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Development of a Predictive Tool For Estimating Well Performance In Horizontal Shale Gas Wells In the Barnett Shale, North Texas, USA
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2009
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Unknown Venue
Shale Gas ReservoirsEngineeringHorizontal PermeabilityWell Performance EvaluationEarth ScienceDrillingReservoir EngineeringGeotechnical EngineeringPetroleum ReservoirHorizontal Well ApplicationsNorth TexasStatisticsHydrogeologyGas Field DevelopmentPredictive AnalyticsPredictive ToolForecastingTight OilCivil EngineeringFormation EvaluationUnconventional ResourceBarnett ShalePetroleum Engineering
Production from unconventional shale gas reservoirs has seen increased attention and economic viability in recent years through the use of horizontal development wells. Maximizing horizontal permeability in such wells has been found to be one of the largest keys to unlocking shale gas reservoirs and producing them at economic rates. Currently, a world-class shale gas accumulation is being developed in and around the Dallas-Fort Worth, Texas, area using horizontal well applications. A multi-component approach to derive reliable and accurate predictions of horizontal shale gas well performance is presented here, using open hole well log data from several vertical pilot boreholes that have been drilled targeting the Bamett Shale. Fundamentally, this approach is founded upon four key elements: a thorough probabilistic volume estimation of lithology, calculation of total porosity, estimation of free gas present using a modified dual water saturation model and prediction of kerogen and total-organic-carbon (TOC) of the interval. From the primary evaluation from open hole logs, net kerogen-feet, TOC-ft and adsorbed gas-feet have all been identified as meaningful measures of shale quality that are useful as a vehicle to obtain accurate predictions of horizontal well ultimate recovery gas volumes (EUR). These factors have been weighted as a function of drilled lateral length for the horizontal production hole that has been subsequently drilled from each pilot. Varying the values calculated at the pilot well according to horizontal length is a key aspect of this evaluation technique and the weighting of these parameters found to correlate to decline-curve based EUR volumes for the study wells. The net product has been a reliable indicator for visualizing and quantifying well performance in five existing Bamett Shale horizontal wells, using standard open hole well log data acquired in the vertical pilot holes.