Degradable Fiber Pill for Lost Circulation in Fractured Reservoir Sections

Abstract

Lost circulation is one of the main causes of nonproductive time during drilling and impacts the success of cementing operations. Losses into the reservoir not only impact drilling, they potentially impact the reservoir, due to influx of quantities of drilling fluids that are potentially damaging, or will influence the production rate. Existing solutions are based mainly on particulates, which often are added to drilling fluids to plug fractures or to build up filtercake to cure fluid losses. When particulates are applied for curing losses in reservoir sections, it is desirable that the plugging materials maintain stability for sufficient time to allow well completion but eventually self-degrade to leave undamaged formation for future hydrocarbon production. The main challenges are the design of the lost-circulation material to cure losses into fractures of various widths and to provide plug stability and cleanup within a desired time frame over a broad bottomhole temperature range.Fibers have shown good fracture-plugging behavior. Parameters affecting fiber performance include, but are not limited to, fluid viscosity, fiber concentration, fiber geometry, flow rate, effect of the wall, and fracture width. To effectively apply fibers as lost-circulation applications, a novel, fiber-laden fluid was designed for easy preparation on surface, allowing compatibility with bottomhole assemblies (BHAs). The decrease in velocity inside the fracture enables fibers to bridge and then plug the fracture, thus regaining circulation. The fibers are specially designed to degrade in an adjustable time frame sufficient to ensure plug stability until the well is completed. With time, the plug undergoes further degradation, leading to nondamaged formation for production.This novel degradable solution has been successfully proven during field trials in various drilling scenarios ranging from severe to total losses with effective and efficient loss mitigation, without issues on placement through BHA and bit nozzles, and mitigating further reservoir damage.

A Novel Solution for Severe Loss Prevention While Drilling Deep Wells

“…Priening et al [25] reported that the advanced engineering fibers composed of inert material are easy to disperse in the drilling fluid and can make a 3D network across the loss zone, thereby allowing the solids in the drilling fluid to form bridging plug and cure the losses. According to Droger et al [26], the performance of fiber LCM is affected by fiber concentration, fluid viscosity, fiber geometry, fracture width, and flow rate. They concluded that degradable fiber systems are effective for preventing losses in fractures as wide as 5 mm.…”

Alternative Lost Circulation Material for Depleted Reservoirs

“…Natural Fibers Natural fibers (Droger et al 2014;Mukherjee andKao 2011, Driscoll et al 2013;Fuqua et al 2012;Gupta and Kumar 2012;Hughes 2012;Fidelis et al 2014) have been widely used in the oil and gas industry for applications in lost-circulation curing. Fiber technology can enhance the mechanical properties of the bridge.…”

“…The addition of these components to fluid formulations can increase the viscoelastic properties, enhancing the ability to sustain pressures and temperatures (Lécolier et al 2005). Acid treatments can react with the carbonate reservoir creating large wormholes and reducing the efficiency of the treatment (Droger et al 2014). However, they cannot always be removed, causing severe permeability damage (Samuel et al 2003).…”

“…(Verret et al 2000;Boukadi et al 2004;Griffin and Cowan 1997;Droger et al 2014;Mukherjee and Kao 2011;Driscoll et al 2013;Fuqua et al 2012;Gupta and Kumar 2012;Hughes 2012;Fidelis et al 2014). • Biodegradable fibers can be subject to bacterial degradation.…”

“…(Droger et al 2014;Mukherjee and Kao 2011;Driscoll et al 2013;Fuqua et al 2012;Gupta and Kumar 2012;Hughes 2012;Fidelis et al 2014). (Droger et al 2014;Mukherjee and Kao 2011;Driscoll et al 2013;Fuqua et al 2012;Gupta and Kumar 2012;Hughes 2012;Fidelis et al 2014).…”