Lithologic description and vertical permeability measurements of ODP Site 180-1109

Vertical permeability testing was conducted on four samples collected from Site 1109, a borehole advanced during Ocean Drilling Program Leg 180. Closed conditions were applied during each test, and the samples were measured using a constant flow approach and permeant solutions that matched the geochemistry of nearby interstitial waters. Vertical permeabilities measured at 34.5 kPa effective stress generally decreased with depth and ranged from 10**-14 m**2 at 212.53 meters below seafloor (mbsf) to 10**-18 m**2 at 698.10 mbsf. The three deepest samples differed in permeability by less than one order of magnitude. Reconsolidation testing on the shallowest sample yielded a minimum permeability of 1.56 x 10**-16 m**2 at 276 kPa effective stress. Subsequent rebound testing yielded a hysteresis-type curve, with the final permeability measuring lower than the initial permeability by nearly 1.5 orders of magnitude. Dilution experiments indicated that use of a permeant solution matching the geochemistry of the interstitial waters may be necessary for accuracy in measurements and mitigation of clay swellage and collapse during testing, but further research is mandated.

本数据集针对大洋钻探计划（Ocean Drilling Program）第180航次在1109站位施工的钻孔采集的4个岩心样品开展了垂向渗透率测试。所有测试均在封闭条件下进行，采用恒定流量法，并以与附近间隙水（interstitial waters）地球化学特征匹配的渗透液完成渗透率测定。在34.5 kPa有效应力（effective stress）条件下测得的垂向渗透率整体随深度增加而降低，数值范围为海底以下212.53米（meters below seafloor，简写为mbsf）处的10⁻¹⁴ m²至海底以下698.10 mbsf处的10⁻¹⁸ m²。3个最深层样品的渗透率差异不足一个数量级。对最浅层样品开展的再固结试验（reconsolidation testing）显示，在276 kPa有效应力条件下，其最低渗透率为1.56×10⁻¹⁶ m²。后续开展的回弹试验（rebound testing）得到了滞后型曲线（hysteresis-type curve），最终测得的渗透率较初始值低近1.5个数量级。稀释试验结果表明，采用与间隙水地球化学特征匹配的渗透液，或为保障测试精度、缓解试验过程中黏土膨胀与坍塌（clay swellage and collapse）现象的必要条件，但该结论仍需进一步研究予以验证。