AAPG Southwest Section

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Investigation of Hydraulic Fracture Heights in Wolfcamp Horizontal Wells

Abstract

Wolfcamp reservoirs in the Southern Midland Basin have a reservoir architecture comprised of two distinct end members, highly fractured and mechanically weak TOC rich source rocks interbedded with less fractured but mechanically strong thin limestone beds. These inherent vertical heterogeneities make determination of the completion effective fracture height problematic.

In this paper, we will show fracture height results obtained from two separate subsurface experiments, both utilizing vertical pilot wells with image logs that offset nearby fracture stimulated lateral wells. Both FMI (Formation Micro Imager) and UBI (Ultrasonic Borehole Imager) data were acquired in vertical wells and a pipe conveyed FMI in a lateral well. Note the FMI is capable of imaging both cemented (resistive) and open fractures (conductive), while the UBI tool can only detect open fractures.