O'Malley D, Karra S, Currier R P, Makedonska N, Hyman J D, Viswanathan H S
Computational Earth Science, Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545.
Physical Chemistry and Applied Spectroscopy, Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM, 87545.
Ground Water. 2016 Jul;54(4):488-97. doi: 10.1111/gwat.12380. Epub 2015 Oct 15.
During hydraulic fracturing millions of gallons of water are typically injected at high pressure into deep shale formations. This water can be housed in fractures, within the shale matrix, and can potentially migrate beyond the shale formation via fractures and/or faults raising environmental concerns. We describe a generic framework for producing estimates of the volume available in fractures and undamaged shale matrix where water injected into a representative shale site could reside during hydraulic fracturing, and apply it to a representative site that incorporates available field data. The amount of water that can be stored in the fractures is estimated by calculating the volume of all the fractures associated with a discrete fracture network (DFN) based on real data and using probability theory to estimate the volume of smaller fractures that are below the lower cutoff for the fracture radius in the DFN. The amount of water stored in the matrix is estimated utilizing two distinct methods-one using a two-phase model at the pore-scale and the other using a single-phase model at the continuum scale. Based on these calculations, it appears that most of the water resides in the matrix with a lesser amount in the fractures.
在水力压裂过程中，通常会将数百万加仑的水在高压下注入深层页岩地层。这些水可以储存在裂缝中、页岩基质内，并且有可能通过裂缝和/或断层迁移到页岩地层之外，从而引发环境问题。我们描述了一个通用框架，用于估算在水力压裂过程中注入到代表性页岩场地的水可能会储存在裂缝和未受损页岩基质中的可用体积，并将其应用于一个包含现有现场数据的代表性场地。通过基于实际数据计算与离散裂缝网络（DFN）相关的所有裂缝的体积，并使用概率论来估算DFN中裂缝半径下限以下较小裂缝的体积，从而估算出可储存在裂缝中的水量。利用两种不同的方法估算储存在基质中的水量——一种是在孔隙尺度上使用两相模型，另一种是在连续尺度上使用单相模型。基于这些计算，似乎大部分水储存在基质中，而裂缝中的水量较少。
