鄂尔多斯盆地W区致密砂岩油藏压裂液渗吸机理研究

发布时间：2018-01-09 09:18

本文关键词：鄂尔多斯盆地W区致密砂岩油藏压裂液渗吸机理研究　出处：《西安石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：致密储层有低渗、低孔、低压、高毛管压力和高有效应力等特点,储层往往无自然产能,必须经过体积压裂才能进行生产。目前,压裂施工工艺的压裂液返排率普遍低于40%,致密储层高毛管压力产生的自发渗吸是压裂液滞留与吸收的重要因素,研究压裂液的渗吸机理对提高体积压裂的经济效益至关重要。本文通过研究W区的储层特征了解该区渗吸条件,然后结合渗吸理论设计压裂液渗吸实验,分析压裂液的渗吸现象、渗吸力学机制及渗吸影响因素,选择合适的渗吸模型对实验结果进行标度,并应用实验结果预测压裂液渗吸驱油效率和压裂液返排率。研究表明:盐水体系的渗吸效率较高,盐水中加入表面活性剂后渗吸效率降低。不同渗透率的岩心,渗吸效率最高可达21.4%,最低为14.94%,渗吸效率随渗透率的增大而增大,但当渗透率过大时渗吸效率有下降的趋势。岩心的物性条件相似且水相粘度一定时,渗吸效率随油相粘度的增大而减小。不同边界条件下的岩心,渗吸时间最长为185.5h,最短为65h,各岩心渗吸速率相差很大,但最终渗吸效率相当。岩心越短、特征长度越小,渗吸速率越大;特征长度相同时,岩心形状因子越大,渗吸速率越大。关井时间对压裂液返排率的影响很大,关井后40天内的压裂液吸入速度远远大于40天以后。
[Abstract]:Tight reservoir has the characteristics of low permeability, low porosity, low pressure, high capillary pressure and high effective stress, etc. The recovery rate of fracturing fluid in fracturing process is generally lower than that of 40 fracturing fluid. The spontaneous permeability and suction caused by high capillary pressure in tight reservoir is an important factor for the retention and absorption of fracturing fluid. It is very important to study the permeation mechanism of fracturing fluid to improve the economic benefit of volume fracturing. This paper studies the reservoir characteristics of W area to understand the permeability and suction conditions, and then designs the permeation experiment of fracturing fluid based on permeation theory. This paper analyzes the phenomenon of permeation and suction of fracturing fluid, the mechanism of permeability and the influencing factors of permeation, and selects the appropriate seepage and suction model to scale up the experimental results. The experimental results are used to predict the oil absorption efficiency of fracturing fluid and the back drainage rate of fracturing fluid. The results show that the permeation efficiency of salt water system is higher than that of salt water system, and the permeability and suction efficiency of different permeability core is decreased after adding surfactant in brine. The maximum permeation efficiency can reach 21.4and the lowest is 14.94.The permeability efficiency increases with the increase of permeability. However, when the permeability is too high, the permeability absorption efficiency tends to decrease. When the physical properties of the core are similar and the viscosity of the water phase is constant, the permeability absorption efficiency decreases with the increase of oil phase viscosity, and the core under different boundary conditions. The longest permeation time is 185.5 hours and the shortest is 65 hours. The permeation rate of each core is very different, but the final permeability absorption efficiency is the same. The shorter the core, the smaller the characteristic length and the larger the permeation rate. When the characteristic length is the same, the larger the core shape factor is, the larger the permeation rate is, and the effect of shutoff time on the fracturing fluid reflux rate is very great, and the suction rate of fracturing fluid within 40 days after shutoff is far greater than that after 40 days.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357.12

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