Progressive Evaluation and Acquisition Strategies for Improving Success in Re-Entering Abandoned Oil and Gas Well in a Niger Delta Marginal Field

Abstract

Abstract With the awarding of marginal fields from the 2020 bid round, indigenous companies and new players in the Nigerian Upstream oil and gas sectors grapple with the legacy of abandoned wells. Reliability of existing data is a common challenge hence, operators had to plan various re-entry strategies to mitigate the unknown risks and improve well delivery, this entails the process of evaluation, acquisition, and re-evaluation of data. The inherited data that come with these wells may have been obtained using obsolete technology or obtained using analogue methods whose results had to be digitized and re-interpreted thereby increasing the possibility of human error. This challenge underscores the necessity of having an effective data acquisition program for optimal reservoir recovery. This study presents strategies for evaluating and obtaining valuable data from abandoned wells in the Niger Delta Basin. It reviews the operations in the AA-01 well in the AA Field as a case study. To address the issues around data reliability and acquisition, a robust data gathering initiative was proposed after initial evaluation – from obtaining well trajectory surveys to integrating advanced logging techniques such as corrosion logs, cement bond logs, pulse-neutron logs, and gamma-ray logs. While preferring innovative data-gathering programs, historical data are also compared and combined with the new data to justify the data acquisition program and give a more nuanced understanding of the geological history of the well. This paper aims to highlight the difficulties encountered by indigenous companies regarding data reliability and solutions while discussing the strategies for a robust data-gathering initiative and its benefits.