Abstract

Candidate recognition in mature brown fields and depleted fields for stimulation has always been a challenging task. It has become a common practice for many operators that when all else fails they turn to stimulating the well. The application of fracturing for any poor producer in a brown field does not guarantee success. Since traditional reservoir engineering methods like skin analysis via build-ups cannot be applied in these depleted reservoirs alternative techniques have to be used.

Identifying and stimulating key wells requires a systematic candidate recognition process with emphasis on the ability of the well to deliver post stimulation. Having a method to score completion and production integrity based on its petrophysical and geomechanical characteristics and thoroughly understanding the operating environment ensures a much better chance for these wells to be successful. Comprehensive candidate selection methodology with available data was devised to identify best stimulation candidates from existing set of wells. Comparative Petro-physical log evaluation, Mechanical Earth modelling and oriented perforations in selected wells was deployed to further understand reservoir and rock mechanical properties and limit surface pressures by minimizing near wellbore perforation and tortuosity effects.

Further to estimate economic viability; analytical modelling and Arps production decline was combined utilizing local learnings and experience to predict post fracture production. Full set of diagnostic tests was done to make a robust model that can simulate fracture propagation and help in optimizing fracturing design to place desired fracture in place. Post fracturing cleanup and well activation was closely monitored with design and recommendation on required Artificial Lift techniques as and when required. Production results achieved after applying this workflow exceeded initial expectations set by operator. Payout period achieved for total investment in this project was 75-150 days. Due to these encouraging results, same workflow was applied in number of depleted fields in Cambay basin with similar results.

This paper will summarize the workflow used for revitalizing production from some of the major fields including Candidate selection methodology, Petro-physical evaluation, Mechanical earth modelling, diagnostic tests for fracturing design, production forecasting, post fracture well activation and artificial lift design. In the end, possibilities of deploying this workflow for re-vitalizing other brownfields will be discussed.

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