Determination of Caprock Porosity and Permeability Using Drill Cuttings and Core Samples of a Potential CO2 Storage Site – A Case Study

Abstract

Abstract Carbon capture and storage (CCS) provides a safe option to reduce carbon footprint on a large scale. Here, carbon dioxide (CO2) is stored in a reservoir formation, overlain by a seal with low permeability and high capillary entry pressure. Understanding CO2 migration through the seal is one of the main components to assess caprock integrity, thereby ensuring safe and long-term CO2 containment and storage. This research is a combined and detailed study of caprock porosity and permeability using core and well log data to overcome a major issue: Coring and logging operation are expensive, and rarely done in caprocks. Drill cuttings, however, are available as byproduct of all drilled wells. By studying the caprock porosity and permeability of a potential CO2 storage site, this study aims to develop porosity/permeability relationships which can be used as input to predict matrix migration and capillary leakage to ensure permanent storage of CO2. In this paper, drill cuttings and core samples, which were obtained from a potential CO2 storage site, went through a series of laboratory measurements to determine porosity and permeability. This includes mercury injection capillary pressure (MICP), unsteady state pulse decay permeability on plug samples, and poro-permeameter measurements on crushed samples. Preliminary results have shown that drill cuttings produce higher porosity and permeability values than core samples. Nevertheless, further analysis is needed to establish relationships and correlations between drill cuttings and core samples. By applying a multi-method approach, resulting in trends for porosity and permeability, we may be able to reduce the operational costs of coring by using drill cuttings as alternatives and at the same time help de-risking CO2 storage projects for wider scale of deployment.