Cairn India Limited operates over 600 wells in the Barmer basin in Rajasthan with over 30 well intervention (rig and rigless) units deployed on an average to perform over 5000 interventions per year. Maintaining the quality of interventions and analyzing the performance of such a scale of operations is a major challenge. This paper describes "An holistic approach" for evaluating well intervention campaigns, reviewing candidate selection, intervention techniques and technologies utilizing an intensive data warehouse and the techno-economical tool, "Scorpion Plot" to optimize intervention costs and rewards.

The performance of all Well & Reservoir Management (WRM) activities are analyzed in terms of cost and associated gain. The data gathered is categorized into four types namely Well Surveillance, Production Enhancement, Restoration, Well Integrity and Support. The expenditure on non-oil and gas gain generating interventions (Well Surveillance, Restoration, Well Integrity & Support) plotted on cumulative cost basis gave an overall idea of the health of the well stock and understanding of the value of information from data gathering. The Production Enhancement activities, sorted in increasing order of cost per barrel gained were plotted on a cumulative cost vs cumulative gain curve termed as "Scorpion Plot" because the shape always largely resembles a "scorpion tail" with low cost-high gain jobs lying in the bottom left part of curve and high cost and negative value interventions forming the "tail" of the scorpion to the top right. The analysis of the type of jobs falling in the different tranches of the plot on the basis of $ spent per barrel gained, helps in identifying the areas for optimizing the process of candidate selection and job execution.

The objective is to remove negative gain and reduce high cost low gain activities (the tail of the "scorpion plot") and shift the curve towards the bottom left to improve oil realization while reducing cost. After Action Reviews are carried out for all the negative and lower value activities and the lessons learnt are fed back into the intervention management system to enhance future intervention campaign results. Production enhancement activities such as ‘Well Stimulation’ positioned in the negative value group were further analyzed based on the selection criteria, technique of stimulation, chemical recipes/volumes were benchmarked against the high value interventions. Case studies showing how the analysis helped in better candidate selection and best technique for interventions are discussed.

This paper also describes how the process of candidate selection, cost, resource allocation and job impact assessment is automated ensuring engineering focus on job planning and after action review.

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