Since its establishment in 1956, Oil and Natural Gas Corporation Limited (ONGC) has been at the forefront of India’s energy security. Over the decades, ONGC has grown from being a domestic oil explorer into a fully integrated global energy major with operations spanning exploration, production, refining and renewable energy.
Being a Maharatna Company, ONGC carries the critical responsibility of discovering, developing and augmenting hydrocarbon reserves which form the backbone of the nation’s energy security. Its exploration operations span over Ultra Deep Water, Deep Water, Shallow Water and Onshore domains, covering a geologically diverse portfolio across the Indian subcontinent.
ONGC continues to demonstrate its role as a pioneer in energy exploration, leveraging advanced technologies, expanding into frontier areas and diversifying into unconventional hydrocarbons. With strong national responsibility, global collaborations and alignment to India’s energy transition goals, ONGC is well-positioned to play a transformative role in ensuring the nation’s energy security while driving towards a sustainable, low-carbon future
Exploration Process
The process of hydrocarbon exploration starts with prognostication and geo-scientific surveys on the identified sedimentary basins. The information collected from these surveys is processed and interpreted to construct a geological model of the basin. The model so constructed is tested by drilling exploratory wells. If the area proves to be hydrocarbon bearing, delineation wells are drilled to determine the boundaries or the extent of reservoir of the new oil or gas field. This is followed by drilling of development wells, laying oil pipelines and installation of facilities to put the field on regular commercial production.
The first phase in the process for extraction of hydrocarbons is exploration – the search for oil and gas deposits beneath the earth’s surface. Such deposits could either be onshore or offshore.
Exploration Process consists of following phases:
- Preliminary Surveys: Remote sensing, aerial surveys, geological, gravity-magnetic, Magneto-telluric, geochemical, topographic and other surveys to detect large-scale features of subsurface geology
- Seismic Surveys: Two-dimensional (2D), three-dimensional (3D) standard/high resolution, broad band , multi component, wide azimuth surveys.
- Data Processing & Interpretation: Computer-based processing of the data and its interpretation. Seismic data and all available Geological data are integrated and interpreted to identify high probability of hydrocarbon locale for drilling of wells.
- Exploratory Wells: Exploratory wells are drilled to conclusively determine the presence or absence of oil or gas in commercially viable quantities. Based on the drilling & testing results, new hydrocarbons (oil and/or gas) could be “discovered” or alternatively, the well could turn out to be “dry.”
- Exploratory Appraisal Wells: Once a discovery of hydrocarbon is made, exploratory appraisal wells are drilled to ascertain the limit and size of reservoir (in terms of thickness and lateral extent) and volume of recoverable oil/gas reserves are estimated.
Exploration Capabilities and Strengths
Seismic Data Acquisition, Processing & Interpretation (API)
At the core of ONGC’s exploration lies the ability to acquire and interpret high-quality seismic data. This is executed through ONGC’s Geophysical Services, supported by both departmental survey teams and contractual crews. The data acquisition operations covers:
- 2D and 3D surveys in both land and marine environments.
- Borehole seismic (VSP).
The collected seismic data are processed at Regional Computer Centres (RCCs) at different work-centres (Basins) and at state-of-the-art Geodata Processing and Interpretation Centre (GEOPIC), Dehradun with technical support from Regional Electronic Laboratories (RELs).
Technology induction and upgrades have been continuous for:
- Use of low frequency geophones (MEMS) for seismic acquisition.
- Use of ‘nod’ technology
- Expansion of RCC capacities to meet increasing demand for advanced processing
- ISO certification across field crews, RCCs and RELs, ensuring global quality standards
- AI/ML Innovation-Seislytics: ONGC has developed Seislytics, an open-source Python-based machine learning application that integrates multiple seismic attributes for advanced analysis. This in-house tool significantly reduces analysis time and uncovers hidden data patterns, offering a competitive technological edge. Copyright for Seislytics has been secured.
Non-Seismic Data Acquisition and Processing
ONGC is equipped with inhouse capabilities of non-seismic data acquisition like Gravity-Magnetic (GM), Magneto-telluric (MT) and advanced processing facilities for Remote Sensing, Geochemical, GM and MT data.
