Cairn Reveals Results of First Two Wells on N-A Field

Cairn announces the successful results of the first (N-A-2Z) and second (N-A-3) appraisal wells on the N-A oil field in northern Rajasthan, India on Block RJ-ON-90/1.

N-A-2Z was drilled from the N-A-1 discovery well surface location and deviated 200 metres away in an up-dip direction. N-A-3 was a down-dip appraisal well drilled 1.5 kilometres south of N-A-1 and N-A-2Z.

The results of the first three wells on the N-A field demonstrate some variability in reservoir thicknesses over the structure. N-A-1 encountered 55 metres of net high quality Fatehgarh sands with 15 metres of net oil pay. N-A-2Z and N-A-3 encountered 60 metres and 39 metres respectively of net Fatehgarh sands with 47 metres and 7 metres respectively of net oil pay. The oil down to in the N-A-2Z and N-A-3 wells is consistent with the oil water contact (OWC) determined from pressure readings in N-A-1.

Four Fatehgarh sand units in N-A-2Z, the bottom three of which had been water bearing in the original N-A-1 well, were selected for open-hole drill stem tests (DSTs). The first tested zone was from an excellent quality 5 metre basal sand encountered just above the OWC. The second DST was from a 14 metre thick but loosely consolidated sand, the third and fourth zones were from thinner 5 metre and 3 metre sands respectively, with the objective of assessing their lateral extent. Following mechanical problems with the open-hole DSTs the second and third zones will be re-tested in cased hole at a later date to obtain representative rates. Structurally higher reservoir units in N-A-2Z were not tested as they were previously tested in the N-A-1 discovery well.

The following stabilised rates were obtained in the open hole DSTs:-

  • Zone 1 tested at 1,600 barrels of oil per day of 28 degrees API oil on a 40/64 inch choke.
  • Zone 2 tested at 200 barrels of oil per day of 31 degrees API oil on a 24/64 inch choke.*
  • Zone 3 tested at 450 barrels of oil per day of 30 degrees API oil on a 24/64 inch choke. *
  • Zone 4 tested at 165 barrels of oil per day of 32 degrees API oil on a 20/64 inch choke.

  • * Rates were restricted by sanding problems within the test string.

    Additional Appraisal Activity

    At least two additional appraisal wells, N-A-4 & 5 are planned during June and July.

    Bill Gammell, Chief Executive, commented:

    "The results of the first two appraisal wells on N-A are consistent with our initial views of the field. Further appraisal drilling and re-mapping, incorporating recently acquired 2D seismic, is required before updating volumetrics."