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.