Scientific Drilling into the San Andreas Fault: Rare Gas 'Ages' of Matrix Fluids in Drill Core and Fluid Dynamics

圣安德烈亚斯断层的科学钻探：钻芯中基质流体的稀有气体“年龄”和流体动力学

• 批准号: 0745965
• 负责人: Martin Stute
• 金额: --
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-15 至 2011-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0745965&HistoricalAwards=false
• 关键词: Scientific; Drilling; into; San; Andreas

This project analyzes matrix fluid samples collected during SAFOD Phase III core runs to determine the flow of fluids into/from the fault zone using established noble gas methodologies pioneered by Osenbrueck (1996) and demonstrated by this group [Stute et al.,2005, 2007, Ali et al., 2007, AGU and EarthScope abstracts]. The 17 matrix fluid samples obtained from drillcore collected with previous NSF support during the SAFOD Phase III coring program (2007) will be evaluated with regard to pore fluid ages, age gradients and 3He/4He isotopic profiles of matrix fluids. These results will be interpreted to indicate the magnitude and direction of fluid flow into/from the SAFZ. The 4He and 40Ar "age" of the matrix fluid is a function of the water/rock ratio, production rates in the solid phase and the fraction of produced gases released to the pore fluid. The suite of noble gas isotopes to be measured in this study will be used to separate non-atmospheric (produced and accumulated) and atmospheric noble gas components. Essentially, the outer rind of the recovered drillcore was removed on site immediately after core recovery and a small subsample from the center was placed in a vacuum container. Atmospheric gases were then removed from the container and the container was sealed. Noble gases and matrix fluids are currently diffusing out of the recovered sample. During the course of this project, the noble gases released to the headspace will be determined mass spectrometrically and the total volume of matrix fluid will be determined by weight. Noble gas concentrations in solids are also used to determine the source function for excess noble gas abundances in matrix pore fluids and the release of noble gases from the rock. Step heating experiments will be used to determine the diffusive loss from the solid phase. The calculation of the matrix fluid "age" and "age" gradient will be used to estimate the time scale and direction of fluid transport in/near the fault zone on the time scale of the transport (10s to 100s of years).

该项目分析了 SAFOD 第三阶段岩心运行期间收集的基质流体样本，以确定流体流入/流出断层带的流量，使用由 Osenbrueck (1996) 首创并由该小组证明的既定稀有气体方法 [Stute 等人，2005 年，2007 年，Ali 等人，2007 年，AGU 和 EarthScope 摘要]。在 SAFOD 第三阶段取芯计划（2007 年）期间，从先前 NSF 支持的钻芯中获得的 17 个基质流体样本将根据基质流体的孔隙流体年龄、年龄梯度和 3He/4He 同位素分布进行评估。 这些结果将被解释为表明流体流入/流出 SAFZ 的大小和方向。 基质流体的 4He 和 40Ar“年龄”是水/岩石比、固相生产率以及释放到孔隙流体中的所产生气体的分数的函数。本研究中测量的稀有气体同位素套件将用于分离非大气（产生和积累）和大气稀有气体成分。本质上，在岩心回收后立即将回收的钻芯的外皮在现场去除，并将来自中心的小子样品放入真空容器中。然后从容器中除去大气并将容器密封。 目前，稀有气体和基质流体正在从回收的样品中扩散出来。 在该项目过程中，释放到顶部空间的稀有气体将通过质谱法测定，基质流体的总体积将通过重量测定。固体中的稀有气体浓度也用于确定基质孔隙流体中过量稀有气体丰度的源函数以及稀有气体从岩石中的释放。逐步加热实验将用于确定固相的扩散损失。 基质流体“年龄”和“年龄”梯度的计算将用于估计断裂带内/附近流体在输运时间尺度（10s至100s年）上输运的时间尺度和方向。