【摘要】 针对页岩储层微纳孔喉结构复杂、非均质性强、传统渗透率法难以准确评价伤害程度的问题,提出基于核磁共振(nuclear magnetic resonance,NMR)技术并结合T2谱归一化处理的伤害评价方法。选取鄂尔多斯盆地延长组长7段与山西组页岩岩心,模拟典型压裂液体系下的储层伤害过程,利用小尺寸岩心在线采集核磁信号,开展归一化定量分析,并与传统渗透率变化率结果进行对比验证。结果表明:两类储层对压裂液的响应存在显著差异:在长7段储层中,清洁压裂液体系的归一化进液量变化率最高(45.06%),而清水体系最低(-3.19%);在山西组储层中,小分子体系表现最优(41.16%),胍胶体系较差(5.02%)。各体系在两类储层中的伤害趋势与渗透率法高度一致,验证了该方法的准确性与可靠性。研究结果表明,“在线核磁共振+归一化分析”可有效减小岩心非均质性和尺寸差异带来的干扰,提升评价结果的可比性与稳定性,为页岩储层伤害识别与压裂液体系优化提供了一种高效可靠的新路径。更多还原

【Abstract】 To address the challenges posed by the complex micro-nano pore structure and strong heterogeneity of shale reservoirs,which limit the accuracy of conventional permeability-based damage evaluation methods, a new evaluation approach based on nuclear magnetic resonance(NMR) combined withT2spectrum normalization was proposed. Shale cores from the Chang 7 Member of the Yanchang Formation and the Shanxi Formation in the Ordos Basin were selected as representatives. Simulated damage experiments were conducted using typical fracturing fluid systems, with NMR signals collected online from small-sized cores and analyzed through normalized processing. The results were then compared with traditional permeability-based evaluations for validation. The results indicate that the two types of reservoirs exhibit significant differences in their response to fracturing fluids: in the Chang 7 reservoir, the clean fracturing fluid system shows the highest normalized fluid intake rate change(45. 06%), while the clean water system has the lowest(-3. 19%). In the Shanxi Formation reservoir, the small-molecule system performs best(41. 16%), whereas the guar gum system shows relatively poorer performance(5. 02%). The damage trends of each system in both reservoir types are highly consistent with the permeability method, validating the accuracy and reliability of this approach. The findings demonstrate that the “ online NMR + normalization analysis” can effectively reduce the influence of core heterogeneity and size differences, enhancing the comparability and stability of evaluation results. This method provides a rapid and robust tool for shale reservoir damage assessment and fracturing fluid optimization.更多还原