Experimental Investigation of Tight Sandstone Reservoir Damage Induced by Silicate-Based Drilling Fluid

Silicate-based drilling fluid (SDF) has a strong inhibition effect on shale swelling and provides good wellbore stability. SDF has also been widely used in drilling through the reservoir in recent years. However, SDF has certain damage effects on the reservoir, and its damage mechanism is not well understood. In this work, the damage of the tight sandstone formations induced by SDF was assessed by conducting fluid displacement and filtrate imbibition experiments. In addition, the damage mechanisms were further analyzed based on microscopic experiments. The research results mainly included the following four aspects: First, SDF caused significant reservoir damage by solid-phase particles and filtrate intrusion in tight sandstone reservoirs, and the latter was the main reason. Second, the incompatibility between the filtrate of the SDF and formation led to reservoir damage. This was because the SiO32-, CO32-, and OH- in the SDF reacted with Ca2+, Mg2+, and Al3+ in the formation, resulting in the generation of new minerals such as kaolinite and gibbsite. Third, the filtrate of the SDF increased the hydrophilicity of the rock surface, which induced the aqueous trapping damage. Finally, SDF was strongly alkaline (pH = 13.08), in which OH- produced by sodium metasilicate hydrolysis had alkaline corrosion effect on minerals, enhancing pore permeability. This work provides experimental evidence for the feasibility discussion of the SDF in tight sandstone reservoirs.