Understanding Proppant Flowback

Abstract

Proppant production from hydraulically fractured wells can cause severe operational problems, increase safety concerns, and dramatically reduce economic returns on well-stimulation investments. Methods that have helped eliminate or minimize proppant flowback include modified completion designs, the use of controlled fracture closure for obtaining early closure on the proppant pack, and the use of materials designed to reduce proppant production. Curable resin-coated proppants, chopped fiberglass, thermoplastic strips, and chemicals that modify the surface of the proppant are all accepted methods for minimizing flowback. This paper presents the results of both physical and numerical modeling of proppant flowback recorded during the development of a chemical designed for modifying the proppant surface. The goal of this study was to develop an understanding of the mechanisms that control proppant flowback. Laboratory experiments performed in slot models with no closure stress helped establish the interaction of proppant size, proppant distribution, and fluid velocity. Additional studies of the impact of closure stress, fracture width, and fluid rate on proppant flowback were performed with modified API linear conductivity cells. Data obtained from the physical modeling were used to calibrate a numerical model that predicts proppant flowback. In this model, fluid flow in the proppant pack is described by Darcy's equation for flow through porous media. The resulting velocity distribution allowed local stability to be assessed along the free surface between the proppant pack and the continuous fluid phase. Repeating these steps allowed evaluation of the interface that develops over time.

Mechanics of light weight proppants: A discrete approach

“…Formation of a stable pack is easier with softer rock platens which permits deeper particle embedment [15] iii) Presence of softer deformable particles in the pack increases flowback resistance, but will result in loss of porosity and subsequent loss of fluid flow rate [49][50][51].…”

“…needle like shape of aluminium compared to a more rounded walnut particle. Commercial products also include chopped fibers or thermoplastic sheets as the softer proppants [51].…”

“…The influence of addition of softer particles to a proppant pack on pack permeability has been studied extensively and a reduction in the flow rate has been observed [49][50][51][52].…”

“…A modification to the conductivity test wherein an arrangement is made to collect loose proppant and measure their flow rate is used to study proppant flowback. Several researches have focused on understanding the factors affecting proppant flowback and finding ways to reduce it [14,15,[49][50][51][52]. Apart from the DEM (discrete element method) simulations by Asgian [14] the rest focus on experimental approach.…”

A proppant mechanical model in postfrac flowback treatment

“…Nowadays, proppant researches are mostly focused on physics model, such as perforating device (Mark and Diederik, 1999), slot device (Naval and Subhash, 1999), API linear groove (Barree and Mukherjee, 1995) .To the researches of flowback mechanical models, it is hardly found literature to particularly describe it. There are only some few scholars who have done some researches about proppant deposition mechanical model (Wang and Zhang, 1998).…”