Integrated Approach to Addressing Well Integrity Challenges: A case study of Well AA

Abstract

Operating wells safely is a critical aspect of E&P business because of the significant exposure and huge negative impact of associated incidents on People, Asset, Community and Environment. Well integrity failure has grave reputational and financial consequences which can ultimately lead to losing license to operate and/or loss of lives. In our company, well integrity management receives topmost leadership focus, with requisite standard guidelines, which are regularly reviewed and updated to ensure the objective of operating wells safely are achieved. The risk of loss of well integrity is higher as wells age, however, in some very few cases newly completed wells may also fail. Loss of well integrity could result in sustained annular pressure, hydrocarbon spill, underground blow-out, or contamination of ground water aquifer in some cases. The potential causes include (but not limited to) poor cement annular cementation or bonding, casing/tubing corrosion and/or compromised completion jewelries. Our case study, Well AA is situated in the shallow offshore terrain of the Niger Delta. The well was completed as a Single String Single (SSS) horizontal oil producer. Shortly after the well came on-stream, sustained high A-annulus pressure was observed during ramp-up. This eventually exceeded the Maximum Allowable Annular Surface Pressure (MAASP), resulting in a well integrity concern. A comprehensive risk assessment was carried out to identify potential leak path, generate risk assessment matrix and recommend preliminary leak investigation activities. In line with the guideline, initial bleed-down procedures were deployed but this did not abate the A-annulus pressure. Detailed downhole investigation integrating spectral noise and high precision temperature logs confirmed the production packer was compromised. Subsequently, well AA was worked over and integrity restored, safeguarding production promise of over 1500 bopd. This paper therefore details the integrated approach taken by the asset team to identify the well integrity issue, assess risk level, investigate cause of A-annular pressure build up and how it was addressed. This paper is intended to provide a guide to technical staff facing similar well integrity challenge.