Investigating the Role of Alkyl Chain Length of the Inhibitors on Its Intercalation Inhibiting Mechanism in Sodium Montmorillonite

Abstract

Shale hydration and swelling are the major problems in using water-based drilling fluids in developing shale gas. In this work, the intercalation inhibiting mechanism of alkyl chain length on the swelling of sodium montmorillonite (Na-MMT) has been innovatively investigated using isothermal adsorption, adsorption kinetics, scanning electron microscopy, X-ray diffraction, cation exchange capacity, elemental analysis, and X-ray photoelectron spectroscopy techniques. The results indicate that an increase in the alkyl chain length of the inhibitor reduces the saturated adsorption capacity of the inhibitor on Na-MMT accordingly, thus reducing the dosage of the inhibitor. The adsorption rate constant increased rapidly when the length of the alkyl chain was increased, which also reduced the degree of hydration of the clay minerals and improved the inhibitory potential. When a flat-lying monolayer of alkyl chain containing four to seven carbon atoms was inserted, the d-spacing of Na-MMT was minimized compared to the hydrated Na-MMT, which in turn replaced the sodium ions in the interlayer space of Na-MMT. The inhibitor was strongly attached in the Na-MMT interlayer between the silicon–oxygen tetrahedron and the primary amine groups. Finally, the water molecules were expelled from the interlayer of Na-MMT. Therefore, the alkyl chain length inhibitors should be considered to design a better class of inhibitors when using the water-based drilling fluid system.

Intercalation Inhibits the Surface Hydration of Sodium Montmorillonite: Experiments and Density Functional Theory Simulation

“…Since the backbone of HMDA and BPEI is hydrophobic, the backbone of HMDA and BPEI can squeeze the water molecules out, thus synergistically enhancing the inhibitory performance. The experimental results also confirm that a suitable hydrophobic chain length can enhance the inhibitory performance . The two adsorption groups of inhibitors, lying flat, adsorbed on the Mt (001) surface.…”

“…The experimental results also confirm that a suitable hydrophobic chain length can enhance the inhibitory performance. 22 The two adsorption groups of inhibitors, lying flat, adsorbed on the Mt (001) surface. These results are consistent with the arrangement of inhibitor in the interlamellar space of Mt, as determined from the results obtained using XRD analysis.…”

“…These do not take into account the molecular sizes of HMDA and BPEI, which should be investigated further. It is worth mentioning that the molecular sizes of the primary amine groups and protonated primary amines are 0.34 and 0.37 nm, − respectively, while the diameter of the water molecule is 0.25 nm. The difference in the d 001 values of the Mt-HMDA complex (1.32 nm) and dry Mt (1.01 nm) was 0.32 nm, whereas the difference in d 001 values of the Mt-BPEI complex (1.39 nm) and dry Mt (1.01 nm) was 0.38 nm.…”

Enhanced Desalination Capacity and Stability of Alkylamine-Modified Na0.71CoO2 for Capacitive Deionization

“…Because of the increase of population of interlayer metal sites and the electron conductivity and mobility of Na + ions, the charge/mass transport have been significantly improved. It is demonstrated that the organic molecules can be successfully inserted into the interlayer of 2D-layered materials to engineer the ionic channels, giving rise to a favorable electrochemical performance. − In light of these research works, we propose to introduce n -alkylamine into layers via an acid–base mechanism to manipulate interlayer distances, which promote the ion and electron transfer in electrode materials and helps to maintain the layered structure . The experimental results reveal that the n -propylamine (PA)-intercalated NCO (pNCO) had enhanced ability to adsorb Na + ions, prevent structural deformation, and hinder the degradation of performance.…”

Ultra-Stable Silica Nanoparticles as Nano-Plugging Additive for Shale Exploitation in Harsh Environments

“…It is known that shale formations are prone to be hydrated during shale gas drilling processes, leading to downhole complexities such as borehole collapse, tight hole, stuck pipe, etc. [1,2]. Thus, the stability of wellbore is of great importance for shale gas exploitation [3].…”