Oil and Natural Gas Corporation Limited (ONGC) is a global energy holding company, engaged in the oil exploration, development, and production of crude oil and natural gas. Its segments include Exploration & Production (E&P), and Refining.
ONGC's on-going upstream exploratory efforts are an important segment of its core E&P Business in India with the responsibility of finding and accreting oil and gas reserves. It has three facets of hydrocarbon exploration activities viz. Deep Water, Shallow Water, and Onshore exploration activities.
Seismic Data Acquisition Processing & Interpretation (API)
Seismic data is collected through special wing called “Geophysical services” in form of 2D/3D surveys done by ONGC’s own survey party/vessels/equipment (in-house) as well as through contractual hiring by survey contracts. The same process is applicable for bore-hole seismic/wire-line logging through a separate arm called “Logging services”.
Geophysical Services carry out 2D, 3D, and VSP seismic survey operations in on-land and marine through its departmental field parties/ contractual crews. The operation, maintenance, and processing of data acquired are to a large extent done regionally, e.g. Vadodara region caters to entire West India land Geophysical operations, Dehradun region caters to North and Central India, Jorhat to North East, Mumbai to entire marine requirements, etc. The equipment support to field operations is provided by the Regional electronic laboratories (RELs). The seismic data acquired is processed at Regional computer centers (RCCs) including GEOPIC. Presently, the marine 2D, 3D and VSP data acquisition operations are carried out through outsourcing. All the field crews, RCCs and RELs are accredited with ISO certification.
The Geophysical Services, to keep pace with the latest developments in Geosciences and exploration, routinely replaces and upgrades its equipment, lab equipment and computers and its peripherals. Recently, it has acquired 3 new VSP data acquisition systems and 10 Field Processing Units (FPUs). Advanced imaging software modules like Earth Study ES-360 and add-on modules namely MPFI (5D interpolation) and GSMP (De Multiple) of OMEGA software have been procured for SPIC, Mumbai.
Logging is known to be the “Eye” of E&P Industry enabling the geo-scientists to visualize the formation and reservoir characteristics. Logging services are responsible for the good logging field operations involving a number of techniques for measurement of petrophysical parameters of geological formations penetrated by the drill bit. Data is collected and processed in the form of logs (Petrophysical parameters vs. depth).The data is then interpreted to obtain the parameters for hydrocarbon potential, flow characteristics etc. of the well.
The entire Logging database is captured on the EPINET platform which is accessible across the organization for timely and effective decision making. A dedicated R&D institute for Logging services ‘’Centre for Excellence in Well Logging” (CEWELL) is operational at Vadodara which is catering to field specific formation evaluation and Reservoir Characterization problems of assets and basins. Very few companies in the world are equipped with in-house logging capabilities. Today the Logging Services of ONGC is the biggest national endeavor of its kind with strong Operations, Repair Maintenance, Data Interpretation and R&D capabilities.
Presently, 28 Departmental Logging Units (24 in Onshore locations and 4 units in Mumbai Offshore) and 65 Contractual units have been deployed.
ONGC is in the process of replacement of 23 state-of-art logging units with tools, 19 for onshore locations and 4 units for western offshore. Two new Departmental Logging Bases will be coming up at Agartala and Bokaro with 2 units each. With this replacement, the entire logging fleet would consist of latest equipment which would improve technical capabilities and operational efficiency.
Recently, several initiatives for sprucing up the safety environment in Logging operations have been taken which include installation of speed governors and GPS for the motion tracking of Logging Units. Initiative for CCTV coverage of Logging operational area during logging for better surveillance and operational safety has been ensured at all locations.
Non- Seismic Data Acquisition Processing & Interpretation (API)
ONGC initiated efforts for better subsurface imaging in logistically difficult areas of North-East and has acquired about 5574 Km2 of Airborne Gravity Gradiometry (AGG) survey data in Cachar (Pre-NELP Block, AA-ONJ/2) and NELP block, AA-ONN-2001/2 in Mizoram and South East Geleki in North Assam Shelf. This data will help to unlock new hydrocarbon reserves which would augment its reserves base and increase in production.
