Degradable Fiber Pill for Lost Circulation in Fractured Reservoir Sections | Schlumberger
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Degradable Fiber Pill for Lost Circulation in Fractured Reservoir Sections


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 mainly based on particulates, which are often added to drilling fluids to plug fractures or build up filtercake to cure losses. When 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 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 on surface, allowing compatibility with bottomhole assemblies (BHAs). The decrease 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.

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