Minimizing Cross Flow Among Fractured Stages in Horizontal Wells Using the D-Exponent Calibrated GR Data

Abstract

This paper presents a method for examining the potential of fracture stimulation in horizontal wells targeting unconventional oil plays. The observation of crossflow among fractures has been of great concern as this phenomenon affects the productivity of producing wells. The cause is related to the effectiveness of fracturing stages, which by itself depends on the rock lithology and brittleness. We identified interaction among fractured intervals from diagnostic modeling of performance data that exhibited cross flows in the wellbore. On wells exhibiting the most prolonged duration of crossflow, we noted the disadvantages of equal space fracturing. We then used the drilling parameters from MWD data for individual wells and computed the d-exponent profiles and noted significant differences in rock brittleness as characterized by their d-exponent data. We examined the d-exponent data using the Hurst coefficient. Wells exhibiting a trend with uniform H coefficient showed the least indications of cross flows from performance data while in wells with significant cross flows we see the nonuniformity of the d-exponent profile examined with the H coefficient method. It is our observation that before fracturing, interval selection with GR log can be enhanced if supplemented with the trend analysis of the d-exponent data.