Exploratory performance of ONGC
So far, 26 sedimentary basins have been recognized and have been divided into four categories based on their degree of prospectivity by DGH. ONGC is carrying out oil exploration in India, its operated acreages in Nomination and NELP regime in 13 sedimentary basins to tap the potential reserves of oil and natural gas. The sedimentary basins identified include Assam Shelf, Assam and Assam-Arakan Fold Belt, Cambay (including offshore), Cauvery (including offshore), Krishna-Godavari (including offshore), Mumbai Offshore, Rajasthan (Jaisalmer), Kutch Offshore, Mahanadi Offshore, Saurashtra Offshore, Himalayan Foreland, Bengal, and Vindhyan Basins spread over the states of Assam, Mizoram, Tripura, Gujarat, Tamil Nadu, Andhra Pradesh, Rajasthan, Himachal Pradesh, West Bengal and Madhya Pradesh including the east and the west coast of the country.
FY 2016-17 was one of the most successful years of the last decade in oil and gas exploration with more thrust in increased exploration activities during the year. Being one of the leading oil and gas exploration company, ONGC overachieved Seismic Survey targets for 2D & 3D by 122% and 105% respectively. 263 LK of 2D seismic data was acquired against a target of 215 LK and 3D seismic acquisition of 7408 SKM was completed against a target of 7060 SKM. A total of 100 exploratory wells were drilled which is higher by 8.7% as compared to 92 wells drilled in the previous year 2015-16. Of these, 43 wells were proved to be hydrocarbon bearing with a success ratio of 43%.
ONGC made 23 new discoveries in FY'17, a 35% jump in a number of discoveries year-on-year, from 17 discoveries made in the previous year, reinforcing its position in the industry. Of the 23 new discoveries, 12 are new prospects (a prospect is considered to be a new area having hydrocarbon accumulation) while 11 are new pools (a pool is a hydrocarbon accumulation in a known area in a new horizon). 13 new discoveries were made in onland and 10 in offshore wells. The exploration feat in the year has given a major shot in the arm to India's potential producing basins. Two discoveries MBS051NAA-2 and GKS101NCA-1 in NELP blocks in Kutch and Saurashtra Offshore have reinforced confidence to upgrade these basins to Category-I (Producing) basins through fast track monetization.
SRI-1 discovery in the NELP block KG-OSN-2009/2 in offshore KG basin has established the huge potential for syn-rift/deeper play in east coast shallow water. Jabara-4 discovery established hydrocarbons for the first time in Vindhyan Basin and has given impetus for putting Vindhyan basin on hydrocarbon map of India. In addition, Dayalpur-1 in Assam Shelf has given success in multiple plays (Basement to Tipam) and has given a boost in exploration in the area.
ONGC made 12 discoveries in FY’18. Of the 12 discoveries, 6 discoveries were made in onland (Nominaton-5, NELP-1) and 6 in offshore (Nomination-6, NELP- NIL). Out of 6 onland discoveries, 2 discoveries were monetized during the year itself. In FY’18, ONGC has registered an RRR in excess of ‘One’ for the twelfth consecutive year. This reflects ONGC’s strong exploratory record over the years.
ONGC made 13 discoveries in FY’19. Of the 13 discoveries, 8 discoveries were made in onland (Nominaton-6, NELP-2) and 5 in offshore (Nomination-2, NELP- 3). Out of 13 discoveries, 5 discoveries were monetized during the year itself. In FY’19, ONGC has registered an RRR in excess of ‘One’ for the thirteenth consecutive year. This reflects ONGC’s strong exploratory record over the years. During the FY’19, ONGC has adopted Petroleum Reserve Management System (PRMS) of estimation of reserves wherein reserves are classified in two categories viz. Reserves and Contingent resources. As on 01.4.2019, the reporting is in PRMS system.
ONGC has declared total 12 discoveries (7 onland, 5 offshore) during FY 2019-20 in its operated nomination acreages. Out of these, 7 are prospects (3 onland, 4 offshore) and 5 are pools (4 onland, 1 offshore). Total 8 discoveries were notified so far in FY' 2020-21.