Integrity of Wells in the Nearshore Area Gippsland Basin

Abstract

The CarbonNet Project is seeking CO₂ storage sites in the nearshore area of the Gippsland Basin that provide permanent and safe storage for 25 to 125 Mt of CO₂. The integrity of legacy or existing wells (which may include abandoned, production, injection, mineral/water bores and Measurement, Monitoring and Verification (MMV) wells) is recognised around the world as one of the most significant operational risks to CO₂ storage projects. The number of wells and quality of completions can vary significantly in different basins and jurisdictions. Furthermore, the drilling and completion requirements for onshore and offshore wells are subject to various regulatory, industry and operator standards and practices. The Gippsland Basin has been an active oil and gas production province since the 1960's and there is a reasonable database of well data and parameters to assess well integrity. In the nearshore area of the Gippsland Basin, the integrity of twelve (12) wells has been assessed and risks identified. The assessment was based on existing documentation lodged with the regulator under Australia's comprehensive offshore petroleum legislation. The assessment concludes that the risk of leakage from the twelve (12) legacy wells reviewed is low, even though the primary purpose of the completion was to secure the wells in a petroleum context. Ultimately for any CO₂ storage project, there is a requirement to demonstrate how to safely monitor legacy wells in an Australian context to show they are not potential leakage pathways and to outline plans for remediation of wells if they are shown to have problems. Options are explored for completion and monitoring of future petroleum wells and other boreholes to avoid any new risks.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015