Experimental Study on Injectivity Reduction during Fracturing Fluid Disposa

Explorations of significant tight shale gas reserves; triggered a rapid increase in the number of hydraulic fracturing operations. Although it offers sustainable energy for several decades, there are some serious concerns about effects of the hydraulic fracturing on the environment. One of the most important concern is related to wastewater management. Each fracturing operation results with hundreds of thousand gallons of wastewater, which is called flow-back water (FBW). FBW contains very high concentration of inorganic components, relatively lower concentrations of organic components and hydrocarbons from the formation. FBW although there are several methods to treat FBW, the most dominant way that is used in industry is to drill deep saltwater disposal wells and inject FBW in to these wells. Injection FBW into the wells is causing anxiety due to potential percolations to the drinking water aquifers.;Flow-back water typically contains dissolved solids, suspended solids and oil. This research is aimed to determine effects of each of these components while being injected at the sand stone core sample. seven core flood experiments were conducted to investigate the effects of total dissolved solids (TDS), total suspended solids (TSS) and oil concentrations at the permeability of the of the sandstone core. Four identical core samples were prepared. Before each experiment, cores were cleaned and saturated with water. Seven core flooding with seven different injection fluid was done with the constant flowrate of 0.2 ml/min. injection fluids were; FBW, filtered FBW (to ensure only dissolved solids are left before injection), a mixture of distilled water and suspended solids and mixture of oil and distilled water. Different concentrations of these fluids were also used to have enough data for comparison.;This research indicates that the decrease in the permeability of the sand stone core sample during core flooding is mostly because of the oil that FBW carries. Effects of dissolved solids and suspended solids are much lower compared with oil.;Additional experiments are needed to be able to understand the effect of the temperature. Since experiments were conducted at the room temperature. It is possible two have different results at the reservoir temperature.