Frank Hartley • Houston
Longest well in the world
Maersk Oil Qatar has finished drilling the longest hole in the world on the BD-04A well at a length of 40,320 ft (12.3 km) with Transocean jackupGSF Rig 127, the smallest and one of the oldest jackup rigs of the six currently operating, says Hans Flikkema, head of drilling engineering, Maersk Oil Qatar AS.
With a horizontal section of 35,770 ft (10,903 m), the BD-04A well also extended the company’s previously held world record for the longest horizontal well by 9,000 ft (2,743 m). The entire horizontal reservoir section was placed within a reservoir target which is only 20 ft (6.1 m) thick. It was achieved mainly through optimizing the drillstring design and the drilling parameters of the well, Flikkema says.
The company recently identified limiting factors to its horizontal hole length through reviewing the basic drilling parameters on past wells and then engineered solutions to push the envelope further, Flikkema says. In addition, engineering made optimum use of available technology, best ERD practices, and monitoring of the downhole drilling parameters. Quoting from a recent ERD conference, “To drive a nail deeper, oiling the nail often is more effective than using a bigger hammer”, this well really proves that point.
All drilling parameters were well within the normal operating envelope, and even making a 40° turn in the horizontal plane beyond 35,000 ft (10.7 km) did not cause a problem, the company reported. The 35,449 ft (10.7 km) 8 ½-in. (21.6-cm) hole trajectory to TD was drilled through a thin limestone reservoir with a two-bit run, using rotary steerable for directional control and LWD for geo-steering.
Qatar Petroleum and Maersk Oil have a successful history of applying horizontal well technology for the development of the Al Shaheen field offshore Qatar, with Maersk Oil Qatar as operator, says Maersk.
“When we contracted Maersk Oil for the challenging reservoirs in the Al Shaheen field, where other oil majors had given up, we were not fully aware of Maersk Oil’s capabilities, but we trusted their entrepreneurship,” says Saad Sherida Al-Kaabi, director of Oil and Gas Ventures for Qatar Petroleum. “Our decision was proven right, thanks to the vision of the Emir His Highness Hamad Bin Khalifa Al-Thani and the guidance and support of His Excellency Abdullah Bin Hamad Al-Attiyah, deputy prime minster and minister of energy and industry.”
“It is not our goal to break drilling records, but rather to be an efficient and prudent operator to add value to our stakeholders,” says Jakob Thomasen, managing director of Maersk Oil Qatar. “We have found that Maersk Oil’s horizontal well technology adds indispensable value to the Al Shaheen field development. Not only do we gather information at highly competitive costs, but with our technology we minimize the number of wells, platforms, and infrastructure required for oil and gas field development.” The company estimates that its existing six-location development would have required at least 20 platform locations with conventional horizontal well technology.
“Imagine the cost and environmental load of a 20-platform infrastructure compared with our energy efficient approach,” Thomasen says.
Maersk has been active with exploration and production in Qatar since 1992 under a production-sharing agreement with Qatar Petroleum. Maersk Oil Qatar operates the Al Shaheen field in block 5, 80 km (49.7 mi) off the coast and is currently executing a $6 billion field development to bring the oil production from the current level of 330,000 b/d to a plateau of 525,000 b/d by the end of 2009.
Developments for wireline in coiled tubing
AnTech says it has developed two systems to log and perforate while running with wireline in coiled tubing. The systems are the collector bulkhead and a 2 7/8-in. (7.3-cm) logging head that features seven conductors.
AnTech’s addition of a 2 7/8-in. (7.3-cm) logging head to the 1 11/16-in. (4.29-cm) and 2 1/8-in. (5.4-cm) versions provide options with a seven-conductor option for running video or open hole tools.
The collector bulkhead provides a means of connecting wireline to surface. Using field-proven design features of its wellhead outlet simplifies the installation and connection, the company says. The electrical connections are situated on rails that make it possible for one person to carry out installation and maintenance. The collector bulkhead is designed in single and seven-conductor configurations.
The addition of a 2 7/8-in. (7.3-cm) logging head to the 1 11/16-in. (4.29-cm) and 2 1/8-in. (5.4-cm) versions provide options with a seven-conductor option for running video or open hole tools. With the tools’ modular design, they can be manufactured to meet specified connections and cable sizes. The 2 1/8-in. (5.4-cm) and 2 7/8-in. (7.3-cm) tools have a mechanical release featuring precision shear pins or an electrical release when a controlled release is required.
The range of options means that these systems can be used in highly deviated and horizontal wells where wireline is not suitable, such as open and cased hole logging and perforating.
The logging heads have a top connect that attaches to coiled tubing, and check valves that allow fluid to be pumped downhole, but prevent fluid from returning. In the event of an emergency, its cable weak point allows the cable to be broken downhole and pulled back. The mechanical shear disconnect can be set in 1,000 lbf increments to prevent coil damage. The electrical disconnect makes it possible to plan a separation of the head from the string. In addition, all tool sizes have a fishing neck which means that operators can pull the separated string following a disconnect operation. Its non-rotating bottom connection makes it easy to attach to other tools located below when they are held by the grips of a BOP.
The logging head screws to the top housing onto the coiled tubing connector and then the check valve cartridge is inserted. In cases where separation is required, the electrical disconnect is released by applying a reverse voltage for one minute. The mechanical disconnect is released by overpull from surface.
Live annulus camera inspection
EV Offshore Ltd. says it has completed a downhole inspection operation for Nexen Petroleum UK Ltd. in the North Sea. The customized camera inspection operation was carried out on behalf of Nexen on its Buzzard project, located in the Outer Moray Firth in the central North Sea, 100 km (62.1 mi) northeast of Aberdeen.
EVO designed and manufactured a custom camera for Nexen that made it possible to inspect conditions within a live annulus using a third-party lubricator system via Platform B annulus valves. Following initial technical discussions and instructions to proceed from Nexen, EVO was on-site to carry out onshore trials in just 18 days. To access the areas of concern, the camera had to be designed to operate within an extremely small area within the 32-mm (1.26-in.) side-outlet bore and operate at 3,000 psi.
Following onshore trials, the offshore inspections were carried out following procedures, as dictated by the trials. Included in the actual inspection was a flushing procedure to ensure that the view was not obscured by turbid fluid. Nexen engineers were able to view high-resolution images to determine the condition of the equipment, which would influence future plans or contingencies.
“Looking ahead, we are extremely pleased to be working on behalf of Nexen, and are confident that we will continue to provide them with the highest quality real-time images,” says David Clover, director at EV Offshore.
