Sandstone acidizing is very challenging because of the complex reactions that occur between the multiple-stage treatment fluids and the formation minerals. Such reactions are more likely to occur at elevated temperatures and can result in potentially damaging precipitation reactions. In conventional acid treatments, fluid is usually pumped in multiple stages of pre-flush, main fluid and over flush. The drawback of conventional sandstone acidizing treatments is that the success rate is generally low due to the uncertainty associated with the fluid-formation interactions.

This paper presents the results of a laboratory investigation of a single-stage sandstone acidizing fluid designed to address some of the problems associated with conventional sandstone acidizing fluids. The application of the fluid system is sandstone reservoirs with bottom hole static temperatures greater than 200°F.

Core flow tests demonstrated that the single acid system minimized the potential for precipitation due to secondary and tertiary reactions. This system did not cause sand deconsolidation, and maintained the integrity of sandstone cores. Corrosion tests conducted for low-carbon steel and 13 Cr coupons demonstrated that the fluid had lower corrosion rates.

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