Silica and Graphene Oxide Nanoparticle Formulation to Improve Thermal Stability and Inhibition Capabilities of Water-Based Drilling Fluid Applied to Woodford Shale
Drilling-fluid design for shale plays aims to deal with the lack of wellbore stability associated with fluid-invasion, shale-swelling, and cuttings-dispersion phenomena. Although oil-based mud can be used to achieve these goals, environmental and economic concerns limit its application. This research evaluates the potential of using silica (SiO2) nanoparticles (NPs) (SiO2-NPs) and graphene nanoplatelets (GNPs) as drilling-fluid additives in a single formulation to improve shale inhibition and long-term stability of water-based mud (WBM) against temperature effects. The design of the nanoparticle WBM (NP-WBM) followed a customized approach that selects the additives according to the characteristics of the reservoir. Characterization of Woodford shale was completed with X-ray diffraction (XRD), cation-exchange capacity (CEC), and scanning electron microscopy (SEM). The aqueous-stability test and ζ-potential measurements were used to assess the stability of the NPs. NP-WBM characterization included the analysis of the rheological properties measured with a rotational viscometer and the evaluation of the filtration trends at low-pressure/low-temperature (LP/LT) and high-pressure/ high-temperature (HP/HT) conditions. In addition, dynamic aging was performed at temperatures up to 250°F for thermal-stability evaluation. Finally, chemical-interaction tests, such as cutting dispersion and bulk swelling, helped to analyze the effect of introducing NPs on the inhibition capabilities of the WBM. Conventional potassium chloride (KCl)/partially hydrolyzed polyacrylamide (PHPA) fluid was used for comparison purposes. The results of this investigation revealed that SiO2-NPs and GNPs acted synergistically with other additives to improve the filtration characteristics of the WBM, with only minor effects on the rheological properties. NPs exhibited high colloidal stability with ζ-potential values less than -30 mV, which warrants their dispersion within the WBM at an optimal concentration of 0.75 wt%. The high thermal conductivity of NPs played a key role in promoting a nearly flat trend in the cumulative filtrate for the NP-WBM at aged conditions, whereas KCl/PHPA suffered a dramatic increase. Also, NP-WBM preserved 43.97% of its initial cuttings-carrying capacity, whereas KCl/PHPA experienced a severe reduction of 95.24% at extreme conditions (250°F). Despite the high illite content of the Woodford shale, the NP-WBM exhibited superior inhibition properties that reduced cuttings erosion and swelling effect by 24.48 and 35.24%, respectively, compared with the KCl/PHPA fluid. Overall, this investigation supports the potential use of nanomaterials to enhance the inhibition capabilities and the long-term stability of WBM for unconventional shales, presenting an environmentally friendly alternative for harsher environments.
J. Aramendiz and A. Imqam, "Silica and Graphene Oxide Nanoparticle Formulation to Improve Thermal Stability and Inhibition Capabilities of Water-Based Drilling Fluid Applied to Woodford Shale," SPE Drilling and Completion, vol. 35, no. 2, pp. 164 - 179, Society of Petroleum Engineers (SPE), Jun 2020.
The definitive version is available at https://doi.org/10.2118/193567-PA
Geosciences and Geological and Petroleum Engineering
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01 Jun 2020