Abstract

Operators use curable (precoated or on-the-fly coated) resin- coated proppants (RCPs) for controlling proppant flowback after hydraulic-fracturing treatments and in screenless, fracpack completions. A very important but much ignored consideration when choosing an RCP for a particular treatment is the cure kinetics of the proppant. This paper presents the results of a study to compare the consolidation performances of RCPs with different cure kinetics under simulated treatment and downhole conditions of extended pump times and delayed or insufficient fracture closures throughout packs. Techniques developed for determining RCPs' cure kinetics are described. These techniques include differential scanning calorimetry (DSC), rock-mechanical measurements, and scanning electron microscopy (SEM). The cure kinetics of different RCPs are related to their consolidation strengths and photomicrographs obtained of these proppants after they are subjected to conditions simulating different times before onsets of closures at bottomhole temperatures (BHTs).

SEM micrographs showed that in the faster-curing RCPs, there was a dramatic decrease in the numbers and areas of contact points between proppant grains. These micrographs correlate well with the losses of consolidation strengths determined when faster-curing RCPs were exposed to fluids at temperature for various times before onsets of closures. For consolidations simulating wells with high BHTs, the losses of consolidation strengths were more severe, and the numbers and areas of contact points decreased.

This study provides dramatic new answers as to why many RCP consolidations might have failed in the field. Operators can use the information presented to help themselves select the best RCPs for their applications. The information presented is particularly useful for selecting the RCP to be used in screenless completions where consolidations are expected to withstand production conditions of high flow rates and stress cycling. This study improves understanding of the failure mechanisms of RCPs and provides guidelines for proper design and candidate selection for proppant-flowback control and for screenless completions.

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