Proppant Flowback Solutions for Low-Temperature Applications Proves Success in Large Stimulation Project of Bahrain Field

Abstract

Abstract The success of a fracturing treatment and long-term productivity is dependent on the residual proppant pack conductivity over time. One of the challenges operators face is conductivity loss due to proppant flowback. As proppant particles come out of the fracture, the near-wellbore fracture conductivity diminishes with time as the propped fracture width decreases. This choking effect causes the production of the well to decline while the high-velocity and low-concentration proppant particles wreak havoc on both downhole and surface equipment. As a result, proppant flowback costs millions of dollars through loss of production and expensive equipment damage. Wells experiencing these problems require remediation ranging from routine wellbore cleanouts to expensive artificial lift equipment repairs. Magwa formation is a common carbonate reservoir in the Bahrain field. It is characterized as highly faulted and naturally fractured with permeability of 2 md to 3 md. The complexity of these reservoirs has prevented an efficient recovery with average production of wells limited to 15 BOPD with bottom hole static temperature (BHST) of 125°F and less than 2000 ft depth. This has prompted a detailed integrated study that was performed to better understand the reservoir and to evaluate different stimulation techniques. Propped hydraulic fracturing was selected as the preferred technique to further develop the low permeability Magwa reservoir. Massive fracturing treatments were proven to be the optimum choice to provide long fractures for the tight Magwa reservoir. However, post fracturing proppant flowback has been a major concern due to the relatively low formation stress and high fluid drag velocity that could lead to poor fracture conductivity in the near-wellbore area. Solids flow back can also have a detrimental effect on production equipment, leading to plugging, abrasion, or erosion of surface and downhole completions. Rod-shaped proppant (RSP), which was developed for enhanced fracture conductivity along with improved proppant pack stability, as well as proppant flowback control in environments and reservoirs under conditions where traditional methods and products are not applicable or effective. Another innovative solution that can be used for flowback control is a new nondegradable fiber proppant flowback technology designed specifically for low-temperature applications that provides extraordinary proppant-pack integrity by interlocking proppant grains in a flexible 3D network. They do not require temperature activation and thus perform equally well at any temperature below 200°F, both in oil and gas reservoirs. The fibers can be applied with any proppant (sand or ceramic), and they keep the proppant consolidated even at stress cycling conditions. Unlike resin-coated proppant (RCP) or other chemical treatment methods, both RSP and nondegradable fibers rely on mechanical interference of the particles as opposed to chemical bonding. Some key advantages of these techniques are that consolidation is not dependent on activation temperature or time, and that they do not interfere with fracturing fluids or additives, such as breakers, that are known to be adversely affected by the presence of RCP. For the first 10 wells with large-size fracturing operations, this technique enabled continuous proppant-free production with artificial lift and yielded an increase in oil cumulative production by an average of at least 24%. This paper presents the results of the application of proppant flowback solutions in the Bahrain field including comprehensive laboratory testing and production analyses. The study can be very beneficial to many shallow, low-temperature formations that require proppant flowback control.