D&C Tech Digest

World’s first subsea facility to separate, inject water, sand from wellstream goes on-stream at Tordis field

The world’s first complete subsea solution for separating and injecting water and sand from the wellstream is on stream and creating added value at the Tordis field, said StatoilHydro. This technology is a breakthrough for a new generation of subsea solutions in the oil industry. The Tordis subsea development is part of a project that will improve the recovery factor for the Tordis field from 49% to 55%. This amounts to roughly 35 million bbl of oil, in addition to associated gas.

The full potential of the subsea facility has not yet been realised due to unforeseen challenges with the injection well, but alternative solutions are being evaluated.

Seabed separation makes it possible to improve recovery and accelerate oil and gas production. This increases the utilisation of installed facilities.

The technology provides added recovery of oil in cases where production is limited by pressure and capacity at the processing plants. The technology is particularly suitable in developments at great depths or far from shore and in areas where natural conditions and weather make subsea developments most appropriate.

While it is usual to send the wellstream up to the platform, where oil, water and gas are separated from each other in a processing facility, the new Tordis subsea separator removes water and sand before the oil and gas are pumped to the Gullfaks C platform. The separated water and sand are pumped down into the Utsira formation directly from the subsea installation and stored there.

This solution means that large amounts of water from the reservoir avoid the 10-km journey to Gullfaks C at sea level. This saves energy and reduces the discharge of produced water to the sea.

StatoilHydro believes its experiences from Tordis will be helpful in deepwater Gulf of Mexico, in the Shtokman development in Russia, and elsewhere in the world.

Widespread RFID ‘on the horizon’

M-I SWACO is allowing iiiTEC the use of patented radio frequency identification (RFID) technology for open- and cased-hole drilling and pre-completion wellbore clean-up applications. The use of RFID technology to actuate downhole equipment has the potential to save operators millions of dollars annually. Successful field trials have been conducted in the North Sea.

“We believe widespread use of this technology is on the horizon,” said M-I SWACO vice president Neale Browne.

The technology represents a significant improvement over the traditional mechanical/hydraulic/fluid systems currently in use to actuate downhole equipment. Developed and patented by Marathon Oil Company, RFID technology uses an intelligent chip to activate the tool.

This ability brings a new dimension in control, such as allowing a critical circulation valve to be activated in more than just the open or closed position. The technology being developed by M-I SWACO enables flow rate to one or more devices being run in a single tubing string to be opened, closed or retracted as many times as needed.

iiiTec’s core business is developing RFID applications for drilling and coiled-tubing operations.

Cesium formate brine used as well kill, suspension fluid in extreme HPHT well

Hungarian TXM Energy, a subsidiary of Canada’s Falcon Oil & Gas, and Cabot Specialty Fluids, a subsidiary of Cabot Corp, recently set a new record for the use of cesium formate brine in extreme well construction operations. The brine was successfully used as a well kill and suspension fluid in an extreme HPHT gas appraisal well in Hungary. The well measured a total depth of 5,692 m, with a bottomhole static temperature of 455ºF (235ºC), and pressures exceeding 14,000 psi. Approximately 60 cu m of 2.15 sg cesium formate was bullheaded into the well to minimize wellhead pressure so that a packer and test string could be snubbed into the hole. The bottom of the column of cesium formate brine was at a depth of 5,300 m, where the temperature was 437ºF (225ºC). The cesium formate brine remained in the well for 39 days before being displaced by reverse circulation to a packer fluid before conducting well test operations. Analysis of the returned formate brine showed no significant change in properties or composition, and it was put on stand-by for further use.

High-density cesium formate brine has now been run back into the well as a long-term suspension fluid, where it may remain for up to a year.

Baker Oil Tools completes 100th installation of its intelligent well system

Baker Oil Tools has completed the 100th worldwide installation of its intelligent well system (IWS) at the Okume Complex, offshore Equatorial Guinea. The technology provides permanent monitoring of downhole flow, pressure and temperature, enabling the operator to optimize production and reduce costly interventions.

