A Comprehensive Study of Barriers for Underground Natural Gas Storage Wells

Overview

Main Objective

The main objective of this project is to provide an inclusive source of knowledge about the formation, diagnostics, and mitigation methods of microannulli as potential leak paths in gas storage wells experiencing cyclic injections and depletions, through a comprehensive literature review and knowledge gathering. The project aims to develop improved guidelines and techniques for identifying, characterizing, and effectively sealing leak paths by evaluating current practices, barrier materials, and testing methods and introducing new lab tests and modeling tools. The anticipated results will include a comprehensive guidebook of diagnostic methods, a list of effective sealing materials and their application methods, as well as a decision tree for material selection and testing. These outcomes are ultimately contributing to enhanced safety and integrity in underground natural gas storage operations to curtail greenhouse gas emissions.

Public Abstract

Project Description: In this project, we conduct a comprehensive literature review and knowledge gathering about micro annulus, potential leak paths, and mitigation strategies in gas wells, especially storage wells experiencing cyclic injection and depletion. Technical reports, peer-reviewed journal papers, conference papers, manufacturer catalogs, and relevant industry standards in different countries with progressive regulations will be considered as potential resources for this project. Case studies, historical examples, recent diagnostic and remedial tools, as well as existing technology gaps will be reviewed to re-evaluate current practices and materials in the field and assess the limitations of available standards. As a part of this process, the required height and properties of single and dual barrier systems will be examined specifically under cyclic mechanical and thermal loading that often occurs in storage wells. Cement tests especially at the interfaces will be discussed and shortcomings of current standard codes will be addressed by introducing new experimental tests and modeling tools to incorporate interfacial cement failure into the analysis. Furthermore, the impact of mixed hydrogen on cement and sealing components of existing gas storage wells will be discussed and potential materials to serve as a replacement for cement in well barrier applications will be evaluated.

Anticipated Results: The outcome of this project will provide a comprehensive guidebook of available diagnostic methods to identify and measure leak paths and their limitations in gas storage wells. Then a list of existing and novel promising materials for re-sealing the leaky wells and their application methods will be provided. A decision tree for the material selection and testing methods will be provided to be used in evaluating new materials coming to the market.

Potential Impact on Safety: Knowledge and technology collected in this research can be used by USDOT engineers and technicians to address different leakage scenarios encountered in underground storage systems.

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