Concentric coil tubing well vacuuming technology for cleaning well in south west Iranian oil field

With advancement in oil production technology world-wide, Estimated Ultimate Recovery has been improving steadily. However, as reservoirs reach semi-maturity, pressure decline to the point where Artificial Lift Systems becomes common in almost every well. Optimizing oil production in wells by ensuring blockages and contaminants are cleared is an efficient economic preference over drilling new wells, nevertheless this comes with its own set of challenges. Some of the conventional well clean-out practices as Nitrogen, Foam Coiled Tubing (single Coil) cleanouts, Circulation, Bailing, etc. require high pressure to push solids to surface, resulting in large amounts of fluids and solids pushed back into the formation.The most common way of dealing with a depleted well is to utilize nitrogen to reduce the hydrostatic head of the return fluid column .if a light weight fluid is not used, some other method is required to drive the return fluid column back to surface in other words, a down hole pump is required.One alternative is to clean out the fill by means of concentric coiled tubing (CCT) with downhole vacuum tools.High pressure fluid is accelerated through the nozzle, creating a pressure drop that essentially draws in well bore fluids, jetted fluid and suspended solids. A diffuser allows the velocity of the combined flow to decrease and the pressure to increases, the pressure gain is sufficient to drive the column of return fluids back to surface.According to experience some of Iranian oil well can’t unload with conventional method hence, this technology could be useful for to discharge the fluid in the well after drilling in Iranian oil field.