ONGC plans 5 wells to evaluate MBS053NAA#1

Vol 19, PW 21 (30 Jun 16) Exploration & Production

ONGC and partner Essar have laid out plans to drill five wells to commercialise their impressive MBS053NAA#1 gas discovery at Mumbai offshore block MB-OSN-2005/3 announced in February (2016).

ONGC sources confirm the consortium is aiming to begin the three-year Rs140cr ($21m) appraisal programme around October (2016) when monsoon rains subside. Hopefully with environmental clearance to hand.

"It takes up to six months to secure environmental clearance," says a source. ONGC submitted a pre-feasibility report for the Phase-III appraisal programme on May 23, 2016 to the environment ministry which is expected to take three months to grant Terms of Reference, a crucial first step towards securing environmental clearance.

ONGC wants to drill the first appraisal well MBS053NAA#B to 2100 metres TD over four or five months after which it will drill two wells each year for the next two years. Mumbai High reservoirs are typically at a depth of 2000 to 2500 metres with claystone and shale dominant rock and thin bands of limestone and siltstone.

For the appraisal programme ONGC will target Pliocene or Miocene era formations at shallow depths. In February (2016) ONGC announced that well MBSO53NAA#1, the first exploration well on this block, flowed 47,128 cm/d from a six-metre interval between 932 to 938 metres in the Pliocene age Chinchani formation and 21,282 cm/d through a half inch choke from a four-metre interval at 585 to 589 metres.