Near-wellbore halo effect resulting from tip-screenout fracturing: Direct measurement and implication for sand control

The near-wellbore geometries of four fracture stimulations are evaluated to determine if fracturing soft, unconsolidated formations can result in plac ing proppant in a concentric halo around the casing, in addition to placing proppant in the fracture. Whether or not the "halo" exists impacts whether or not fracture stimulating is a viable means of sand control in unconsoli dated formations. This paper presents the findings of an investigation to determine whether a near-wellbore halo is generated during the process of fracture stimulating a well in a soft, unconsolidated formation. The investigation delves into whether net-pressure generation has any effect on the halo's formation and, finally, whether the halo could be used by petroleum operators as an inexp ensive way to control formation sand production. Results from four fracture stimulations in perfectly vertical wells are the primary data used in this investigation. In each case, all necessary steps were taken to ensure that collected data would show conclusively whether o r not the halo occurred and, more qualitatively, to what extent a significa nt net-pressure increase resulting from a tip screenout (TSO) affected the halo's formation. All data presented here resulted from direct downhole mea surements, either by bottomhole pressure gauges or by specialized azimuthal gamma ray (GR) logging tools that can directionally measure GR intensity. To date, the possible existence and benefit of the halo has been a topic of conjecture. This study represents the first attempt at directly confirming the existence and extent of the halo under actual downhole conditions.