Despite many advances in drilling technology, the method routinely used to monitor the weight and viscosity of drilling fluid has remained unchanged since the 1950s.
However, with input from the UK offshore sector’s Industry Technology Facilitator (ITF), small Aberdeen-based company Mud Automatics has set out to tackle this with the development of a new approach for the 21st century.
Changes in the physical properties of mud during drilling can warn of a drilling hazard, with potentially serious safety implications as well as the expense of lost rig time.
Consequently, mud weight and viscosity are monitored throughout drilling. While many other drilling parameters, such as standpipe pressure, rotary torque, pit levels and gas content, are monitored continuously, the method for mud monitoring involves a manual batch-testing process using a Marsh funnel and mud balance.
Ross Colquhoun, MD at Mud Automatics, decided to tackle this incongruity with the development of Mud Watcher, a simple device that allows real-time, continuous monitoring of mud weight and viscosity.
He explains: “When I started in the industry 37 years ago, I was shown how to check the weight and viscosity of drilling mud, and today, even though drilling rigs and procedures have become far more technically sophisticated, they are still using the same labour-intensive method – despite the clear advantages of improving it.
“A properly conducted check of mud weight and viscosity takes 10 minutes. While drilling, this should be performed twice every hour, so a total of 20 minutes every hour – or one-third of a valuable team member’s time – is used to carry out this simple task. It is a very poor use of skilled personnel.
“The Mud Watcher is a user-friendly piece of equipment that has been designed for operation by a rig crew in the harsh rig site environment. Mud properties can be displayed and recorded remotely either on the rig or in an onshore control room.”
This system can monitor any drilling fluid, including oil-based or water-based muds, brines, completion fluids, workover fluids and clean-up fluids.
The technology also offers health-and-safety benefits as it minimises the potential for skin-to-mud contact and it can continue to operate in an area that has been evacuated due to, for example, HS (hydrogen sulphide).
ITF worked with Mud Automatics to secure support for a field trial of this technology. The outcome was that a test was carried out during 2007 which demonstrated Mud Watcher’s cost, safety and control benefits, and also identified some required improvements.
A revised model has since been produced and a Norwegian distributor has been appointed.
Eight systems have already been delivered and Mud Automatics plans to start supplying Mud Watcher to the Aberdeen market in the coming months.
ITF’s operations director, David Liddle, said: “The Mud Watcher really is a very straightforward piece of technology development, but it is significant in that it brings mud monitoring in line with other advances in drilling technology, something which will be of great benefit to our member companies.
“For example, efficient underbalanced drilling is very weight sensitive – it is critical to have information about, and control of, the mud weight all of the time, which the system of manual sampling cannot provide. Mud Watcher is perfect for this.
“Of course, weight-sensitive drilling can also apply the other way – in some places, the weight can be too much and lost circulation and expensive lost rig time can occur. Continuous mud monitoring would be of great benefit in these circumstances as well.”