A Comprehensive Review of Casing Deformation During Multi-Stage Hydraulic Fracturing in Unconventional Plays: Characterization, Diagnosis, Controlling Factors, Mitigation and Recovery Strategies

Abstract

The objective of this paper is to provide a review of casing deformations that are related to the placement of Multi-Stage Hydraulic Fracturing (MSHF) in unconventional plays. This work aims to identify practical mitigation and management strategies to reduce the overall impact of such events on the economic outcome of any development. The methodology incorporates a comprehensive literature review and leverages insights from the authors’ extensive field experience. This approach aims to explore the current state of knowledge regarding casing deformations associated with MSHF in unconventional reservoirs across key global basins. This paper encompasses the identification, diagnostics, surveillance, and monitoring of such deformations as they manifest and progress, along with the implementation of mitigation and management strategies prior to and during the well-completion process. The authors recognize the disparity between the number of publications available and the actual incidence of casing deformation in specific basins and are conscious that obtaining an exact estimate may often be elusive. The technical aspects of the review rely on the examination of numerous case studies from various unconventional basins. This is achieved by establishing a comprehensive understanding of the potential causes and mechanisms of casing deformations, including their occurrence, detection, and identification. Subsequently, an analysis is performed that presents the inherent characteristics of the different types of casing deformation, encompassing their nature, severity, distribution, and frequency across the basins considered, their lateral locations, event occurrence, specific nature and other pertinent factors. Additionally, the review addresses the geological, geo-mechanical, engineering and operational control factors that are likely to contribute to such deformations. Furthermore, it identifies a range of potential mitigation strategies aimed at minimizing the occurrence and ultimately the economic effects of casing deformation occurrence. This review builds upon various ongoing industry technical initiatives undertaken by the SPE Well Integrity Technical Section - Casing Deformation Work Group. The study findings can potentially provide practical measures to manage and mitigate casing deformation in unconventional basins within horizontal wells, thus minimizing the associated economic impact. Remaining knowledge gaps that require consideration should be addressed by actively sharing best practices and case histories within the industry on a global scale. This collaborative review paper, involving operating companies and other experts, serves as an initial step in that direction, aiming to catalyse further discussion among professionals working in this sector. It is intended as a rallying cry to encourage broader participation, deeper and shared consideration of the considerable effects of casing deformation occurrence.