Impact of laponite on the formation of NGHs and its adaptability for use in NGH drilling fluids

Abstract

Natural gas hydrates (NGHs) are important potential alternative energy sources of oil and gas, which are efficient and clean. Their exploration and development are inseparable from drilling and drilling fluids. Adding nanomaterials into drilling fluid can effectively weaken the invasion of the drilling fluid into a formation, which is conducive to safe and efficient drilling. Therefore, this study explores the impact pattern and mechanism of different types and dosages of laponite on the formation of hydrates and analyses the adaptability of laponite in offshore NGH drilling fluids. The results show that the hydration of laponite prevents the directional arrangement of water molecules from forming a clathrate structure, and laponite forms a “house of cards” structure in the aqueous phase, which increases the resistance to mass transfer and inhibits the nucleation and growth of hydrates. Under the action of hydration, laponite planarly adsorbs a certain amount of strongly bound water that fails to participate in the formation of hydrates, thereby reducing the amount of hydrates formed. In addition, laponite basically does not increase the viscosity of drilling fluid at low temperatures but strengthens the inhibition and settling stability of the drilling fluid, significantly improving the comprehensive performance of the drilling fluid. It is concluded that 1.0 wt% laponite-RD is suitable for use in hydrate drilling fluid systems, the induction time was extended to 451.33 min, the methane consumption was reduced to 0.12623 mol, the average methane consumption rate was reduced to 0.23983 × 10−3 mol/min, and the linear expansion rate of sediments is as low as 10.2%, which shows excellent rheological property and sedimentation stability.