渝东南下志留统龙马溪组页岩理化性能实验

为了研究长水平井钻井中页岩储层井壁失稳的内在原因，采集渝东南下志留统龙马溪组露头页岩样品，进行了理化性能和页岩声波响应室内评价实验，并结合灰色关联度法分析了理化性能参数间的相关性。通过实验结果可以看出：1渝东南龙马溪组页岩孔隙度范围为1.5%~2.5%，平均值为1.9%，渗透率平均值为6.72×10^-4mD，岩样层理、微孔隙和微裂缝发育；2页岩主要矿物成分为石英、斜长石、黄铁矿和黏土，脆性矿物含量高，石英平均含量超过45%，黏土含量约为22%，并以伊利石为主，含少量的膨胀性黏土伊/蒙混层；3实验样品阳离子交换容量CEC值均小于10 mmol/100 g，平均值为8.2 mmol/100 g，比表面积的平均值为18.39 m²/g，孔径分布平均值为3.76 nm，比表面积和孔径呈现出负相关性；4随层理与岩心轴向夹角的变大，波速呈现出减小趋势；5比表面积和孔径与波速关联度较好，分别呈正、负线性相关。

Physical and chemical properties experiment on shale in Longmaxi Formation of Lower Silurian,southeast Chongqing

To analysis internal causes of shale reservoir wellbore instability in long horizontal well drilling, based on outcrops shale in Longmaxi Formation of Lower Silurian, Chongqing southeast, physical and chemical properties experiments, and acoustic response tests have been carried out. Associating with gray correlation analysis, the correlations between the physical and chemical performance parameters are analysed. Experiments show that: (1)Shale porosity of Longmaxi Formation is in range of 1.5%-2.5%, an average of 1.9%. Average permeability is 6.72×10^-4mD. Bedding, micro-pore and micro-fracture of samples are developed; (2)The main shale mineral compositions are quartz, plagioclase, pyrite and clay. Average silica content exceeds 45%, and clay content is about 22%, mainly illite, containing a small amount of swelling clay of illite/mectite; (3)Cation exchange capacity (CEC) values are less than 10 mmol/100 g, average is 8.2 mmol/100 g. Average specific surface area is 18.39 m²/g, and average pore size distribution is 3.76 nm, the two shows negative correlated behavior; (4)As angle between with bedding and core axial is increasing, ultrasonic velocity has decreased trend; (5)Specific surface area and pore size have good correlation with velocity, respectively as positive and negative linear correlation.