Novel technologies vie to improve subsea flows

Paul Boughton

From undersea compression to improved drainage and blockage removal, E&P companies are turning to novel technologies to improve their product returns.

As deepwater fields move towards more complex reservoir conditions and fluids in challenging conditions, Paradigm has developed a range of engineering solutions which allow significant cost savings to be made.

One such solution is Pipe-Pulse, a flow oscillation method for the non-intrusive removal of subsea blockages. It effectively takes the treatment to the topside for the first time and test trials for a number of operators have been very successful. This includes clearing a 4-in multi-phase flowline for Shell UK that had been blocked with sand and wax for 11 years and an adjacent 6" flowline with a wax blockage for over 10 months.

The system is designed to be connected on the topsides of the host platform through either the pig launcher or the umbilical termination unit to remove the blockages. The Pipe-Pulse unit delivers high energy and volume pressure pulses into the fluid within the pipeline or subsea umbilical, which are transmitted to the blockage face several miles away (Fig. 1).

Operated by three Paradigm engineers per operation, persistent blockages can be completely removed in a matter of days by sending pressure pulses into the flowline, whilst controlling the length and pressure of the pulse. The system operates using a complex series of control valves which are contained within the main body of the Pipe-Pulse unit. These are automatically operated by the touch screen control panel.[Page Break]

Paradigm says that a significant market opportunity for Pipe-Pulse lies in deepwater operations as it delivers dramatic cost savings: "In the case of chronic blockages which have gone unresolved over a number of years, the only solution has often been to replace the umbilical or pipeline which can cost millions of pounds, rendering it economically unviable."

In other developments, the new Hughes Christensen Talon platform of PDC bits from Baker Hughes improves cuttings evacuation for greater bit cleaning, offers application specific bit profiles for superior directional control and utilises Baker Hughes' StaySharp premium PDC cutter technology - all helping to maximise rates of penetration, increasing performance and getting operators into the pay zone faster.

The platform, which includes the Talon high-efficiency bit, the Talon 3D vector-accurate bit and the AutoTrak Curve rotary steerable system bit, also provides operators with enhanced durability and an optimal performing bit for virtually any drilling environment.

The innovative Talon technology includes what Baker Hughes describes as the industry's most advanced mechanical and hydraulic designs, such as specially shaped and positioned blades and nozzles, application-specific bit profiles, low-torque gauge designs and diverging junk slots. These improved efficiency designs mean more energy for rock removal, less vibration, increased durability and improved large-volume cuttings removal - all factors that boost rate of penetration (ROP) and run life.[Page Break]

All Talon high-efficiency bits include Baker Hughes' StaySharp premium PDC cutter technology. This reduces bit erosion, maximising run life and improving penetration rates. The patented polished cutter minimises friction and reduces heat buildup for improved wear resistance and cutter and bit balling.

For increased protection, every Talon 3D bit also includes the Baker Hughes StayTough hardfacing, which combines advanced materials with precision welding procedures to give the bits maximum levels of strength and durability. The use of this proprietary high-alloy steel also improves run life, helping operators redefine traditional interval well construction plans. Drilling curve and lateral sections is accomplished faster, more reliably and with fewer bits.

The Talon high-efficiency PDC bit is ideal for first-bit-under-the-surface applications, intermediate, vertical, directional and near-vertical drilling, as well as hard-to-drill and abrasive formations. The bits have improved gauge holding capabilities due to a new gauge pad configuration that utilizes tungsten carbide and thermally stable polycrystalline diamond materials for protection.[Page Break]

The bits' short shank decreases make-up length for higher levels of directional control on conventional assemblies and increased bit side force on rotary steerable assemblies. This increases control and improves steering for peak performance in extended-reach laterals. When paired with the Baker Hughes AutoTrak Curve rotary steerable system, Talon bits offer exceptional speed and performance in getting through laterals and into the pay zone.

For unconventional gas applications, including shale plays, and conventional directional drilling, Talon 3D high-efficiency vector-accurate bits feature a one-piece steel body frame creating a short bit-to-bend dimension. They provide improved hydraulic efficiency, greater buildup aggressiveness, and longer life, often allowing curves and lateral sections to be drilled in a single run.

An operator in the Eagle Ford shale in South Texas recently chose Baker Hughes' 8 3/4-in Talon high-efficiency PDC drill bits for two wells. The Talon bits easily met the operator's requirements after drilling two curve sections quickly, with superior stability and efficiency. Each Talon bit performed nearly twice as well as the average offset wells, with a 93 per cent improvement over the average ROP.[Page Break]

Subsea gas compression

Statoil and partner Petoro have agreed to apply subsea gas compression on the Gullfaks South field. This technological leap forward represents an important milestone in the efforts to improve recovery from this and other gas fields.

This technology adds 22 million barrels of oil equivalent to the production from the Gullfaks South Brent reservoir. The partners will invest some NOK3 billion (EUR420 million) in the technology project scheduled to be completed in the autumn of 2015.

"Innovation and technology development are essential to improved oil and gas recovery and extended life for the fields on the Norwegian continental shelf. The development of subsea compression and processing is a central part of Statoil's technology strategy for long-term production growth," says Statoil's executive vice president for technology, projects and drilling, Margareth Ovrum.

The Gullfaks project is the second large subsea gas compression project planned by Statoil. In April this year the plan for development and operation for Asgard subsea compression was approved by the Norwegian parliament.

Both projects are scheduled to be completed in 2015. Furthermore Statoil is responsible for the technology qualification for Shell for a third not yet decided project, the Ormen Lange pilot. There are good synergies between the different projects.

Subsea gas compression is an important step on the road towards Statoil's ambition of installing the elements for a 'subsea factory'. Subsea processing is key to getting access to resources in Arctic areas and deepwater assets

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