Risk Mitigation Measures Implemented by Use of Expandable Liner to Prevent Alpha-beta Gravel Pack Failure When Unstable Shale Formation is Exposed

Abstract

Current oil and gas volatile market environment and the increase focus towards sustainability, it is essential to develop more economically and ecofriendly technologies in oil and gas industry environment. Maintain well integrity is mandatory towards developing oilfields to contain the reservoir fluids within the wellbore, however it becomes more critical in developing new underground gas storage reservoir in Italy. During construction phase of gas production and storage wells, one goal, besides hydraulic isolation of the production casing with cement, is the sand production containment during production cycle of the field. Sand production, even in small quantities, will eventually erode downhole and surface equipment leading to potential catastrophic scenarios of uncontrol reservoir fluid reaching surface. These can have significant health, environmental, and economic impact. Additionally, the impending need for well intervention, along with high re-entry costs, will further weaken revenue margins. In high permeability reservoirs required for underground gas storage projects, the injection and production cycles can lead to stresses applied in nearby wellbore formation which will destabilize the sandstone grains leading to sand production. To mitigate the sand production into the wellbore, a gravel pack operation will support the wellbore, consolidating the space behind the production screens. In this field, a high-risk failure was identified for traditional alpha-beta gravel pack methodology. This could lead to expensive recovery operations for the client and service provider to restore the well and re-perform the gravel pack. To tap different part of the reservoir, one well in particular had to be sidetracked from 9-5/8in casing resulting in a long clay interval being exposed susceptible of instability. It was required to isolate this interval to avoid disturbing the clay interval during gravel pack operations, however, to accommodate the completion, the optimum solution was to use expandable liner. Using this zonal isolation technique to regain well integrity, along with redesign of gravel pack carrier fluid technology led to a successful job securing client position as a reliable field operator. The field operator was committed for high level of safety during operations, starting from design phase through the execution, to achieve long-term well integrity and performance.