Billion Barrels Of Oil Equivalent Research Articles

Exploration of the Brent Province

Abstract The Brent Province is situated in the central part of the northern North Sea between 60°30′ and 62° North. A few licences were issued in 1965 (Round 2) and again in 1969 (Round 3). