Looking at the Bigger Picture - Better Understanding of Well Behavior through Integration of Petrophysical, Production Logging and Corrosion Evaluation Data in a Challenging Environment, Ensuring Maximum Well Life and Overall Productivity

This paper describes optimal field development and appraisal in complex reservoirs and challenging environments in field ‘ABC’. Most of the wells are laterals with ICD (lower) completions across heterogeneous carbonate reservoirs. Highly corrosive environments i.e. up to 20% H2S present an added risk, particularly in the event of water encroachment. Optimal development needs a multi-disciplinary surveillance approach involving an integration of input form stakeholders, including geoscience and petroleum engineering, to ensure productivity optimization during the whole life of the field. Field ABC is an offshore field with extremely heterogeneous carbonate reservoirs and acid stimulation is usually done to improve production. The wells in the field are mostly horizontal, oil producers with ICD lower completions. The upper completion uses carbon steel L80 and for corrosion mitigation, inhibitors are injected through chemical injection valves. In this paper, a pilot well is reviewed where a methodical approach was used for evaluation. Baseline production logging and reservoir saturation monitoring were done in the lower completion and a corrosion log was acquired in both the upper and lower completions. Data acquired was integrated and observations show that the measurements correlate well with each other. This case study integrates and correlates downhole zonal contribution, phase holdups, pressure and temperature data from production logging with metal loss data from a high-resolution multi-finger caliper tool. Well trajectory shows a depression across the heel of the well which is incidentally between the EOT and the topmost ICD. Although there is no water production at surface, a static water sump is observed across this depression on the production logs. This static water is possibly completion fluid or unremoved fluid from the acid job. Minor localized corrosion is also observed across the same depression on the corrosion logs, also confirming presence of some water. The H2S production and the presence of water is an added risk to completion integrity as it creates a corrosive environment. Therefore, in such cases it will be necessary to monitor the production and corrosion at regular intervals of time. This case study shows that by applying a multi-disciplinary approach and integrating various measurements, well conditions can be viewed not just as pieces of a puzzle but as a complete picture to improve the understanding of the well behavior. Time-lapse monitoring of production and corrosion along with reservoir saturation is also necessary to prevent surprises and help in making informed decisions towards better field development.