Making time

Loading rock on to the Flintstone at Shenzhen, mainland China. Photo from Tideway.

Fast local sourcing and past experience helped Tideway turnaround a Chinese rock placement project in quick time.

Early this year, DEME Group’s Tideway got an invitation to tender for a rock-placement project in the China Sea, involving placing 120,000-ton of rock material on a 30in. two-phase export pipeline.

A contract was signed on 8 April, and by 29 April, Tideway’s fall pipe vessel Flintstone was ready on location in Shenzhen, mainland China, after diverting from the Caribbean. In addition, 70% of the rock material was ready on a quayside, all just ahead of the 1 May start date.

The work was on the Liwan 3-1 project, providing protection and fill-up of freespans on locations where trenching results were insufficient on the 260km pipeline connecting the Liwan 3-1 platform to China National Offshore Oil Corp.’s (CNOOC) Gaolan gas plant. Tideway was also contracted to fill up two footprints left by a drilling rig near the Panyu 10-1 jacket.

Liwan 3-1 is in block 29/26, in the Pearl River Mouth Basin, China Sea, about 300km south of Hong Kong.

“The Flintstone had been on its way to Mexico for another project when the Chinese contract was awarded,” says Marald Mortier, deputy project manager at Tideway. “We re-scheduled a number of vessels so that the Flintstone could be diverted to China, via the Cape of Good Hope, following the letter of intent on 21 March.”

But mobilizing the vessel is only one piece of the puzzle. “Another matter was the supply, stockpiling and loading of rock material,” Mortier says. The rock material, in two gradings, 1-2in. and 2-8in., was to be produced locally. “During the tender preparation phase, alternative supplies and loading locations were evaluated and a choice was made. After the [letter of intent,] the plan was implemented and agreements with the rock supplier and a harbor for stockpiling and loading services were made. On 1 May, about 70% of the total amount of rock material was produced and ready in stockpile in the harbor area.”

The work scope involved placing about 120,000-ton of rock material, which was sourced about 15km from the load-out location. Load-out required two conveyer belts on the quayside for transport into the vessel’s hoppers. These had to be supplied and refurbished locally, due to the late delivery of conveyor belts ordered.

A slightly less obvious but important element of the project was local understanding about rock placement. “This was the first rock placement project in China’s oil and gas industry, so it was important to make the client understand what the possibilities and limitations were. Another important contribution was the onshore organization—50% of the project team is Chinese/English speaking, which is helpful in a country where few speak English,” Mortier says.

The project, completed on 12 June, was not Flintstone’s first in China. The vessel had previously delivered a non-oil and gas project. Its ability to place rock material close to a platform, due to the hinged hang-off point of the fall pipe, was also beneficial for the project.

There are nine deepwater wells at Liwan 3-1, in 1200-1500m water depth, about 75km from a shallow water platform, described by Husky Energy as the largest platform built and installed in Asia to date.

Liwan 3-1 is part of the Liwan gas project, which is operated by Husky Energy (deepwater segment) and CNOOC (shallow water segment and platform). Husky Energy has 49% interest in the Liwan gas project, with CNOOC owning the remaining 51% interest.

The tie-in of Liuhua 34-2 is expected 2H 2014, and Liuhua 29-1 during 2016-17, taking gas sales to 400-500MMcf/day (gross). Initial sales of condensates and natural gas liquids from Liwan 3-1 are expected to be about 10,000- 14,000boe/d.