Outcrop Characterization of Heterogeneity: Explicit Linkage of Hydrological and Sedimentological Properties

9706116史密斯野外对非均质含水层露头模拟的沉积学和水文学研究提供了地下信息无法实现的非均质性的概念化，并提供了一种评估基于井数据内插的流行随机模型的有效性和性能的手段。这种方法在碳氢化合物行业被广泛使用了几十年，但在水文问题上几乎没有应用。对暴露良好的裂谷盆地冲积物的沉积学研究将得到渗透率的现场测量的补充，从而能够指定具有明确的水力传导性、形状和边界的水相，这些水相与岩相有关，其分布与形成含水层材料的沉积过程有关。露头数据将用于在典型的地下污染物迁移情景的尺度上建立非均质性的三维模型。研究地点的地层学也将通过地质统计学技术进行模拟，使用测量剖面作为条件数据，其方式与将数据用于条件地下模型的方式大致相同。模拟的预测能力将通过与露头数据的比较来衡量。露头模型将接受不同尺度(从米到几十米)露头定义的非均质性的流动模拟，以评估高分辨率预测流动路径和流量所需的数据量和类型。为描述露头特征而选择的沉积环境对于了解美国西南部伸展盆地的含水层非均质性尤为重要，因为迄今为止的研究还没有充分描述具有水文地质意义的沉积学特征。不对称伸展盆地中沉积的最大体积的碎屑是从上盘向主断层输送的。这些冲积斜坡相是裂谷盆地中最不为人所知的沉积。该项目将通过提供新墨西哥州里奥格兰德裂谷北部非常暴露的盆地充填序列中的水相渗透率、形状和边界的详细三维记录，产生第一个冲积斜坡沉积的含水层特征的露头模拟。

9706116 Smith Field sedimentological and hydrological studies of outcrop analogs for heterogeneous aquifers provide conceptualizations of heterogeneity unrealized by subsurface information and provide a means for assessing the validity and performance of popular stochastic models based on interpolation of well data. The approach, widely used for decades in the hydrocarbon industry, has seen little application to hydrological problems. Sedimentological studies of well-exposed rift-basin alluvium will be complemented by in-situ measurements of permeability, thus permitting designation of hydrofacies with defined hydraulic conductivity, shape, and boundaries that are linked with lithofacies whose distribution is related to depositional processes that formed the aquifer material. Outcrop data will be used to formulate a three-dimensional model of heterogeneity at the scale of typical subsurface-contaminant-migration scenarios. The study-site stratigraphy will also be simulated by geostatistical techniques using measured sections as conditioning data in much the same way as well data are used to condition subsurface models. The predictive ability of the simulation will be gauged by comparison to the outcrop data. The outcrop model will be subjected to flow simulations for varying scales (meters to tens of meters) of outcrop-defined heterogeneity to evaluate the quantity and type of data required for high-resolution prediction of flow paths and rates. The depositional environment selected for outcrop characterization is especially important for understanding aquifer heterogeneity in extensional basins of the southwestern United States, where studies to date have not adequately described the sedimentological characteristics that are of hydrogeological importance. The largest volume of clastic detritus deposited in asymmetric extensional basins is delivered from the hanging wall to the master fault. These alluvial-slope facies are the least well known deposits in rift basins. This projec t will produce the first outcrop analog for aquifer characteristics of alluvial-slope deposits by providing detailed three dimensional documentation of hydrofacies permeability, shape, and boundaries within an extraordinarily well exposed basin-fill sequence in the northern Rio Grande rift of New Mexico.