Recognizing the challenges of exploration in geologically complex and logistically challenging areas, ONGC supplements seismic studies with non-seismic methods, such as:
- Airborne Gravity Gradiometry (AGG) in logistically difficult terrains like in the North-East basins including Cachar, Mizoram, and South-East Geleki
- Inhouse capabilities for recording Low-Frequency Passive Seismic (LFPS)
- Passive Seismic Tomography (PST) in logistically challenging area, AAFB, Tripura
- Remote Sensing Nuclear Magnetic Resonance (RS-NMR) studies in Vindhyan Basin
Well Logging & Formation Evaluation
Well logging, often termed the “eye of the E&P industry”, enables geoscientists to visualize subsurface formations and reservoir characteristics.
Key highlights of ONGC’s logging capabilities include:
- 24x7 logging operations for exploration and development activities are managed by offices situated at Asset / Basins and database are supported by EPINET, a centralized digital platform for real-time data access and decision-making.
- Large fleet of 31 departmental logging units (27 Onshore + 4 Offshore) and more than 60 contractual units, making ONGC’s logging services among one of the largest in the world
- Specialized log evaluation studies are supported by Centre for Excellence in Well Logging (CEWELL), Vadodara
Exploratory Interpretation & Operations across different sedimentary basins:
India’s sedimentary basins are central to its energy exploration strategy. With 26 basins covering 3.4 million km², they have been categorized by the Directorate General of Hydrocarbons (DGH) into Categories I, II, and III based on hydrocarbon potential.
- ONGC has hydrocarbon exploration footprints in 21 basins out of 26 sedimentary basins, underscoring its pan-India presence.
- Currently ONGC holds 424 active acreages spread across 20 basins both onland and offshore, spanning ~2,45,500 km² area.
- The basins where ONGC has active exploration include Assam, Cambay, Cauvery, KG, Mumbai Offshore, Rajasthan, Kutch, Mahanadi, Andaman, Saurashtra, Bengal, Ganga, Vindhyan, and others.
- ONGC’s Exploratory framework includes multiple work centres spread across India to carry out and monitor exploration activities in different basins, these are:
- Western Offshore Basin- Mumbai: Operational area includes Kutch Offshore, Saurashtra Offshore, Mumbai Offshore & Kerala-Konkan Offshore.
- Western Onshore Basin - Vadodara: Operational area includes Cambay Basin, Gulf of Cambay, Kutch Onland, Saurashtra Onland & Jaisalmer Basin.
- Assam & Assam Arakan Basin - Jorhat: Assam Shelf & Assam Arakan Fold Belt Basins.
- MBA Basin - Kolkata: Operational area includes Onland & Offshore sector of Bengal Basin, Offshore sector of Mahanadi & Andaman Basin.
- KG-PG Basin - Rajahmundry: Operational area includes Onland & Offshore sector of Krishna - Godavari Basin.
- Cauvery Basin- Chennai: Operational area includes Onland & Offshore sector of Cauvery Basin.
- Frontier Basins - Dehradun: Operational areas include majority of Category III & II Onland sedimentary basins such as Himalayan Foreland, Ganga, Vindhyan, South Rewa, Narmada, Cuddapah etc.
- Regional Geoscience Laboratory (RGLs) are strategically situated at Mumbai, Vadodara, Jorhat, Rajahmundry & Chennai to carry out Geological & Chemical Analysis of data acquired in the regional basins.
- The Basin work centres are supported by various R & D institutes like Keshava Deva Malaviya Institute of Petroleum Exploration (KDMIPE), Dehradun; Geodata Processing and Interpretation Centre (GEOPIC), Dehradun; Institute of Reservoir Studies (IRS), Ahmedabad; Centre for Excellence in Well Logging (CEWELL), Vadodara and Institute of Biotechnology & Geotectonics Studies (INBIGS), Jorhat.
- Since Inception, ONGC has drilled more than 7000 Exploratory wells and made 664 Hydrocarbon discoveries (500 Prospect & 164 Pool) across different sedimentary basins.
