Surface Jet Pumps Enhance Production and Processing

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 164256, ’Novel Examples of the Use of Surface Jet Pumps To Enhance Production and Processing: Case Studies and Lessons Learned,’ by Syed M. Peeran, Najam Beg, and Sacha Sarshar, Caltec UK, prepared for the 2013 SPE Middle East Oil and Gas Show and Exhibition, Manama, Bahrain, 10-13 March. The paper has not been peer reviewed. Surface jet pumps (SJPs) are simple, low-cost, passive devices that use a high-pressure (HP) fluid as the motive force to boost the pressure of produced-gas and -liquid phases. In recent years, the oil and gas industry has become more aware of their applications and benefits. These systems enable the flowing wellhead pressure (FWHP) to be reduced in order to increase production while meeting downstream production-pressure requirements. SJP Operation and Applications In an SJP, the HP fluid passes through the nozzle, where part of the potential energy (pressure) is converted to kinetic energy (high velocity). As a result, the pressure of the HP fluid drops in front of the nozzle. It is at this point that the low-pressure (LP) flow is introduced. The mixture then passes through the mixing tube, where transfer of energy and momentum takes place between the HP and LP fluids. The mixture finally passes through the diffuser, where the velocity of fluids is gradually reduced and further recovery of pressure takes place. The pressure at the outlet of the jet pump will be at a value between that of the HP fluid and that of the LP fluid. Fig. 1 illustrates the general configuration of the SJP. In the case of gas production, both HP and LP fluids are primarily gas. The presence of liquids (condensate, oil, or water) in the LP flow can be tolerated as long as the volumetric flow rate of liquids is less than 1 to 2% of the volumetric flow rate of the LP gas at the operating pressure and temperature. Beyond these values, the effect on the achieved pressure difference (ΔP)—discharge pressure minus LP pressure value—could be significant, requiring the LP liquids to be separated upstream of the SJP and to be boosted separately. Alternatively, the LP liquids can be sent to a part of the process system that operates at a lower pressure, if such a source is available. The presence of liquids in the HP gas also has a similar limitation, beyond which the liquids need to be separated upstream of the SJP. The main reason in this case is that the performance and sizing of the nozzle are affected on the basis of whether the HP flow is liquid or gas phase. A further point is that if the HP flow is multiphase, the fluctuating flow regime associated with multiphase flow reduces the efficiency of the SJP significantly further, because the mixture is not usually homogeneous. The exceptions in these cases are transient conditions such as startup, when the system may be subjected to a high flow rate of liquids passing through the SJP. The SJP recovers quickly in such cases as soon as the liquids pass through. If no HP gas is available in gas-production applications, the HP source can be an HP liquid (oil or water). In this case, the solution is viable and economical mainly when the LP-gas-flow rate is small and is limited to a few MMscf/D. The reason for this limitation is the relatively high volumetric flow rate of liquids needed for each MMscf/D of the LP gas.