致密储层水敏感性伤害垂向差异因素分析及保护措施优选

库车北部构造带吐格尔明段明南1井水敏感性损害在垂直方向存在明显差异特征,研究表明以克孜勒努尔组(J1 kz2)、阳霞组(J1 y2)和阿合组(J1 a1、J1 a2)为主的小层位表现出较高的水敏感性损害.结合X衍射分析、CT扫描和铸体薄片等方法进行验证,结果显示储层组中黏土矿物整体体积分数处于8.77％ ～17.52％,较高的黏土含量且含有大量溶蚀颗粒等因素是造成水敏感性损害的主要原因;从物性因素分析,退汞率和孔喉半径随井深深度呈现逐渐降低的趋势,部分小层位孔喉连通性较差;上述控制因素在垂向上表现出明显的差异性,是明南1井水敏感性损害垂向差异的主要原因.此外,通过黏土稳定剂损失率实验,优选出降低明南1井水敏感性损害的两种最佳选择,3％YLN-07可最有效防止黏土损失,黏土损失率降低14.97％;若综合考虑经济效益等方面,0.5％HES黏土稳定剂是最为理想的选择,黏土损失率降低12.5％.

Analysis of vertical difference factors of water sensitive damage in tight reservoir and optimization of protective measures

The water sensitivity damage of well Mingnan 1 in tugerming section of North Kuqa structural belt is obviously different in the vertical direction. The study shows that the small layers mainly composed of Kizilnur formation (J1kz2), Yangxia formation (J1y3) and Ahe formation (J1a1, J1a2) show high water sensitivity damage. Combined with X-ray diffraction analysis, CT scanning and casting thin sections, the results show that the overall volume fraction of clay minerals in the reservoir group is in the range of 8.77% ~ 17.52%, the main reason for the damage of water sensitivity is the high clay content and a large number of dissolution particles. Based on the analysis of physical factors, the mercury removal rate and the radius of the pore throat gradually decreased with the depth of the well, and the connectivity of the pore throat in some small layers was poor. The above control factors show obvious difference in vertical direction, which is the main reason for the difference in vertical direction of water sensitivity damage in Minnan 1 well. In addition, through the clay stabilizer loss rate experiment, the two best choices to reduce the water sensitivity damage of Minnan 1 well were optimized. 3% YLN-07 was selected to prevent the loss of clay most effectively, and the clay loss rate was reduced by 14.97%. When economic benefits are taken into account, 0.5% HES clay stabilizer is the best choice, reducing the clay loss rate by 12.5%.