Production logging (PL) has long been in use in the industry for evaluating the well performance for making strategic decisions. However, understanding the production profiles is challenging in complicated flow regimes and complex wellbore completions. To increase productivity in underperforming sick wells, electrical submersible pumps (ESPs) are generally effective options if planned and installed judiciously. This unique case study validates the application of production logging in planning and executing workover operations and by diagnosing the issues for suboptimal production performance of an ESP completed well.

Located in XYZ field of Mumbai offshore in India, Well G has been in production since October 2006, predominantly producing at the rate of 900 barrels of oil per day (BOPD) with 10% water cut (WC). After producing for 2 years, well production declined significantly to 600 BOPD. PL data were used efficiently to increase productivity at three different stages during the life of the well. In the first stage, PL played a key role in mapping the zonal production profile. On the basis of these data, an acid job was suggested, which increased production by 300 BOPD. In the second stage, when the production rate again declined to 600 BOPD within a year, PL played a key role in defining perforation and re-perforation strategy by identifying the silent zones and helping to plan ESP installation when the well was incapable of lifting fluids to surface. This led to an increase of only 50 BOPD as compared to the expected increase of 600 BOPD. During the third stage, PL combined with a Y-tool was instrumental in diagnosing a mismatch between ESP design capacity and reduced reservoir deliverability, which was the key reason for the unexpected underproduction. On the basis of the diagnosis, an acid job was suggested to increase well deliverability. Following the acid job, production increased by almost 75% to 1034 BOPD without changing and damaging the ESP.

This case study is of interest to plan workover operations and to diagnose production problems using PL to optimize production in ESP completed wells with changing reservoir productivity.

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