Page 16 - A Primer of Oilwell Service and Workover Completion
P. 16
SAND CLEANOUT AND WORKOVER
Petroleum Extension-The University of Texas at Austin
SAND CLEANOUT AND WORKOVER
orkover jobs may include The method of cleaning
Wcleaning sand out of the out the sand depends on where
well and adding a means of the sand is and how tightly it is
preventing sand from entering packed. All methods use circula-
ANNULUS
it, replac ing liners, plugging tion of a fluid, usually salt water,
MACARONI
the well, repairing casing, drill- to flush the sand out. TUBING
ing deeper, and drilling around
obstruc tions in the well. Some Using a Macaroni Rig or SALT WATER
work over jobs require only a Coiled Tubing AND SAND
wireline to lower tools, but OIL STRING
others need to rotate tubing or One method uses either a maca- CASING
drill pipe, so the workover rig roni rig (fig. .) or coiled tubing PRODUCTION
TUBING
has equipment to rotate the pipe (fig. .). A macaroni rig is a rel- SAND
string. Operations that need to atively small rig that handles spe-
circulate workover fluid into the cial lightweight, small- diameter PACKER
well require pumps and storage pipe called macaroni. The crew
tanks. leaves the production tubing and
packers in place and lowers the
macaroni string or coiled tubing,
SAND CLEANOUT generally about to ¼ inches
In a wire-wrapped screen (about – mm) in diameter,
completion, fine sand eventu- inside the production tubing. OIL SAND
ally infiltrates the gravel pack Crew members lower the string
and the screen and fills up the until it just reaches the top of
inside of the slotted liner. Some- the sand. Then they circulate salt
times, however, in spite of every water down the tubing at a high
attempt to exclude it, sand enters velocity, lowering the string as PERFORATIONS
the well and causes trouble. the sand washes out. This high-
When this happens, a workover velocity salt water forces the sand
crew cleans the well out. to the surface through the annu- Figure .. Macaroni tubing fits
lus between the production tub- inside the production tubing to
ing and the macaroni or coiled wash sand out.
tubing.
