National Assessment of Oil and Gas Project - Williston Basin Province (031) Assessment Units

The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources. The Assessment Unit is defined within the context of the higher-level Total Petroleum System. The Assessment Unit is shown here as a geographic boundary interpreted, defined, and mapped by the geologist responsible for the province and incorporates a set of known or postulated oil and (or) gas accumulations sharing similar geologic, geographic, and temporal properties within the Total Petroleum System, such as source rock, timing, migration pathways, trapping mechanism, and hydrocarbon type. The Assessment Unit boundary is defined geologically as the limits of the geologic elements that define the Assessment Unit, such as limits of reservoir rock, geologic structures, source rock, and seal lithologies. The only exceptions to this are Assessment Units that border the Federal-State water boundary. In these cases, the Federal-State water boundary forms part of the Assessment Unit boundary.

评价单元（Assessment Unit）是国家未发现油气资源评价项目中用于评估未发现油气资源的基本单元。评价单元的定义依托于更高层级的石油系统（Total Petroleum System）的研究语境。本次展示的评价单元为负责对应油气省的地质学家通过解释、界定与编绘得到的地理边界，其包含一套在石油系统内具备相似地质、地理与时间属性的已知或推测油气藏，相关属性涵盖烃源岩、成藏时序、运移路径、圈闭机制以及烃类类型。评价单元的边界在地质层面被定义为构成该评价单元的各类地质要素的分布范围，例如储集岩、地质构造、烃源岩以及盖层岩性的分布边界。唯一的例外为毗邻联邦-州水域边界的评价单元，此类情形下，联邦-州水域边界将作为评价单元边界的组成部分。