OVERVIEW

Mud cleaners are a combination of hydrocyclones mounted above shaker screens with small openings. Mud cleaners can be leased, rented, purchased as independent units, or assembled on location. When mud cleaners were invented in 1971, main shale shakers on drilling rigs were either unbalanced elliptical or circular motion machines. The finest screen at that time could separate solids only larger than about 177 microns (API 80) from a normal drilling-rig circulating rate. Barite specifications restricted solids to sizes predominantly smaller than 74 microns (API sand). Hydrocyclones removed large quantities of barite from a weighted drilling fluid and were not generally used. This meant that all of the drilled solids between 74 and 177 microns were available for removal but could not be removed with equipment available at that time. The mud cleaner was invented to remove those drilled solids.

Most 4-inch hydrocyclones discard around 1 3 gpm for every 50-gpm input. With a 1000-gpm flow rate input, the underflow from twenty 4-inch hydrocyclones would be only 20 60 gpm. Most shale shakers in the early 1970s could process this small flow rate through 74-micron (API 200) screens. Barite smaller than the openings, as well as drilled solids smaller than the openings, returned to the drilling fluid. Solids larger than the screen opening, and the solids clinging to those larger solids, were discarded. Solids larger than 74 microns made filter cakes incompressible and also increased the coefficient of friction between the drill string and the well bore. This...