No abstract

One of the major problems associated with the use of water‐based drilling fluids is the interaction of water with specific rock formations, such as shales, and the consequent swelling of reactive clays that may be present in that type of rock. Several types of clays reactivity inhibitors have been used by the oil industry, and the most effective ones are the cationic polyelectrolytes, such as the poly(diallyldimethylammonium chloride) (PDADMAC). However, this polyelectrolyte is very toxic. In this work, a series of cationic starch derivatives with different cationic degrees were synthesized with the objective of evaluating their potential as environmentally correct shale reactivity inhibitors. The results showed that the synthesized derivatives presented a good capacity of adsorption on bentonite and an efficient inhibition of the shale reactivity. The derivative with an intermediate cationic degree presented the best performance. In the tests with the formulated fluids this derivative provided an intact cuttings recovery of 84.8% and a total recovery of 92.3%. These values are very close to those found for the PDADMAC additive, therefore indicating that this cationic starch derivative presents a good potential as inhibitor of the shale reactivity. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46621.

To further investigate the influence of the d‐spacing of montmorillonite types derived from Cloisite Na on the process of the intumescent layer formation, composites of poly(ethylene‐co‐butylacrylate), EBA‐30, with an intumescent formulation consisting of ammonium polyphosphate and pentaerythritol were processed and heated at different temperatures. The residues were analyzed by 13C, 31P, and 27Al solid‐state nuclear magnetic resonance (NMR). 13C NMR peaks in the aromatic range of 100–150 ppm for samples heated at 350 °C suggest that the montmorillonites with smaller d‐spacing (13.5 and 21.8 Å) accounted for the greater amounts of condensed aromatic structures, leading to the char. For d‐spacing of 35 Å, the condensation of the polyaromatic structures occurs more slowly, retarding the char formation. The 27Al NMR peak around −15 ppm for samples heated at 280 °C indicates the destruction of montmorillonite structure, producing aluminophosphate species, meaning that the d‐spacing influences the reactions under this temperature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48053.