow assurance. The data and results obtained from this study suggest that line size of 0.29 m, the flow rate of 3280 m 3 /d, poly-urethane foam, and pipe-in-pipe insulation type are favourable to flow assurance of waxy crude with respect to maintaining the temperature of the fluids above the wax appearance temperature of 26 o C; and also to deliver the fluids to the platform at the recommended pressure of over 11 bar. Keywords: Waxy Crude. Flow Assurance. Flow Rates. PIPESIM software, wax control. DOI: 10.7176/ISDE/11-3-02 Publication date: April 30 th 2020
Highlights
Oil and gas exploration and production accounts for over 35 per cent of energy sources worldwide, making it a major and crucial source of energy to the world energy mix. (International Energy Agency, 2018)
6.Conclusions Several multiphase simulations were carried out in this work using PIPESIM software to investigate the effects of flowline sizes, flow rates, insulation material, type and configuration on flow assurance of waxy crude over 10.2 km between the wellhead and the first stage separator on the platform
The data and results obtained from this study suggest that line size of 0.29 m, the flow rate of 3280 m3/d, poly-urethane foam, and pipe-in-pipe insulation type are favourable to flow assurance of waxy crude with respect to maintaining the temperature of the fluids above the wax appearance temperature of 26oC and to deliver the fluids to the platform at the recommended pressure of over 11 bar
Summary
Oil and gas exploration and production accounts for over 35 per cent of energy sources worldwide, making it a major and crucial source of energy to the world energy mix. (International Energy Agency, 2018). The gradual depletion of onshore hydrocarbon reserves has led to the rapid increase in oil and gas exploration in offshore regions These regions contain reserves which may be situated in shallow, deep or ultra-deep waters. Flow assurance refers to the guarantee of the flow of hydrocarbon from the wellbore up until the point of sale or processing (Jung et al, 2014; Kang et al, 2014) This is a challenge due to the large water depth from the seabed to the host platform, in cases where a floating platform is utilized, or the long tie-in distances in cases where tie-backs are used to develop such a field. The huge temperature differential between the subsurface temperature and the seabed temperature leads to flow assurance issues This makes flow assurance a major aspect of offshore field development (Hoffmann, 2012)
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