J.N. McCoy, O. Lynn Rowlan and Dieter Becker
Echometer Company
A.L. Podio,
University of Texas
This paper describes a downhole separation technique that diverts the formation fluids into the basing annulus near the top of the downhole separator so that the liquids and gas can separate by gravity. A seating nipple is positioned at the bottom of the separator that is within inches of the liquids that exist in the casing annulus surrounding the gas separator to obtain unobstructed liquid flow into the pump inlet and result in higher pump fillage.
The separator design is used with a conventional packer, or a special pack-off assembly consisting of elastomer rings on a tube positioned between the separator and the tubing anchor below the separator, or a packer with tail pipe when the pump is set a considerable distance above the formation.
Two conditions affect pump fillage that can severely reduce pump displacement. A recent complicating factor that must be considered when evaluating gas separator performance is the recent use of high clearance plungers in the pumps. Large plunger clearances for sand problems are common in some areas that result in a pump plunger leakage of 50% the pump capacity, so the pump appears to be full or almost full when actually the liquid in the pump is circulated liquid that is bypassing the plunger and not new liquid being drawn into the pump chamber. The second condition is the lack of separation of free gas from liquid as the formation liquid enters the pump inlet.
The paper describes gas separation techniques and presents field data on several types of downhole gas separators.