An Integrated Transport Model for Ball-Sealer Diversion in Vertical andHorizontal Wells

摘要

Ball sealer diversion has been proven to be both an effectivernand economic way to selectively stimulate low permeabilityrnoil and gas reservoirs in hydraulic fracturing and matrixrnacidizing treatments. However, the design and implementationrnof a successful ball sealer diversion treatment is still arnchallenge. Often the designer depends on experience, andrnlacks the knowledge of accurate ball transport and sealingrnbehaviors. An integrated model for selecting operating factorsrnsuch as fluid and ball properties, as well as predicting the ballrnsealers transport and hydraulic behavior prior to pumping isrnneeded for optimizing the stimulation process.rnIn this paper, an integrated transport model is presented torndescribe the relationships among the ball sealer transportrnsealing behavior, wellbore deviation, wall effect, perforationrndensity and size, fluid properties, pumping rate and ballrnproperties. In addition, the smoothness of ball, perforationrnphasing, and velocity profile inside the wellbore during ballrnseating are also taken into consideration. Recommendationsrnare provided for determining the number of ball sealers per jobrnfor either single or multiple stage treatment, the designedrnpumping rate, and the physical properties of the fluid and ballrnsealer. A hydraulic analysis model is presented for the overallrnfluid dynamics starting from surface, through wellbore, tornreservoir. This analysis describes the effects of reservoirrncondition, pressure drop on perforations, and actual sealingrnefficiency on the surface treatment pressure profile. This paperrnwill investigate the effects of the diversion factors on the ballrntransport behaviors such as transport time, ball sealerrnefficiency and surface pressure.