The primary cementing operation is a crucial activity carried out during drilling any type of well.Three main purposes of a primary cementing job are assuring zonal isolation,providing mechanical support for casing strings,and protecting the steel construction against corrosion.When one of these points is not achieved,wellbore integrity is compromised.High-temperature geothermal wells proved to have an issue regarding provision of mechanical support.Additionally,zonal isolation may be easily compromised due to the extensive water circulation,common in hydro-thermal systems.Such phenomena have been changing recently as much deeper and hotter wells,frequently with multiple and separated aquifers with different fluid chemistry and temperatures,are being drilled in countries such as Iceland,Italy or Mexico[1].In these”super-hot”fields,reservoir temperatures often approach,or even exceed,the critical point of clean or seawater and corrosion-inducive reservoir fluids are being produced.The demand for effective zonal isolation in these systems is acute.This article presents an analytical method of predicting cement sheath integrity with the incorporation of wire-line acoustic measurements using an example of a deep,high-temperature geothermal well,located in the central part of the Los Humeros Geothermal Field(LHGF)in Mexico[2].
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