# An Experimental Analysis of Gas Reduction in Multiphase Flow with a KMS Helical Static Mixer
## 1 Introduction  
In the oil industry, artificial lift systems (ALSs) [1] become the natural alternative when the inner pressure decreases in a mature oil well. Depending on the ALS, such as the hydraulic pumping, the fluid mixture extracted is composed of different volumes of phases as a complex mixture of oil, water, gas, and, sometimes, solid particles. When the phase separation is introduced in the continuous process, separators work typically based on either gravity or centrifugal segregation through vertical, horizontal, as well as spherical configurations [2], and commonly for the gas-liquid segregation [3]. Other separation mechanisms such as impaction or electromotive force are also used for specific mixtures [4]; a comparison of multiple methods as absorption and membrane separation for gas-liquid mixture is studied in [5]. A separator could be implemented in different locations along the stream column, but is typically defined with horizontal configurations and complemented with additional inlet devices, as the helical separator, experimentally analyzed in for viscous fluids, and the so-called poor boy degasser, a vertical low-pressure loss device over two stages of separation, for gas and mud [6]. For multiphase fluids, a three-phase gravity separator is very common, and its performance is influenced by its configuration, the flow pattern, the design pressures, and the complexity of the mixture. In the process, a pre-separation is performed in the inlet section by means of components such as as diverter plates, reversed pipes, dished heads, or cyclonic devices [7]. For many oilfields, the separation of the phases from the mixture frequently involves emulsion and foaming into a horizontal separatorwithout an inlet mechanism. This fact drives an improvement in gas separation, from the inlet device study. According to [8], the cyclonic device might be more efficient than other devices; however, it has limiting factors as its sensitivity to small changes in flow and the large pressure required to generate the centrifugal effect. A recent gas separation strategy based on the cyclonic effect [9] considers a numerical analysis for contours in velocity and pressure to set a mechanical configuration to deviate the gas. Though the cyclonic phenomenon is not explicitly addressed, in [3], an inlet device producing centrifugal effects is used to separate wet gas in high-velocity conditions. An interesting computational fluid dynamics (CFD) analysis of the flow pattern is developed in [10], where a mixture of gas is studied for different diplegs producing cyclonic dynamics. In [11], the separation of a gas-liquid two-phase flow is modeled and analyzed with CFD tools by considering a cone as a cyclonic generator; also, the dynamics of a cyclone separator with helical fins is studied by CFD in [12]. In [13], the cyclonic phenomenon is also studied for an absorption separator of ammonia from a liquid solution. An innovative horizontal separator is designed with inclined pipelines [14], reducing the liquid at the top, but depending on the dynamics conditions such as the velocity and amount of liquid in the mixture. On the other hand, a static mixer is a device to homogenize the particle distribution into size scales, depending on the nature of the mixture [15; 16]. However, for a mixture with a high concentration of gas, the density difference of the phases makes the static mixer fail in mixing; in this case, an interesting dynamics is produced, which favors the separation of gas [17]. In other research fields such as boiling flow fields, separation devices such as the one studied in this paper might be helpful [18], mainly for heat transfer enhancement and liquid evaporation models over the boiling temperature. In general, the inlet section in a horizontal separator can provide a momentum degradation and promote a phase distribution, being a critical phase in the global separation process.