The Rose Run Sandstone consists of individual quartz and feldspar grains cemented by dolomite, clay minerals, and overgrowths of quartz and feldspars. Historically, the Rose Run has been stimulated with hydrochloric(HCl) acid with appropriate additives to remove the dolomitic cement matrix to improve permeability. Post stimulation results vary widely.

The production from some wells suffered from steep declines. When shut-in, most wells exhibited good pressure recovery. Reservoir analysis calculated skin factors as high as +10 indicating formation damage.

An in-depth study of wells in Randolph Township of Portage County, Ohio (Fig. 1) was initiated to try to identify the mechanisms that effect well productivity. Drill cutting samples, well logs, rotary sidewall cores, petrologic data, core analysis, and SEM photos were analyzed. The primary goal of this study was to determine possible improvements to current stimulation treatments. An additional benefit of this study was to evaluate the viability of remedial acid treatments in removing damage from producing wells.

Drill cutting samples, mud logs, natural production shows, and well logs are used on site to determine if the well would be completed.

Rotary sidewall cores were obtained from several wells for in-depth analysis. Routine laboratory core analysis measured permeability, porosity, and core fluid saturations. Thin sections were prepared and SEM photos were taken for petrographic analysis. Rotary sidewall cores from one well were analyzed and deemed representative of the Rose Run Sandstone. Rotary sidewall cores were tested to determine initial permeability to Rose Run formation brine and regained permeability to various acid solutions. The results of all analyses were considered in revising initial well stimulations as well as designing remedial acid treatments to address the problems that have been identified.

Production rates, decline curves, and pressure build-up data of conventionally treated wells were compared to wells treated with a new acid solution to determine if any positive benefits could be realized. The evaluation of remedial acid treatments using the new acid solution was based on the treatments ability to reduce the rate of production decline.

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