Surface Management of Gas Breakthrough in Thin Oil Rim Waxy Reservoir: A Case Study

摘要

With technological advancements, new and improved techniques have progressively been deployed to maximize recovery from a thin oil rim development. While some of them have a lasting influence on the well behavior such as placement of the well bore in the oil column, others such as zonal control using Sliding Side Doors (SSDs), Interval Control Valves (ICVs) or Interval Control Devices (ICDs) provide flexibility for altering well performance during operating life of the well. However, any intervention be it the subsurface zone manipulation or surface choke manipulation or ICV control needs to be justified in view of the anticipated gains against the risk incurred and resources required for the intervention on the basis of well performance (test data) and subsurface interpretation. The field for this case study is a thin oil rim with a large gas cap and a high wax content facing twin challenges-gassing out of wells and waxing of tubulars and flowlines-both of which require an optimization of preventive interventions to minimize deferment and corrective interventions. The required interventions such as choke and gas lift changes, zone changes, scraping, hot-oiling, steaming and pigging consume significant man-hours for surveillance, planning, execution and monitoring of the impact of the job on well performance. The desire to follow each intervention by a well test for system optimization overwhelms an already stretched routine well testing schedule. The resultant deferment due to sub-optimal production was estimated to be 10-15%. The solution was in breaking down the problem into mini-challenges and addressing them by deploying robust technologies and adopting smarter ways of working.