An integral part of onshore and offshore drilling, mud pumps circulate the drilling fluids used to facilitate drilling oil and natural gas wells. Used to stabilize pressure and support the well during the drilling process, drilling fluids also provide friction reduction and a means to remove cuttings.
While drilling with some type of fluid has been in practice for centuries, the term "drilling mud" was coined when a herd of cattle was driven through a wet field near Spindletop, and the resulting mud was used to lubricate the drillstring and drill bit. Drilling fluids have come a long way since those early days of drilling, and offshore mud pumps are constantly taxed to help operators find and develop hydrocarbons in harsher, deeper and more difficult locations.
"A mud pump delivers drilling fluid from the mud tanks, through the top drive, down the drill string and through the bit," explained Juan Lerma, Mud Pumps Product Line Manager at National Oilwell Varco. "When the mud exits the bit, it travels back to the surface carrying the cuttings made by the bit where it flows over a shale-shaker removing the cuttings, cleaning the mud and returning it to the tanks, where it's used over and over again."
Drilling Offshore with Mud Pumps
Varying according to the conditions of well being drilled, as well as the type of rock formations the bit is encountering at each depth, drilling fluids are composed of numerous ingredients, including clay, water, oil and synthetic materials. When drilling offshore, the environmental impact of drilling fluids must be more closely considered.
"A mud pump is one of the critical and required pieces of equipment for a drilling rig whether on land or offshore," Lerma stated. "Offshore, where real estate is at a premium, mud pumps are configured with a compact top-mounted drive system, reducing the overall length with a smaller package and strategically placing it in the pump room for permanent installation."
"On the other hand, space is not as much of an issue on land rigs," continued Lerma. "Here special consideration is paid to truck specifications and height restrictions for travel on roads, instead."
There are a number of different situations encountered when drilling offshore. For example, while jackups focus on waters not exceeding a depth of 350 feet, drillships and semisubs can drill in waters measuring up to 12,000 feet deep.
"Jackups semis and drillships all use the same mud pumps; however, the number of pumps installed in the pump rooms changes from rig to rig depending on the drilling specifications," explained Lerma.
Additionally, the rock formations and pressure encountered when drilling may vary; HT/HP and environmental conditions also may affect the drilling process, as well as the drilling fluids chosen and mud pumps required.
"As the drilling programs require higher flows and higher pressures, it is necessary to increase pressure ratings and either increase the number of mud pumps required or utilize larger capacity mud pumps," Lerma continued. "Most early jackups utilized two mud pumps and piping systems rated for 5000 psi work pressures and 1600 horsepower, while most of today's jackups have 7500 psi working pressure and up to four 2200 HP pumps piping systems."
According to information gathered by premium rig data service RigLogix, National Oilwell Varco leads the pack in providing mud pumps to offshore oil rigs. Of the top six brands of mud pumps, NOV supplies four of them, garnering more than 70% of the offshore mud pump market.
Those leading NOV brands include National Oilwell, Continental Emsco (which was acquired by NOV in 1999), National and NOV. The other leading mud pump system is provided by Gardner Denver and is the third most popular type of system offshore. Additionally, Lewco, a division of Rowan, has about 4% of the offshore mud pump market, putting it fifth on the list of leading suppliers.
Furthermore, NOV leads the industry regionally and by type of rig.
With more than four decades of experience providing the offshore industry with mud pumps, Lerma revealed that the company has been able to sustain such a high market share by constantly transforming the product to meet the needs of the industry. As offshore drilling programs have required higher flows and pressures, the company has strived to provide the best quality equipment, while maintaining the lowest cost of ownership.
To better serve its offshore clients, the company developed the Hex Pump in the last several years, and this new line of mud pumps has proven a success in offshore waters worldwide. Boasting 2400 HP, the Hex pump is capable of delivering up to 1,034 gallons of drilling fluids per minute, making it one of the most powerful mud pumps on the market today.
In 2004, the first two Hex Pumps were deployed on a Global Santa Fe rig working offshore West Africa, and in 2005, both the Noble Max Smith and the Noble All While started using the Hex Pump as well. In fact, the Noble Al White, working in the harsh conditions of the North Sea, was the first rig to be solely dependent on the Hex Pumps with two of them located in its pump room, and the rig now has more than 8,000 hours of successful drilling operations using the system.
Through these successes, the company has been able to lock in orders for many of the newly built and under-construction offshore rigs joining the global fleet now and in the future.
"The first drillship to use the system, Transocean's Discoverer Clear Leader just started drilling in the Gulf of Mexico with five Hex Pump systems," said Lerma. "Additionally, the soon-to-start-drilling Discoverer Americas houses four Hex Pumps, and the soon-to-be-delivered Discoverer Inspiration will have five."
Most Popular Articles
From the Career Center
Jobs that may interest you