This paper presents a generic workflow to assess direct and indirect production in reservoirs with layered contrasted permeability. The objectives are to quantify the total individual production split from those zones when compared to volumetric and evaluate the productivity efficiency.
The workflow comprehensively integrates reservoir surveillance tools such as Production Logging Tools (PLTs) to perform a zonal decline analysis through analytical approach. The numerical simulation modeling is utilized to support this assessment. The paper describes a method of capitalizing the flowmeter results and correlate them with production decline to identify the volumes swept from the tighter zones of interest.
The workflows identifies, as a result of this analysis, the split of the two portions of this swept volumes in the tight zones : a portion easy to identify, as it is produced directly through the logged wellbore or migrated vertically to most permeable zones to build-up on the attic portions of the reservoir. Such analysis when conducted in a specific field and coupled with simulation result is a powerful tool to decide on the actual mechanism affecting the sweep including the importance of gravity and percolation process. Consequently, strategic decision could be taken based on the options to develop the contrasted zones. This is including the decisions on wells configuration, whether it is more justified to fetch the tight zones volumes through vertical wells or to rationally exploiting the top layer through horizontal wells.
The workflow was applied to real case study and showed a quantitative conclusive result, it demonstrated the equilibrium, required to maintain, in the withdrawals ratio of the contrasted zones. This equilibrium will ensure to have a better sweep of lower productivity zone.