Shale Inhibitor In Water-based Drilling Fluids Research Articles

An amphiphilic polymer as shale inhibitor in water-based drilling fluid

Shale hydration inhibitor in water-based drilling fluids (WBDFs) is the key to solve the problem of shale wellbore instability during drilling. In this study, a new amphoteric polymer was studied as a shale inhibitor. The amphiphilic copolymer ADL was synthesized by using acrylamide (AM), diallyl dimethyl ammonium chloride (DMDAAC) and dodecyl acrylate (LA) as monomers, benzoyl peroxide as initiator and hexadecyl trimethyl ammonium bromide (CTAB) as an emulsifier in aqueous solution. Infrared spectra indicated that the target product was synthesized successfully. TGA showed that the copolymers had good temperature resistance and the decomposition temperature was 240°C. The performance of ADL was evaluated by linear expansion experiment, rolling recovery rate experiment. The inhibition mechanism of the ADL was analyzed by particle size distribution experiment, zeta potential experiment and contact angle experiment. The experimental results show that ADL can adsorb on the surface of shale to change its wettability and increase the repulsive force between shale particles, thus inhibiting the hydration of shale. Because of its excellent shale inhibition performance, ADL has a potential application prospect as a shale inhibitor in WBDF.

Investigation of the inhibition mechanism of polymer/nano-silica composite as shale inhibitor in water-based drilling fluids

Wellbore instability caused by shale hydration and swelling is the critical issue in the drilling process of oil and gas wells. In this study, the nano-silica/cationic polymer composite (NS-DD) was synthesized and evaluated as novel shale inhibitor in water-based drilling fluids (WDFs). The inhibition performance of NS-DD was carried out and compared with the conventional inhibitor potassium chloride (KCl) and the extensively utilized inhibitor polyether diamine (PDA), where the inhibition performance tests consisted of bentonite inhibition tests, linear swelling tests, and shale cuttings rolling recovery tests. The results revealed that NS-DD exhibited outstanding inhibition performance compared to KCl and PDA even in high temperature environment. Specifically, in the presence of KCl and PDA, the third roll recoveries of shale cuttings after hot rolling at 150 °C for 16 h were 28.62% and 42.15%, respectively, however, the recovery of shale cuttings was as high as 70.06% when NS-DD was attended. Additionally, we proposed that the excellent inhibition ability of NS-DD may be attributed to its strong adsorption with clay through hydrogen and ionic bonding and plugging of nano-pores in WDFs filter cake and shale, preventing water penetration into the reservoir causing shale hydration and swelling based on the results of scanning electron microscopy, zeta potential, thermogravimetric and X-ray diffraction analysis. This study revealed the potential application of NS-DD as the shale inhibitor in WDFs.

Mechanistic assessment of Seidlitzia Rosmarinus-derived surfactant for restraining shale hydration: A comprehensive experimental investigation

The physicochemical aspect of wellbore stability is linked to the interaction between the drilling fluid and rock (e.g., shale). By far, most of the surfactants utilized in the oil industry are identified with environmental drawbacks. This paper appraises for the first time the functionality of a novel environmentally-friendly bio-based surfactant, Seidlitzia Rosmarinus leaf and stem extract (SRLSE), in water-based drilling fluids (WBDF) for inhibiting shale hydration. The swelling inhibitive property of SRLSE was thoroughly evaluated using several experiments including clay inhibition, cuttings dispersion, filtration, particle size measurement, scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). The findings implied that as opposed to deionized water, the aqueous solution of SRLSE indicated fairly low rheological profiles which resulted in a greater degree of montmorillonite (MMT, an active mineral in shale) loading (22.5mass%). Addition of 3 mass% SRLSE and 8 mass% SRLSE to deionized water resulted in a shale cuttings recovery improvement of 20.8% and 40.5%, respectively. MMT in deionized water gave a fluid loss of 26ml. However, it exhibited a poor fluid loss control in the aqueous solution of SRLSE so that the fluid loss volume increased up to 73ml. As opposed to deionized water, the particle size of MMT in SRLSE aqueous solution rose extremely. According to TGA, the modified MMT in the aqueous solution of SRLSE imposed 2.88% less water content with respect to the modified MMT in deionized water. From SEM observations, MMT in SRLSE aqueous solution exhibited larger aggregates than deionized water. In addition to the aforementioned results, compatibility tests proved that SRLSE is well-compatible with typical WBDF additives. All the experimental results implied that SRLSE can be considered a capable shale inhibitor in WBDF. The interaction between the hydrophilic tail of saponin (a dominant constituent of SRLSE) and MMT's surfaces which forms a hydrophobic shell is perhaps the leading inhibition mechanism for SRLSE.