Selker Frank, Selker John S
SelkerMetrics, LLC., 4225 SW Agate Lane, Portland, OR 97239, USA.
Department of Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97331, USA.
Sensors (Basel). 2018 Mar 29;18(4):1023. doi: 10.3390/s18041023.
There are few methods to provide high-resolution in-situ characterization of flow in aquifers and reservoirs. We present a method that has the potential to quantify lateral and vertical (magnitude and direction) components of flow with spatial resolution of about one meter and temporal resolution of about one day. A fiber optic distributed temperature sensor is used with a novel heating system. Temperatures before heating may be used to evaluate background geothermal gradient and vertical profile of thermal diffusivity. The innovation presented is the use of variable energy application along the well, in this case concentrated heating at equally-spaced (2 m) localized areas (0.5 m). Relative to uniform warming this offers greater opportunity to estimate water movement, reduces required heating power, and increases practical length that can be heated. Numerical simulations are presented which illustrate expected behaviors. We estimate relative advection rates near the well using the times at which various locations diverge from a heating trajectory expected for pure conduction in the absence of advection. The concept is demonstrated in a grouted 600 m borehole with 300 heated patches, though evidence of vertical water movement was not seen.
目前几乎没有方法能够对含水层和储层中的水流进行高分辨率的原位表征。我们提出了一种方法，该方法有可能以约一米的空间分辨率和约一天的时间分辨率来量化水流的横向和纵向（大小和方向）分量。一种光纤分布式温度传感器与一种新型加热系统配合使用。加热前的温度可用于评估背景地热梯度和热扩散率的垂直剖面。本文提出的创新之处在于沿井身采用可变能量施加方式，在这种情况下，在等间距（2米）的局部区域（0.5米）进行集中加热。相对于均匀加热，这为估算水流运动提供了更大的机会，降低了所需的加热功率，并增加了可加热的实际长度。文中给出了数值模拟结果，展示了预期的行为。我们利用不同位置偏离无平流情况下纯传导预期加热轨迹的时间来估算井附近的相对平流速率。尽管未观察到垂直水流运动的证据，但该概念在一个有300个加热贴片的600米注浆钻孔中得到了验证。
