Mitchell to drill first BP corehole at Birbhum in March

Vol 12, PW 17 (29 Jan 09) Exploration & Production

Mitchell Drilling might be under investigation by Indian tax authorities but that isn’t holding up its plans to begin drilling for BP in West Bengal.

PETROWATCH learns BP is “ready to take possessionâ€‌ of a Mitchell rig within the next few weeks and start drilling the first of five committed coreholes at CBM block BB-CBM-2005/III in the Birbhum district by March. First drilling will target the Barakar Formation of coal seams in the “southern two thirdsâ€‌ of the 248-sq km block.

“Several possible drilling locations have been identified,â€‌ we hear. “248-sq km is a big area to evaluate with just 13 wells (eight coreholes and five test wells).

â€‌ BP admits knowing very little about the block’s prospectivity, except that it has a vague estimate of between 2-tcf to 6-tcf in-place gas based on poor quality data from past wells drilled by the DGH and the Geological Survey of India. “We don’t know a great deal about the coals,â€‌ says BP.

“Except that there’s likely to be a lot of variety.â€‌ Exactly what this variety is, whether it is â€کpure coal with high carbon content’ or â€کpoor quality coal with sand and shale’ will only become clear after drilling.

“The better the coal the more chance there is of gas,â€‌ adds BP. “The distribution and depth of the coal can also affect gas content.

â€‌ At Birbhum coal seams are located at 600 to 1000-metre depths sub-surface. But for now the only comparison BP has is with nearby fields with “same age coalsâ€‌ such as the producing Raniganj field, operated by Great Eastern.

If all goes to plan BP’s Phase-I work programme at the block should be over in April 2010 after it completes five test wells with another rig. Then follows a 30-month Phase-II programme where BP will identify three “mini-developmentâ€‌ locations of five wells each and embark on a two-year production-testing programme.

“Water is the big unknown in CBM production,â€‌ says BP. “Sometimes you need to produce and manage a lot of water before you can produce the gas.