Improving stimulation results in shaly sandstone reservoir after investigating reservoir characteristics: a review

World oil reserves increased rapidly during the decade of 80s due to improved recovery techniques. Stimulation and hydraulic fracturing played a key role in those techniques used to enhance recovery. Stimulation is a sensitive technique to improve production and ultimate recovery, but stimulation of clastic reservoirs is a tedious job due to complex mineralogy of matrix rocks and cement, compared to carbonate rocks. A multidisciplinary approach is essential to stimulate clastic rocks for getting required results. Petrography is one of the vital tools to interpret minerals, but this is not sufficient to identify minerals composing rocks. Experimental study was conducted to observe the reaction of mineral presets in rocks and stimulation fluids under microscopes. The objective of the study was to highlight the sensitivity of different minerals present in rocks. Petrography and X-ray Diffraction information about composition of sandstone rocks (mineralogy) was obtained in laboratory and this paper mentions the sensitivity of these grains with stimulation fluids of different rates. Mostly sandstones are dominantly composed of Quartz (SiO2), subordinating feldspars ((KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8) and lithic fragments (sand size fragments of pre-existing rocks). Quartz grains are highly resistive to 15% hydrochloric acid as compared to calcite, carbonaceous, carbonate, minerals. HCl reacts with carbonate and carbonaceous quickly to enhance near borehole permeability. Besides this, when iron minerals (mostly in red color sandstone and act as cement) react with stimulation fluids caused precipitation and permanent damage to the reservoir. Therefore, petrographic information is vital in designing stimulation jobs to minimize formation damage by identification of sensitive minerals to stimulation fluids.