BG, Statoil, ExxonMobil and their partners off the east coast of Africa are having to further ramp up their plans for a major offshore development tied back to a multi-train onshore LNG plant after finding more gas.

As the recoverable gas resources offshore Tanzania continue to build with the recent news of operator BG Group’s latest discovery in Block 4 on the Kamba and Fulusi prospects, the joint plan for the onshore receiving terminals now looks likely to be expanded to feature a third LNG train. BG’s 20% partner in Block 4, Ophir Energy, said that the Kamba-1 well found just over 1.03 Tcf of recoverable reserves in the Kamba and Fulusi prospects and provided “critical mass” for the additional train to be supplied by the Block 4 finds.

Nick Cooper, Ophir’s CEO, said the find had confirmed “sufficient aggregate resource in Block 4 to supply one 5 MMtpa train of LNG. In combination with the discovered resource in Block 1, the Block 1 and 4 joint venture is now close to the threshold resource volumes for three 5 MMtpa LNG trains."

The companies are already of course working with the Block 2 consortium of Statoil and ExxonMobil to jointly develop the onshore receiving terminal – something stipulated by the Tanzanian government – to enable the most economic development of the deepwater gas reserves from the various blocks. A preferred LNG site has already been presented for approval to the Tanzanian government, and an integrated project team set up with the Block 2 partners to progress the joint facility and optimise infrastructure plans.

The Block 1 and 4 partners only recently confirmed a successful drill-stem test on the Mzia discovery in Block 1 (see DI, 27 August 2014, page 1), with direct subsea-to-shore and alternative floating production and storage solutions also being considered for both this and the other blocks that will feed the proposed onshore plant. Full offshore FEED work will kick off next year.

Consultants Genesis Oil & Gas were earlier this year awarded the upstream concept select study by BG. The workscope of that study included considering the upstream facilities required to develop the discoveries via an onshore plant. Genesis’ workscope also includes concept selection and pre-FEED activities.

The latest find, Kamba-1, was drilled by the Deepsea Metro I drillship in a water depth of 1,379 m (4,524 ft) to a total depth of 3,969 m (13,022 ft), with the twin objectives of intersecting the Fulusi prospect (a northern extension of the earlier Pweza discovery) and the Kamba prospect.

The probe encountered an 18 m (59 ft) gross gas column on Fulusi and, after sidetracking to test Kamba, the Kamba-1ST well hit another gas column of 140 m (459 ft). The well encountered better quality reservoir sands than expected and further analysis is expected to confirm discovered volumes “somewhat in excess of the pre-drill estimated mean (2C) recoverable resources of 1.03 Tcf, comprised of 650 Bcf in Kamba and 380 Bcf in Fulusi”.

Impressively, Kamba-1 is the JV’s 16th consecutive discovery well in Blocks 1, 3 and 4. Ophir now estimates total Block 1, 3 and 4 mean (2C) recoverable resources at 17.1 Tcf. Kamba-1 was the final well in the present campaign in Block 4, with the Deepsea Metro I however to remain off Tanzania to drill two wells for Ophir in the nearby East Pande and Block 7 production sharing contracts.

The Tende-1 well in East Pande will be spudded first, with Ophir holding a 70% interest as operator. The prospect is on trend with the recent Taachui-1 discovery in Block 1 and lies in a water depth of 680 m (2,231 ft) and will be drilled to a planned total depth of 4,200 m (13,780 ft). The well is targeting gas with a mean prospective resource estimate of 2.38 Tcf with drilling operations expected to take approximately 35 days.

On Block 7 a well will be drilled on the Mkuki prospect by the drillship, where Ophir has an 80% operated interest. It is to the north of the significant gas discoveries in Blocks 1, 2, 3 and 4, with Mkuki-1 to be drilled in the western, inboard portion of the block in a water depth of 1,655 m (5,430 ft) to a planned total depth of 3,200 m (10,499 ft). The well is again targeting gas with a mean prospective resource estimate of 2.19 Tcf. Drilling operations are expected to take approximately 20 days.

  • The success on these wells has not however stopped BG deciding to exit Block 3, where Ophir and its remaining partner Pavilion Energy have committed to move into the next exploration phase without them.

Ophir has, under the terms of the PSC, applied to enter the next PSC term under which it will hold an 80% interest and formally reassume operatorship as of this month, while Pavilion will retain 20%. The 2012 Papa-1 gas discovery is the only well to have been drilled in the block 3 so far. A BG spokesman said: “Our view of the resource does not support BG Group proceeding to the next phase of development.”