Sunday, December 16, 2018

Organizing the weather off Sakhalin

June 13, 2013

Air discharge indicating success of the pigging and pressure testing of one of the two pipes running from shore to the GBS. Photo by F. KredensorOther than economics, logistical planning is the heart of any major project. Weather can have a significant impact on project success or failure, and while it can’t be controlled, it can be managed, even in a relatively remote location.

The operating conditions off 950-km long Sakhalin Island include severe wave, wind, and earthquake activity year-round and pack ice 1-1.5m (3-5ft) thick for half the year.

To overcome these “daunting weather-related barriers,” Exxon Neftegas Limited (ENL), a subsidiary of Exxon Mobil Corp. and operator of the Sakhalin-1 project, used on-site meteorologists for the 2012 offshore (ice-free) season.

Setting

Sakhalin Island, off the east coast of Russia, is situated between 54° 42’N latitude at its northernmost point, Cape Elizabeth, and 45° 54’N latitude at its southernmost point, Cape Crillon. Hokkaido, Japan’s northernmost island, is separated from Sakhalin Island by only 40km across the La Pérouse Strait. Also known as the Soya Strait, this international waterway connects the Sea of Okhotsk with the Sea of Japan.

The Sea of Okhotsk borders the east coast of Sakhalin Island, but it is separated from the Pacific Ocean by the Kuril Islands, which stretch northeast from the east coast of Hokkaido to the southern tip of the Kamchatka Peninsula.

The west coast of Sakhalin Island is separated from mainland Russia by the Tartar Strait, which narrows to only 7.3km across the Nevelskoy Strait.

Yuzhno-Sakhalinsk, which means “South Sakhalin City,” is the capital of Sakhalin Island. It is also the administrative center of the Sakhalin Oblast (one of 46 oblasts in Russia), and runs the Kuril Islands. The city was founded in 1882, but the modern infrastructure is from oil and gas development on the Sakhalin shelf.

Sakhalin-1 background

Sakhalin-1 is a consortium that produces oil and gas from three sub-Arctic fields off the northeast coast of Sakhalin: Chayvo, Odoptu, and Arkutun-Dagi. The consortium is managed and operated by Exxon Neftegas Ltd. (ENL), a subsidiary of Exxon Mobil Corp. Partners in Sakhalin-1 include Exxon Mobil (30%); Japan’s Sakhalin Oil and Gas Development Co. Ltd. (Sodeco; 30%); Indian state-owned ONGC Videsh Ltd. (20%); and Russian state-owned Rosneft subsidiaries Sakhalinmorneftegas-Shelf (11.5%); and RN-Astra (8.5%).

The first phase of Sakhalin-1 development started in 2002 and included extended-reach wells drilled from the land-based, 70m-tall drilling rig, Yastreb, meaning “hawk.” The rig was designed to withstand earthquakes and arctic conditions. The Chayvo field was developed first, using the Yastreb rig and the Orlan rig on the Orlan platform, a concrete island drilling structure just of the coast from the Chayvo wellsite. Production from Chayvo began in October 2005, with 50Mbo/d.

Following the Chayvo drilling, ENL moved the Yastreb rig north to drill the Odoptu field in 2008, and drilling there began in 2009, followed by first production in 2010.

Weather, seismicity

Perhaps unfairly known for hostile conditions, the weather in Sakhalin is cold and humid, with average rainfall between 600-1200mm (23-47 in.), winter temperatures between -24°C (-11°F) and 10°C (50°F), and summer temperatures usually below 13-15°C (55-59°F). Temperatures fluctuate with monsoonal circulation and the Sea of Okhotsk, the coldest in East Asia, can carry floating ice even in summer. 

Earthquakes are now most prevalent at the north end of Sakhalin Island and in the Sea of Okhotsk, although 8-10 years ago, epicenters were located in the south and central parts of the island (www.earthquaketrack.com).

Some of the seismic activity can cause considerable damage, even in this sparsely populated area. In August 2007, an earthquake nearly destroyed Nevelsk and nearby villages on the southwest coast. The offshore epicenters of the two tremors, registering 6.2 and 5.9 on the Richter scale, were 10km and 20km deep in the Tatar Strait.

Forecasting

Wilkens Weather Technologies LP, a Rockwell Collins Company (WWT) has provided offshore and onshore weather forecast services to ENL in the Sakhalin Island area since 1999. The forecast services encompass daily wind, wave, temperature, visibility, and weather condition forecasts for multiple locations, but the primary operating areas are the Orlan platform and Chayvo area. In 2003, WWT also began working with a third party, Calgary-based Canatec Associates International Ltd., to include ice forecasting services. Weather forecasting services are fully integrated into daily operations for Sakhalin-1.

Extensive activity during the short summer work season brought many different contractors to the Sea of Okhotsk in 2011, for initial development work on the Arkutun-Dagi project, which included laying pipe from the shore base to the platforms. Vessels came from all over the world, with company policies extending from Europe, USA, and Asia. Each company and vessel captain had their own preferred weather forecast provider. At least half of the ten major weather forecasting companies were providing reports to the various contracted parties, causing a massive conflict of information and opinion. Major contractor Heerema, for example, relies on the UK’s Met Office. Some ship captains would refuse to work based on private weather reports. There was a great deal of lost work time due to poor weather decisions. Some operations were delayed and not completed until the beginning of ice season (December).

