International Journal of Oil, Gas and Coal Engineering 2019; 7(3): 73-81 http://www.sciencepublishinggroup.com/j/ogce doi: 10.11648/j.ogce.20190703.11 ISSN: 2376-7669 (Print); ISSN: 2376-7677(Online) A Study of Flow Regimes in the Upper Part of a Compact Gas-liquid Separator Sunday Kanshio Department of Petroleum and Gas Engineering, Baze University, Abuja, Nigeria Email address: To cite this article: Sunday Kanshio. A Study of Flow Regimes in the Upper Part of a Compact Gas-liquid Separator. International Journal of Oil, Gas and Coal Engineering. Vol. 7, No. 3, 2019, pp. 73-81. doi: 10.11648/j.ogce.20190703.11 Received: July 3, 2019; Accepted: July 22, 2019; Published: August 6, 2019 Abstract: In the offshore oil and gas environment, there is usually the challenge with regards to available space offshore platforms for equipment installation; hence, compact separators are more attractive due to their small footprint. Also, in subsea oil and gas production, compact separators are attractive because of their light weight and ease of installation. A good understanding of the flow regimes in the upper part of the separator is essential for a robust design and operation. The performance of gas-liquid compact separator in terms of liquid carryover (LCO) and pressure drop depends on the type of flow regime in the upper part of the separator. However, there is a lack of experimental data on flow regimes in the upper part gas- liquid cyclone separators. In this research, data on flow regimes in the upper part of a 1.5-inch horizontal-inlet gas-liquid cylindrical cyclone separator was acquired using electrical resistance Tomography (ERT), wire mesh sensor (WMS), pressure transducer and visual observation. Based on flow imagining, observations and statistical analysis, the flow regimes were classified as swirling-annular, light-mist, heavy-mist and churn flow. A flow regime map for the separator was proposed based on a modified liquid and gas-Froude number. The work would be a useful guide to process engineers during the preliminary design and sizing of separators with similar geometry configuration. Keywords: Compact Separator, Flow Regime, Sub-sea Production, Offshore Platforms, Flow Regime Maps 1. Introduction In the petroleum industry, a separator is used in the oil field and process plant to separate a multiphase mixture into oil, gas and water. Traditionally, the petroleum industry relies on gravity-based separators for phase separation. Gravity- based separators are considered mature technology [1]. However, gravity-based separators are usually bulky, heavy and require more plot space. Where space and weight are a constraint, a compact and efficient phase separation technologies is more attractive. Cyclonic separators are light- weight and have a small footprint, making them attractive to applications such as subsea separation, un-manned platform, flare gas scrubber, portable-well-testing skid, multiphase measurement and debottlenecking of gravity separators [2, 3]. In subsea development, project economics is the critical driver for application of cyclonic separators [4]. Considering that the performance of the separator is sensitivity to inlet flow rates and inlet multiphase flow phenomena, its application is not as versatile as gravity-based separators. Liquid carryover (LCO) and gas carry under (GCU) are the two complex hydrodynamics phenomena in the gas-liquid cyclonic separator. Liquid carryover (LCO) in the separator is a physical phenomenon that defines the separation efficiency and the operational limits of the separator. LCO occurs when the gas stream transports drops of liquid out of the gas outlet of the separator. Research on liquid carryover phenomenon in the gas- liquid cylindrical cyclone (GLCC) which is published widely has associated LCO with some flow regimes in the upper part of the GLCC [5–7]. The knowledge of flow regimes in the upper part of the GLCC separator is essential for the prediction of both pressure drop and separation efficiency. However, only a few experimental data on flow regimes in the upper part of the GLCC separator are available. Chirinos et al., identified annular, transitional and churned flow as the flow regimes in the upper part of the of a 3-inch diameter GLCC [5]. They concluded that the annular and churn flow regime were the two mechanisms responsible for LCO in the gas leg of a GLCC separator. Kolla et al., identified churn