Title : Reservoir screening and feasibility assessment for underground natural gas storage in upper Assam basin
Abstract:
India is actively exploring the development of strategic underground gas reserves for the country’s strategy to raise the share of natural gas in the energy mix from 6% to 15% by 2030. UGS will be critical for India as it enhances energy security, price stability, supply flexibility and emergency preparedness. Beyond energy security, UGS also supports India’s climate agenda and Net Zero 2070 target by enabling flare gas capture, reducing emissions and conserving valuable resources.
Oil India Limited (OIL), together with DeGolyer & MacNaughton, conducted a comprehensive study to evaluate UGS opportunities within OIL’s operational areas in Northeast India. Candidate reservoirs were screened using preliminary criteria such as gas initially in place, depletion status, wellbore availability, storage potential, productivity and injectivity, wellbore condition, and pipeline connectivity to the gas network. The assessment identified five reservoirs as technically favourable for UGS development. These reservoirs were further analysed for estimation of working gas, cushion gas, operating pressures, storage capacity, injectivity, withdrawal rates, and pressure response using advanced reservoir engineering workflows.
This study introduces a structured screening methodology for evaluating and ranking reservoirs, enabling the identification of suitable UGS candidates and providing a framework applicable worldwide. The approach integrates reservoir engineering workflows, including material balance analysis, well performance analysis, and production network modelling, to support reservoir selection and forecast UGS performance. The assessment also covers compression, dehydration, and pipeline requirements for lean gas injection to ensure operational readiness. Notably, the pilot storage implementation validates the overall feasibility of UGS.
The five reservoirs exhibited favourable geological and reservoir properties, along with good infrastructure compatibility. Sensitivity and uncertainty analyses across more than 270 cases validated injectivity and withdrawal performance under varying GIIP, permeability, and pressure conditions, helping to further rank the reservoirs. A pilot implementation in one of OIL’s reservoirs demonstrated its ability to store gas, reinforcing the broader applicability of UGS to other shortlisted reservoirs. Although challenges such as legacy wellbore remediation, high upfront infrastructure costs, and long-term operational requirements were identified, the results demonstrate that UGS is technically viable in the Indian context. With appropriate policy support and infrastructure investment, UGS can become a transformative tool, enabling countries to advance gas storage and support the clean energy transition.
