Tullow Oil Plc announced that the C1 well, located in Block CB-ON-1 in the Cambay Rift Basin of India, has failed to encounter hydrocarbons. Well C1, in a basin margin location in the east of the CB-ON-1 block, spudded on 27 June and reached its total depth of 1,916m on 19 July.
The main objective sands between approximately 650 metres and 750 metres were present as prognosed but proved to be water-bearing based on petrophysical log evaluation and pressure gradient data. Minor gas shows were encountered in a deeper claystone / siltstone sequence, however the objective sand in this sequence was poorly developed and could not be logged as hole stability problems in the lower part of the well prevented the logging tools passing below 1,183m. Consequently the precise extent and quality of this sand cannot be determined.
This is the first well in a campaign which will comprise at least 4 wells, targeting multiple play types within the Block. The John Energy #20 rig will now move to drill the G1 target, which will test a separate play area to the north of the block. The G1 well is expected to commence drilling by mid August and has an anticipated duration of 30 days.