Characterization and Modeling of Polymer -Treated and Nano Particle Modified Sulfate Contaminated Soils, Drilling Muds, and Hydraulic Fracturing Fluids under Groundwater
Mohammed, Ahmed Salih
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In this study, the effects of acrylamide polymer on the physical and mechanical behavior of the calcium sulfate-contaminated soils were investigated. The variation of the compacted compressive and tensile strength with calcium sulfate concentrations for the treated soils were quantified. Compressive stress-strain relationships of the sulfate soil, with and without lime and polymer treatment, have been quantified using two nonlinear constitutive models. Polymer-treated sulfate soils had higher compressive and tensile strengths and enhanced compressive stress-strain relationships compared to the lime-treated soils. Also, the effects of calcium sulfate and contaminated soil treated with lime and fly ash on the index properties, compacted soil properties, free swelling, and compressive stress-strain relationship of a CL soil obtained from the field were investigated and quantified. Acrylamide polymer was used to modify the water-based bentonite mud to reduce the fluid loss and yield point and maximum shear stress produced by the mud during the drilling operation. Also, the hyperbolic model has a maximum shear stress limit whereas the other two models did not . The effect of nano silica proppant on the rheological properties, fluid loss, and electrical resistivity of the fracturing fluids and transport characteristics in the pre-cracked sandstone was investigated at various temperatures up to 85oC and up to a pressure of 700 psi, , respectively. Two different mixes of the fracturing fluids were developed and used in this study to investigate the effects of nano silica proppant. The apparent permeability of the rock increased when the fracturing fluid was modified with nano silica at a temperature of 85oC and pressure of 700 psi. The fluid loss and shear-thinning behavior of fracturing fluid with and without nano silica has been quantified using a new hyperbolic model. The effect of temperature on the electrical resistivity and rheological properties of a water-based bentonite drilling mud modified with nanoclay and nanoFe was investigated. The electrical resistivity was considered a sensing property of the smart drilling mud so that the change in the properties can be monitored in real-time. The temperature was varied from 25oC to 85oC. The results also showed that 0.6% nanoclay decreased the electrical resistivity of the drilling mud from 15% to 36%, based on the bentonite content in the drilling mud. The electrical resistivity of drilling mud with and without nanoclay decreased with the increase of temperature. Short-term and long-term fluid loss tests of the drilling mud with different percentages of bentonite, up to 8%, were performed using API filter paper and porous media at a pressure of 100 psi. A new kinetic hyperbolic model was developed to predicate the fluid loss and permeability of the drilling mud through the API filter paper and the soil (porous media). The new kinetic model prediction was compared to the API model and predicted both short-term and long-term fluid loss very well. Hence, the new kinetic model can be used to better model the filter loss in real-time as a function of changes in permeability. In this study, the rheological properties and electrical resistivity of the oil well cement Class H was investigated. The sensing properties of smart cement modified with 0.1% carbon fiber (CF) and water to cement (w/c) of 0.38, 0.44, and 0.54 were monitored immediately after mixing up to 7 days of curing. Experiments showed that initial electrical resistivity (o) of oil well cement were sensitive to varying water to cement ratios. A unique constitutive model was used to predict the electrical resistivity of cement during 7 days of curing.