Offshore environmental control of low toxicity oil based muds

Diesel oil based muds first introduced as spotting drilling fluids in 1942 and then as continuous drilling fluids in 1974 have been very beneficial to the drilling industry but are ecologically undesireable and a maintenance problem on offshore drilling rigs. Mineral type, low toxicity oil based muds have all the drilling benefits but are much less toxic, in proper levels can be ecologically acceptable and as such have largely replaced diesel oil's use offshore. Because of the popularity of these muds in lubricating hot holes, reducing pipe sticking and particularly in directional drilling, their use is becoming increasingly common offshore. The rig owner has to modify his drilling and containment systems for them and use special systems in discharging residues and keeping the rig safe, clean and habitable.