DeGolyer and MacNaughton (D&M) in a report established that reservoirs in ONGC's Krishna Godavari basin KG-DWN-98/2 (KG-D5) and the Godavari Producing Mining Lease (PML) are connected with Dhirubhai-1 and 3 (D1 & D3) field located in the KG-DWN-98/3 (KG-D6) Block of RIL.
"As of March 31, 2015, the FFRM (Full Filled Reservoir Model) estimated a gas migration of approximately 11.122 billion cubic metres from the Godavari-PML and KG-DWN-98/2 contract areas to KG-DWN-98/3," D&M said in its preliminary report.
D&M is of the opinion that there exists one big gas resource several metres below sea bed which extends from Godavari PML and KG-D5 to KG-D6.
Of the 58.68 bcm of gas produced from KG-D6 block since April 1, 2009, 49.69 bcm belongs to RIL and 8.981 bcm could have come from ONGC's side, D&M said in its 553-page report.
At gas price of $4.2 per million British thermal unit, the volume of gas belonging to ONGC which RIL has produced comes to $1.7 billion (Rs 11,055 crore).
ONGC had in 2013 claimed that RIL had deliberately drilled wells close to the common boundary of the blocks and that some gas it pumped out was from its adjoining block.
RIL, on the other hand, has maintained that it has "scrupulously followed every aspect of the production sharing contract and has confined its petroleum operations within the (boundaries of its) KG-D6 block" in Krishna Godavari basin.
D&M estimated that ONGC's Godavari-PML had 14.209 bcm of gross in-place reserves and KG-D5 another 11.856 bcm. RIL's D&D3 fields held 80.697 bcm gross in-place reserves.
Of these, 12.80 bcm of Godavari-PML, 8.01 bcm of KG-D5 and 75.33 bcm of KG-D6 are connected, it said.
It estimated that 11.89 bcm of gas from ONGC blocks would have migrated to KG-D6 by January 1, 2017. This volume would rise to 12.713 bcm by May 1, 2019.
The volume of gas remaining after this would not be economically viable for ONGC to develop.
D&M was jointly appointed by ONGC and RIL to find if the neighbouring fields are connected.
ONGC believes the KT-1/D-1 gas find in its Krishna Godavari block KG-DWN-98/2 (KG-D5) and G-4 Pliocene gas find in Godavari Block extend outside the block boundaries into KG-D6.
According to ONGC, RIL's D6-A5, D6-A9 and D6-A13 wells drilled close to the block boundary may be draining gas from the G-4 field while the D6-B8 well may be sucking out gas from DWN-D-1 field of KG-DWN-98/2 block.
RIL started production in April 2009 whereas ONGC is yet to finalise an investment plan for its fields.
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