Study on influence of flow rates on voids in waxy crude oil subjected to dynamic and static cooling

Abstract

The assumption of constant yield stress in the conventional restart pressure equation neglects the effects of thermal shrinkage and gas voids formation, which in turn resulted in an over-designed production piping systems. This paper presents a study on the effects of flow rates on the formation of voids in gelled waxy crude oil. A flow loop rig simulating offshore waxy crude oil transportation was used to produce a gel. A Magnetic Resonance Imaging (MRI) was used to scan the gelled crude oil over the three planes. Waxy crude oil underwent both dynamic and static cooling to observe the effects of volume flow rates on the voids formed in wax-oil gel. Volume flow rate was found to have different influences on the intra-gel voids in the pipeline. A volume flow rate of 5 L/min resulted in a maximum total voids volume of 6.98% while 20 L/min produced a minimum total voids volume of 5.67% in the entire pipe. Slow flow rates resulted in a larger voids volume near the pipe wall. In contrast, faster flow rates produced insignificantly higher voids volume around pipe core. Generally, slower flow rates favoured the formation of higher total voids volume following sufficient steady time of wax crystal formation, producing larger voids areas in gelled waxy crude oil.

New Method for Gelation Temperature Measurement without Disturbing the Crystal Network

“…During gelation, thermal shrinkage of waxy crude oil results in void formation. , Recently, many studies have focused on the formation and measurement of voids. − A sudden volume contraction is observed at the gelation temperature during the cooling of waxy crude oil. Due to a contraction in the waxy oil sample, the wax crystal network formed during gelation tries to pull (tensile force) the shear cell’s surface.…”

Numerical predictions of sand erosion in a choke valve

“…Crude oil with API (American Petroleum Institute) gravity of 21.9 is used as the working fluid and it is considered as incompressible Newtonian fluid with density = 931.3 3 ⁄ and dynamic viscosity = 0.0177 ⁄ [19]. For waxy crude oil, refer to reference [20]. The sand material is considered as inert anthracite spherical particles with uniform diameter of 10 -6 m with density of 1550 kg/m 3 injected from the inlet face with different mass flow rates.…”

Formulation of Polymeric Inhibitor for Viscosity Reduction of Crude Oil

“…During cooling process, waxy crude oil encounter thermal shrinkage where the gas voids appear while the fluid turn into multiphase (Singh et al, 2008). Voids in the gel occur because of decrease in volume of waxy-oil gel during that process (Chala et al, 2015, Chala et al, 2016Lionetto et al, 2007;Kané et al, 2003). Those conditions caused in reduction of pressure which break the gel along pipelines due to non-uniform gel formation (Wachs et al, 2009;Sakthipriya et al, 2015).…”