In February 2012, ENL asked WWT to send personnel on site to work onboard the lead project vessels. The ENL-designated forecaster would act as the project weather expert and all decisions would be based on the forecasts produced on site. External (remote) forecasts could not be used for operational decisions. Captains could choose to keep their other forecasts, but in the field, installation go/no-go decisions would be based on the project forecaster’s input. The idea was to centralize decision-making, streamline operations, and keep conflict to a minimum.

This involved a lot of trust among the contractors, especially those operating on lump-sum contracts. However, the cost of keeping forecasters on site was apparently worth the investment, to complete the project on time, rather than running over schedule and over budget.

2012 project scope

WWT meteorologist Francis Kredensor with recovered weather buoy.The first phase of the work was to tow the Berkut platform base to Sakhalin from Vostochny, Russia, and install it at the Arkutun-Dagi field. Then, the platform was connected to the pre-laid pipeline system, additional pipeline installed, and the pipeline route and the margin of the GBS protected from scour.

Three meteorologists from the Houston WWT office worked off Sakhalin through the summer, May- August 2012. The first onsite meteorologist was Jennifer Hibbert, who was mobilized to Vostochny to assist with the initial float-out of the GBS all the way through the end of the GBS installation, about 5-6 weeks, May-July. The second forecaster, Eric Brozefsky, was mobilized via Wakkanai, Japan on a Heerema vessel and spent about 4 weeks on site. Finally, Francis Kredensor rotated onto the EMAS AMC vessel Lewek Crusader and spent about 4 weeks on site until all critical project elements were complete in early September.

The scope of the forecast service entailed preparing a weather forecast every six hours. The meteorologist on duty answered to the Master, to help him make an informed judgment whether to remain connected to the GBS or to prepare for possible disconnection. The forecast also helped them plan daily staffing for the projected work requirements. Briefings were held twice daily, morning and evening, beginning with safety and followed by weather. Evening weather reports were especially important, since good weather was needed for lifts. During less-optimal weather, personnel concentrated on subsea work.

The meteorologists were also asked to quantify the probability of abnormal weather occurring, such as the onset of sea fog or rogue waves, and were also responsible for preparing typical marine weather charts.

Onsite advantage

Brozefsky told OE that the advantage of onsite forecasting is that the meteorologist can observe and interpret any subtle change in weather and update forecast immediately, based on the current trends.

The forecasters relied on shipboard anemometers and weather buoys (wind, current, sea surface temperature), and used markings on the GBS legs to record wave height. Currents were generally light, one-half to one knot.

Meteorology reports included a weather synopsis, graphs, and a table of wind and wave forecasts for 5-7 days out. A benefit of six-hour report spacing was that there was less-dramatic fluctuation between forecasts.

Visibility varied through the season. There was fog almost every day in July, triggered by warm and moist southerly air blowing from the northwest Pacific; its dew point was higher than the colder sea surface temperature, The weather was mostly sunny through August, as sea surface temperature increased and dry air blew east off the Asian continent.

With good visibility, Kredensor noted that those aboard the Lewek Crusader could see both the Orlan and Chayvo platforms. In particularly clear conditions, it was also possible to see the top mast of the Molikpaq drilling and production platform, an Arctic caisson operated by Sakhalin Energy Investment Co. Ltd. on the Piltun-Astokhskoye field, part of Sakhalin-II development. Kredensor noted that weather moves faster in the Polar Regions; stronger jet streams cause systems to change rapidly, so forecasting models need constant revision. In August, two decaying tropical systems swept into the Sea of Okhotsk from the northwest Pacific, causing a few days’ delay.

Before leaving location, they pulled the weather buoy. The onsite meteorology work concluded the first week of September 2012. Says Brozefsky: “Working offshore can be unpredictable. You have to be flexible.”

Safety, logistics 

Fog obscures the view of the Arkutun-Dagi GBS from the vantage point of the Lewek Crusader. Photo by F. KredensorThe WWT forecasters’ main tools were long-range models, laptops, and personal protective equipment (PPE)!

ENL places the highest emphasis on process safety. Heerema is equally diligent about personal and specific safety. Overall, WWT said there was good oversight, with an environment that encouraged reporting, and a “see something, say something” rule. Planes and ferries travel between Sakhalin and Hokkaido, and the two regions have good relations, with several towns on Sakhalin twinned with towns on Hokkaido.

Most of the support operations were staged out of Japan; Sapporo has the closest major airport, and Wakkanai, the northernmost city on Hokkaido Island, is closest by sea. Travel from Wakkanai to the Sakhalin operations site required 2.5 to 3 days by ship. All- Nippon Air (ANA) offers service from Wakkanai.

Another mobilization point was Vostochny Port, the largest port in the Russian Far East, in Vrangel, on the coast of the Sea of Japan. The Arkutun- Dagi GBS was constructed in a drydock at Vostochny. This deepwater, ice-free port, at 42° 46’ N latitude, operates year-round and encompasses the Special Sea Oil Terminal in Kozmino Bay, Primorsky Krai. Vostochny is at the eastern end of the Trans-Siberian Railway, and Kozmino is the terminal point of the Eastern Siberia – Pacific Meridian pipeline. OE

 

Online Exclusive: Sakhalin photo essay, OEdigital.com

Categories: Russia Asia

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