The ministry of environment and forests has cleared Oil and Natural Gas Corporation Ltd's exploratory drilling project in blocks CB-ONN-2004/1/2 under NELP-VI in the Gulf of Cambay in Gujarat. The cost of drilling the wells is Rs 7 crore per well.
ONGC proposes to drill three exploratory wells at a depth of 2,050m-4,500m in block CB-ONN-2004/1, covering an area of 32km2. Water-based drilling mud will be used for the drilling operations. A DG set of 380 and 350KVA will be installed to meet the power requirement. About 150 litres per hour of HSD will be required for the diesel engines per month per well and 20 litres per hour of HSD will be used for lighting purposes.
The total water requirement of 50m3 per day per well is to be sourced from the nearby ONGC installation. The wastewater generation will be 25m3/ day during the drilling operation from a single well. The effluent generated will be discharged into an HDPE lined evaporation pit.
Flaring of gases during the drilling testing will contribute to additional air pollution. Adequate stack height is proposed for diesel generating set and flaring of gases.
Solid waste generation will be in the form of drill cuttings (30-50 mt/well) which will be separated from water base mud properly washed while contaminated drilling fluids will be disposed off in a well-designed pit lined with impervious liner located on-site.