A just published study commissioned by Rockhopper Exploration shows just how tantalisingly close the late-1990s exploration drilling campaign to the north of the Falkland Islands was, especially one of the two operated by Shell.
In a nutshell, the results of the six wells drilled were:
14/5-1A – Shell, 4,525m depth, oil shows plus gas.
14/10-1 – Shell, 3,005m, live oil of 27 Deg API.
14/9-1 – Amerada Hess, 2,590m, oil stains.
14/9-2 – Amerada, 2,345m, oil stains.
14/13-1 – Lasmo, 1,475m, dry hole.
14/24-1 – Lundin, 2,914m, oil stains.
All this acreage was eventually let go by the various consortia and eventually picked up by Desire Petroleum and Rockhopper.
According to RPS, which carried out the analysis for Rockhopper in the run-up to drilling restarting this year, well 14/5-1 encountered significant gas shows and kicks within the deeper drilled sections (3,500-4,525m).
Energy’s parent, the Press and Journal reported gas kicks at the time based on information leaked from the rig drilling the well. Shell was not at all forthcoming.
Log analysis from the eventual Shell well report indicates that, within the deeper sand units, more than 165m of gas pay was present.
Independent log analysis performed by Rockhopper indicates that 5-130m of gas pay was intersected by the well.
However, RPS says the shape of the geological trap holding the gas is “difficult to assess” with the present seismic data and no clear structural closure can be mapped within the area covered by 3D seismic.
The 2D data suggests that the confining feature could be the boundary fault some 25km to the north of well 14/5-1; hence the possible area of closure has a large potential upside.
For now, these volumes of gas – perhaps several trillion cu ft – have been classified as “contingent resources”. According to RPS, at least 5-8TCF would be needed to justify an on-site LNG plant.
The drilling campaign planned for 2009 will also target prospects in the North Falklands Basin. The final decision as to which will be selected for drilling has not yet been made, although RPS says it seems certain, even at this stage, that the Ann prospect will be drilled and would be followed up by the drilling of another called Liz. These have been deemed by their operator, Desire, to be both technically and commercially attractive.
RPS says: “The drilling campaign strategy will, to some extent, be flexible and, in the case of a discovery being made, it is most probable that an appraisal well will be drilled on that prospect with the aim of confirming the presence of a potentially commercial hydrocarbon volume at an early date.”
RPS goes on to say that the drilling of the primary prospects in the Rockhopper-operated blocks, namely Ernest and Sea Lion, will be subject to drilling funds being available. The Perth, Western Australia, consultancy has assumed that, in the event of success in any of the prospects drilled by Rockhopper, appraisal drilling would take place the year of any discovery and that two appraisal wells would be drilled in each of the successful prospects.
It has been assumed that first production from any discovery would be achieved in 2014, five years after drilling the successful exploration well.
Rockhopper currently has a 100% interest in licences PL023, PL024, PL032 and PL033, all located to the north of the Falkland Islands. In addition, Rockhopper has a farm-in agreement with Desire, the terms of which require Rockhopper to pay 15% of the dry-hole costs of the Ann prospect exploration well to earn a 7.5% beneficiary interest in licences PL03 and PL04.
Rockhopper has acquired 1,500km of 2D data to add to the pre-existing 1,832km of 2D seismic within blocks PL023 and PL024, plus four CSEM (controlled-source electromagnetic) lines have also been acquired over the main prospects.
As for blocks PL032 and PL033, the company has acquired 850sq km of 3D data to add to the 368sq km of 3D seismic acquired by Shell, and 1,546km of pre-existing 2D seismic data.
Blocks PL03 and PL04, operated by Desire, are partly covered by 3D seismic (804sq km), with the remainder of the area covered by 2,122km of 2D seismic.