Abstract
High-performance water-based drilling fluids (HPWBFs) are essential to wellbore stability in shale gas exploration and development. Laponite is a synthetic hectorite clay composed of disk-shaped nanoparticles. This paper analyzed the application potential of laponite in HPWBFs by evaluating its shale inhibition, plugging and lubrication performances. Shale inhibition performance was studied by linear swelling test and shale recovery test. Plugging performance was analyzed by nitrogen adsorption experiment and scanning electron microscope (SEM) observation. Extreme pressure lubricity test was used to evaluate the lubrication property. Experimental results show that laponite has good shale inhibition property, which is better than commonly used shale inhibitors, such as polyamine and KCl. Laponite can effectively plug shale pores. It considerably decreases the surface area and pore volume of shale, and SEM results show that it can reduce the porosity of shale and form a seamless nanofilm. Laponite is beneficial to increase lubricating property of drilling fluid by enhancing the drill pipes/wellbore interface smoothness and isolating the direct contact between wellbore and drill string. Besides, laponite can reduce the fluid loss volume. According to mechanism analysis, the good performance of laponite nanoparticles is mainly attributed to the disk-like nanostructure and the charged surfaces.
Highlights
The concept of high-performance water-based drilling fluids (HPWBF) (Galindo et al 2015; Jain et al 2015; Jung et al 2013; Kosynkin et al 2011; Morton et al 2005) has been proposed for decades
This paper introduces the application of laponite in WBF
According to experimental results of scanning electron microscope (SEM) observation, laponite could form a seamless nanofilm on the surface of the wellbore, which could reduce capillary imbibition and pressure transmission, benefiting to wellbore stability
Summary
The concept of high-performance water-based drilling fluids (HPWBF) (Galindo et al 2015; Jain et al 2015; Jung et al 2013; Kosynkin et al 2011; Morton et al 2005) has been proposed for decades. HPWBF is defined as water-based drilling fluids (WBF) with good performance parameters, Edited by Yan-Hua Sun. For shale gas reservoirs, the content of clay minerals is as high as 30%–50% or even more (Li et al 2020b; Yang et al 2014; Zou et al 2010). The majority of the horizontal sections is drilled by oil-based drilling fluid (OBF) (Li et al 2014; Sun et al 2018) to avoid shale hydration (Huang et al 2018; Jiang et al 2016; Shadizadeh et al 2015) and enhance lubrication property (Sönmez et al 2013). In the process of shale gas drilling in China, the existing water-based drilling fluid technology has not solved the technical problems such as instability of the wellbore and high friction due to lack of inhibition, plugging and lubricating performances. Experimental results indicated that laponite had good shale inhibition property, plugging property and lubricating property
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