There are different ways to analyze downhole conditions and get information about the formation while drilling the well.
Downhole information is very important to get the most production from the well.
A few ways to achieve this are to take advantage of measuring while drilling (MWD), logging while drilling (LWD), or mud logging.
Related: What are MWD and LWD in Oil and Gas?
What is Mud Logging?
Mud logging involves analyzing rock cuttings coming to the surface with drilling fluid.
Drilling fluid is pumped while drilling the well to control downhole pressure, lubricate the wellbore and help to bring cuttings from the bit to the surface to keep the wellbore clean.
These rock cuttings are analyzed to find their composition, and physical properties like porosity or permeability and potentially improve drilling rates and prevent unexpected kicks.
These rock samples or cuttings are usually taken from shale shakers.
Mud logging is also used to confirm that the well is being drilled in the right formation and to get a better understanding of the downhole lithology and fluids trapped in the formation.
In addition to analyzing rock samples, mud logging can also involve analyzing the gas coming from the well with the help of gas chromatography to quantify hydrocarbons in gas samples and to determine their composition.
Related: What Is Drilling Mud And How It Is Used?
Working as a Mud Logger
Some mud loggers have a degree in geology or engineering while others only have a high school diploma.
However, these are usually the people that had previous experience in the oilfield like for example from working on a drilling rig.
Often mud loggers work with wellsite geologists and supply them with rock samples when needed.
Both office and wellsite geologists use mud logging reports to perform more in-depth well drilling analyses.
The mud logging reports usually have information on drilling speed or rate of penetration, rock compositions, and physical properties as well as information about the hydrocarbons detected by gas chromatography.
Depending on the well complexity sometimes wellsite geologists might perform all the tasks of the mudlogger.
Some new grads with a degree in geology start working in the oil and gas industry as mud loggers before becoming on-site or office geologists.
This helps them to gain more field experience and understanding of the entire drilling process and makes it easier to transition to something else after a few years.
In general, if you have a degree it is usually a good idea to avoid getting stuck as a mudlogger for a long time because salaries are usually not as great in comparison to what everyone else is making on a drilling rig.
Most mud loggers stay on location in a trailer during the drilling operation and work 12 hours a day.
However, if the drilling is simple sometimes you might be required to provide full 24-hour coverage.
The rate at which rock samples are caught and analyzed depends on the complexity of the formation and drilling speeds.
This means that you will usually only work several hours during your shift and the rest will be spent waiting.
There is also quite a bit of downtime during drill bit changes or when something goes wrong during drilling.
The rotation schedules can vary and can be anything from 2 weeks on and one week off to working the entire time the well is being drilled which can be more than a month.
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