SUBSEA SYSTEMS

This graph illustrates ConocoPhillips’ assessment of additional Ekofisk recovery resulting from water injection. Blue: Production profile without water injection. Green: Increased production with water injection.

Aker Solutions and Well Processing have teamed to develop new technology for subsea water treatment/injection.

According to the agreement, Well Processing will contribute its subsea seawater treatment technology and Aker will provide its experience with subsea water injection, boosting, and pumping.

“What we can jointly offer together with Well Processing is a cost efficient and effective process for water treatment and injection, with all equipment located on the seabed,” says Knut Nyborg, vice president for subsea processing and boosting, Aker Solutions. “The aim is to unlock oil reserves that would otherwise have been unrecoverable.”

“Extracting seawater from the seabed, where there is a lower degree of biological growth, gives us some inherent advantages compared to traditional topside systems,” says Helge Lunde, managing director of Well Processing. “Additionally, our system contains significant innovations within seawater and system sterilization as well as solids removal. All together, we believe we have a unique water treatment solution which will help prevent blocking of reservoirs or turning them sour when water is injected into them.”

Aker Solutions also has an EPC contract from Dong E&P Norge for a complete NOK 400 million ($61 million) subsea production system for Trym field some 300 km (186 mi) southwest of Kristiansand, Norway, in 65 m (213 ft) water depth.

Contract scope of work includes engineering, procurement, and construction of two subsea well sets including trees, controls, wellheads and a tie-in system with four-slot template and manifold, 6 km (3.75 mi) of steel tube umbilicals, high-pressure riser, tools, and services. The tie back is to Maersk’s Harald platform in the Danish North Sea.

In the Gulf of Mexico, BHP Billiton Petroleum (GOM) Inc. has contracted Stress Subsea Inc. to design a subsea water injection system for Shenzi field in Green Canyon blocks 609-610, 653-654. TheShenzi TLP is in 4,300 ft (1,311 m) of water.

The contract includes engineering and project management of the subsea hardware, umbilicals, risers, and flowlines leading up to the execution phase of the project.

Shenzi went onto production this past March. The TLP has a capacity to handle 100,000 b/d of oil and 50 MMcf/d of gas. The initial development is with seven subsea wells tied back to the TLP. BHP says full field development will include 15 producing wells and some number of water injection wells.

BHP as operator holds 44%, with Hess Corp. and Repsol E&P USA Inc. each with 28%.

New umbilical installation design unveiled

A simpler J-plate installation of a subsea umbilical using an ROV manipulated flying-lead-installation-running tool has won a patent for Deep Down Inc. Deep Down says the new technique eliminates the damage prone acme screw thread and collet locking mechanisms and associated complex mechanical override systems of traditional J-plates.

Further, the new design interconnects with any umbilical and subsea distribution system and makes reconfiguration possible without retrieving the flying lead, Deep Down says.

Angola block 31 to use ELSA technology

BP plans to use Expro Landing String Assembly (ELSA) technology on its development work offshore Angola in block 31 on Plutao, Saturno, and Venus Matre.

According to Expro, the system allows control of isolation valves which means there is no requirement to set and retrieve wireline plugs. In addition, Expro will provide a control system designed for well intervention that meets BP’s dual redundant and control monitoring requirements.

The system permits dual bore completions to be deployed using a monobore landing string, allowing the wells to be flow-tested to the rig prior to installing the production trees. The system was designed in Expro’s Aberdeen Engineering Technology Centre and will be delivered through the remainder of 2009. First offshore operations are anticipated in spring of 2010.

Consortium to research ultra deepwater moorings, risers

Noble Denton is funding a three-year research program at the University of Cambridge into effective modeling of ultra deepwater mooring and riser developments, saying that water depths exceeding 1,500 m (4,921 ft) make integrated modeling of the floater, moorings, and risers difficult.

In the case of computational models, the dynamics of the floater, moorings, and risers are highly coupled, and complex mathematical equations are required to capture this behavior, leading to excessive computation times, says Nobel Denton. Also, for physical model tests it is impossible to produce a scale model which accurately captures all aspects of the system, given the restricted water depth of testing tanks.

The research will consider the development of an efficient truncated model of the mooring lines and risers.

BP is providing industry expertise and guidance to the research program.

Using this approach, the dynamics of the upper section of each line will be modeled in detail, terminating in an approximate analytical model which aims to simulate the remainder of the line.

As to physical modeling, two strategies will be investigated:

1. The use of actuators to replicate the behavior of the lower sections of the lines, using the type of model developed for the computational work

2. The use of dynamic similitude to develop a passive shallow water line with the same vibrational characteristics as the full line.