Laboratory Technique for Screening Asphaltene Inhibitors for Kuwaiti Reservoirs

Abstract

AbstractCurrently Kuwait Oil Company (KOC) is facing asphaltene deposition problems in the wellbore of some of the Marrat Jurassic reservoirs in West Kuwait (WK) and South East Kuwait (SEK). This has caused a reduction in production and shutting of some of the wells and a severe detrimental effect on the economics of oil recovery. This paper describes the results of the laboratory studies on the characterization and phase behavior studies of three different crude oil samples from Marrat reservoirs, and the screening of a number of commercially available inhibitors, which were proposed as a remedy and prevention of asphaltene deposition for this reservoir.Initially the samples were characterized for their chemical and physical properties. Then the phase diagram (P-T) and Asphaltene Deposition Envelope (ADE) for bottom-hole samples were established by measuring the saturation and Asphaltene Onset Pressures (AOP) at different temperatures from reservoir to surface conditions by using the laser technique Solid Detection System (SDS). Asphaltene Flock Point (AFP) analyses were then performed by the titration technique using Stock Tank Oil (STO) samples and n- Heptane as the asphaltene precipitant. The effects of different concentrations of each inhibitor on different reservoir fluids were investigated in the laboratory, using the AFP technique. The most efficient inhibitor with the optimized concentrations for each reservoir fluid was established for economical evaluation purposes. Based on these studies, a selected inhibitor is now being used for a pilot field study.