Field Deployment of Nanomaterial Based Shale Inhibitors

Abstract Shale inhibition solutions that are commonly used in water-based fluids employ chemical systems that are not universally applicable. For example, kaolinite rich shales, can lose strength when exposed to KCl through cation exchange with potassium. In the United States, government regulations prohibit the disposal of greater than 3,000 ppm chloride on lease or 1,000 ppm chloride off lease. The hazardous nature of choline chloride restricts its use as shale inhibitor for water-based fluids. Nanosilica Based Shale Inhibitor (NSBSI) has been developed to mitigate the difficulties in clay stabilization in particularly challenging formations. NSBSI is used when drilling with low solids, non-dispersed muds, such as polymer and PAC muds. It can be used as an alternative to polyamine-based shale inhibitors and silicate-based shale inhibitors. Field trials were conducted in three wells. Commonly used shale inhibitor (polyamine based) were replaced by NSBSI in mud formulations in order to complete the field trials. Trouble-free drilling through problematic shale sections with no changes in mud properties, and no indications of lack of inhibition were experienced. Further addressing field requirements for shale inhibition in water-based muds, we have also developed a second shale-inhibiting product which is functionalized nanoplatelets composed of amine functionalities anchored on the nanometer-thick magnesium silicates (LMS-NH2). A facile synthetic approach was employed to synthesize lab-scale quantity of LMS-NH2 through combination of sol-gel and precipitation techniques. The structural characterization was conducted using powder X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) to evaluate generation of anticipated LMS-NH2. Shale stabilization characteristics of LMS-NH2 were tested and compared with other commercial shale inhibitors. Clay swelling and clay dispersion tests were performed to demonstrate the effectiveness of the impermeable coating of nano-platelets on to the clay-rich shales. The LMS-NH2 have demonstrated 87% recovery of swellable shales after dispersion tests. The microscopic study conducted on the treated shales reveals the formation of inorganic film on the shales, which provide impervious coating to protect the water susceptible clays. The linear swelling measurements were also performed to understand the effectiveness of LMS-NH2 over 72 hours demonstrating minimized the hydration and subsequent swelling of clay-rich shales. The newly developed inhibitor in the current study has outperformed conventional shale inhibitors wherein the presence of inorganic constituents aids stronger film formation compared to solely organic inhibitors. Comparative studies have been carried out against commercially used shale inhibitors using linear swell meter, dispersion test and pore pressure penetration test and the results will be presented.