Completion length optimization in gas wells

Document Type

Conference Proceeding

Publication Date

1-1-2018

Abstract

Water-drive gas systems are economically important but gas recovery may be limited by water loading of the production string or incomplete sweep in the reservoir. Efforts to improve recovery from water-drive gas wells have focused on limiting the completion length. However, limiting the completion interval decreases the gas production rate and may have a substantial negative effect on project economics. The effects of limited completion length on gas rate, cumulative gas production, and discounted revenue stream are considered for a range of reservoir and economic factors in this study. A multilevel factorial design in 8 factors (576 simulations) was analyzed using response models and Monte Carlo simulation. The gas price, discount rate and initial reservoir pressure are the most important factors affecting present value, followed by horizontal and vertical permeability and completion interval length. Because decreased completion interval length has a strong negative effect on gas rates and economics, methods that control water completion while maintaining longer completions are desirable. The completion length can be optimized using response surfaces and Monte Carlo methods. The optimum completion length depends on the distribution of the uncertain factors; computing the optimum at factor mean or median values is not equivalent and is less reasonable. Methods to address this uncertainty are presented. For the models considered in this study, productivity is often the most important factor and the expected project value is often maximized by using the maximum completion interval length.

Publication Source (Journal or Book title)

Canadian International Petroleum Conference 2003, CIPC 2003

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