Field investigation of surface casing vent flow and gas migration around leaky petroleum wells

泄漏井是油气行业最大的环境负担之一。此外，当油井成为“孤儿”（即没有法律上负责或经济上有能力的一方来管理遗弃）时，这种责任可以转移到公共钱包，这种情况在当前的经济气候中更经常发生。泄漏井可能会出现地面套管排气流（SCVF），即气体（主要是甲烷）在套管内泄漏，以及/或气体迁移（GM），即气体从目标层或中间层，或通过一定深度的套管孔迁移到地面。特别是，转基因的范围没有很好地描述，天然气运输途径没有很好地理解，补救努力很少在第一次尝试（或第二次或第三次）成功。很明显，我们需要进行研究，1)增加关于天然气在地下如何运动的知识，2)制定最佳实践，以监测和指导泄漏井周围的补救措施。**与行业合作伙伴和天然气运移服务提供商合作，该项目将包括在选定的泄漏井场进行一系列调查，从广泛的范围开始（对5-6口井进行非侵入性调查），然后集中在一个井场进行全面详细的研究。根据各个天然气运移服务提供商的管理实践，在项目的第一部分将采用各种天然气运移评估方法，这将允许在提供SCVF/GM数据的同时对方法和技术进行比较。然后，这些信息将用于进行详细的地下调查，包括钻井、取心、地球物理、广泛的地下水采样等。最终的结果将是一个全面的地下天然气输送概念模型（同类中的第一个），以及关于监测和补救泄漏井的最佳管理实践的数值模型和指导方针的发展。************

Leaky wells represent one of the greatest environmental liabilities to the oil and gas industry. Furthermore, this liability can be transferred to the public purse when wells become "orphaned" (i.e. no legally responsible or financially able party exists to manage abandonment), which is occurring more frequently in the current economic climate. Leaky wells can exhibit surface casing vent flow (SCVF), where gas (primarily methane) leaks inside the well casing(s), and/or gas migration (GM), where gas migrates from the target or intermediate zone, or through a hole in the well casing at some depth, to the ground surface. In particular, the extent of GM is not well delineated, gas transport pathways are not well understood, and remediation efforts are rarely successful on the first attempt (or second or third). There is a clear need for research to i) increase knowledge about how gas moves in the subsurface and ii) to develop best practices to monitor and guide remediation attempts around leaky wells.**In collaboration with industry partners and gas migration service providers, this project will comprise a series of investigations at select leaky well sites, starting broad in scope (non-intrusive investigations at 5-6 wells) before focusing on one well site to conduct a comprehensive detailed study informed by the previous investigations. A variety of gas migration assessment approaches will be employed in the first part of the project, as per management practices of individual gas migration service providers, which will allow comparison of methods and techniques while providing data on SCVF/GM. This information will then be used to conduct a detailed subsurface investigation, including drilling, coring, geophysics, extensive groundwater sampling, among others. The end result will be a comprehensive conceptual model of subsurface gas transport (the first of its kind) as well as the development of a numerical model and guidelines for best management practices regarding monitoring and remediation of leaky wells.************