Understanding Temporal Variations in Fault-Controlled Fluid Flow

FAIRLEY 0511061断层在地下热量和流体传输中的作用在许多社会和经济重要领域都有影响，如石油和地热储层工程、CO2封存、核废料处理和矿床。 虽然大量的工作表明，热，水化学和压力分布断层可能是由地震活动和热对流不稳定性，建立这些因素之间的明确关系已被证明是困难的，主要是由于无法直接观察地下过程。 在这项研究中，我们将检验一个假设，即在断层控制的泉水中观察到的温度和地球化学变化是地震活动、热对流不稳定和环境强迫（即，昼夜和季节性大气温度变化）。 为了验证这一假设，我们每隔15分钟从18个地热泉收集温度数据，这些地热泉与硼砂湖断层直接水力接触，硼砂湖断层是俄勒冈州东南部Alvord盆地的一个活动正断层。 将使用离散傅立叶分析来分析该温度数据，以建立周期性/准周期性（即，环境强迫）和地震驱动力对春季温度的影响。 将检查与环境和地震驱动因素无关的时间序列数据中的剩余可变性，以获得非线性确定性行为的证据（即，“混沌”），可能是由不稳定的对流或复杂的变化，在应力场的断层。 除了其科学/技术优点，这项研究将进一步在地球科学研究生教育，并通过提供实习和/或暑期研究项目，提高非博士授予机构的本科生的教育机会。

FAIRLEY 0511061The role of faults in subsurface transport of heat and fluids has implications in many socially and economically important areas, such as petroleum and geothermal reservoir engineering, CO2 sequestration, nuclear waste disposal, and ore deposition. Although a large body of work suggests that thermal, hydrochemical, and pressure distributions in faults may be driven by seismic activity and thermal-convective instability, establishing definite relationships between these factors has proven difficult, largely due to inability to observe subsurface processes directly. In this study, we will test the hypothesis that temperature and geochemical variability observed in fault-controlled springs are the result of a combination of seismic activity, thermal-convective instability, and environmental forcing (i.e., diurnal and seasonal atmospheric temperature changes). To test this hypothesis, we are gathering temperature data at 15 minute intervals from 18 geothermal springs that are in direct hydraulic contact with the Borax Lake fault, an active normal fault in the Alvord Basin of southeast Oregon. This temperature data will be analyzed using discrete Fourier analysis to establish the influence of periodic/quasi-periodic (i.e., environmental forcing) and seismic driving forces on spring temperatures. Residual variability in the time-series data not related to environmental and seismic drivers will be examined for evidence of non-linear deterministic behavior (i.e., "chaos") that may arise from unstable convection or complex variations in the stress-field of the fault. Apart from its scientific/technical merits, this research will further graduate education in the geosciences, and enhance educational opportunities for undergraduates from non-PhD granting institutions by providing internships and/or summer research projects.