Inflow Performance Methods for EvaluatingDownhole Water Sink Completions vs.Conventional Wells in Oil Reservoirs WithWater Production Problems

摘要

A new method and software have been developed toidentify promising reservoir candidates for productionimprovement using DWS technology. DWS employs dualcompletion in wells affected by excessive water problem.The bottom completion drains the water and keeps thetop completion open to oil inflow. The system has provento be effective by increasing oil rate, particularly whenthe drained water – not contaminated with oil – can bedisposed off without further processing. Decision onusing DWS must be based upon pre-evaluation ofreservoir candidates through a theoretical comparisonof DWS and conventional well performances. Analyticalmodeling, to date, would predict oil productivityperformance but has fallen short of precision inforecasting conditions for clean (oil-free) water drainage, because it cannot model distributed watersaturation around well.New algorithms and an interface to a commercialreservoir simulator have been written and used as anumerical tool for DWS well performance analysis anddesign. The tool captures hydrodynamic interactionbetween the two completions of the well in terms ofpressure interference, water saturation (coning), andproducing water cut for any combination of top andbottom production rates in presence of heterogeneities,capillary forces, and relative permeabilities. It is used todetermine a cluster of inflow performance relationships(IPR) for a DWS well to be compared with a single IPRfor the conventional well. It is shown that optimizedinflow conditions for maximum oil rate provide anunbiased criterion for comparing performance of DWS