iProdTech were requested by an E&P company to conduct a review of wells for reactivation in two mature oil fields in Nigeria onshore which had been shut-in in the early 1990s
The well review was used to prioritise key development areas for field re-activation as well as to identify the highest ranked wells for re-start and well intervention opportunities.
The review of each well generally consisted of the following key steps:
- Reviewing the well files and any other documentation supplied by the operator to identify the key events and interventions in the well history.
- Reviewing the production history of each well to understand the performance of the various producing zones and reasons for the historical interventions and zone changes.
- Reviewing the computer processed log interpretations (CPI’s) for the currently active zones to identify opportunities for additional perforations (add-perf), reperforations (re-perf), stimulation, water shut-off (WSO), gas shut-off (GSO), auto-gas lift and other potential optimisation activities.
- Building Petroleum Experts’ PROSPER well models for the currently active zones in order to characterise the reservoir inflow performance (well productivity index) at the time of shut-in and then to estimate the maximum watercut at which natural flow could be sustained.
- Generating high level estimates of the remaining reserves for the active zones using techniques including cumulative oil production vs. ln(WOR) analysis.
- Review the well CPI’s to identify any behind pipe opportunities and whether or not these opportunities could be exploited via the existing completion or if a workover would be required.
High level forecasts were then generated for various field reactivation scenarios considering with or without future intervention/workover activities in order to estimate the potential additional recovery from the fields.