理论分析和油田现场钻井实践表明,钻井液中液相及固相颗粒侵入裂缝是造成裂缝性气藏储层伤害的主要因素。将理想充填暂堵理论扩展应用到裂缝性气藏的储层保护,把理想充填暂堵剂与成膜剂进行复配优化,利用“迭加增效”作用优选出了保护裂缝性气藏的新型超低渗透水基钻井液。室内评价试验表明:该钻井液体系流变性能优良,易于调整和控制,抗高温能力强,泥饼致密、光滑,可在井壁形成一层致密的隔离层(非渗透膜)。API滤失量可控制在2.3mL以下,高温高压动态累计滤失量≤0.3mL,可显著提高裂缝性气藏的储层保护效果。
Theoretical analysis and field application suggest that the invasion of liquid and solid of drilling fluids into fractures are the main reason for damage to fracture reservoirs. Extending "ideal packing theory" to fracture type reservoir protection and optimizing the ideal packing agent and film-forming agent, a carefully designed ultra low osmosis water based drilling fluid by synergistic interaction was developed. Laboratory experiments show that this drilling fluid has better rheological property, higher temperature resistance and slicker mud cake which can form a homogeneous and compact seal coat on borehole. The API filter loss could be controlled under 2.3mL, and HTHP dynamic filtration was less than 0.3mL. Lab tests demonstrate that this system can effectively improve fractured gas reservoir protection.