Mud logging is a term that has been around for over half a century. During that time, mud loggers have grown in importance, and their duties have evolved as new technologies have been adopted. They are an integral part of the modern-day drilling process. When working offshore, they typically utilize specialized modules that house and protect them and their equipment from the harsh conditions of working at sea.

Before we can talk about what an offshore mud logging module is, we must understand what a mud logger is and what their job entails. This will give context to the module's features and why a mud logger would need this specialized unit when working offshore.

Background: What is Mud Logging?

In the early 1940s came the beginnings of what we know today as mud logging. While the methods and equipment have evolved since then, the basic premise has remained the same.

Pressurized mud pumps are used to supply drilling fluid, or mud, down the hole and out through the drill bit. As the drill bit grinds through the earth, the mud, along with the cuttings and any oil or gas present, flows back up the hole. After exiting the hole, the mud and its contents are sent through a screening process where the cuttings are separated from the mud. The mud is then re-circulated back down the hole, and the process is repeated.

After being screened out of the mud, the cuttings are then taken to a mud logging unit. At the mud logging unit, they are analyzed to learn more about the hole. Logs are created of the cuttings that track the lithology, color, shape, and other aspects of the rock type. Ultraviolet light, combined with solvents, helps detect hydrocarbons in the cuttings and, based on the color of the fluorescence, helps indicate oil gravity.> 

Today mud loggers do not just monitor and interpret the cuttings. They also monitor gas levels within the hole through the use of flame ionization detectors and gas chromatographs. By studying the gas levels within the hole, the mud logger can advise the company man of any potential problem areas present and adjust the drilling accordingly to prevent costly delays. With the introduction of more sophisticated instruments, the mud logger’s role and importance at the drill site has grown.  

Offshore Mud Logging

When it comes to mud logging offshore, there are some differences from working onshore, but the duties and instruments are generally the same. One of the biggest differences is using an offshore module versus a trailer, which is typically used on land.  

What Does a Mud Logging Module Need to Include?

Offshore mud logging modules need to be engineered and built to meet the tough demands of working at sea. This includes being certified to multiple regulatory bodies such as:

• American Bureau of Shipping (ABS)
• United States Coast Guard (USCG)
• International Convention for the Safety of Life at Sea (SOLAS)
• Det Norske Veritas AS (DNV)

Which regulatory standards need to be meet are dependent on the type of installation or vessel and the location of the work at sea.

With the limited amount of deck space out at sea, the mud logging modules can be placed near the well in locations that are deemed hazardous. When located in hazardous areas, the modules are required to meet additional safety regulations. Depending on the presiding governing body, this means either meeting Division 1 / Division 2 rating or Zone 1 / Zone 2 ratings. 

These modules are typically built using standard CSC dimensions, such as 8' wide by 20' long in dimension. Due to limited deck space, it’s not uncommon to see smaller, 12' or 16' modules utilized. Some service companies have combined Mud Logging with other services, such as Measurement While Drilling, MWD, and may offer a larger module to accommodate both service lines. Due to the small footprint, the layout within these modules is designed to maximize the space available. They are designed to give mud loggers room for themselves and the instruments and equipment they need to do their work. These design features include:

• Versa mounts for computer monitors built into the walls, to remove monitor stands that take up desk space.
• A sink with running water, to help with performing the necessary tests on the cuttings, as well as vent hoods and ovens.
• Numerous electrical plugs placed around the module to ensure that power can be supplied to any instrument (computers, ultraviolet lights, etc.), no matter where it's placed within the module.
• Cable transit frames to allow penetrations for cables to be run to equipment and computer racks installed inside the module.

Having the right equipment for the job makes everything run smoothly. When mud logging offshore, having your work area specifically designed to provide all the necessities in a functional layout can make all the difference. Armoda has a full line of mud logging modules certified to all the relevant regulatory bodies and designed to meet the demands of mud logging offshore. This includes ensuring operational performance for mud logging while also focusing on safety concerns (fire ratings, blast ratings, and hazardous area ratings) to protect the crew. To find out more, contact us.