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What is Mud Logging?

Ken Black
Ken Black

Mud logging is the term used for drilling a bore hole into a piece of ground and then taking a sample from that hole for analysis. This is usually in the form of a complete piece, or several pieces of ground, which is known as a mud log. It is especially helpful in the oil industry and geothermal drilling industry as a mud logging analysis can help detect the presence of oil or geothermal areas.

The mud logging process begins when a company interested in harvesting natural resources below the ground decides on a spot to drill a testing well. Once a well, or multiple wells, are drilled, the process of extraction takes place. This process can often take some very expensive and specialized equipment in order to get a successful sample. There are companies that specialize in providing equipment specifically for mud logging tasks.

Man with a drill
Man with a drill

In many cases the liquid in the mud log can reveal a substantial amount of information, including being able to answer the question if a well in a particular location would yield the desired results. This applies to both oil and geothermal areas. Once that is determined, the mud logging process is usually completed and the drilling moves from a purpose of analysis to a purpose of harvesting. This process could take months or years to complete, as some areas may be thoroughly searched to find the best possible spot in which to drill.

Mud logging, despite being a drilling application, can actually be a very good thing for the environment. It causes minimal disruption to the ecosystem, unlike what traditional drilling by trial and error may cause. Also, with its newer use in the geothermal area, mud logging is key to helping find renewable sources of fuel, especially sources that can be used for space heating.

After mud logging detects the existence of a geothermal water area, that water can then be tapped into and brought to the surface. Once there, it usually runs directly into a building where it can provide radiational heating. Then, once the heat in the water is used, it can be returned to its original location to be reheated and reused, thus providing a substantial cost savings and reducing the need to burn fossil fuels and use other non-renewable sources of energy for space heating.

Discussion Comments


Trip Gas (in continuation of earlier posting), it appears as a peak on the gas plot after one lag time. During connection time or P/O for bit change time there is no C and C, so the gas which is released from formation is stored there only. After C and C is started, it will come to the surface.


Trip gas is the gas increase seen after pulling out of the hole to change bits (or some other reason). It occurs because the combined pressure of the mud column (hydrostatic pressure) and the pressure caused by the pumping of mud (pressure loss in the annulus of the wellbore) is reduced by the subtraction of this circulating pressure. This may also be seen as connection gas, which occurs when the pumps are shut down to add another joint of drill pipe. Either may be an indication that a potential reservoir exists.


hi just wondering what trip gas is in an oil well drilling process.

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      Man with a drill