Static separator sub

Abstract

A downhole separator sub for separating drilling mud into a more dense portion and a less dense portion. The apparatus includes a barrel having a central opening therethrough and a cyclone separator cartridge positioned in the central opening. The barrel is attachable to the drill string and the drill bit. The cyclone separator cartridge includes an upper insert, an intermediate cyclone separator housing and a lower insert. An annular flow passage is defined between the cyclone separator housing and an inner surface of the barrel. The upper insert includes an inlet passage providing communication between an upper portion of the barrel central opening and the annular flow passage. The lower insert includes a cyclone inlet providing communication between the annular flow passage and a cyclone chamber in the cyclone separator housing. A removable vortex finder tube is positioned in the cyclone separator housing and has an outlet hole through which less dense fluid is discharged into a lower portion of the barrel central opening. The upper insert also includes an underflow passage in communication with the cyclone chamber. The underflow passage has an outlet positioned adjacent transverse holes in the barrel through which more dense fluid is discharged from the apparatus into a well annulus. Alternate embodiments include deflectors adjacent the transverse holes in the barrel to prevent direct impingement of fluid on a wall of the well annulus and a sleeve interconnecting the upper and lower inserts to separate the annular flow passage from the remainder of the barrel central opening.