A conceptual study of finger-type slug catcher for heavy-oil fields

The gas/liquid-separation processes in heavy- and extra-heavy-oil fields are performed mainly with gravity conventional separators. However, the separation efficiency of this equipment depends on the operating conditions, an appropriate design, and the properties of the fluids. Therefore, the separation efficiency is affected mainly by the high liquid viscosity, low pressures, and the low gas-flow rate that are present in heavy- and extra-heavy-oil fields. Additionally, these conditions increase the probability of slug-flow formation through pipelines, which causes operational problems, mainly in the separation process. This situation raises the need to design a gas/liquid separator able to handle viscous liquid, reduce the effects of slug flow, and perform an efficient separation. There are different technologies that can help improve gas/liquid separation, among them the finger-type slug catcher. This technology is usually used in gas fields or light- and medium-oil fields as a flow conditioner and slug-flow mitigator. However, this paper has changed that focus toward considering a heavy-oil design. This paper presents an improvement in the methodology of Sarica et al. (1990), predicting the dimensions of a finger-type slug catcher for heavy-oil fields. It is derived from the effect from the transition of stratified flow to nonstratified flow when the liquid phase is viscous and only considers slug-flow characteristics under normal flow; on the basis of the improvement, the required diameter and length of the finger are determined. This improvement is used to design a finger-type slug catcher for heavy-oil fields in the Orinoco belt. An economic comparison against conventional separators is presented, demonstrating the finger-type slug catcher to be more economical than the conventional separator. Copyright © 2010 Society of Petroleum Engineers.