Mudlogging or Mud Logging as it is somtimes referred, is a geology related occupation in the oilfield. When an oil or gas well is drilled the drill bit goes through many layers of different kinds of rock. To a geologist working for for an oil company these different kinds of rocks and what they contain mean something and that is where mudloggers come into play.
Some rock samples contain clues to what geologic formation or rock strata the well is being drilled through and this is important so that the well is not being drilled blindly. Because of faulting each well is different and geologists need clues as to “where they are” in terms of the drill bit at any given time.
Certain fossils contained in that rock may date the age of the rock formation being drilled. Other layers of rock may contain oil or gas. All of these clues can be interpreted by a skilled mudlogger once the rock cuttings from the drill bit are flushed back up to the surface in the drilling fluid or “mud”.
The mudlogger creates a “log” or paper chart of the well’s progression based on what kind of cuttings he finds in the drilling mud.
The job of mudlogger is one that takes years to perfect. It requires that the person have geology training and also the skills of a forensic scientist.
The tools of a mudlogger are very much like that of a forensic scientist, except the mudlogger is peering back into time millions of years. Under a high powered microscope a mudlogger can spot certain forams or remains of foraminifera or ancient marine “bugs”.
These can tell the mudlogger what age the rock formation is. By comparing these “bugs” to those from the same geologic age the mudlogger can tell the oil company geologist what formation or strata of rock they are drilling through.
Mudloggers look for oil and gas using visual cues, such as porous sand or other rock and the appearance of fluorescence under a UV light (which illuminates oil) and also by instruments such as a “hot wire” which registers the amount of natural gas present in the drilling fluid as it returns to the surface from the drill bit.
The mudlogger also has at his disposal a gas chromatograph which shows the kinds of gasses present in the drilling fluid.
It can be a good paying job but it is demanding. Mudloggers are gone from home much of the year.
They remain on the well site until drilling is done, which in some cases can be months.
For a single person with experience in geology it can be a rewarding career. For more on mudlogging and what mudloggers do see http://www.energyindustryphotos.com