Holistic Management of Calcium Carbonate Scaling in a Mature Field: A Case Study

Abstract

Calcium carbonate scaling within well tubing and surface piping leads to significant production loss in many oilfields across the world. Scaling tendency of produced fluids increases multi-fold in a mature reservoir with increase in water production and decline in operating pressures. This paper demonstrates the use of modelling to help anticipate scaling issues and convert predictions into operational decisionmaking which has prevented significant value erosion in a mature field. Majority of the efforts in tackling scaling related losses have traditionally been centered on performing scale treatment after observing a significant change in flow parameters. Although this approach delivers value, it is more reactive in nature and becomes challenging to address in a logistically constrained offshore environment. This paper presents a case study on a new proactive framework on Scale Management. This new framework is driven by P2P approach - Prediction to Prevention. Prediction of scale formation tendency in wells was carried out using a thermodynamic model. Once wells with scale formation tendency were identified using thermodynamic model, scale prevention was done by selection and application of scale inhibitor chemical along with progressively reducing number of surgical acid washes. The scaling behavior was compared against the operating conditions of wells and the findings complemented the understanding from thermodynamic simulations. Paper deliberates on the cost optimization while application of this approach so that it remains extremely cost efficient in comparison to traditional approach. It details the evolution of scale management strategy right from project initiation to field maturation spanning across 30 years of production. With periodic reviews of this framework, additional ~10% of available well stock was identified as new wells migrating into scaling envelope over the last one year and added to Scale Inhibitor dosage program. This prevented production losses and well integrity issues in these wells. Wells put on continuous scale inhibitor injection as per recommendations of this approach did not have down-hole safety valve failures, protecting 35% of field oil production volume and ensuring safer operations demonstrating strong business value. Overall, application of this P2P framework has helped asset to reduce yearly scaling related losses by more than 90%.