India’s Oil & Natural Gas Corp. Ltd. has discovered the third largest reservoir in Mumbai High at a development well that found a new pool in D1 field offshore western India.
ONGC estimated initial oil in place at D1 at 600 million bbl, but after the new pool discovery the company has hiked the estimate to 1 billion bbl. D1, in 85-90 m of water 200 km west of Mumbai, consists of four blocks: D1-4, D1-12, D1-14, and D1-2/5.
The first well in the D1-4 block was drilled in 1976. The low gas-oil ratio and the then-understanding of the reservoir led to a slow pace of exploration and appraisal. As a result, the first development scheme for D1 field was confined only to the D1-4 block, and 12 wells were drilled in two phases. After completion of Phase 2, the field peaked at 17,500 b/d of oil in 2009. Current output is 12,500 b/d.
ONGC is implementing an integrated development plan for D1 field. The D1-B, D1-C, and D1-D well platforms have been commissioned in the D1-4, D1-12, and D1-14 blocks. Development drilling has begun on D1-4 and D1-14 that will raise production to 36,000 b/d by February 2013.
D1-D No. 1, the first development well on the D1-14 block, spudded in May 2012 and was initially planned to be drilled to 2,648 m. It found oil at 2,635-40 m. ONGC decided to drill 100 m more, and the entire 100 m consisted of oil-bearing sand. Drilling continued to 2,830 m.
ONGC notified the Directorate General of Hydrocarbons that D1-D No. 1 uncovered an additional oil-bearing zone of about 142 m. On full development of D1 field, production is expected to rise to 60,000 b/d. The additional development program will start yielding results from January 2014, ONGC said.
Meanwhile, ONGC reported three other discoveries in the last 30 days. The Madnam-3 well on NELP Block CY-ONN-2002/2 in the Cauvery basin in Tamil Nadu produced 725 b/d of 35.7° gravity oil and 406 Mcfd of gas on a 6-mm bean. Compared with earlier lower-productivity basement discoveries, ONGC said, Madnam-3 is a major breakthrough in basement play exploration in the basin.
The Mukkamala-1 exploratory well on PEL Block 1B in the Krishna-Godavari basin, in Andhra Pradesh 7 km northwest of Amalapuram, flowed 1.36 MMcfd of gas.
The BH-86 exploratory well on PEL Block WOFF 123 in Mumbai offshore produced 280 b/d of 43° gravity oil and 4 MMcfd of gas on a 6-mm bean. ONGC said the discovery “further consolidates the potential of the basal clastic-basement play in Mumbai offshore.”