Surprise Reservoir Discovery Could Boost Horizon Oil’s Production Risks
Horizon Oil has commenced production from its newly drilled A9H infill well in China’s Beibu Gulf, revealing an unanticipated oil reservoir that could boost future output.
- A9H infill well successfully drilled and producing in WZ12-8 Mid field
- Unexpected discovery of oil in shallower U1 reservoir alongside targeted U4 zone
- Initial production from U1 reservoir at 372 barrels per day gross
- Reserves to be booked at 0.4 million barrels gross as of June 30, 2025
- Well equipped with Electric Submersible Pump for dual reservoir production
Strategic Infill Drilling in Beibu Gulf
Horizon Oil Limited has announced a significant milestone with the successful drilling, completion, and commencement of production from the A9H infill well located in the WZ12-8 Mid field, within Block 22/12 of the Beibu Gulf, China. This well represents the final drilling slot on the WZ12-8W wellhead platform and targets previously unswept oil in the primary U4 reservoir, which is already being produced by existing wells in the area.
A Fortuitous Reservoir Discovery
In a notable surprise, the A9H well also intersected 19 meters of oil-bearing formation in the shallower U1 reservoir, a zone not previously tapped or expected to contain producible hydrocarbons. This unexpected find adds a new dimension to the field’s production potential and could enhance the overall recovery from the site.
Production and Technical Setup
The well has been completed with an Electric Submersible Pump and specialized downhole equipment designed to enable production from both the U1 and U4 reservoirs. Initial testing focused on the U1 reservoir, which began flowing at a gross rate of 372 barrels of oil per day (bopd), with Horizon’s net share being 100 bopd. The bottomhole flowing pressure recorded at 893 psi suggests that, depending on water-cut development, there may be room to increase production rates further.
Reserves and Future Outlook
Horizon plans to book reserves as of June 30, 2025, consistent with its pre-drill estimates of 0.4 million barrels gross (0.1 million barrels net to Horizon). The company’s CEO, Richard Beament, highlighted the well as an example of the joint venture’s ability to identify and convert incremental opportunities into production, emphasizing the potential added value from the U1 reservoir discovery.
Collaborative Effort in Block 22/12
The Block 22/12 joint venture comprises several key players, including CNOOC as the operator with a 51% stake, Horizon Oil holding 26.95%, Roc Oil at 19.6%, and Oil Australia Pty Ltd. with 2.45%. This collaboration continues to drive incremental production growth in the Beibu Gulf region, a strategically important area for all participants.
Bottom Line?
The A9H well’s unexpected reservoir discovery could reshape production forecasts and warrants close monitoring in upcoming reports.
Questions in the middle?
- How will water-cut development impact the longevity and productivity of the U1 reservoir?
- What are the implications of the U1 reservoir discovery for future drilling plans in Block 22/12?
- Could the dual-reservoir production setup influence operational costs or efficiencies?
