Chayvo

Location and Geology

The Chayvo field is situated approximately 370 miles north of Yuzhno-Sakhalinsk, on the northeast coast of Sakhalin Island. It is part of the Sakhalin-1 project, which also includes the Odoptu and Arkutun-Dagi fields. The field is characterized by a northwest/southeast-trending anticlinal structure, with the western flank closer to the shore than the eastern flank.

Discovery and Reserves

The Chayvo field was discovered in 1979. It is estimated to hold significant reserves, including approximately 2.3 billion barrels of oil and a substantial portion of the 17.1 trillion cubic feet (Tcf) of natural gas reserves associated with the Sakhalin-1 project.

Development History

• Initial Development: Development drilling at the Chayvo field began in 2003 with extended-reach drilling (ERD) wells drilled from an onshore wellsite pad using the Yastreb drilling rig. In 2005, further development drilling commenced from the offshore Orlan platform.
• Expansion: In 2008, the Yastreb rig was moved to the Odoptu onshore wellsite pad, where it drilled nine ERD wells. The rig was later moved back to the Chayvo onshore wellsite in 2011 for further development and infill drilling of the Chayvo reservoirs.

Drilling and Production

• Extended-Reach Drilling: The project has been notable for its use of ERD techniques. The second drilling campaign at Chayvo, which started in early 2012, targeted a new reservoir zone using ERD wells from the onshore wellsite. This campaign included the drilling of Well Z-44, which set a world record with a measured depth (MD) of 12,376 meters and a horizontal reach of 11,371 meters.
• Well Design and Challenges: The wells drilled in this campaign were at the edge of the ERD envelope in terms of MD and horizontal reach. Key challenges included high torque and drag, wellbore positioning in a thin oil column, wellbore stability, and long horizontal completions. Novel techniques using formation-pressure-while-drilling data were developed to minimize vertical-position uncertainty.

Infrastructure

• Onshore Processing Facility: The Chayvo onshore processing facility has a capacity to produce 250,000 barrels of oil per day (bpd) and 800 million cubic feet (Mcf) of gas per day. This facility processes oil and gas from the Chayvo, Odoptu, and Arkutun-Dagi fields.
• Offshore Platforms: The Chayvo field is developed with the Orlan offshore platform. Additionally, the Odoptu field has an onshore oil and gas treatment facility, and the Arkutun-Dagi field is developed with the Berkut gravity-based offshore platform.
• Pipeline and Export Terminal: The oil from the Chayvo onshore processing facility is transported through a 226-km long, 24-inch diameter pipeline to the De-Kastri terminal in Khabarovsk Krai, Russia. The De-Kastri terminal has an annual capacity of 12 million tonnes and features an elevated single point mooring facility for tanker loading.

Production Details

• Production Start: The Chayvo field came on stream in October 2005. By 2018, the Sakhalin-1 project had produced over 11.63 million tonnes of oil and condensate and supplied 2.48 billion cubic meters of gas. The total crude export from the project reached 100 million tonnes in August 2018.
• Gas Utilization: The gas produced is used for domestic consumption and for maintaining reservoir pressure. There are also plans to build an LNG terminal for exporting natural gas from the project, with an expected export capacity of 6.2 million tonnes per annum (Mtpa).

Technological Advances

• Record-Breaking Wells: The project has seen the drilling of several record-breaking ERD wells, including the world’s longest well drilled from the Orlan platform at the Chayvo field, completed in November 2017, which was over 15 km long.
• Formation-Pressure-While-Drilling: The use of downhole formation-pressure-while-drilling tools and novel techniques to minimize vertical-position uncertainty has been crucial in the successful execution of the ERD wells.

Partners and Contractors

• Operator: The Sakhalin-1 project is operated by Exxon Neftegas (ENL), a subsidiary of Exxon Mobil, which holds a 30% participating interest.
• Partners: Other partners include the Japanese consortium Sakhalin Oil and Gas Development Company (SODECO, 30%), India’s state-owned ONGC Videsh (20%), and Russian oil company Rosneft (20%).
• Contractors: Key contractors involved include Parker Drilling Company for the Yastreb land rig, Fluor Daniel Eurasia for the engineering, procurement, and construction (EPC) of the onshore processing facilities, ENKA for mechanical and piping works, and Hyundai Heavy Industries for fabricating the modules for the processing facility.

The Chayvo oil project is a testament to the technological advancements and collaborative efforts in the oil and gas industry, particularly in challenging arctic environments.