Yemen Regional Geology
Yemen is dissected by a number of world class basins with multi-billion barrel oil potential.
The Masilah and Sab’atyan basins comprise the two main productive Jurassic rift basins in Yemen. They contain rich Upper Jurassic, Mabdi Shales that charge multiple Upper Jurassic to Lower Cretaceous carbonate and sandstone reservoirs,most notably the Lam, Alif and Qishn sandstones. Fractured Pre-Cambrian basement, and the overlying Kuhlan basement wash, also comprise important reservoirs in Yemen.
Octavia’s Blocks 9 and S1 are well placed in each of the highly productive Masilah and Sab’atyan basins.
Yemen Block 9 and Block S1 LocationClick image to enlarge
Yemen Stratigraphic ColumnsClick image to enlargeParticipation Interests
Block 9
History, Production and Reserves
Octavia Energy entered Block 9 in 2016 through the acquisition of Calvalley Petroleum Cyprus Ltd. Between 2016 and 2019, Octavia worked closely with the Government of Yemen to rehabilitate producing wells and restore production to Block 9.
Over this period, Octavia, through its wholly owned subsidiary, Calvalley Petroleum, invested in excess of $40mm in surface and subsurface work including a pressure maintenance program and upgraded production and water injection facilities. Octavia is the only oil and gas company in the Republic of Yemen to have maintained its workforce on pay during the conflict.
Production resumed in July 2019, with 34 producing wells. Today, three fields, Hiswah, Ras Nowmah and Al Roidhat, produce approximately 6,200 bopd gross. Gross proved reserves from these fields total 20.1 mm barrels (McDaniel, Jan 2015).
In addition to maintaining and increasing its production base in Block 9, Octavia has also built an extensive exploration prospect inventory for future drilling. This inventory was augmented through the acquisition of a major 3D seismic program in 2021.
Block 9 : Leads, Prospects and Producing FieldsClick image to enlarge
Block 9 Regional Seismic LineClick image to enlargeProduction and Reserves
Production resumed in July 2019, with 34 producing wells. Today, 3 fields, namely Hiswah, Ras Nowmah and Al Roidhat produce at approx. 6,200 bopd.
Click image to enlargeBlock 9 2021 Seismic Acquisition Program
Calvalley managed the acquisition of a major seismic program in 2021 across Block 9, the first 3D seismic acquisition program in Yemen since 2009. The program comprised an ‘Independent Simultaneous Source’ acquisition method with vibrators shooting into an autonomous nodal recording system. The survey was undertaken by Terraseis over a 45 day period, in March and April, 2021.
The primary objective of the program was to provide more accurate depth imaging of basement targets over the Qarn Qaymah area.
During acquisition, over 195,000 VPs were recorded, from 5 Nomad 65 vibrators. The nodal acquisition system comprised real time monitoring, utilizing continuous recording and GPS synchronization, allowing each vibrator to move around the spread independently, recording time and position for each sweep.
With a total of 13,000 nodes in the field, the survey provided for an extremely large recording spread allowing for very long offset recording. The survey also provided acquisition for less cost and at greater speed than conventional seismic acquisition, reducing both the environmental impact of seismic imaging and the health and safety risk.
2021 Seismic Acquisition ProgramClick image to enlargeBlock S1
History, Production and Reserves
Octavia secured a 75% controlling interest and operatorship in late 2020 through the acquisition of the share interests in Block S1 from West Yemen Oil. Octavia is now working closely with the government, local authorities and contractors to release the block from Force Majeure, restart production and repeat the successes that the company has achieved in Block 9.
In Block S1 there are 2 suspended oil fields, An Nagyah and Osaylan and 3 undeveloped discoveries at Wadi Badyam, An Naeem and Harmel, In addition, Block S1 has and an extensive prospect inventory at Lam, Alif and Basement reservoir levels.
Block S1 Leads, Prospects and FieldsClick image to enlarge
Block S1 Regional Seismic LineClick image to enlargeProduction and Reserves
The block has produced 26 mmbbls to date with over 18 mmbbls of total proved plus probable reserves remaining.
Click image to enlargeCameroon
Bolongo Exploration Block
In April 2026, Octavia Energy was awarded the Bolongo Exploration Block in Cameroon’s offshore Rio del Rey Basin. Located within Cameroon’s most prolific hydrocarbon basin and the eastern extension of the Niger Delta petroleum system, the block sits in a proven oil-producing region with established infrastructure, extensive seismic coverage and significant exploration potential.
The Bolongo Block forms part of a mature yet highly prospective petroleum province, offering opportunities for further resource development through modern exploration and subsurface evaluation. Octavia is working closely with Cameroon’s national hydrocarbons company, Société Nationale des Hydrocarbures (SNH), to advance the next phase of exploration activities.
Etinde Project
Through its strategic investment in New Age Limited, Octavia Energy has exposure to the Etinde Project, one of Cameroon’s largest undeveloped offshore gas and condensate resources. Located offshore Cameroon, Etinde benefits from extensive exploration and appraisal activity, significant discovered resources and a strong technical foundation for future development. The project has the potential to contribute meaningfully to Cameroon’s long-term energy security and economic growth while supporting expanded domestic gas utilisation and regional energy supply.
CameroonClick image to enlargeCrude Oil Evacuation
Block 9 and S1 Crude Evacuation RoutesClick image to enlargeCrude oil is evacuated from Block 9 by secured, 500-barrel truck to two main pipeline terminals in Blocks 51 and Block 4, 250-300 km distant, each supplying storage terminals on the coast. Contracts with operators of other blocks ensure that Block 9 production volumes are securely metered and signed off on a daily basis as part of a custody transfer arrangement before being piped to the coast. Oil is lifted from the sea terminal by tanker at six-weekly intervals with any unlifted Block 9 crude credited to the Calvalley balance maintained at the storage terminal.
