Characterization of Hydrologically Active Sheet Fractures

水文活动薄片裂缝的表征

• 批准号: 0001146
• 负责人: Lawrence Murdoch
• 金额: $ 22.5万
• 依托单位: Clemson University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0001146&HistoricalAwards=false
• 关键词: Characterization; Hydrologically; Active; Sheet; Fractures

0001146MurdochSheet fractures in crystalline rock are an important control of ground water whose occurrence, characteristics, and processes of formation are poorly understood. The objective of this project is to combine information from several well-studied sites in the vicinity of western South Carolina with results from a new borehole test to improve the ability to characterize sheet fractures. The new test will use a straddle packer fitted with a precision borehole extensiometer, similar to devices used to measure rock deformation during geothechnical investigations. The device will be centered on a fracture and then used to conduct either injection or recovery tests. The resulting data will provide fracture aperture, or axial displacement of the borehole, as functions of pressure and the volume of injected (or recovered) fluid. The transient aperture change during an injection-displacement test will provide an additional descriptive record that goes beyond what can be measured during conventional packer tests. Preliminary theoretical analyses have been derived, and additional analyses will be developed, to predict transient aperture, volume and driving pressure, as functions of fracture length, spacing, connectivity and other variables. Those solutions will be invested to estimate characteristics of sheet fractures, such as fracture length and connectivity, which are beyond the resolution of conventional packer tests. Characteristics that can be measured using conventional packer test, such as fracture storativity, will also be evaluated using the new method. The results of the analyses will be compared to findings from field mapping of surface exposures, as well as core descriptions, borehole flowmeter logs, temperature logs, borehole radar, concentional packer tests, and other methods. This study will also investigate natural variations in pore-fluid pressure and fracture aperture due to Earth tides, barometric pressure fluctuations or other effects. Those loadings may contribute to the growth of sheet fractures, and provide insights into conceptual models of sheet fracture formation. In addition, the response of fracture aperture to natural stresses holds the potential for estimating properties, such as hydraulic conductivity, storativity and elastic modulus, without pumping tests. The primary contribution of this research is expected to be the development of a new method for determining mechanical and hydrologic characteristics of gently dipping fractures in crystalline rock. This will advance the ability to site productive wells, stimulate well productivity by hydraulic fracturing, and evaluate risks associated with contaminant migration.

0001146结晶岩中的Murdoch席状断裂是地下水的重要控制因素，其发生、特征和形成过程知之甚少。 该项目的目标是将联合收割机的信息与新的钻孔测试结果结合起来，这些信息来自南卡罗来纳州西部附近几个经过充分研究的地点，以提高描述席状裂缝的能力。 新的测试将使用一个跨隔式封隔器，该封隔器配有一个精密的钻孔伸长计，类似于在地质技术调查期间用于测量岩石变形的设备。 该装置将以裂缝为中心，然后用于进行注入或回收测试。 所得到的数据将提供作为压力和注入（或回收）流体的体积的函数的裂缝孔径或钻孔的轴向位移。 注入-驱替测试期间的瞬时孔径变化将提供超出常规封隔器测试期间可测量的额外描述性记录。初步的理论分析已经得出，并将开发更多的分析，以预测瞬态孔径，体积和驱动压力，作为裂缝长度，间距，连通性和其他变量的函数。 这些解决方案将被投资来估计席状裂缝的特征，如裂缝长度和连通性，这超出了常规封隔器测试的分辨率。 可以使用常规封隔器测试测量的特性，如裂缝储集性，也将使用新方法进行评估。 分析结果将与地表暴露的现场测绘结果以及岩心描述、钻孔流量计日志、温度日志、钻孔雷达、浓度封隔器测试和其他方法进行比较。 这项研究还将调查由于地球潮汐、气压波动或其他影响而引起的孔隙流体压力和裂缝孔径的自然变化。 这些载荷可能有助于片层裂缝的生长，并提供对片层裂缝形成概念模型的见解。 此外，裂缝孔径对自然应力的响应具有在不进行抽水试验的情况下估计水力传导率、储气率和弹性模量等特性的潜力。 这项研究的主要贡献预计将是一个新的方法来确定力学和水文特性的缓倾斜裂缝结晶岩石的发展。 这将提高确定生产威尔斯井位置的能力，通过水力压裂提高油井生产率，并评估与污染物迁移相关的风险。