The morphology and mechanical properties of epoxy nanocomposites based on synthetic R-zirconium phosphate (R-ZrP) layer structure have been investigated. The interlayer surfaces of R-ZrP can be easily modified because of its high surface ion exchange capacity characteristics. The R-ZrP structure is layered claylike and possesses aspect ratios of at least 100. The state of exfoliation has been confirmed using direct transmission electron microscopy observation at various locations of the sample. With an addition of only 1.9 vol % R-ZrP, the tensile modulus of the R-ZrP-reinforced epoxy nanocomposite is increased by 50%, and the yield strength improved by 10%. However, the ductility of the matrix (elongation at break) is drastically reduced after the R-ZrP reinforcement. The fundamental structureproperty relationship of R-ZrP-based epoxy nanocomposite is discussed.

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Recovery of frac-pack fluids is often poor in offshore operations. Large amounts of stimulation fluids left in the fracture may leak-off into the porous formation or block part of the proppant pack thus impairing hydrocarbon production. A typical frac-pack treatment fluid contains water-wetting surfactants to maximize flow-back fluids. However, the amounts recovered are still low and new methods are needed to improve well cleanup. Using a proppant that is neither oil nor water wet has the potential to solve some of these issues. Proppant surfaces were permanently modified to a neutral wettability state. Molecules having both hydrophobic and oleophobic properties were covalently bonded to the oxide surfaces, leading to robust engineered interfaces with low surface energy thus potentially improving flow. To support this concept of neutral wettability proppant, laboratory studies were conducted to determine performance under flow and cleanup ability compared to native proppant surfaces. This neutral wettability proppant was also used in several completions in the Gulf of Mexico. Two case histories using the neutral wettability proppant are presented and compared with offset wells as well as performance laboratory data. Flowback data as well as production data are reported. Laboratory results showed that the neutral wettability enhanced surfaces not only reduce water saturation but also improve oil movement. This demonstrates the ability of these materials to improve clean up and hydrocarbon flow within the proppant pack. When this proppant was applied in frac-pack completions it was observed that flow-back recovery was dramatically increased compared to offset wells that used similar proppant. Cleanup time was reduced allowing first oil to appear more rapidly. Furthermore, production data show that oil flow that the productivity index is higher when the surface of the proppant is neutral. These results demonstrate this material as next generation proppant for improving flow and cleanup in frac-pack completions.

In oil and gas wells that are hydraulically fractured, wetting properties of surfaces (formation and proppant) significantly affect hydrocarbon and liquid displacement. During the life of a well, the water saturation of surfaces changes, leading to reduction of relative permeability to oil or gas and consequently affecting production. In order to reverse the formation to a reduced water wet state and improve the movement of hydrocarbons, strong water-wet surfactant is pumped. The surfactant is then adsorbed onto the surfaces reducing the capillary pressure and water saturation within the porous systems. This is, however, not a permanent solution, as the surfactant is washed out over time. A more permanent and robust solution is needed. Nature encompasses many examples of biological systems and surfaces that are permanent and have special wettability and interfacial interaction with fluids. Research and development within the last decade in bio-mimicking nature has been fruitful and led to the development of many new surfaces such as superhydrophobic, ice phobic and low-drag surfaces. In this work we apply some of the knowledge and principles found in nature to modify proppant surfaces (silica sand and ceramic proppant) in order to study how wettability will affect the fluids recovery and their interaction with the solid surfaces. Nanotechnology was used to deposit hydrophobic/oleophobic moieties onto the proppant surfaces, and several surface modifiers were tested. These molecules were covalently bonded to the surfaces. The new surfaces were characterized for wettability and flow to water and oil. A new proppant that show promises for improved stimulation fluids recovery and flow was identified and further developed.

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