Schlumberger

SXE Emulsified Acid

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Improve your reservoir acidizing and acid fracturing treatments

SXE emulsified acid improves your reservoir acidizing and acid fracturing treatments in high-temperature reservoirs. SXE acid is a viscous, highly retarded HCl system designed to overcome acid penetration problems in stimulating reservoirs above 250 degF [121 degC].

Standard hydrochloric acid reacts very quickly in carbonate formations. The reaction is so rapid in high temperatures that it is impossible for acid to penetrate, or wormhole, more than a few inches into the formation. In such cases, the acid is rendered ineffective in stimulating the well. Deep, live-acid penetration can be achieved if the acid reaction rate is retarded—a feat accomplished with SXE acid. This oil-external emulsion is formed with a 70:30 HCl-to-oil ratio, stabilized with an emulsifier. HCl concentrations ranging from 7.5 to 28% may be used in either a batch or continuous mix system.

Reaction retardation

SXE acid is significantly retarded with respect to HCl. The retardation depends on temperature, acid concentration, flow regime (laminar, transitional or turbulent) and type of rock (dolomite or limestone). Between 250 degF and 350 degF [121 degC and 177 degC] the HCl-limestone and the HCl-dolomite reactions are mass-transfer controlled.

Emulsion stability

The stability of SXE emulsified acid is temperature dependent. Quality of oil phase and mixing time also affect the emulsion stability.

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