Beibu Gulf, WZ6-12 & WZ12-8

Producing oil from 30 wells from 3 wellhead platforms; WZ6-12, WZ12-8W, and WZ12-8E.  The development incorporates three remote wellhead platforms and one joint processing platform, which are connected by bridge to the CNOOC WZ12-1A platform complex and utilise existing water injection and oil and gas processing facilities.

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 WZ12-1 (production from Weizhou Formation), 1,800m from the original Block 22/12 boundary.  The WZ12-1 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 WZ6-12 oil field. ROC acquired operatorship and increased its equity to 40%.

In 2004, ROC drilled an appraisal well on the WZ12-8 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 WZ6-12S-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 WZ6-12, WZ6-12S and WZ12-8 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 WZ6-12 platform and five development wells from the WZ12-8W platform.

Drilling in 2014 secured undeveloped areas and allowed boundary expansion. A successful discovery in the WZ12-8 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.

In 2022, two infill wells were drilled and a 5-well workover campaign was completed at WZ6-12.

An infill well and two workovers in the WZ6-12 field are planned in 2024.

Cumulative oil production of 36.5 mmbo at year-end 2023 far surpassed the original ODP of 14.8 mmbo.(economic reserves).

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 was completed in 2022, consisting of six horizontal production wells and one water disposal well, a new self-installed wellhead platform, a multi-phase subsea transportation pipeline and subsea cable. Production commenced on 8 April 2022 while drilling continued.

Following revised structural interpretation post-drilling, the JV agreed to proceed to a phase 2 development. Four additional horizontal production wells were drilled and completed by January 2023.

Three infill wells are planned to be drilled in 2024.

ROC operated the development and early production phase, with CNOOC assuming operatorship on 1 April 2023.

A production area around WZ12-8E field was formally defined in December 2022, with the residual WZ12-8 development area relinquished in accordance with the PSC.