Multilayer Reservoir Model Enables More Complete Reservoir Characterization During Underbalanced Drilling

摘要

In order to effectively analyze reservoir inflow data from arnwell drilled underbalanced, a true multilayer reservoir modelrnis required. In a previous paper,1 a single layer analyticalrnmodel was developed to handle reservoir inflow resultingrnfrom the changing wellbore geometry during thernunderbalanced drilling process. A method to analyze datarnacquired during underbalanced drilling for reservoirrnpermeability was developed and presented. The resultingrnreservoir model was shown to be unique in the industry.rnHowever, it was recognized that a multilayer model wasrnneeded to fully analyze the data and generate a more completernreservoir evaluation during underbalanced drilling.rnThis paper presents a true multilayer model that describesrninflow from multiple reservoir layers encountered duringrnunderbalanced drilling. The model is fully transient and isrnbased on the single layer model presented in previous work.rnThe model accounts for the lengthening of the wellborernthrough any number of reservoir layers having similar orrndifferent properties and the resulting flow into the wellbore.rnResults from validation of the model are presented. The modelrnenables formation evaluation during the underbalancedrndrilling process.