Subsea riserless mud recovery
A riserless mud recovery (RMR) technology has been developed by Ability Subsea, part of the Norway-based Ability Group ASA, as a means of recirculating and re-using drilling fluids. According to the company, the benefits of the technology include cost savings from reduced operating time and minimal environmental impact from avoided discharges in the sea.
Total E&P UK Plc used the RMR technology to drill the Jura West 3/15-10 prospect in the North Sea. The recently completed well was drilled using Transocean’sSedco 714 semisubmersible rig in 113 m of water.
Total says it achieved significant time savings compared to the previous technology it used to drill similar 26-in. hole sections. In response, Ability Subsea plans further use of the technology later this year.
Industry’s acceptance in using the RMR technology has grown rapidly. For instance, it recently has been deployed off Sahkalin Island and in the Barents Sea where no drilling discharge is permitted. Other operator applications have been used in areas of poor hole stability where an engineered fluid system is required. One of the primary advantages of using this system is its ability to push planned casing setting depths deeper, thus allowing for a simplified design.
Operators can deploy the RMR technology in water depths up to 400 m. Ability Subsea has started development work with two oil companies to increase the technology’s capacity for operations in up to 1,500 m of water. Field trials are scheduled to begin in 2007.
Subsea intervention
Aberdeen-based DES Operations with Shell plans to install three new subsea technology systems.
DES has developed subsea processing technology that removes the need for divers during subsea intervention, allowing operators to squeeze more oil out of subsea wells with ROVs.
Known as MARS (Multiple Application Re-injection System), the system is slated for installation on Shell’s Bittern field in the North Sea where it will be used to upgrade the field’s subsea trees to maximize oil production.
DES has built five MARS systems, with the first two slated for BP’s King field in the Gulf of Mexico. The project is also using the first multiphase pump in the GoM. It is considered the deepest pump deployment ever and the longest high voltage subsea tie-back to a platform to date.
The users describe the MARS system as a sort of “USB port” in their existing subsea trees. The equipment is placed over the wellhead to control the well so that flow can be accessed on new and existing wells. This flow loop can then be used to increase production, therefore extending the life of the field while enabling other processing equipment such as pumping, metering, water management, and separation to be installed at any time.
“Flexible plug-and-play subsea processing has long been the Holy Grail of the oil and gas industry,” says Ian Donald, DES managing director. “With MARS, operators now have a simple, low risk, low cost method of achieving this.”
Commenting on the agreement with Shell, he says: “The current method to get more oil out of a subsea well can be diver intensive and therefore high risk and expensive. By using the MARS system, Shell is able to eliminate divers and complete the entire underwater operation using ROVs.”
Shell will install two MARS systems on the Bittern field in 2007, with the third slated for an undisclosed location. It is being fitted onshore on a new subsea tree before deployment.
Regulating drilling torque
Tomax AS, a Norwegian company with operations in Norway, USA, and Canada, developed a new “closed network” technology, known as anti-stall technology (AST), through inventors Nils Reimers at Bjoa, Vindafjord, and Per Olav Haughom at Tonstad, Sirdal.
Norwegian operator Statoil ASA has actively supported AST from the beginning based on their strategic program to improve key areas of oilfield operations.
The AST is the first ever downhole tool designed to actively regulate drilling torque and stop overload situations. This effect is obtained through a telescopic system that will contract and pull back the drillbit if the torque increases above a safe level, which is controlled from the surface.
The company’s field experience with the system has reduced drillstring overload and increased general drilling speed. The initial field operations were performed on coiled tubing type well intervention strings while operations on regular rotary drilling started this year. The company’s first rotary drilling test with AST technology at the Ullrigg facility resulted in a sustainable drilling speed of 44 m/hr compared to earlier recordings between 8 and 12 m/hr.
The company’s operations are coordinated by Norwegian field service experts, PI-Intervention AS. Activity accelerated passed 40 coiled tubing runs after the technology was introduced by PI-Intervention together with Thru Tubing Solutions Inc. in US and Canadian natural gas fields in June of this year.
Årdal Maskinering AS manufactures the AST tools at Nærbø where a new machining method was developed for the tools. Årdal is part of the group referred to as a closed network of engineering, manufacturing, and field services companies that work closely together to provide the technology to the end-user. This network replaces the need to build and educate a new organization from scratch, and makes it possible to meet the high standards of quality and safety required for commercial operations from day one.
Frank Hartley, Houston
