Novel Nanocomposite Coated Proppants for Enhanced Scale Inhibition Lifetime in Tight Shale Formations

Controlling scale deposition in tight formations such as shale is commonly achieved by combining fracturing stimulation with squeeze treatment. The squeeze treatment process's success relies on the targeted formation's ability to adsorb the right amount of scale inhibitor and slowly release it during hydrocarbon production. The inhibition lifetime of a standard squeeze treatment lasts from 3 to 6 months depending on the compatibility between the formation and scale inhibitor-operators desire a prolonged inhibition lifetime. Herein, a novel approach of resin-based nanocomposite coated proppants is developed to act as a propping agent and high active surface platform for scale inhibitors to be adsorbed and subsequently slowly released during oil production. In this study, proppants were coated with a thin layer of polyurethane, followed by a layer of carbon-based nanomaterials (Multi-Wall Carbon Nanotubes (MWCNTs) and Graphene Nanoplatelets (GNPs)), and characterized using Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Analysis (EDX). Due to the concerns of climate change, polyurethane was selected due to its quick curing at lower temperatures and minimal environmental impacts. The potential of the proposed proppant to enhance the adsorption and slow the desorption of a Diethylenetriamine Penta (DTPMP) scale inhibitor, the necessary strength to withstand closure stress, and its thermal stability were evaluated. FESEM and EDX results revealed that an ultrathin uniformed coating layer was established. The stress resistance data showed that the proposed proppants (MWCNTs-RCP and GNPs-RCP) could withstand closure stress as high as 68.9 MPa with less than 10 wt % fines production. In addition, the thermal stability of MWCNTs-RCP and GNPs-RCP reached 347 degrees C. Scale inhibitor adsorption experiments showed that MWCNTs-RCP and GNPs-RCP adsorbed 583.5 mg/kg and 832.0 mg/kg of DTPMP, respectively. Desorption results indicated that MWCNTs-RCP and GNPs-RCP extended the inhibition lifetime of DTPMP by 400% PV compared to a conventional proppant. Intraparticle diffusion was found to dominate the desorption of DTPMP from MWCNTs-RCP and GNPs-RCP, which explains the slow desorption rate they exhibited. Therefore, the developed proppants could be a promising multifunctional proppant in the oil and gas industry.

Automated summary

In this study, a novel approach of resin-based nanocomposite coated proppants was developed to control scale deposition in tight formations. The coated proppants showed high adsorption capacity, slow desorption rate, and improved stress resistance, making them a promising multifunctional proppant in the oil and gas industry.