Hydrophobically modified poly(ethylene glycol) as reactive clays inhibitor additive in water‐based drilling fluids

Abstract

Adsorption measurements and inhibition tests were used to investigate the mechanisms of shale stabilization by hydrophobically modified poly(ethylene glycol) (PEG). Commercially available PEG with a large range of molar masses and PEG diesters were adsorbed on smectiterich clay from saline solutions and the clay/polymer complexes obtained were characterized by thermogravimetric analysis and x-ray diffraction. The adsorption isotherms obtained for all unmodified PEG showed low affinity for the clay surface, however they all accessed the interlamellar spaces of the clay and reduced the clay water content of the complexes obtained. The PEG macromolecules had their affinity for the clay strongly enhanced by the hydrophobic modification especially with dodecanoic acid and were intercalated into the clay matrix, reducing, in a more efficient way, the water uptake by the clay. Conventional rolling tests were performed to evaluate the effect of polymers on the clay cuttings integrity. Results show that under conditions promoting the adsorption of polymers on both external and interlayer clay surfaces, displacement of the water from the clay was obtained and dispersion and disintegration of clay cuttings were inhibited.

Synthesis and clay stabilization of a water‐soluble copolymer based on acrylamide, modular β‐cyclodextrin, and AMPS

“…It is important to maintain wellbore stability during drilling, especially in water-sensitive shale and clay formations. [11][12][13][14] The studies of clay stabilizer become much more important as never before. 1 What's more, clay minerals in hydrocarbon reservoirs often cause formation damage.…”

Partially hydrophobized hyperbranched polyglycerols as non-ionic reactive shale inhibitors for water-based drilling fluids

“…This behavior was observed for all the materials prepared in aqueous dispersions, in the same polymer concentration range (0 to 4000 ppm). For non-ionic polymeric structures this behavior was observed in partially hydrophobized polyglycols (Souza et al, 2010). However the isotherm for PG shows the presence of a pseudo-plateau which is not observed for HPGs materials.…”

“…TMP is 1,1,1-tris(hydroxymethyl)propane used as initiator on PG synthesis. hydrophobized molecules are better inhibitors than the PG polymer, probably due to the decreased solubility of the HPGs in comparison to PG and also as a consequence of their increased adsorption on clay (Souza et al, 2010). The relationship between solubility and the amount of adsorbed polymer on the clays surface is demonstrated by the adsorption isotherms shown in Fig.…”

“…Also, the increase of the isotherms inclination with the degree of the HPGs hydrophobization is a clear indication that the bentonite affinity increases with the hydrophobization degree for the polymer concentration range considered. For linear structures the literature (Souza et al, 2010;Volpert et al, 1998) suggests the formation of additional polymer layers by hydrophobic interactions, besides the interaction between (OCH 2 CH 2 ) groups and the clay surface. However, in the case of the hyperbranched structures only monolayers are observed, and the increase in the adsorption could be associated to the decrease of solubility with the increase of the hydrophobization degree, favoring bentonite-polymer interactions in comparison with the water-polymer interactions, as previously mentioned.…”

“…It has been demonstrated that the performance of these hyperbranched structures is superior to the ones obtained with linear PEGs. Also, the literature indicates that the performance of linear non-ionic inhibitors can be improved by increasing the degree of hydrophobicity of the polymers (Souza et al, 2010). In this work we are committed to the development and evaluation of new and unique hyperbranched polymeric structures, the hydrophobized hyperbranched polyglycerols, as reactive shales inhibition additives for water-based drilling fluids.…”