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

漏井是石油和天然气行业最大的环境责任之一。此外，当油井成为“孤儿”（即没有法律责任或经济能力的一方来管理废弃）时，这种责任可以转移到公共资金上，这种情况在当前的经济环境下更为常见。漏水井可能表现出地表套管通风流 (SCVF)，其中气体（主要是甲烷）泄漏到井套管内，和/或气体迁移 (GM)，其中气体从目标或中间区域迁移，或通过井套管中一定深度的孔迁移到地面。特别是，转基因的范围尚未得到很好的界定，气体传输途径尚未得到很好的了解，并且修复工作很少在第一次尝试（或第二次或第三次）中取得成功。显然需要进行研究，以 i) 增加对天然气如何在地下移动的了解，ii) 制定最佳实践来监测和指导泄漏井周围的修复尝试。**与行业合作伙伴和气体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 口井进行非侵入式调查），然后重点关注一个井场，根据之前的调查进行全面详细的研究。项目第一部分将根据各个气体运移服务提供商的管理实践，采用多种气体运移评估方法，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，包括钻探、取芯、地球物理学、广泛的地下水采样等。最终结果将是地下天然气输送的综合概念模型（同类第一个），以及有关泄漏井监测和修复的最佳管理实践的数值模型和指南的开发。************

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.************