This report was prepared to provide a concise description of offshore operations related to exploration for petroleum (oil and natural gas} from the initial geologic and geophysical investigations to production. Petroleum deposits differ in their physical and chemical properties and are associated in the rocks with saline water. The origin of petroleum and its migration through rocks are not well understood. Commercial accumulations are found in certain suitable rocks or geologic structures - stratigraphic and structural traps, respectively. Prospective areas offshore are leased to exploration companies by the federal government. Exploration begins with geological and geophysical investigations that lead to the selection of smaller, promising areas. Detailed studies and drilling are then carried out and, if petroleum is found, various tests are performed to determine the volume of oil or gas or both. If the quantities are large, production facilities are designed and located on the site. The petroleum produced is transported to refining facilities or gas companies onshore by pipelines or tankers. Experience has shown that large, damaging oil spills are very rare. The most common cause of spills is marine transportation. To find new, large petroleum accumulations exploration will have to be expanded into deeper waters and into less hospitable regions.
MS5 Map of Exposed and Buried Early Mesozoic Rift Basins/Synrift Rocks of the U.S. Middle Atlantic Continental Margin
A series of elongate rift basins of early Mesozoic age is exposed in eastern North America in a belt extending from Nova Scotia to South Carolina. The Upper Triassic-Lower Jurassic synrift rocks that fill the basins are called the Newark Supergroup comprising continental (fluvial and lacustrine) clastic sedimentary rocks (predominantly colored red) interbedded with basaltic volcanic rocks (Froelich and Olsen, 1985). Similar basins are buried beneath the sediments of the Atlantic Coastal Plain and continental shelf.
MS2 Structure Contour Map of Pre-Mesozoic Basement, Landward Margin of Baltimore Canyon Trough (North and South Sections)
The structure contour map of pre-Mesozoic basement
indicates the structural complexity of the landward margin of
the Baltimore Canyon trough, especially that shown by the
buried rift basins of probable early Mesozoic age. Information
on depth to basement is important in determining the economic
limit of drilling through overlying rocks in the search for oil
The nature and occurrence of subsurface resources, whether ground water, minerals, or petroleum, are controlled by the geologic history and framework of any particular area. Several years ago the staff of the Delaware Geological Survey began an informal assessment of the potential resources of southern Delaware and demonstrated the lack of basic data on the deep subsurface in this area. This assessment was later summarized by Benson (1976) with particular emphasis on the possibilities for petroleum occurrence.
This review summarizes the present knowledge of the subsurface geology and resource potential of southern Delaware and outlines the needs for future studies to gain further understanding of these matters. Because of the present interest in exploring for oil and gas beneath the Atlantic Outer Continental Shelf it is most timely that the primary resource considered in this report be the hydrocarbon (petroleum and natural gas) potential of the State. Hydrocarbons occur in commercial quantities only in thick sections of sedimentary rock, therefore, southern Delaware (primarily Sussex County) is the focus of this study because the thickest sedimentary rock section in the State is here. Assessment of the hydrocarbon potential of this area also has bearing on other resources such as groundwater (both fresh water and subsurface brines), underground storage of natural gas, and underground waste disposal.
RI36 History of Oil and Gas Exploration in the Mid-Atlantic Region and Delaware's Involvement in the Federal OCS Leasing Program
There has been sporadic exploration for oil and gas in the Mid-Atlantic region for over 50 years. Non-commercial deposits of oil and gas have recently been discovered in the sedimentary rock section of the Outer Continental Shelf (OCS) 80 miles off the New Jersey-Delaware coast. The oil and gas occurs within entrapment structures in ancient rocks deposited and buried in a deep basin called the Baltimore Canyon trough. This trough forms part of the Coastal Plain and continental shelf geologic provinces on the Atlantic Coast.
It is now possible to evaluate some of the earlier assessments and offer tentative conclusions about the hydrocarbon resource potential of the Baltimore Canyon trough, a major northeast-southwest trending sedimentary basin off the Mid-Atlantic coast of the United States. For this purpose the Delaware Geological Survey has examined more than 2,500 miles (4,022 km) of seismic reflection profiles, the results of some offshore magnetic and gravity surveys, the results of the COST B-2 well, and the nonproprietary results through 1978 of exploratory drilling by the petroleum industry on federal leases.