Evaluation of Nonreactive Aqueous Spacer Fluids for Oil-based Mud Displacement in Open Hole Horizontal Wells

Abstract

Reactive mud cake breaker fluids in long open hole horizontal wells located across high permeability sandstone reservoirs has had limited success because they often induce massive fluid losses. The fluid losses are controlled with special pills, polymers and brine or water, causing well impairment that is difficult to remove when oil-based mud (OBM) drill-in fluids (DIFs) are used. This situation has resulted in the drive for an alternative cleanup fluid system that is focused on preventing excessive fluid leak off, maximizing the OBM displacement efficiency and allowing partial dispersion of the mud cake for ease of its removal during initial well production. The two-stage spacer application is composed of a nonreactive fluid system, which includes a viscous pill with nonionic surfactants, gel pill, completion brine and a solvent.Extensive laboratory evaluation was conducted at simulated reservoir conditions to evaluate the effectiveness of the OBM displacement fluid system. The study included dynamic high-pressure/high temperature (HP/HT) filter press tests and coreflood tests in addition to wettability alteration, interfacial tension and fluid compatibility tests.The spacer fluid parameters were optimized based on wellbore fluid hydraulic simulation and laboratory test results, which indicated minimal fluid leak off and a low risk of emulsion formation damage. Three well trials were conducted in a major offshore field sandstone reservoir drilled with OBM. All three trial wells (one single and two dual laterals), which were treated, have demonstrated improvement in production performance. This paper will discuss in detail the spacer fluids optimization process, laboratory work conducted and the successful field treatments performed.

Remoção De Fluido De Perfuração Base Óleo Por Colchões Lavadores Compostos Por Óleo Vegetal, Tensoativo E Salmoura

“…Nesses locais, fluidos de perfuração base óleo têm sido utilizados por apresentarem características como, lubricidade, fricção mecânica, inibição química, estabilidade do sistema, entre outras, superiores quando comparadas com os fluidos de perfuração base água, minimizando a ocorrência de inúmeros problemas durante a etapa de perfuração (Osode et al, 2012).…”