Completions & Workovers

Foam Air Completion and Workover

Drilling plugs – Air foam or nitrogen foam is a very effective method of drilling cast iron or composite plugs when there is little to no bottom hole pressure. Putting the wellbore in an underbalanced state will also have the added benefit of a better cleanout after drilling plugs by allowing the formation to flow back any unwanted fill.

N2 Foam Completion and Workover

Cleanouts – Air foam or nitrogen foam is a very effective method of cleaning out wells after Fluid – Sand Fracturing (fracking) has been performed on wells with low pressure formations that cannot be circulated by conventional fluid techniques. When cleaning out with air foam or nitrogen foam, a large percentage of the fluid that was used to frac the well is recovered. This allows the well to produce excessive sand and fluid for a more thorough cleanout. Air foam and N2 foam is also utilized for just cleaning out a well to improve its production capabilities. While using air/mist, the operator can observe what the well will produce while it is being cleaned out.

Deepenings – Air mist/foam or N2 foam is an effective method for deepening wells into pay zones when low bottom hole formation pressure makes marginal producers when drilled by conventional fluid systems. Not only is formation damage minimal when drilling into these pay zones, but formation evaluations can be continuously observed while drilling. Penetration rates are 5 to 8 times faster than conventional fluid drilling.

Cavitation – A process where air mist or N2 foam is pumped into coal seams at high volumes and high pressures. The pressure is then released quickly, which cavitates or breaks down the coal seam to improve methane gas production. Air mist/foam or N2 foam is then used to clean the fragmented coal out of the wellbore.

Jetting – A process where air mist/foam or nitrogen foam is injected into the well bore thus reducing hydrostatic head and therefore achieving a faster oil cut.

Concentric String Injection

The major problems encountered when drilling out during completions include lost circulation, poor hole cleaning techniques that cause stuck pipe, and the inability to clean out to TD. To reduce these problems, underbalanced completion techniques are employed. In an underbalanced completion technique, the wellbore fluid gradient is less than the natural formation gradient; this is achieved either by inducing nitrogen into the liquid at surface before it enters the drill pipe or injecting it down hole into the annulus using concentric casing.

Concentric String Injection is a process in which a gas lift system is utilized to inject gas into the fluid column at a given depth; however, in this case a liner is run in the well to provide a secondary annulus between the drill pipe and the existing casing, thus allowing injection via this inner cavity. One of the chief advantages of concentric string injection is continuous gasification of the fluid in the inner annulus when making connections or tripping, which aides in minimizing loss circulation during connections and bit trips. This system helps to overcome the challenge of lost circulation while cleaning out and stuck pipe issues. The concentric string injection technique is a proven and innovative procedure to aerate the fluid column.

Advantages of Concentric System
The concentric string injection method provides several advantages over using the more common aerated fluid techniques:

  • Conventional downhole motor and bit hydraulics can be used
  • Ease of operation, no special training or procedure needed for drilling crews for performing connections or trips