Fiber/Proppant Mixtures Control Proppant Flowback in South Texas

Abstract

Backproduction of proppant from hydraulic fractures (proppant flowback) is a continuing operational problem in the oil and gas industry. Up to 20% of the proppant can be flowed back after the treatment. Curable resin-coated proppants are used to control proppant production, but are known to chemically interact with fracturing fluids and may be prone to several failure mechanisms. Curable resin-coated proppants also require either well shut-in or the use of activators at low temperatures. A new method to control proppant flowback relies on fibers mixed with the proppant to stabilize the proppant pack. The main advantage of this patented3 technology is that it is physical rather than chemical. Therefore, proppant flowback is controlled without specific shut-in time, temperature, or pressure constraints. This paper presents flowback results from fractures of dry gas wells (<1 millidarcy permeability) where fiber/proppant mixtures were used to control proppant flowback (11 cases). Fluid flowback rate, gas rate and proppant production were monitored during the cleanup period. These wells are compared to wells where either curable resin-coated proppants or no flowback control were used (15 cases). The fiber/proppant mixtures controlled flowback of proppant for both sand and ceramic proppants when used with all the proppant or in only the last part of proppant (tail-in). Flowback could begin right after the fracturing equipment was rigged down (15 to 30 minutes). Cleanup fluid flow rates were up to ten times higher than previously obtainable with curable resin-coated proppants and less proppant was flowed back. Faster flowback rates also resulted in earlier onset of gas production and reduced flowback time. Fibers allow greater latitude in flowback rate than curable resin- coated proppants without the need for shut-in time. Introduction Propped hydraulic fracturing is successfully used in many formations to enhance production. One associated problem is the backproduction of proppant during cleanup and throughout the life of the well (proppant flowback). Up to 20% of the proppant placed in the fracture can return during the cleanup period. The proppant that flows back has a detrimental wear effect on the production equipment. and requires the use of separators in the production line. Concern about proppant flowback can limit the flow rates during cleanup and production. Curable resin-coated proppants (RCP) are the predominant technology to control proppant flowback. They are used as all or the last part (tail-in) of the proppant in the fracture. The resin coating cures to form a strong proppant pack under conditions of sufficient closure stress, shut-in time, and temperature. Curable RCPs control proppant flowback in many cases but can have several disadvantages. They are known to interact with the fluid chemistry (pH, crosslinkers, breakers, etc.), can reduce fracture conductivity, and may be prone to failure under cyclic loading conditions. Further, RCPs need specific temperature, shut-in time and stress conditions to form a strong bond. Shut-in time can be as long as overnight, and at low temperatures (<150 F) additional chemical activators must be added to promote cure. P. 453

Obstacle-induced lateral dispersion and nontrivial trapping of flexible fibers settling in a viscous fluid

“…Small fibers, e.g., microplastics fibers, may propagate in soil and cause pollution of groundwater [1,2]. When flowed through small cracks in natural rocks, such flexible fibers may buckle, leading eventually to clogging and thus closing of small paths [3], which is, for example, used to prevent proppant flowback in petroleum engineering [4]. Similar clogging may happen in the vascular system, where biofilm streamers may form in irregular channels, detach, be transported, and ultimately remain attached and clog small vessels or structures such as stents [5,6].…”

Experimental Study of Self-aggregating Proppants: New Approaches to Proppant Flowback Control

“…Jiang et al pointed out that the forced closure technique in fracturing operation ahead of the natural fracture closure is another technique to encapsulate the maximum proppants within the fracture [7]. In addition, adding fibrous materials into the fracturing fluid to enhance the integrity of proppant pack is another effective method to control proppant flowback [8,9]. The fibers, which bond proppants together, are thought to provide framework for the particles.…”

Deformation of a flexible fiber in a viscous flow past an obstacle

“…A first example is the paper industry in which the orientation and spatial distributions of the fibers in the flowing pulp must be controlled 1,2 . Fibers are also widely used by petroleum engineers 3 to enhance the proppant transport capabilities of fracturing fluids, or to prevent the backflow of proppant. Other domains of application are civil engineering (special cements, structural reinforcement), textile engineering, bio engineering and medicine.…”