Saudi Aramco, while developing the carbonate Khuff formation sought to continue increasing gas reserves for the Kingdom of Saudi Arabia. A recent optimization initiative was developed to tailor acid-fracturing fluid blends, including a nonionic microemulsion surfactant (ME), to reduce surface tension and modify the contact angle. This initiative resulted in reduced water saturation, higher load recovery, and improved relative permeability to gas, producing the wells back in record time. In recent years, the use of ME in hydraulic fracturing operations has been documented (especially in tight-gas formations) as a key variable to further improve production and increase reserves. These studies, based on both lab research and field data, have shown that ME enhances core permeability to gas and fluid recovery. Particularly for this operator, the use of ME reduced well cleanup time on average by 50%, while also reducing the environmental impact, indirect costs, and increasing cost savings in general.

This paper presents the learning curve with respect to the use of ME, including laboratory fluid screening, surfactant selection, and optimization of acid blends, including corrosion, volume optimization, and lessons learned about field implementation. Additionally, case histories are presented. Evaluation of well flowback and productivity analysis is also included for different permeability scenarios, demonstrating how the use of ME helps speed the cleanup of injected fluids. This evaluation has been useful for selecting the optimum surfactant concentration as a function of reservoir permeability and pressure. Benefits with respect to time optimization and safety are also included based on analysis of actual job data. Because of the benefits obtained, the use of ME is being extended to other field operations, such as well killing, coiled tubing (CT) well interventions, and fluid blends improvement (e.g., inhibited water), which is extensively used in in Saudi Arabia matrix acidizing jobs and proppant fracturing.

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