Investigation and geophysical monitoring of caprock integrity

Offentlig prosjektsammendrag

During the operations for oil and gas exploitation, the stability and safety of the reservoir formations are very important. Hazards include leakage through the overburden, lack of buffer zones in the formations, faulted rocks and water injection possibly above thr local rock fracturing pressure within a formation. These result in potential leakage through the caprock, and the consequences of such leaks are unacceptable, especially during an offshore operation. The risks need to be managed. The uncertainty is related to the mapping of the faults and sub-seismic faults and the potential activation and opening of faults. The behaviour of such barriers during production and injection is key for the reservoir performance, particularly if a field is to be developed by subsea wells. Associated risks are an inability to inject the expected amount of water and connectivity issues between producers and injectors. All these factors can have impact on reservoir depletion and recovery. The research project aims at developing an optimum production plan while maintaing appropriate safety, based on an understanding of the most important risk factors, caprock integrity mechanisms and production opportunities, and identifying the most effective monitoring parameters, monitoring methods to ensure safety and cost-effectiveness, and to recommend th rissk to expect and associated contingency measures for best and safe practice. The project develops methods to investigate the integrity of caprock and ensure optimum and safe oil and gas production, with the following results: 1) geomechanical analysis-based approach for planning a safe operation; 2) methods for geophysical monitoring to detect sealing quality,fluid losses and faults; 3) recommendation for integrated damage assessment and intervention in case of failure. The new integrated approach will be verified with one case study. The project delivers a novel roadmap for increased safety and preparedness in oil and gas operations.