The latest exploration results from Africa show the presence of both conventional and unconventional resources. Eugene McCarthy reports.
Ophir Energy has announced results from the Taachui-1 and subsequent Taachui-1 ST1 well in Block 1, Tanzania, resulting in a new gas discovery. Ophir holds 20% of Blocks 1, 3 and 4. BG Group operates with 60% (Fig.1).
The Taachui-1 well was drilled by the Deepsea Metro I drillship close to the western boundary of Block 1. For operational reasons this well was sidetracked to be completed as the Taachui-1 ST1 and was drilled to a total depth of 4,215m measured depth (MD).
The well encountered gas in a single gross column of 289m within the targeted Cretaceous reservoir interval. Observed reservoir properties are in-line with those encountered at Mzia, the other Cretaceous-aged discovery on Block 1. Estimates for the mean recoverable resource from the discovery are around 1trillion ft3. The size of the gas column is such that the discovery could extend into a second compartment to the west that has the potential to be a similar size. An appraisal well is required to confirm this upside and is under consideration by the joint venture partners.
A drill stem test will now be performed on the Taachui discovery with results expected soon.
Nick Cooper, CEO, commented: "The Taachui-1 discovery continues the 100% drilling success rate on Blocks 1, 3 and 4 and adds further resource to support the LNG development in Tanzania. The result is important to Ophir for two reasons: firstly it extends the proven hydrocarbon system to the eastern limit of, and partly de-risks, Ophir's East Pande permit on which the Tende-1 well will be drilled later in 2014; secondly the aggregate recoverable volumes of around 16.7 trillion ft3 are now approaching the threshold needed to underpin a potential third LNG train from Blocks 1, 3 and 4."
Less successful has been the company's efforts with the Affanga Deep-1 well in the Gnondo Block offshore Gabon. The well encountered thinner than expected sandstone sections with poor reservoir characteristics. Gas and indications of liquids were encountered during drilling but significant hydrocarbon shows were not encountered in the target formations. Drilling operations have concluded there.
Tower Resources has announced the completion of its farm-in to Block 2B, onshore Kenya. Its subsidiary, Tower Resources (Kenya), has agreed to acquire a 15% interest in the block from Lion Petroleum, a subsidiary of Taipan Resources, which holds 40% of the licence. Completion was conditional on consent from Premier Oil group, which holds 55% of the licence. This has now been given.
In February 2014, Taipan announced a 51-101 compliant independent assessment of Block 2B, completed by Sproule International, which estimated Block 2B, located in the Anza Basin, to hold gross mean unrisked prospective resources of 1593 million barrels of oil equivalent (mmboe), based on 19 exploration leads.
Activity in the Anza Basin has also increased. In Block 9, adjacent to Block 2B, Africa Oil and its partner Marathon Oil are currently drilling the Sala-1 exploration well, which will test a large prospect in the Cretaceous Anza rift system. The results are expected later this year and the well is targeting gross risked prospective resources of 402 mmboe.
The recently acquired 2D seismic data across Block 2B is being used to determine the drilling location of the first potentially play-opening well, Badada-1, which is expected to spud at the end of 2014/early 2015 and will target gross mean unrisked prospective resources of 251 mmboe - estimated by Sproule International.
Finally, Tullow Oil has announced that the Shimela-1 well in the South Omo Block, onshore Ethiopia, has encountered water bearing reservoirs.
Shimela-1 was drilled to test a prospect in a north-western sub-basin of the vast Chew Bahir basin. The frontier wildcat well encountered lacustrine and volcanic rocks including almost 100m of net sandstone reservoir within siltstones and claystones. Trace thermogenic gas shows were recorded at 1,900m.
The Exalo 205 rig drilled Shimela-1 to a final depth of 1,940m. The rig will now be moved to drill the Gardim-1 wildcat exploration well in a completely separate sub-basin, in the south-eastern corner of the Chew Bahir basin.
Angus McCoss, exploration director, Tullow Oil, commented: "Although the Shimela well only found traces of thermogenic gas, it has provided key data to build our understanding of the north-western part of the Chew Bahir basin."
In a separate development, Africa Oil, Tullow Oil's partner in Blocks 10BB and 13T in Northern Kenya has issued an update stating that the Twiga-2 sidetrack encountered 62m of net oil pay.
The discovery of the Kudu gas field and anticipated oil resources could help Namibia achieve greater energy self-sufficiency and reduce its dependence on imports, according to Frost & Sullivan.
"A breakthrough in the oil and gas sector in Namibia, which is relatively underexplored, holds enormous potential for the country," says Energy & Environmental research analyst Muneera Salie. "If these resources are proven to exist, it could result in the country becoming one of the richest in Africa in terms of GDP per capita within the next five to 10 years."
Vallourec lands pipesmand welding services contract in Ghana
Vallourec has been selected to supply premium line pipes and welding services for the TEN ultra-deepwater oil and gas project, operated by Tullow Oil in Ghana, and executed by a consortium of Subsea 7 and Technip.
The TEN fields (Tweneboa, Enyenra and Ntomme) lie in the deepwater Tano block, around 60km offshore Ghana. The reservoirs are spread over 800km2 and lie in water depths of between 1,000 and 1,800m.
Under the contract Vallourec will provide 15,000 tonnes of anti-corrosion coated pipe to Subsea 7. The pipes will then become dedicated production flowlines using ITP's pipe-in-pipe system.
Vallourec's subsidiary Serimax, an international welding company, will carry out the associated welding services for the double jointing operations related to the production pipe-in-pipe and the gas export lines.
Dominique Richardot, MD of Vallourec's Pipe and SURF activities, declared: "Vallourec's involvement in several parts of the TEN project demonstrates our ability to generate added value for our clients through flexibility, synergies and close cooperation. By providing an important number of non-standard pipe dimensions we help Subsea 7 facilitate the pipe-in-pipe design optimisation, and thus reduce total costs. Moreover, thanks to our lean logistics, our performing welding services, as well as our strong execution team, we offer a full support to our client to efficiently conduct this offshore project in Ghana."
Vallourec is a key supplier for Subsea 7 and has maintained this position through the successful delivery of line pipe products for the BG Knarr Project in Norway. It says that this new contract for the TEN Project reinforces the existing cooperation between the two parties.