Abstract

The PY-3 field, located some 18km offshore Tamil Nadu in the Cauvery Basin in southeast India, was discovered by ONGC in 1988. The field which lies in license CY-OS-90/l was awarded to the consortium in the 4th exploration licensing round offered in 1991.

The appraisal of the PY-3 field has shown the structure to be complex from a subsurface perspective. The reservoir comprises moderate to low quality Cretaceous sandstones of the Nannilam Formation. The sands were deposited as debriflow deposits in a trough formed by basement highs to the east and west of the field. Laterally the reservoir exhibits significant variation in reservoir quality. Variations in the overburden stratigraphy, result in large velocity variations and hence difficulty in modelling the depth to top structure which does not exhibit closure in time.

These subsurface uncertainties have been accommodated by adopting a phased development. The initial phase of development activity commenced in 1996 with first production in 1997. The development comprises subsea wells tied back to a floating production unit. A total of four wells have been used to develop the field, two of which were re-entries of existing appraisal wells.

Further development of the PY-3 field, involving potential water injection or infill drilling, will be implemented depending upon early reservoir performance.

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