India’s state-run ONGC Ltd. is preparing to launch a revised integrated development plan for gas fields in two adjacent offshore blocks in the Bay of Bengal, a project it shelved two years ago.

The plan for the KG-OSN-2004/1 and GS-49-2 blocks involves drilling 11 producer wells in the two concessions and constructing associated offshore and onshore production facilities at Odalarevu. The estimated investment is about US$559.5 million.

The total production potential is 5.55 million standard cubic meters per day (MMscm/d) of gas, and cumulative gas production could reach about 13.16 billion cubic meters (Bcm) during a 12-year period, ONGC said in a proposal submitted the environment ministry for approval.

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The plan has been approved by the Directorate General of Hydrocarbons (DGH) and is awaiting environmental clearance from the ministry of forests and environment.

An engineering, procurement and construction tender for the project is expected to be floated later this year.

The two concessions, located in water depth ranging from 7 m to 140 m (23 ft to 459 ft) in the offshore Krishna Godavari Basin of the Bay of Bengal, are estimated to hold in-place gas resources of over 20 Bcm.

Revised Plan

The plan involves drilling nine wells in KG-OSN-2004/1 and two wells in GS-49-2. The nine wells in the KG Block will be drilled in water depths of 16 m to 140 m (52 ft to 459 ft), while the two GS-49-2 concession wells will be drilled in a water depth of 7 m (23 ft).

The project also includes constructing a four-legged platform, called CN-B, in the KG-OSN-2004/1 Block, one monad in GS-49-2, infield pipelines of over 50 km, 20-in. diameter and a 44-km subsea pipeline to transport produced gas to a 4.60 MMscm/d-capacity onshore processing unit at Odalarevu on the Andhra coast.

The proposed wells in the two concessions will be tied to CN-B platform, and collected well fluids will be evacuated to the Odalarevu facility. The “CN-B platform will act as [a] centralized gathering well platform, accordingly the manifold is to be sized for connecting well fluids from all attached platforms and subsea wells with the provision of additional spare tapping or connection of future well fluid risers,” the report said.

ONGC initially prepared in March 2017 an integrated development plan with seven development wells in KG-OSN-2004/1 and two in GS-49/2 with five unmanned platforms and an onshore processing plant at Odalarevu.

But the operator put the project on hold, citing “low gas prices prevailing at that point of time in the Indian market.”

The Indian government’s move to align prices for locally produced gas once in six months with the average rates in gas-surplus nations such as the U.S., Russia and Canada encouraged the operator to revive the project.

Reserves Estimate

ONGC has proposed an integrated development plan for the gas fields in the two shallow water blocks as many of them are marginal and economically not viable on a stand-alone development basis.

During the exploration stage, the operator discovered hydrocarbons in seven of 12 wells drilled in KG-OSN-2004/1. They are Chandrika South (CS#1), Alankari (AL#1), Saveri (SA#1), NANL#1, NANL#2, Saranagi (SG#1) and Malhar (ML#1). NANL#3 established the extension of CS-1 pay to the north and Marwah (NAMA#1) indicated the presence of gas.

Geophysical studies of this block indicate that the Chandrika South channel extends south into the open acreage and the total gas initially in place (GIIP) and ultimate recoverable reserves, including in the open acreage, are 16.566 Bcm and 11.294 Bcm, respectively.

As per the revised field development plan, total gas production potential from the Alankari, Saveri, Chandrika South, NANL-2, NANL-3, Sarangi and Malhar fields of the KG-OSN-2004/1 block could together deliver a peak gas rate of 4.55 MMscm/d with a production life of 12 years.

One of the two wells drilled in the neighboring block—GS-49-2/2—encountered multi-stack reservoirs within the Matsyapuri/Ravva zones. The total GIIP reserves in this concession are estimated at 3.94 Bcm with recoverable reserves are 2.80 Bcm.

ONGC holds 100% participating interest in the KG-OSN-2004/1 and GS-49-2 concessions.

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