Development of a High-Performance Drilling Fluid Additive for Application in Indian Shale Gas Formations

Abstract

With increasing energy demand, it has become pertinent to develop high-performing drilling fluids and additives with environmental compatibility for troublesome shale gas formations. In this research work, carboxymethyl chitosan (CM-CS) was synthesized using carboxymethylation reactions and characterized using advanced analytical techniques. The synthesized CM-CS was used as an additive in a water-based drilling fluid system comprising clay, carboxymethyl cellulose, polyanionic cellulose, and xanthan gum. The experimental investigation results of the drilling fluid properties, including the filtration and rheological tests, showed improvement compared with poly-(ethylene glycol) (PEG), a conventional shale inhibitor. At 0.3, 0.6, and 0.9 (w/v%) CM-CS, the filtrate loss was reduced by 38.75, 50, and 53.12% in comparison to the base fluid. Other tests included ζ-potential and shale recovery tests. The ζ-potential was used to determine the suspension stability of the drilling fluid. Shale recovery tests were conducted to assess the effectiveness of the fluid to address the wellbore instability issues for the chosen shale samples. The primary shale recovery percentages of CM-CS and PEG in drilling fluids were compared. Results show that the primary recovery factors increased by 32.42, 33.81, and 34.12 (wt%) when 0.3, 0.6, and 0.9 (w/v%) CM-CS was used as an additive. CM-CS shows minimum interaction of the fluid with the Indian shale samples based on shale recovery tests and filtration studies, which suggests that it can be better suited for the drilling fluid application in troublesome shale gas formation.

Investigation of Filtration and Shale Inhibition Characteristics of Chitosan-N-(2-hydroxyl)-propyl trimethylammonium Chloride as Drilling Fluid Additives

“…The cation exchange phenomenon occurs when HACC is introduced, and the additive adsorbs and intercalates between the clay layers through hydrogen bonding and electrostatic attraction. Since clay particles are electronegative, the most efficient shale inhibitor is usually electropositive, following the fundamental electrical law that states that opposing charges attract Figure shows a schematic representation explaining the interaction between HACC and clay particles as well as shale formation.…”

“…The broad characteristic peak of CS and HACC at 3350 and 3430 cm –1 is attributed to the axial stretching of O–H and N–H 2 bonds and intermolecular hydrogen bonds. 37 , 44 , 45 The characteristic peaks at 1652 and 1592 cm –1 correspond to the amide I and amine II (bending vibration of −NH 2 ) absorption bands of chitosan, respectively. 37 For the FTIR spectrum of quaternized chitosan, the adsorption band at 1592 cm –1 almost disappeared, indicating that N-alkylation in chitosan occurred.…”

“… 37 , 44 , 45 The characteristic peaks at 1652 and 1592 cm –1 correspond to the amide I and amine II (bending vibration of −NH 2 ) absorption bands of chitosan, respectively. 37 For the FTIR spectrum of quaternized chitosan, the adsorption band at 1592 cm –1 almost disappeared, indicating that N-alkylation in chitosan occurred. A new band, observed at 1480 cm –1 , is attributed to the methyl groups of the ammonium; this corresponds to quaternized ammonium chloride due to C–H bond vibrations in CH 3 groups.…”

“…(2023). 37 The CEC of used shale samples was found to be 15 mequiv/100 g. The EDX, XRF, and XRD results showed a significant amount of quartz and clay minerals, such as montmorillonite and kaolinite. The FESEM results showed the presence of a few undulations on the surface which can be attributed to the stacking of the sheets and crystalline arrangement.…”

“…The clay composition of shale samples was characterized using FESEM, EDX, X-ray diffraction (XRD), wavelength-dispersive X-ray fluorescence (XRF), and cation exchange capacity (CEC) as reported by Doley et al (2023). 37 The CEC of used shale samples was found to be 15 mequiv/100 g. The EDX, XRF, and XRD results showed a significant amount of quartz and clay minerals, such as montmorillonite and kaolinite. The FESEM results showed the presence of a few undulations on the surface which can be attributed to the stacking of the sheets and crystalline arrangement.…”