Increased Efficiency on Plug and Abandonment Campaign Using New-Generation Ultrasonic Pulse-Echo and Pitch-Catch Configuration Technology

Abstract

An operator on the Norwegian Continental Shelf oversaw the execution of a plug and abandonment (P&A) campaign comprising 32 wells in a mature field. The barrier evaluation plan was developed based on previous experiences in a field with similar properties and conducted by another operator that included the cement and solids evaluation using conventional ultrasonic technology. This paper describes how the introduction of the latest generation transducers aided in shortening the P&A campaign duration, saving days of rig time. The entire logging plan for barrier evaluation within the32 well P&A campaign was custom developed, executed, and jointly analyzed by the operator and the service company. The logging intervals, well fluid and multiple casing size targets were considered during the strategic selection process. This enabled convergence to a solution that provided a comprehensive evaluation while avoiding multiple logging descents and achieving a faster acquisition speed without degradation of the results. Acquisition capabilities have been constantly evolving over the past decades. The full data acquisition campaign described in this paper was improved from the original plan and adjusted to include a combination of ultrasonic pulse-echo and pitch-catch imaging measurements, third interface echo (TIE), an output of the pitch-catch method supported by and the traditional sonic technology response, enabling quick annular material identification as well as casing cut-and-pull decision making. The combination of all measurements allowed a robust solution that is independent from wellbore logging fluid and potentially unknown annular materials that segregates or changes through the life of these wells. The technology blend adopted in this field enabled a direct logging time reduction of 50% and allowed the acquisition of multiple nonconcentric casing sizes in a single descent, which is not possible with previous generation technologies. The overall result helped the operator to reduce their greenhouse gas (GHG) emissions during those operations by shortening the barrier evaluation campaign length by 10 rig days. The operator was able to significantly reduce the rig time spent in the campaign the implementation of the latest ultrasonic barrier evaluation logging technology, thus reducing their overall GHG emissions without compromising the results of the original objectives.