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This work involves the synthesis of a nanocomposite hydrogel from just polymer and clay without the use of conventional organic crosslinkers. Conventional hydrogel design usually involves a multicomponent reaction that incorporates monomer (or polymer), initiator, and an organic crosslinker. However, because of the many limitations, setbacks, and inconsistencies involved with organic crosslinkers, authors herein present a nanocomposite hydrogel that incorporates polymer and clay only. It was found that these hydrogels show surprising mechanical toughness, tensile moduli, and tensile strengths. Study of gel behavior reveal physical interaction between polymer and clay, due in part to adsorption of polymer chains onto clay surface and ionic interactions between anionic carboxylate groups of polymer chains and positive clay surface. X-ray diffraction patterns and Scanning Electron Microscopy revealed the formation of intercalated and exfoliated clay morphology. Increase in clay concentration and gel strength had a direct proportionality. The effect of clay concentration on hydrogel decomposition temperature was also reported by thermogravimetric analysis.

Nanoparticles (NPs) are currently being studied as a drilling fluid additives especially for application in very lowpermeability formations such as shales. Application for conventional permeable rocks is still a subject of discussion. In this work, successful application of in-house prepared iron-based nanoparticles (NP1) and calcium-based nanoparticles (NP2) to reduce filtration loss in conventional permeable media has been experimentally quantified for oil-based mud (OBM) utilizing the high-pressure high-temperature (HPHT) filter press at 500 psi and 250°F. Ceramic discs were used as the filtration medium in this application to test the performance of the NPs and glide graphite as a conventional lost circulation material (LCM) for porous media. These experiments were carried out in the presence of graphite at low and high concentrations. Filtration reduction trends were observed and a reduction up to 76% was achieved. API filter press was also used to investigate the behavior of NPs and graphite under low pressure and temperature conditions (LPLT). NP1 and NP2 at the two graphite concentrations showed a reduction up to 100%. NP1 gave higher reduction especially at low concentrations under HPHT conditions, while NP2 yielded significant reduction at high concentration under HPHT. These trends were reversed under LPLT, giving a new insight on NPs performance under different pressure and temperature conditions. At HPHT and LPLT, the effect of graphite as a filtrate reduction agent is less significant as the NPs concentration increases. High graphite level had a positive effect on filtration reduction in combination with NP1 at HPHT and LPLT. This was not the case for the blends containing NP2 at HPHT. The effect of NPs and graphite was tested individually showing a different performance compared to the combination of them. Impact of NPs and graphite on rheology was also quantified allowing identification of the more sensitive parameters in the blends. It is concluded from this study that blends containing NPs and graphite can be successfully implemented in OBM to minimize formation damage in porous media.

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