Investigation of Solids Flowback after Hydraulic Fracturing and Remedial Treatments

Abstract One of the major concerns with hydraulic fracturing treatments has been the flowback of proppant and solids at various stages after the treatment. To mitigate this problem, it is necessary to understand the factors causing the proppant to flow back, which can help in the design of successful treatments. This paper outlines the various analytical techniques used to identify the composition of solids recovered after performing a hydraulic fracturing job in the Middle East region. A laboratory test setup was designed to conduct tests by simulation of downhole conditions. Finally, a treatment was proposed to prevent flowback in future wells to be treated. Analysis of recovered solids using X-ray diffraction (XRD), particle-size distribution, and high-resolution stereomicroscopy revealed the presence of formation sand, fibers, resin-coated proppant (RCP), non-RCP, and crushed proppant. Proppant flowback was observed in laboratory tests conducted using the same source of RCPs that was used for the job. The RCP packs exhibited poor consolidation after curing for 24 hr at 320°F. However, application of liquid-resin coating (LRC) to these RCPs resulted in well-consolidated proppant packs with high unconfined compressive strength (UCS). This in turn prevented proppant and formation-sand flowback when tested under simulated bottomhole conditions. The results obtained further confirm the advantages of LRCs compared to conventional RCPs in hydraulic fracturing treatments.