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7th. Generation Ultra Deep Water semi-submersible drilling rigs from Frigstad Engineering.

Everything is bigger on the new Frigstad D90TM rig from Frigstad Engineering. With an operating displacement of 69,800 MT, VDL of 10,000 MT, and drilling depth capacity of 60,000 feet, the Frigstad D90TM is the world's largest semi-submersible drilling rig. But size is not the most important feature. The large, open deck and rational logistics solutions makes the Frigstad D90TM the most effective rig available.

The Frigstad Groups experience as drilling contractor has played an important part in the development and modernization of the design. Two new semi-submersibles of the Frigstad D90TM design were recently ordered by Frigstad Deepwater for delivery in Q4-2015 and Q2-2016. These units are tailor-made for safe and efficient exploration, and for drilling at extreme depths. The owner of Frigstad Engineering, Harald Frigstad, has been uncompromising towards his designers. With his background from drilling operations, he constantly searches for solutions that will optimize the rig. This includes clear and uncluttered deck areas, efficiency and safety of all processes during operations and optimal living conditions for the crew. On the Frigstad D90TM, there are no air vents obstructing open deck areas, practically no blind zones for cranes, and high comfort for the crew. The Frigstad D90TM is equipped with 200 single cabins, each with its own window.

Frigstad Engineering create their designs with focus on the main purpose of the rig, namely the drilling operation, and designs optimal solutions from this viewpoint. The aim of the Frigstad D90TM design is to provide a drilling unit with optimal functionality on deck and below, as well as high transit speed.

"Our new Frigstad D90TM builds on the success we have had with the Scarabeo 9, the first unit of the design which commenced operations in 2012. When Scarabeo 9 operated offshore Cuba, the rig received particular attention from U.S. authorities. The rig successfully passed a thorough inspection performed by the U.S. Coast Guard prior to entering Cuba and has since performed well for several reputable operators. For us, this is proof that the Frigstad D90TM design lives up to our promise of high standards and quality", says ystein Bondevik, Managing Director of Frigstad Engineering in Norway.

Effective design

The two new Frigstad D90TM rigs that are now under construction, are each equipped with a NOV Dual Activity Rig with 2 x 1,400 short ton API lifting capacity ( 2 x 1250 short ton in elevator) and two seven ram BOP's.

The rig solution, developed in collaboration between Frigstad Engineering and NOV, makes the drilling process more efficient by allowing the running of two loadpaths at the same time. A new process can be completed without interrupting the ongoing activity.

This is not a unique solution for the Frigstad D90TM the same technology can be found on drillships today but the capacity and logistics for Frigstad D90TM is unique. A semisubmersible has high positional stability and can perform simultaneous activities in a stable mode, as opposed to a drillship that could have operational issues with changing wind, current and waves. In addition, the utilization of a Dual Activity Rig will be higher on a semi-submersible rig due to improved station keeping ability.

The clean design is also reflected in the supporting structure. Four columns without cross bracings simplify the construction of the rig. When the rig is submerged, barges can enter in between the support columns carrying heavy components (such as BOPs) for easier and safer loading and unloading. Four horizontally mounted bracings further simplify the construction and reduce costs. The bracings are also placed so that they are above the waterline in transit. This, together with the design of the pontoons, greatly improves the transit speed.

"As designer, it is very rewarding to be constantly challenged to improve efficiency of the rig. This motivates us to provide the best floating rig possible. We tailor-make solutions in close collaboration with our customers and base the design on the different features the customers want and need. Through our experience as an operator we have full insights into the complex work processes and procedures taking place on the rig, and we strive to streamline these processes, without compromising the safety of the rig and its crew. We know that we have a solid concept with the Frigstad D90TM design", says Bondevik.

The Frigstad D90 TM can achieve a speed of 9 knots in transit. The efficiently designed hull moves easily in the water with reduced fuel consumption. Throughout the design process, Frigstad Engineering has been committed to building the most environmentally friendly rig possible. It is designed to install a so-called green HPU, which uses environmentally friendly hydraulic oil to reduce the harmful effects of leaks from equipment that may cause discharges. The drill cuttings facility is designed to provide high flexibility during operation, with drill cuttings handled safely in a fully integrated tank of 600 m3. Drill cuttings can then be pumped directly onto the supply vessel, without having to use traditional skips or deck mounted tanks and the use of cranes.

Ideal storage and material handling

The semi-submersible rig is built to handle extreme water depths. This creates special demands for safe handling of the large volume of required equipment on deck. To streamline the assembly of the risers, 10,000 feet, of the total 12,000 feet total capacity, are stored vertically in double lengths of 110 feet. In addition, space has been allocated for vertical storage of 60,000 feet of drill string, mounted in quadruple stands. The design is made to handle and store two complete 20k BOPs.

The superior riser storage capacity in combination with pre-assembled, long stands, ensures optimal operational efficiency, and at the same time releases valuable deck space for safer and better material handling. A clean and open deck surface reduces the risk of injury to personnel and equipment.

Our focus on safety has resulted in a solution that makes the Frigstad D90TM list considerably less than other designs in so called damaged condition, thereby far exceeding the class regulations. As a result of this, the air vents are moved from the deck into the hull. All anchor handling systems and hose reel stations are also mounted below deck. This further contributes to a clean deck and enhanced capacity for storage and handling of materials. Simultaneously, it enables the rig to be designed with wide and open truck paths on all decks which together with two separate cargo lifts greatly improve the logistics and practically eliminates blind lift crane operation and lowering through open hatches.

Experience meets innovation

"The company's founder, Harald Frigstad, has the experience and creativity to inspire and motivate us at the drawing board and his vision is clear. Frigstad Engineering should always deliver the most effective operational solutions possible, tailored to suit our customers needs. We feel that our solution lies at the crossroad between practical experience and innovative design expertise", says Bondevik. "Although our core business is to supply basic design, our team has expertise down to the last small detail. We had a chance to prove this when SapuraKencana Drilling asked us to develop complete detail drawings for our Frigstad T70TM design a semi-submersible tender assist drilling rig with displacement of 30,500 MT. This is, as the Frigstad D90TM, the largest of its kind and a rig that is in the top range in terms of operational efficiency and comfort for the crew."

Frigstad Engineering has a clear objective to be a leading and preferred designer and collaborator on floating rigs made to work in harsh environments.