Beibu Gulf, WZ6-12 & WZ12-8

Asset overview - Beibu Gulf Development and Production Areas
Location Beibu Gulf, offshore China
Two production areas (WZ 6-12 and WZ12-8W) and one development area (WZ 12-8E) totalling 76.2km2.
Operator CNOOC Limited (development and production phases of WZ6-12/12-8W oil fields)
Roc Oil (China) Company (exploration and WZ 12-8E oil field)
JV partners and interests
Field Development & Production Exploration & Appraisal
CNOOC Limited 51.0% 0%
Roc Oil (China) Company 19.6% 40%
Horizon Oil (Beibu) Limited &
Horizon Oil (Nanhai) Limited 
26.95% 55%
Oil Australia Pty Ltd (Majuko)

2.45%                    5%

Producing oil from eleven wells from the WZ 6-12 platform and eight wells from the WZ 12-8 platform.  The development incorporates two remote wellhead platforms and one joint processing platform, which are connected by bridge to the CNOOC WZ 12-1A platform complex and utilise existing water injection and oil and gas processing facilities.

The development of the WZ 12-8 East field is in progress. FID was reached on the development project in October 2020 and implementation of the development plan is nearing completion. Frist oil was achieved in April 2022.

Review of further appraisal and infill opportunities is ongoing. Infill well drilling is being considered for 2022.

First production Production commenced in March 2013 with production reaching forecast rates.

Reservoirs range from Eocene-aged fluvial-lacustrine sandstones of the Luishagang Formation, to Miocene-aged Jiaowei shallow marine sandstones, and the Oligocene-aged Weizhou sandstones.

Oil quality varies from light to heavy quality, low to medium viscosity, with some waxy crude.

The Block is in an area of known oil fields. The nearest producing field is Wei 12-1 (production from Weizhou Formation), 1,800m from the original Block 22/12 boundary.  The Wei 12-1 field includes a well which yielded one of the highest oil flows encountered anywhere in China: 34,000 BOPD. 


In 2002, ROC farmed into offshore Block 22/12 with 25% interest, drilled a well and discovered the Wei 6-12 oil field.  ROC acquired operatorship and increased its equity to 40%.

In 2004, ROC drilled an appraisal well on the Wei 12-8 East oil field which confirmed the presence of oil but indicated that the oil was viscous so commercial development would not be straightforward.

In 2006, the drilling of the Wei 6-12S-1 exploration well made a significant oil discovery which was appraised by four wells.

Following the formal end to the exploration period for Block 22/12 on 30 September 2008, the Wei 6-12, Wei 6-12S and Wei 12-8 oil fields were declared development areas.

In 2Q 2010 CNOOC elected to participate for its full 51% share in the development, reducing ROC's share to 19.6%.

The Overall Development Plan (ODP) was completed in 2010 and Final Investment Decision was reached in February 2011.  CNOOC assumed operatorship of the project in 2Q 2011 and all project approvals were obtained by 4Q 2012.

In 2013 the Beibu Gulf development project completed, with a fifteen well drilling programme completed safely and within budget.  Ten development wells were drilled from the WZ 6-12 platform and five development wells from the WZ 12-8 platform.

Drilling in 2014 secured undeveloped areas and allowed boundary expansion. A successful discovery in the Wei 12-8 Mid area (WZ12-10-2) was integrated into the Beibu Project. An appraisal well was completed for production and tied into the WZ12-8W production system in late 2015.

Cumulative oil production reached lower tariff tier of 2.21 million m³ (13.9mmbo) on 10 January 2017.

Two infill wells were drilled at WZ12-8W in 2018 and brought onto production.

A successful appraisal well was drilled near the WZ6-12 field in 2019. Two infill wells drilled in WZ6-12 in late 2020 / early 2021 improved production by over 20%. A four-well workover program at WZ12-8W was successfully completed in 2021.

Cumulative oil production of 30.5 mmbo at year-end 2021 has far surpassed the original FDP of 16.5 mmbo.

WZ12-8E Oil Field

An ODP for WZ12-8E was finalised by CNOOC in early 2019.  The development project reached FID in October 2020.  The initial development includes 7 wells (6 producers and 1 water disposal well) and utilises the HYSY163 self-elevating wellhead supporting platform which is linked to the existing WZ12-8W platform via a new pipeline.  

Fabrication of the facilities commenced in December 2020 and is largely complete.  In 2021, completed fabrication and assembly of the wellhead platform modules and completed laying of the subsea pipeline connecting the platform to the existing WZ12-8W wellhead platform.  Development drilling commenced in 1Q 2022.  First production was achieved from the first development well in April 2022.  The remaining 5 production wells of the initial phase of development will be drilled during 2022.

ROC is operating the development, with CNOOC expecting to assume operatorship by the end of 2022.