Feasibility and Evaluation of Surfactants and Gas Lift in Combination as a Severe-Slugging-Suppression Method
An experimental study of severe-slugging suppression by use of a combination of surfactants and gas lift was conducted with a facility comprising a 3-in.-inner-diameter, 65-ft-long, –3°-inclined flowline, followed by a 45-ft-long vertical-riser system. Air and water were used as fluids. The surfactant used was a foaming agent capable of forming stable foams in all brines for a wide range of pH values. Pressure behavior in the flowline/riser system was monitored, and input-gas-, injection-gas-, liquid-, and surfactant-flow rates were measured continuously. In addition, visual observations were made to identify severe slugging. Effects of the proposed method were quantified with a modified elimination performance index (MEPI) that considered not only pressure fluctuations, but also backpressure effects.
Thirty tests were conducted. The data were analyzed for the severe-slugging suppression of the combination of surfactant and gas lift, the effect of gas lift on surfactant injection, and the effect of the surfactant on the reduction of the gas lift gas. The combination technique with the highest gas lift rate completely eliminated the severe slugging for all tests conducted. Surfactants were able to suppress severe slugging for most of the cases. The performance of the “only-surfactant injection case” increases as the gas/liquid ratio increases. For all of the tests, backpressure reduction was observed. The MEPI is used as the main parameter to assess the performance of the severe-slugging-suppression methods. Gas lift not only contributes to density reduction through volumetric increase of gas in the riser, but it also reduces the mixture density by promoting more foam generation. There were reductions in the gas lift rate from the original maximum gas lift injection rate for all the tests conducted with surfactant injection.
Phillips 66 Forms JVs To Boost Takeaway Capacity from Bakken and Permian
Phillips 66 and partners in two separate joint ventures are building the Red Oak and the Liberty pipeline systems to deliver a total of approximately 750,000 BOPD to the US Gulf Coast with startup of service in early 2021.
Cactus II Pipeline To Start Partial Service in the Permian by Year End
Approximately 90% of construction work has been completed on the pipeline, which is expected to transport up to 670,000 BOPD from the Permian Basin to the US Gulf Coast. Cactus II is one of several pipelines aimed at alleviating takeaway concerns in the Permian.
Can Robots Improve Above-Water Riser Inspections?
The criticality of above-water riser hull piping requires frequent inspections. Traditional manual inspection methods present safety and efficiency concerns, but work is being done to see if robotic technologies—such as drones and crawlers—can do the job as good as, or even better, than humans.
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18 June 2019
19 June 2019