UGS Evaluation Services

EXCEED Subsurface’s expertise in characterising subsurface geology, coupled with our knowledge of gas storage technologies will provide you with optimised selection of gas storage locations, as well as cost-efficient planning and managing of the conversion of depleted oil and gas fields to gas storage fields.

Natural gas can be stored under pressure in natural or artificial spaces in underground geological formations, commonly involving depleted reservoirs in oil or gas fields, aquifers, salt caverns and abandoned mines - generally referred to as Underground Gas Storage (UGS). The present day worldwide UGS capacity is in the order of 300 billion m3, which is approximately 10% of the annual worldwide gas production. Around 40% of the UGS capacity is located in Europe.

UGS facilities provide a means for energy companies to mitigate seasonal or daily (peak-load) fluctuations in gas demand and to ensure flexible, reliable and secure gas supply. A detailed understanding of the subsurface geology - such as seal capacity of the overburden and the structural integrity of the reservoirs - is required for selecting an appropriate location and developing an UGS facility.

Our integrated multi-disciplinary team, together with our associates, utilise their expertise in static and dynamic modelling of the subsurface, providing our clients with fit-for-purpose UGS solutions. Typical support we can offer includes:

  • Geological reservoir studies, including screening and feasibility evaluation of depleted oil or gas fields for storage potential
  • Storage capacity calculations using reservoir data (e.g. porosity, permeability, flow data)
  • Detailed 3D static and dynamic modelling studies applicable to UGS facility design, optimisation and operational performance evaluation including calculations of required cushion gas and unrecoverable gas, and assessment of reservoir leakage or seal capacity
  • Conceptual design and front-end drilling and completion engineering for UGS wells
  • Operations performance evaluation including audit and review of your feasibility assessment
  • Due diligence studies, including data rooms, focussed on identifying uncertainties and risks
  • Specialised studies related to UGS (e.g. geomechanics, salt caverns, aquifers)
  • Sensitivity analysis of facilities and operating conditions to identify bottlenecks
  • Evaluation of market needs and storage economics


  • Energy sector, including gas distribution and pipeline companies
  • Gas storage candidate screening and development planning
  • Asset evaluation (data rooms, economics, risk assessment)
  • Environmental and regulatory compliance
  • Construction management and design


  • Cost-efficient, fit-for-purpose UGS facility design
  • Maximum deliverability of UGS facility
  • Improved understanding of storage volumes and injection/withdrawal rates
  • Improved understanding of cushion gas requirements, losses per cycle and unrecoverable gas