“We are very proud of this outstanding track record, made possible through strategic project management and the application of proven technology,” said Craig Coull, IWS manager for Baker Oil Tools. “Our intelligent well systems have been installed throughout the world, including the Middle East, Latin America, Gulf of Mexico and Africa.”

In Equatorial Guinea, a highly deviated well at 500-ft water depth required a stacked completion with independent control of commingled production from two oil zones. The 70° deviation of the well made mechanical shifting of downhole valves expensive and risky. To address these issues, Baker Oil Tools installed its InForce intelligent completion system.

Key system components include remotely operated, multi-position choking valves for selective control of the two oil-producing zones and a fully automated surface control system. ProductionQuest, a Baker Hughes business unit, provided a triple-gauge package to monitor both zones and their commingled flow, displaying the data in real time and providing back-up data storage.

Delmar installs 1st gravity-installed vertical load anchor in Gulf of Mexico for Anadarko

Delmar Systems has successfully installed the Gulf of Mexico’s first gravity-installed vertical load anchor (VLA). The patented OMNI-Max anchor was installed at Anadarko’s Garden Banks 667 location in late December 2007.

The anchor was deployed from the AHTS – Alex Chouest and penetrated the seabed. It was pull tested by the installation vessel and, with mooring line forerunner attached, abandoned on the seabed in the preset configuration. The anchor line was later connected to Diamond Offshore’s MODU Ocean Star using Delmar’s patented subsea mooring connector to connect the preset mooring line to the rig’s self-contained mooring components. The installed OMNI-Max anchor complements the MODU’s 7 other self-contained/deployed conventional drag embedment anchors with attached mooring lines.

“This anchor technology offers great benefit in design of mooring systems that reduces risk to subsea infrastructure in the event of station keeping damage or failure. The OMNI-Max is capable of being loaded in any direction 360º around the axis of the anchor,” said Evan Zimmerman, Delmar engineering manager.

“Under extreme loading and uplift angle conditions, the anchor will penetrate deeper into the soil to gain the needed holding capacity. This technology is an industry first that may allow damaged moorings to survive longer in the event of multiple line failure since the load angle can change without the capacity of the foundation being adversely affected. This is a milestone achievement to assist operators such as Anadarko by developing a more efficient anchor to moor MODUs over and among valuable seabed infrastructure.”

Schlumberger, TESCO offer directional casing while drilling

Most casing while drilling (CwD) is done by attaching a non-retrievable bit to the bottom of the casing and leaving the bit in the hole. Directional casing while drilling (DCwD) uses a steerable BHA that is retrieved, making DCwD a viable alternative to conventional directional drilling in depleted or mature fields that have severe lost-circulation and wellbore stability problems, Schlumberger said during a press conference held at its exhibit booth during the 2008 IADC/SPE Drilling Conference, held in Orlando, Fla., on 4-6 March.

Well construction in mature fields with standard drillpipe sometimes requires extra casing strings to avoid well stability problems caused by depleted formation pressures. Because they improve wellbore stability, the DCwD techniques developed through collaboration between Schlumberger and TESCO may reduce the number of casing strings needed.

DCwD also improves well control because it allows circulating while the BHA is being retrieved or run into the well. They also leave the casing at or near the bottom while the BHA is out of the well. During drilling, DCwD rotation strengthens the borehole wall because of the plastering effect, also known as smear or stress cage, which occurs in the narrow annulus.

The first deployment of DCwD offshore was on a well drilled from the ConocoPhillips-operated Eldfisk Bravo platform in the Norwegian sector of the North Sea. Both the 10 ¾-in. and 7 ¾-in. sections of Well 2/7B-16A, totaling 10,968 ft, were drilled successfully and positioned as planned using retrievable BHAs that incorporated Schlumberger’s PowerDrive X5 rotary steerable systems, PowerPak straight positive displacement motors (PDMs), and Pulse telemetry and surveying systems. The casing strings were rotated at 20-30 rpm from the surface, and the PDMs provided an additional 130 rpm to the RSS, PDC bits and under-reamer. ROP was as high as 80 ft/hr. All directional objectives for the wellbore were achieved, with a maximum dogleg severity of 4.83º/100 ft.

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