A Tale of Two Flowlines—Paraffin Plugging and Remediation

Production impairment due of paraffin deposition and plugging is the second most concerning issue in deepwater Gulf of Mexico after hydrates. This paper discusses two separate instances of well flow impacted by paraffin deposition and the comparison of modeling with field observations. The well being discussed is in 2,315 feet of water depth capable of flowing through two 6.2 mile 4.5" x 7" pipe-in-pipe flowline pigging loop system with insulated SCR (Steel Catenary Risers) and an electro-hydraulic control umbilical. The well is a smart completion of two zones in which the lower zone was flowing initially. After one and half years of production through one flowline, the well was split to flow through both flowlines to improve the production rate. Approximately one year of successful flow through both flowlines which was maintained at similar pressures, it was detected that one of the flowlines was plugging. This paper discusses the results of the plugged flowline and remediation measures attempted. The paper also presents modeling work to correlate field observations with industry available simulator results. After the remediation measures, production from the lower zone was routed through a single flowline at a relatively low flow rate, resulting in temperatures below the fluid's wax appearance temperature. The low flowing temperatures resulted in partial paraffin plugging which were observed based on pressure measurements. To mitigate the partial plugging of the flowline, the production zones were switched (lower was closed and upper was opened). With the upper zone open and able to flow at a much higher rate, temperatures above the wax appearance temperature were achieved. This resulted in melting of the deposited paraffin and eliminated further paraffin deposition. This paper discusses a unique method to mitigate paraffin deposition concerns and a comparison of modeling results to field observations.