Abstract

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.

中文翻译：

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硅酸盐基钻井液致密砂岩储层伤害实验研究

摘要

硅酸盐基钻井液（SDF）对页岩膨胀具有很强的抑制作用，并提供良好的井壁稳定性。近年来，SDF也被广泛用于油藏钻探。但SDF对储层具有一定的损害作用，其损害机制尚不清楚。在这项工作中，通过进行流体驱替和滤液自吸实验来评估 SDF 对致密砂岩地层的损害。此外，基于显微实验进一步分析了损伤机制。研究成果主要包括以下四个方面：一是SDF对致密砂岩储层造成了明显的固相颗粒和滤液侵入储层损害，而后者是主要原因。其次，SDF滤液与地层不相容，导致储层损害。这是因为SDF中的SiO ₃ ²⁻、CO ₃ ²⁻、OH ^{−与地层中的Ca 2+}、Mg ²⁺、Al ³⁺发生反应，生成高岭石、三水铝石等新矿物。 。第三，SDF的滤液增加了岩石表面的亲水性，从而引起了水捕获损伤。最后，SDF呈强碱性（pH=13.08），其中偏硅酸钠水解产生的OH-对矿物有碱性腐蚀作用，增强孔隙渗透性^。该工作为致密砂岩储层中SDF的可行性探讨提供了实验依据。