Innovative Velocity SpoolTM (Surface Jet Pump) technology combined with novel compact separation was tested at a remote onshore wellhead location in Saudi Arabia to see if it could increase multi-phase production from low pressure oil wells that were already producing and revive wells that were backed out/not flowing.
The Velocity Spool (VS) is a passive device which utilises often wasted fluid energy (via a choke) from a high pressure (HP) well to reduce the back-pressure of a low pressure (LP) well and boost its' flow to the production manifold. For the VS to work efficiently on multi-phase oil wells, a compact in-line separator is installed upstream to bulk separate the gas and liquid fluids.
For this trial, one of Caltec's patented VS multiphase skids was installed at an onshore wellhead location and connected to existing HP and LP wells. Production from both wells was diverted to the VS to test its effectiveness. The trial tests lasted 3 months.
Results from the first set of tests showed that the VS boosted production from an LP oil well that was already flowing by an additional average of 400 bbls/d with a corresponding wellhead pressure reduction of 45 psi. Results from the second set of tests showed that the VS revived a dead well that had not been flowing since 2004 and made it flow at an average rate of 1100 bbl/d with a backpressure pressure reduction ranging from 54 to 27 psi. Prior to the trial, several attempts had been made to bring this dead well back into production using other methods but these had not been successful. The results showed conclusively that the VS was very effective in boosting production from LP oil wells using passive surface mounted equipment and avoiding any well intervention. The production gain was achieved by lowering the FHWP of the well and the amount of gain was dependent on the productivity index of the well.
The advantages that the VS offers over conventional technologies such as Multi-phase pumps and ESPs are several: it is tolerant to variations in flow conditions, gas volume fractions (GVF) and associated slugging (without affecting performance), it is surface mounted (so well intervention is not required), low cost, easy to deploy, has no moving parts, consumes zero fuel gas/electrical power and uses already available surplus energy.
This paper reports the trial results and discusses the use of Velocity Spools as an alternative to other boosting methods for oil production. The design and operational criteria of the VS are also highlighted.