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

泄漏威尔斯代表了石油和天然气工业最大的环境责任之一。此外，当威尔斯的油井成为“孤儿”（即没有法律责任方或财政能力方来管理废弃）时，这种责任可能会转移到公共资金中，在目前的经济环境中，这种情况更经常发生。泄漏的威尔斯井可以表现出表层套管通风流（SCVF），其中气体（主要是甲烷）在井套管内部泄漏，和/或气体迁移（GM），其中气体从目标或中间区域迁移，或通过井套管中某个深度处的孔迁移到地面。特别是，转基因的程度没有得到很好的界定，气体传输路径没有得到很好的理解，补救工作很少在第一次尝试（或第二次或第三次）成功。显然需要进行研究，以i）增加关于气体如何在地下移动的知识，ii）制定最佳实践来监测和指导泄漏威尔斯周围的补救措施。 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（在5-6口威尔斯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，以了解以前的调查。根据各个气体迁移服务提供商的管理实践，在项目的第一部分将采用各种气体迁移评估方法，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，包括钻探、取芯、地质物理学、广泛的地下水取样等。最终结果将是一个地下天然气输送的综合概念模型（此类模型中的第一个），以及制定一个数字模型和关于监测和补救泄漏威尔斯的最佳管理做法准则。

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.