The Total Petroleum System is used in the National Assessment Project and incorporates the Assessment Unit, which is the fundamental geologic unit used for the assessment of undiscovered oil and gas resources. The Total Petroleum System is shown here as a geographic boundary defined and mapped by the geologist responsible for the province and incorporates not only the set of known or postulated oil and (or) gas accumulations, but also the geologic interpretation of the essential elements and processes within the petroleum system that relate to source, generation, migration, accumulation, and trapping of the discovered and undiscovered petroleum resource(s).

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.

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.

The USGS Central Region Energy Team assesses oil and gas resources of the United States. The onshore and State water areas of the United States comprise 71 provinces. Within these provinces, Total Petroleum Systems are defined and Assessment Units are defined and assessed. Each of these provinces is defined geologically, and most province boundaries are defined by major geologic changes. The Yukon Flats Assessment Area is located in east-central Alaska, encompassing part of Yukon-Koyukuk Census Area County in Alaska. The main population centers within the study area are Fort Yukon, Venetie, Stevens Village, and Beaver, Alaska. The main highways, State Route 4 and the Trans-Alaska Pipeline System crosses the western tip of the Yukon Flats Assessment Area and State Route 6 enters the Yukon Flats Assessment Area near the south-east corner approximately 7 km east of Miller House Alaska, and travels north-east to Circle, Alaska on the Yukon River. The Yukon River and Porcupine River and their tributaries drain the area. For this study the Yukon Flats Assessment Area is a region of low, forested hills and flatlands with numerous streams and lakes, situated generally to the east of the Trans-Alaska Pipeline System. The assessment area boundary was drawn to include the geologic structures generally considered to be in or bounding the Yukon Flats Assessment Area.

The USGS Central Region Energy Team assesses oil and gas resources of the United States. The onshore and State water areas of the United States comprise 71 provinces. Within these provinces, Total Petroleum Systems are defined and Assessment Units are defined and assessed. Each of these provinces is defined geologically, and most province boundaries are defined by major geologic changes. The Yukon Flats Assessment Area is located in east-central Alaska, encompassing part of Yukon-Koyukuk Census Area County in Alaska. The main population centers within the study area are Fort Yukon, Venetie, Stevens Village, and Beaver, Alaska. The main highways, State Route 4 and the Trans-Alaska Pipeline System crosses the western tip of the Yukon Flats Assessment Area and State Route 6 enters the Yukon Flats Assessment Area near the south-east corner approximately 7 km east of Miller House Alaska, and travels north-east to Circle, Alaska on the Yukon River. The Yukon River and Porcupine River and their tributaries drain the area. For this study the Yukon Flats Assessment Area is a region of low, forested hills and flatlands with numerous streams and lakes, situated generally to the east of the Trans-Alaska Pipeline System. The assessment area boundary was drawn to include the geologic structures generally considered to be in or bounding the Yukon Flats Assessment Area.

The Total Petroleum System is used in the National Assessment Project and incorporates the Assessment Unit, which is the fundamental geologic unit used for the assessment of undiscovered oil and gas resources. The Total Petroleum System is shown here as a geographic boundary defined and mapped by the geologist responsible for the province, and incorporates not only the set of known or postulated oil and (or) gas accumulations, but also the geologic interpretation of the essential elements and processes within the petroleum system that relate to source, generation, migration, accumulation, and trapping of the discovered and undiscovered petroleum resource(s).

The Total Petroleum System is used in the National Assessment Project and incorporates the Assessment Unit, which is the fundamental geologic unit used for the assessment of undiscovered oil and gas resources. The Total Petroleum System is shown here as a geographic boundary defined and mapped by the geologist responsible for the province, and incorporates not only the set of known or postulated oil and (or) gas accumulations, but also the geologic interpretation of the essential elements and processes within the petroleum system that relate to source, generation, migration, accumulation, and trapping of the discovered and undiscovered petroleum resource(s).

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.

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.

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.