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CALEDYNE, A LEADING energy industry engineering services and products specialist, today launches its balance pump, part of its world-first complete commercial deliquification offering,

designed to radically transform operations and offer a new lease of life to mature gas wells.

Liquid loading is a well-known occurrence, particularly in mature reservoirs where the energy is not high enough to transport liquid droplets to the surface. These collect at the bottom of the wellbore and reduce production, ultimately killing the well.

The most common method of dewatering is foam injection, which is widely used on mainland USA. Foamers are effective but unsuitable for the most mature wells as the technology needs a certain amount of well energy to operate successfully. A surface-driven downhole pump does not require well pressure, so can provide a longer-term and end-stage deliquification method for operators, avoiding costly intervention prior to well abandonment.

Developed at the company’s base in Aberdeen, Scotland, the balance pump is a hydraulically actuated reciprocating low volume pump. It can be used to lift oil or, as part of the deliquification offering, it can remove water from onshore or offshore gas producing wells. The pump, which can be retrofitted, is operated by two hydraulic lines - one filled with oil, the other with water. The differential hydrostatic pressure between water and oil moves the pump’s internal piston downwards.

The application of pressure to the oil line drives the piston upwards, lifting the water trapped above the travelling check and drawing water into the lower chamber. Removing the pressure from the hydraulic line allows the water line to return the piston after which pressure is reapplied to the hydraulic line. The technology is designed for maximum reliability and increased run life, for example all metalwork is constructed from corrosion-resistant steel and dynamic seals are non-elastomeric to combat high Hydrogen Sulphide (H2S) and Carbon Dioxide (CO2) concentrations. Caledyne’s complete deliquification system includes its Balance Pump, Torus Safety Valve and Pin-Hole Injection system (PHI). The Torus valve allows the balance pump to be installed in offshore operations.

It is a fail-safe closed insert safety valve, offering a permanent conduit through the centre of the valve. It is installed in the existing safety valve nipple profile and operated by the existing hydraulic control line, using a sliding sleeve mechanism to shut in production which is operated via a power spring and piston arrangements. The PHI is a retrofit surface termination system, minimising disruption at the surface when umbilicals are fed through the wellhead, avoiding the insertion of spool pieces or flow line modifications. It has been designed for all semi-permanent deliquification installations, both on and offshore.

Caledyne has provided several downhole tools for deliquification purposes, but the first installations of an entire system are due in several locations later in 2009, including the Southern North Sea, mainland Europe and offshore Indonesia. Roland van Dort, Caledyne managing director, said: “As existing energy assets around the world mature, focus in the industry is shifting from drilling new wells to maximising production from existing wells and improving intervention, particularly in areas such as the Gulf of Mexico, the UKCS, mainland Europe and Indonesia.

“In fact, it has been estimated that as much as 90% of gas wells suffer from liquid loading, so the opportunities for companies producing a reliable solution are significant. “The Caledyne balance pump provides a cost-effective deliquification method for operators of both onshore and offshore wells suffering from this phenomenon by providing a retrofit solution, avoiding costly workovers and enabling an economical and reliable enhancement of produced hydrocarbons.”