Reduction of Subsurface Losses and Non-Productive Time During Deepwater Drilling by Application of Wellbore Strengthening Mechanism – A Strategic Approach

摘要

To maximize oil and gas production, it is paramount to reach the whole reservoir and extract hydrocarbon resources efficiently. Moreover, to reduce the costs in today's market, the well should be drilled in minimum operating time with no operational failures. This paper presents a detailed study and outline of a neoteric practice of using a wellbore strengthening while drilling, to drill a depleted deepwater reservoir and eliminate nonproductive time related to downhole losses. This novel solution has the potential to be used while drilling depleted reservoir sections in all Middle East areas. In a deepwater block situated on India's east coast, synthetic-based reservoir drilling fluids are used to drill the reservoir section. While drilling depleted reservoir sands, dynamic losses amounting to 300 bbl/hr were encountered that led to nonproductive time and even abandonment of well. To continue the drilling campaign and lessen the downhole losses, fracture sizes of depleted reservoir sands were simulated using proprietary software. Considering the measurement-while-drilling (MWD) tool's limitations and other reservoir behavior, a reservoir drilling fluid with wellbore strengthening material was formulated. Extensive laboratory tests were conducted to confirm the bridge and sealing capability of the solution. Subsequent to laboratory testing, the same reservoir drilling fluid formulation was field trialed. The well was drilled successfully with no hindrance, except minor losses encountered at the top of the sand. Implementing this customized solution, combined with precise running strategy, led to effective results in more than four wells to date. This paper presents a comprehensive study of drilling depleted zones using wellbore strengthening while drilling, identifying ideal products, studying reservoir compatibility, calculating cost effectiveness, evaluating overall performance based results, and overcoming challenges while implementing the strategy in deepwater wells. A detailed comparison of all the challenges that occurred while drilling and the proper troubleshooting steps are also discussed. Finally, the paper aims to compare the existing results with previous drilling techniques, which may help operators with the future development of respective fields. In this application, new technology of reservoir-friendly, loss prevention materials of ultra large size were used successfully.