Abstract

The success of drilling operations is heavily dependent on the drilling fluid. Drilling fluids cool down and lubricate the drill bit, remove cuttings, prevent formation damage, suspend cuttings and also cake off the permeable formation, thus retarding the passage of fluid into the formation. Typical micro or macro sized loss circulation materials (LCM) show limited success, especially in formations dominated by micropores, due to their relatively large sizes.

In the current work, a new class of nanoparticle (NP) loss circulation materials has been developed. Two different approaches of NP formation and addition to oil-based drilling fluid have been tested. All NPs were prepared in-house either within the oil-based drilling fluid (in-situ), or within an aqueous phase (ex-situ), which was eventually blended with the drilling fluid. Under low pressure low temperature API standard test, more than 70% reduction in fluid loss was achieved in the presence of NPs compared to only 9% reduction in the presence of typical LCMs. The filter cake developed during the NP-based drilling fluid filtration was thin, which implies high potential for reducing the differential pressure sticking problem and formation damage while drilling. Moreover, at the level of NPs added, there was no material impact on drilling fluid viscosity and the fluid maintained its stability for more than 6 weeks.

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