Multi-indicator comprehensive selection of well completion method based on Vague sets theory

At present, the selection of well completion methods gets more and more concerns on site, and mathematical method is commonly used to quantitatively select well completion methods based on multiple indicators comprehensively. In order to increase the utilization degree of well completion evaluation data, investigate the initial data comprehensively and improve the understanding level on candidate well completion methods, this paper introduced Vague sets theory to establish the Vague value selection model of well completion method. In this model, eight indicators from the aspects of productivity, economics and engineering constitute the well completion method evaluation system, the weights of evaluation indicators are determined by means of analytical hierarchy process (AHP)-entropy method, the Vague value evaluation matrix of well completion method is built up by virtue of a more reasonable Vague value construction method, and eventually based on the similarity measurement of Vague value, candidate well completion methods are evaluated precisely and accurately by constructing ideal well completion method and performing multi-indicator weighted similarity measurement between the ideal well completion method and candidate well completion methods. This model is applied to the well completion method selection of an actual example well and the optimal well completion scheme is obtained from five candidate well completion methods. The comparison results with the single value selection model show that Vague value selection model is reasonable and effective, has a better discrimination between candidate well completion methods and has the ability to provide more objective and reliable guidance for the selection of well completion methods.