硬脆性泥页岩微纳米裂缝模拟与表征

发布时间：2018-04-23 19:55

  本文选题：硬脆性泥页岩 + 腐蚀　； 参考：《西南石油大学》2017年硕士论文

【摘要】：钻遇硬脆性泥页岩时,因地层中普遍存在微纳米裂缝,钻井液及其滤液会沿着裂缝侵入地层深部,导致井壁失稳。针对现有评价钻井液封堵能力的裂缝宽度下限在10μm左右,明显大于硬脆性泥页岩中的微裂缝宽度而导致封堵评价手段与实际情况不能较好吻合的问题,本文选择石英作为制备模拟裂缝的基质材料,在半圆柱型基质材料的拼接平面利用化学腐蚀和化学镀膜方法,开展微纳米裂缝模拟研究。裂缝宽度的表征方法是制备微纳米级裂缝的基础,本文首先开展了裂缝宽度表征方法的研究。对采用化学腐蚀法制备的裂缝宽度,采用渗透率法、电阻值法和环境扫描电子显微镜观测法进行表征;对采用化学镀膜法制备的裂缝宽度,采用渗透率法和环境扫描电子显微镜观测法进行表征。渗透率法和环境扫描电子显微镜观测法测量裂缝宽度数值的相对标准偏差均很小,证明方法重现性良好。采用渗透率法研究初始裂缝的应力敏感性,得出石英岩心裂缝的应力敏感损害程度很弱,在经过加、卸压处理后,应力变化对裂缝宽度的影响很小。采用渗透率法、环境扫描电子显微镜法、电阻率法对影响化学腐蚀法制备缝宽的时间、温度、酸液比例等因素进行单因素分析和正交试验,结果表明:随着温度升高,反应时间增大,HF浓度增大,制造出的裂缝宽度变大。在正交实验设计水平下得到最小缝宽的制备条件为:温度20℃、5wt%HF:5%H_2SO_4=1:2、反应时间20min,渗透率法表征的缝宽为1.317μm,扫描电镜表征的缝宽为1.625μm。采用渗透率法和环境扫描电子显微镜法对影响化学镀膜法制备裂缝宽度的镀膜配方及镀膜条件等因素进行了探索,正交实验设计水平下得到的制备最小裂缝的配方和条件是:主盐溶液:4g/LAgNO_3、10g/LNaOH,还原液:6g/L葡萄糖,2g/L酒石酸钾钠,反应时间10min,渗透率法测得的缝宽为0.779μm,用扫描电镜表征的缝宽为0.792μm。利用所制备的裂缝开展了封堵模拟实验的可行性探索。
[Abstract]:When drilling hard and brittle shale, the drilling fluid and its filtrate will invade the deep part of the formation along the fracture, which will lead to the instability of the wellbore because of the widespread existence of micro and nano fractures in the formation. In view of the fact that the lower limit of fracture width for evaluating the plugging ability of drilling fluid is about 10 渭 m, which is obviously larger than the microfracture width in hard-brittle shale, the sealing evaluation method does not agree well with the actual situation. In this paper, quartz is chosen as the matrix material to simulate the crack. The chemical corrosion and electroless plating methods are used to simulate the crack in the splicing plane of semi-cylindrical matrix. The characterization method of crack width is the basis of preparing micro-and nano-scale cracks. In this paper, the characterization method of crack width is first studied. The crack width prepared by chemical corrosion method is characterized by permeability method, resistance value method and environmental scanning electron microscope. Permeability method and environmental scanning electron microscope (ESEM) were used to characterize the properties. The relative standard deviation of fracture width measured by permeability method and environmental scanning electron microscope method is very small, which proves that the method has good reproducibility. The stress sensitivity of the initial fracture is studied by permeability method. It is concluded that the damage degree of stress sensitivity of the quartz core fracture is very weak, and the stress change has little effect on the crack width after the treatment of adding and unloading pressure. By using permeability method, environmental scanning electron microscope method and resistivity method, single factor analysis and orthogonal test were carried out on the factors affecting the preparation time, temperature and acid ratio of the chemical corrosion method. The results showed that: with the increase of temperature, With the increase of reaction time and HF concentration, the crack width becomes wider. At the level of orthogonal experimental design, the preparation conditions of the minimum slit width are as follows: temperature 20 鈩，

本文编号：1793379