Recent Milestones
- Approval of Field Development Plans (FDP) and award of Petroleum Mining Lease for Hatta discovery in Category-II, Vindhyan Basin in Madhya Pradesh.
- Approval of Field Development Plans (FDP) and award of Petroleum Mining Lease for Asokenagar discovery in Category-III Bengal Basin in West Bengal.
- Under HELP regime, up to OALP Bid Round-IX, ONGC has secured ~39% of OALP blocks covering ~54% total contracts areas under offer surpassing all bidders. About 62% of the areas awarded to ONGC falls in category-II & III less explored basins to focus on large unappraised areas.
ONGC’s efforts in the Deepwater Exploration:
- ONGC ventured in deepwater exploration in early eighties and continuing these efforts to strengthen energy security of India. More than 150 exploratory wells have been drilled till date.
- ONGC launched Sagar Samriddhi campaign in year 2003 to focus on deep & ultra-deepwater exploration.
- With its relentless efforts, ONGC has established hydrocarbon reserves in deepwater sectors of Krishna-Godavari Basin, Mahanadi Offshore and Cauvery Offshore.
- Discoveries Utkal & Konark during FY 2023-24 have rejuvenated deepwater exploration in Category-II Mahanadi basin.
- Ultra-deepwater discovery Chola-1 in Cauvery Offshore during FY 2024-25 has given impetus for further exploration efforts in ultra-deepwater sector.
- ONGC is continuing its exploration activities in deep and ultra-deepwater sectors of Saurashtra, Kerala-Konkan, Mahanadi, Krishna-Godavari, Cauvery and Andaman basins.
Unconventional Hydrocarbon Exploration
Coal Bed Methane (CBM)
- Exploration initiated in the 1990s in the Damodar Basin
- ONGC currently holds six CBM blocks:
- Production/Development: Four blocks including Jharia, Bokaro & North Karanpura in Jharkhand and Raniganj in West Bengal.
- Exploration: Two blocks awarded under Special CBM Round 2022 in Madhya Pradesh and Jharkhand.
Shale Gas
- Exploration initiated in 2006 with data generation across Cambay, KG, Cauvery and Damodar basins
- Under the 2013 Shale Gas Policy, ONGC drilled 30 wells (10 shale-specific, 20 dual-purpose)
Basement Exploration
- Advanced fracture characterization studies including Ant-Track & Fracture Intensity Modelling, 3D Mechanical Earth Models, VVAZ/AVAZ studies and P-Impedance attribute analysis are being carried out to evaluate the Basement prospectivity.
- Commercial hydrocarbon successes achieved in Western Offshore, Cambay, Assam-Arakan and Cauvery basins.
Technology Induction in Hydrocarbon Exploration:
ONGC has consistently deployed state-of-the-art technologies to enhance exploration efficiency:
- Seismic Innovations: Acquisition of high-fidelity seismic data through Broadband, Ocean Bottom Node (OBN), Wide Azimuth Geometry (WAZ), 3D broadband imaging survey etc.
- Non-Seismic Techniques: AGG-FTG & PST surveys in Assam & Tripura, Passive Seismic methods in Bengal Onland, RS-NMR in Vindhyan.
- Advanced Logging Tools:
- Realtime monitoring of Formation Pressure and Nuclear Magnetic Resonance while drilling as advanced LWD tools.
- Advanced logging tools for measurement of acoustic and mineralogical properties of different Formations encountered in the well.
- 3D logs to identify low-resistivity hydrocarbon bearing zones
- Enhanced Recovery: Multi-stage Hydraulic Fracturing and Fishbone drilling technology in tight reservoirs
- Digitalization Drive: Integration of AI, IoT, and Big Data into exploration workflows
- Seistelligence Software: software developed by the in-house R&D team, integrating over 24 advanced Machine Learning (ML) workflows for seismic interpretation, data analysis, modeling and prediction.
- EXPLORE- Integrated Data Platform: In-house developed integrated data platform for unified exploration data management serving the entire Exploration value chain. The EXPLORE system has modules for handling data related to Acreages, Well Locations, Land acquisition & Civil Work monitoring, Well Information, Daily Monitoring (DPR), Discoveries, GEOMAP, and INSIGHTS for seamlessly data availability.
