Geomechanical characterization of shale samples after pore plugging with nanomaterials

Time-Dependent Measurements of Shale’s Compressive Strength When Contacting Ionic Solutions

“…Alteration of the compressive strength of shale has generated much interest over the past decades, and several researchers tried to understand the reasons and effects of it on the overall integrity of shale to provide methods and techniques for safe shale drilling. − While these studies presented great results and analysis and shed light on the causes and consequences of the alteration of compressive strength of shale on the stability of drilled wellbore, these studies did not monitor the development of shale’s compressive strength alteration (reduction or enhancement) as a function of time. Their recommendations were based on the final state of shale’s compressive strength measurements.…”

Temperature-Responsive Nano-SiO2 Composite for Improving Shale Stability in Oil-Based Drilling Fluids

“…Adding nanosized plugging agents to plug microfractures and nanopores to form a dense plugging film and reduce the lack of drilling fluids is an effective mean to solve the above problem. − Common nano plugging agents are inorganic nanomaterials, organic nanomaterials, and organic/inorganic composite nanomaterials. Inorganic nanomaterials, such as nanosilica (nano-SiO 2 ), nanozinc oxide (nano-ZnO), and nanotitanium dioxide (nano-TiO 2 ) are filled in the near wellbore zone through bridging to form a tight plugging layer, which decreases the permeability of the reservoir and reduces the filtration of drilling fluid. − However, the surface effect of nanomaterials makes them easily agglomerate together, which hardly guarantees the nanometer size. Under the conditions of reservoir temperature and salinity, organic nanomaterials will undergo physical/chemcal reactions, such as cross-linking, expansion, adsorption, and solidification after entering the pores and fractures of the reservoir, thereby plugging pores and fractures. − Nevertheless, high temperature may break polymer chains of organic plugging materials and result in loss of material properties.…”