Fully Automated Wellhead Choke & Flow Line Calibration on a Daily Basis for a Complex Surface Network with Over 1200 Active Producers: A KOC North Kuwait Case Study

Abstract A giant onshore KOC oil asset has a complex surface network with hundreds of jump-overs, several manifolds, trunk lines & thousands of flow lines. The goal of the asset is to identify bottlenecks that is impeding production, determine hydraulic health of pipelines and identify optimization opportunities. Only way to reach the mandate set by the asset is to have a calibrated surface network model on a daily basis which then can be used to confidently identify issues in the network. Wellhead Chokes for individual wells are calibrated using a dedicated workflow called as Automatic Choke Calibration (ACC) workflow. ACC workflow selects only wells which have valid IPR/VLP files. Eight simulation runs are performed by varying wellhead choke discharge co-efficient (CD). Iterations are performed to calculate exact CD which will match pressure delta observed in the test across the choke. If deviation is within +/-5% then choke is flagged as calibrated. Automatic Network Model Calibration (ANMC) workflow is used for calibrating entire surface network starting after the wellhead choke till GC slot. Workflow identifies wells which have valid IPR/VLP, chokes are calibrated, have valid connection length, real time wellhead pressure (WHP), Flowline pressure (FLP) & artificial parameters. Averaged (24 hours, 5:00 AM to 5:00 AM) real time pressure data are updated for pipelines which will be undergoing calibration. Pipeline connections are calibrated by adjusting friction factor multiplier using simulating annealing algorithm to match the observed real time pressure data. For pipelines which are successfully calibrated, their friction factor multiplier values are stored in the database. Finally, model is updated by incorporating friction factor multiplier value identified in the calibration process. With a calibrated model, engineers have greater trust on the virtual rates reported by the simulation tool for individual wells & pipelines. Friction factor multiplier reported by the workflow has given valuable insights into the hydraulic health of the pipelines enabling engineers to take preventive actions effectively. Calibrated model is used by another workflow to identify changes which have to be performed in terms of choke and artificial lift parameter to maximize oil production. This paper describes a pioneering new way of developing an integrated & automated workflow for calibrating choke and surface network on a daily basis instead of traditional way where calibration is performed less often which has major implications on the recommendations provided for the day-to-day operations of the asset.