الفهرس 
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Abstract
Cross-linked poly acrylic acid (PAA), poly acrylamide (PAM) and their copolymers were prepared in different ratios using N,N\-methylenebisacrylamide (BIS) as a across-linker. The ratio of cross-linker was reduced to produce hydrogels with the lowest possible cross-linker ratio that can help in a good dispersion of the polymer and providing good rheological properties. The structures of prepared polymers were studied using FTIR, SEM and elemental analysis. The swelling behavior was identified in water (distilled and tap) and saline solution (1%). In addition the effect of changing the ionic valency in the saline solution was identified by changing from Na+ to Ca2+ and finally to Fe3+. The effect of pH was also identified as well as the water retention of these gels at different temperatures. The rheology of the prepared samples was studied in comparison with their linear forms to suggest the best formulation to be applied in drilling fluids.
Some of prepared linear and cross-linked polymers have been prepared for application in drilling fluids based on rheological studies. The selected polymers were the linear and the cross-linked forms of poly acrylic acid (LPAA and CPAA) as they showed the highest viscosity when the rheological properties were studied. Mud composite (350 ml) were prepared with different concentrations of LPAA, CPAA, xanthan gum (XC-Polymer) to study the effect of changing their concentration on the rheological properties. In addition the effect of adding bentonite to thee mixtures was studied. Moreover, combinations of LPAA or CPAA with XC-Polymer and with bentonite were conducted to study their effect of each other. The chosen polymers (LPAA and CPAA) were evaluated in tap water and saline solution (4.2%) and comparison between them and the natural polymer (XC-Polymer) was identified as well as the effect of the new polymers on bentonite. The effect of increasing the bentonite concentration on the rheological and filtrate loss control properties of LPAA and CPAA was studied. The effect of calcium carbonate addition on the mixture was studied. This was performed in presence and absence of bentonite and using 2g of polymer (LPAA or CPAA). The effect of temperature on the rheological properties was identified by studying the rheological properties for the best samples at three different temperatures (ambient temperature, 120 F and 150 F). The filtrate loss was studied for the prepared mud and the effect of adding calcium carbonates, bentonite and NaCl salt were identified.