Abstract Drilling fluids Invasion and mud filtration is a complex process that is influenced by several variables, and has NPT (Non-Productive Time) implications. Most of these variables are either within operational control limits (mud type, LCM type/concentration, and rotary speed) or pre-existing limits (temperature, fracture width, and rock type/permeability/porosity). It is unclear which of these variable(s) have significant positive or negative impact on dynamic fluid loss, filtration patterns, invasion rates, and plastering effect. The primary objective of the study presented in this paper is to quantify the contributing effects of temperature change, lost circulation material (LCM) type, concentration, size (particle size distribution), and variation in porous media on dynamic drilling fluids invasion. Statistical methods were used to determine the magnitude and significance of these independent variables. The fluid loss experiments reported herein were performed with a dynamic-radial system that accounts for rotary speed, eccentricity, torque, pressure, and temperature. The effects of the variables mentioned above were studied using ceramic filter tubes and thick-walled cylindrical limestone, sandstone, and chalk rock specimens. The results from the experiments showed that a change in temperature significantly affects fluid loss. The importance of rock mineralogy, porosity, and permeability in dictating dynamic fluid loss profiles, mud invasion rates, and plastering effects were also revealed by the fluid loss results. The results from the ceramic filter tubes, often undermines the effect of rock type which can be misleading. Statistical analyses showed no significant change in dynamic fluid loss with the two treatment levels of pore throat diameters that were investigated. These results cannot represent the actual porous media complexities. In the cases where vertical fractures were created and sealed, the combined effects of LCM and low permeability of rock specimen were defined in the reduced dynamic mud filtration results and filter cake plastering effects.

中文翻译：

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多孔介质中钻井液损失的实验和统计研究——第 1 部分

摘要 钻井液侵入和泥浆过滤是一个复杂的过程，受多个变量的影响，并具有 NPT（非生产时间）含义。这些变量中的大多数要么在操作控制范围内（泥浆类型、LCM 类型/浓度和转速），要么在预先存在的限制范围内（温度、裂缝宽度和岩石类型/渗透率/孔隙度）。目前尚不清楚这些变量中的哪些对动态失水、滤过模式、侵入率和抹灰效果有显着的正面或负面影响。本文提出的研究的主要目的是量化温度变化、堵漏材料 (LCM) 类型、浓度、尺寸（粒度分布）和多孔介质变化对动态钻井液侵入的影响。统计方法用于确定这些自变量的大小和显着性。本文报道的流体损失实验是使用动态径向系统进行的，该系统考虑了转速、偏心率、扭矩、压力和温度。使用陶瓷过滤管和厚壁圆柱形石灰岩、砂岩和白垩岩标本研究了上述变量的影响。实验结果表明，温度变化显着影响滤失量。流体损失结果还揭示了岩石矿物学、孔隙度和渗透率在决定动态流体损失剖面、泥浆侵入率和抹灰效果方面的重要性。陶瓷过滤管的结果通常会破坏岩石类型的影响，这可能会产生误导。统计分析表明，在所研究的两种孔喉直径处理水平下，动态滤失量没有显着变化。这些结果不能代表实际的多孔介质复杂性。在垂直裂缝形成和封闭的情况下，LCM 和岩石试件的低渗透性的综合影响被定义为动态泥浆过滤结果和滤饼抹灰效果的降低。