Plunger Assisted Multiphase Pump (PAMP) Pilot in the Midland Basin

Alternatives to Sucker Rod Pumping (ROD) are being sought as late-lift Artificial Lift (AL) solutions for lower Gas Liquid Ratio (GLR) horizontal wells. This is due to the higher ROD lift failure rates seen for pad-drilled horizontal wells in the Midland Basin and in Unconventional fields in general. These pad-drilled wells often exhibit challenging wellbore geometry (severe doglegs) which makes it difficult for ROD lift which is plagued more frequent and costly failures and often the pump is required to be set higher than desired. In addition, gas slugging reduced pump fill, further reducing run life for ROD lift. This paper presents the results of a pilot test of the Plunger Assisted Multiphase Pump (PAMP) system, which seeks to move Plunger Lift (PL) into lower GLR wells where ROD lift would normally be selected. Reducing late-life LOE costs is the driver for this pilot. 

The PAMP system uses a twin-screw MultiPhase Pump (MPP) to inject gas in the tubing-casing annulus and boost downhole pressure; add a driving force to push the plunger to the surface, while also providing additional pressure drawdown at the wellhead. The combination of reducing tubing pressure and simultaneously driving the plunger to the surface allows a PL system to operate at conditions where there is too little gas from the reservoir and no nearby source of lift gas for Gas Assisted Plunger Lift (GAPL). MPPing is a well-established technology which can boost any combination of gas and liquids at a low suction pressure. Lower wellhead pressure created by the multiphase pump already supports downhole pumps in other artificial lift applications creating better well inflow. The PAMP system is delivered on a surface skid, which incorporates a MPM and small vessel for liquid knock-out and storage. It is driven by an electric motor with VFD for speed and flow control as conditions change during the plunger cycle. 

For the pilot project, a well was selected in the Midland Basin which has experienced frequent ROD system failures and was being considered for GAPL. The well was in the normal rate-GLR operational region for ROD lift and exhibited a little too low a GLR for traditional PL. So instead of setting a compressor or running a 1,200 psig gas lift line the PAMP skid was installed. The well was swabbed in initially but stabilized with frequent plunger trips sized to the 500 psig pressure delivered to the annulus by the PAMP skid. During the flow period, after the plunger reaches the surface, the PAMP system increased liquid rates, by drawing down tubing pressure to about 50 psig, taking gas and liquids through the pump and boosting to a liquid knock-out boot or vertical separator where the gas is separated. When the line pressure drops below a certain preset level the plunger is dropped from the lubricator and as it reaches the bumper spring the PAMP unit begins injecting high-pressure gas down the annulus, supporting the formation pressure. Later, the plunger will travel to the surface also assisted by reduced back pressure in the tubing. The separator, which uses a liquid level control, dumps the produced liquids which are boosted to the sales line pressure. The entire plunger travel cycle is supported by the multiphase pump in a closed loop system without any use of blow down tanks. The paper will detail the rates achieved and areas of cost savings.