We at Clover believe that liquid loading is the largest problem affecting production from shallow gas wells in SE Alberta and SW Saskatchewan

A barrel of water in 4½ inch x 9.5 lb-per-ft production casing creates about 27 psi of head. In metric units, a cubic meter of water creates about 1180 kPa of head pressure in the same casing. Any water accumulation in the wellbore is likely to cause more pressure loss than other bottlenecks in most shallow gas systems.

Water loading occurs because typical shallow gas well production rates are far lower than the required rate to lift liquid droplets (Turner Correlation). Many shallow gas wells produce without any tubing installed and therefore have the full casing diameter available for flow. In 4½ casing the Turner rate is a minimum of 350 mscfd (at vacuum), a number 10 times more than the average shallow gas well produces. For these reasons liquid loading is prevalent.

Ironically, the Alberta EUB does not require that any data be collected or reported on water production from shallow gas pools. Data such as water and sand volumes produced after completion are the sole responsibility of the producer and most companies do not collect this extremely valuable information.

Addressing this problem head-on leads to significant production increases (commonly 10-20%) and provides invaluable reservoir and production engineering knowledge such as inflow performance relationships.

Clover provides a fully integrated service to manage liquid loading in shallow gas wells including:

• reservoir analyses (production history matching using multi-zone radial-flow and material balance models),
• liquid loading assessments (pressure losses, liquid-gas-ratio calculations),
• design of liquid-loading management solutions (swabbing / coil tubing clean-outs, velocity strings, plunger lift, etc.),
• implementation and management of routine clean-out programs (field service selection, coordination, supervision, asd collection and storage, cost tracking & control, clean-out frequency optimization analysis)

Clover has developed software for the purpose of collecting and storing clean-out water and sand volumes, coil and swabbing operation costs and gas production increases. This software provides Clover with the capability to effectively manage routine clean-out operations on thousands of wells each month.