Historically, Gulf of Mexico operating costs are such that once wells there begin to liquid load, operators often choose to simply cut their losses by plugging the well rather than spend money on expensive workovers. It is a particularly pressing reality given that 60% of US production today is from 'brown fields'. 'As a formation depletes, pressure falls and water migrates into the well, gas velocity decreases and will not carry the water out,' explains Tom Hill, president and chief executive of GOT partner Tejas Engineering and Research of The Woodlands, just north of Houston. 'As liquids begin to rise in the tubing a pressure head develops and eventually the well stops flowing. In offshore wells, plug and abandon is too often the only alternative, leaving reserves trapped in the ground, considered uneconomic.'
The GOT partners say they have an alternative to either premature P&As or economically unfeasible workovers using what they describe as 'a safe, innovative and elegantly simple' system.
The solution, says Hill, is to economically lift water from the wellbore using specialty chemicals injected via a capillary string run through a specially configured subsurface safety valve to the perforations. Hill believes the so-called InjectSafe SCSSV can potentially increase total recoverable reserves by as much as 15%.