Enhanced Oil Recovery as a second revenue stream in a gas storage facility; understanding and monitoring the Humbly Grove Field, Hampshire, UK

The Humbly Grove field is a unique example of an onshore UK field with two co-existing revenue streams. Its business model is based on oil production coupled with gas storage; relatively low-priced gas being stored in summer and produced at times of elevated demand and price in winter. After seasonal gas price variations were suppressed by imported LNG, Humbly Grove’s oil production creates business resilience.

Gas is stored for customers by injecting it via the wells into the reservoir. The process continues until the storage facility is considered ‘full’. When full, enhanced flow of oil into oil production wells is observed. This provides additional value that would not otherwise exist in a gas-only storage facility. As winter demand rises, or when gas is requested by customers, the process is reversed and gas is withdrawn from the reservoir. Traces of water, H2S and other impurities picked up from the reservoir are removed to meet National Grid specifications and the gas is delivered to the network.

As with other gas storage facilities, Humbly Grove operates under strict national safety legislation. The licence to operate is dependent on a robust safety case. This was developed with an integrated approach to reservoir monitoring and modelling which combines a range of geoscience expertise to understand the behaviour and safe limits for gas storage.