This chapter presents the results of studies into the undersea storage reservoir for CO2, in the Lower Bunter sandstone of the depleted Hewett natural gas field, the design recommendations for new wells and recommendations for abandonment of existing wells. The study addresses the following areas;
- Storage Reservoir integrity and capacity;
- Construction and completion of wells;
- CO2 properties and injectivity;
- Abandonment of existing and new wells;
- Monitoring;
- Hazard Identification (HAZID) and Risk Assessment.
Some of the key aspects of the Wells and Storage technical design are;
- Wells that have already been abandoned using conventional methods pose a risk of future leakage to the surface and thereby compromising the integrity of the CO2 store;
- Data acquisition can be difficult: ensure that all required data sets are identified and make requests as early as possible to ensure quality data is obtained resistant standards;
- The CO2 equation of state and phase diagram is paramount in designing the injection process. Temperature and pressure of the CO2 must be carefully specified to avoid uncontrolled condensation or vaporisation;
- Many standard components and materials used in the offshore industry are suitable for use in CO2 flowing regime injection applications. Particular attention must be paid to corrosion resistance and longevity in a CO2 environment;
- For drilling injection wells into a depleted hydrocarbon reservoir, the principal challenge is drilling into low pore pressures, whilst minimising formation damage.
Further supporting documents for Chapter 7 of the Key Knowledge Reference Book can be downloaded below.