With the ever-increasing trend of oil production from lower pressure wells, application of artificial lift techniques is becoming inevitable. Beam pumps and electrical submersible pumps are two of the most common artificial lift methods for low and high oil production rates. But these techniques are susceptible to high gas-oil ratios, particularly at lower wellbore pressures causing gas break-out and possible gas lock. Various types of downhole separators have been recently designed upstream of the pump to resolve this issue and improve the pump efficiency. The objective of this study is to construct a state-of-art experimental facility and simulate the flow in an oil well with varying gas-oil ratios. The facility is then used to evaluate the performance of a centrifugal downhole separator. The experimental multiphase flow setup is designed, fabricated, and constructed in an efficient and automated way to simulate a typical horizontal wellbore. The well trajectory includes a 31-ft horizontal section, inclinable to ±10o, followed by a 27-ft vertical section. The casing ID is 6-in., and a 2-in. ID tubing is placed with end-of-tubing at the bottom of vertical section. The casing and tubing streams are each led to a return column, where gas and liquid flows are metered. Automated and modulated control valves are used to monitor the pressure and production from casing and tubing streams. Five Coriolis flow meters quantify density and flow rate of different fluid streams. All of the equipment is connected to a control computer via DAQ cards. The experiments are performed with air, supplied by a screw-type compressor, and water, supplied by a moyno pump. The experiments are conducted with different gas (Qg = 30-230 Mscfd) and liquid (QL = 17-700 bpd) flowrates to simulate the cases with both rod pump and ESP operations. The air-water ratio is increased for fixed water rates to identify the ranges of separator effectiveness. The tested downhole separator is an innovative design, applying gravity and centrifugal effects to perform the separation. The results indicate that average gas separation efficiency of the separator is 93% and average liquid separation efficiency is 96% over a wide range of operating conditions, as measured by return line flow meters for casing and tubing streams. The characteristics of multiphase flow in horizontal and vertical sections of the setup are observed and evaluated using surveillance cameras. The separator can be used widely in oil fields to improve gas-liquid separation and artificial lift performance. The application of pumping artificial lift methods in high GOR wells can help significantly improve the production from a wide range of volatile oil and condensate wells. This illustrates the value of utilizing innovative downhole separation strategies. This paper presents one such centrifugal downhole separator and studies its performance in enhancing the production.

The distance to the fluid level provides beneficial information throughout the life of a gas-lift well. From the initial unloading of the well, to maintaining production, and even into troubleshooting the well, the location of the fluid level plays a crucial role in understanding the well's performance.Some of the most valuable fluid level shots occur during the unloading process, when the fluid level is compared to the gas injection depth. Fluid levels can be used to help determine whether a problem is occurring within the wellbore or due to equipment malfunction. A quick surface measurement determines valves below the fluid level are not injecting gas. Finding holes in the tubing string and location of any restrictions in the tubing or casing help identify problems impacting production. During a workover, monitoring the fluid levels of a well filled with kill fluid ensures sufficient hydrostatic pressure is maintained against the formation. In gas-lift wells without a packer, producing bottomhole pressures can be accurately measured using an acoustic fluid level instrument. Bottomhole pressure information is useful in designing and operating gas-lift installations and measuring overall producing efficiency 1 .Examples of fluid level shots on gas-lifted wells will be used to demonstrate these concepts. Acoustic fluid levels acquired on gas-lift wells provide a low cost, direct method to observe the well and benefit the operator through knowledge of the well's producing conditions.

Gas evolution and expansion are natural phenomena in petroleum wells. However, gas is detrimental to pumping artificial-lift (AL) systems, causing incomplete pump fillage and reduced pump efficiency. Pumping AL systems may also be involved in high GLR applications for gas well deliquification. It then becomes essential to separate the gas before the pump's intake in these applications to preserve the life of the pump. Various downhole separators with questionable efficiencies are available today. In this study, an automated experimental separation facility is presented and applied to test the efficiency of two downhole separators. The setup includes a 31-ft horizontal section followed by a 27-ft vertical section that houses the separator. The performance of the separators is evaluated at different air (34 - 215 Mscf/d) and water rates (17 - 867 BPD). The multiphase-flow loop is equipped with pressure transducers and control valves for effective flow control. Data acquisition and process control are performed using LabVIEW™. A newly designed packer-type centrifugal downhole separator is evaluated over a wide range of flow rates and compared to a basic gravity-type separator without the centrifugal part. The performance and outlet flow stability of the separators are compared. Liquid separation efficiency is a measure of the fraction of the inlet liquid produced at the tubing return line. Output flow stability is measured by looking at the ratio of standard deviation over the average flow rate. Separation efficiency is close to ideal (100%) for liquid rates up to 500 BPD for both separators. The efficiency slightly decreases at higher liquid rates, but stays above 80%. This decline in efficiency is more noticeable for the gravity separator compared to the centrifugal, and it is sharper for higher gas rates (over 300 SCF/STB). The centrifugal separator provides a more stable output flow rate with less fluctuations compared to the gravity type. Various flow patterns in the separator outlet and the casing are visualized and recorded. With declining rates of production from oil fields and the need to de-liquefy gas wells, efficient artificial lift is necessary. This system provides a unique and novel tool to simulate the dynamics of flow in wellbores and identify the best tools to improve the efficiency.

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