What a Mudlogger Does In The Oilfield. Mudlogging Jobs

Mudlogging is a geology related profession in the oilfield. When an oil or gas well is being drilled an oil company will hire a mudlogging company to come and set up a mobile lab near the drilling rig to analyze the rock cuttings that are coming up from the drill bit and to look for traces of oil and gas in the rock cuttings and drilling mud that is being pumped up from down below.

A mudlogger will use a sieve type device to catch a sample of rock cuttings at the "mud pits" where the drilling fluid returns to the surface. He looks at these cuttings, after cleaning them, under a high powered microscope to determine what types of rock the drill bit has been going through. On a computer or paper representation of the vertical well he notes the rock types, correlated to the depth from which they came, using universally recognized symbols. Sand for expample would appear as many small dots, limestone as little blocks.

In addition to noting the kinds of rocks being drilled the mudlogger monitors natural gas in the drilling fluid with a device called a hot wire and one called a chromatograph. The hot wire gives a reading of total gas in the mud and the chromatograph tells him what the makeup of the natural gas is, such as how much isobutane, propane, methane, etc it contains.

An important function of mudlogging is to help the oil company geologists determine when the drill bit has penetrated an area that may contain recoverable amounts of oil and gas. The oil company watches the "logs" that the mudlogger produces to know before wireline logs are run down the well if a productive well has been made.

In addition to helping determine if productive zones have been drilled the mudlogger performs an important safety function by continuously watching for "heaving shale" or "popping shale". These jagged flakes of rock that pop off the side of the drilled well bore can indicate if they have drilled into a dangerously pressured zone and if they need heavier weight drilling mud to control the well before a blowout occurs, causing loss of property and life.

Mudlogging companies typically hire only degreed geologists but some smaller companies may be willing to provide on the job training by starting a person off as a "sample catcher" helping an experienced logger for a few months before training as a mudlogger.

Mudloggers typically make around $200 per day while on the rig site plus per diem and more money offshore and overseas.