Proppant Flowback Control in the Burgos Basin

Abstract

Proppant flowback following a hydraulic fracture treatment, is a major problem in the Northern Mexico area. Frequently, Proppant flows back as the well returns to production. Generating huge amount of cost associated with wellbore cleanouts and damage to surface facilities. In addition, production is delayed due to long shut-in times and the need to initially produce the well under choke. Therefore, been able to control proppant flowback at fracture closure would not only eliminate the extra expenses associated with it, but would allow to return the well back to production immediately with optimized chokes. In other words, an optimized proppant free robusted production. This paper presents successful applications of stabilizing proppant packs with randomly oriented fibers of similar density to the proppant in dry gas reservoirs with low permeabilities (<0.5 md). All wells were put on production immediately following fracture treatment, with an average of almost 2 fold production increase over resin-coated proppant treatments, having a case with up to 12 folds of increase. During "clean-up" of the wells, return fluids were collected for evaluation confirming expected proppant control and fluid compatibility between fracturing gels and breakers. Finally, production performance months after the treatments are discussed including conclusions and recommendations derived from treatments. Introduction Proppant flowback has been of concern in hydraulic fracturing for more than 20 years. It has received increased attention in recent years as larger fracture widths and use of higher proppant concentrations have become more prominent. A crucial part of many successful hydraulic treatments is preventing the newly placed proppant from being dislodged by produced fluids flowing back into the wellbore. One common practice for controlling such flowback is to coat the proppant with resin, then allow the resin to cure, thereby holding the proppant in place, before the flow is initiated. Curable resin-coated proppants (RCP) 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 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 cycling loading conditions. In addition, RCPs need specific temperature, shut in time and stress conditions to form a strong bond. At lower temperatures (<150 F) chemical activators must be added to promote cure. An alternative to curable resin-coated proppant is using fibers. Fibers reinforce the proppant pack by forming a net-like structure to hold the proppant in place and allow fluids to flow. The advantage of this method is that it is a physical mechanism without complicating chemical curing reactions. No combination of temperature, pressure or shut in time is needed to stabilize the proppant pack, allowing more flexibility of flowback procedures to maximize well production and reduce costs. P. 201

Experimental Investigation of Proppant Flowback Phenomena Using a Large Scale Fracturing Simulator

“…In a typical flowback operation, well is shut-in for few hours after the fracturing treatment, and it is opened with small size surface chokes; the choke size is increased periodically till most of the fracturing fluid is recovered, and the well begins to produce reservoir fluids. 1,2 A controlled flowback of the reservoir is important to minimize damage to fracture conductivity due to the fracture fluid pumped in the stimulation treatment. 3 The controlled flowback is also necessary to maintain sufficient pressure in the fracture to prevent crushing of the proppants due to excessive closure stresses applied on the pack.…”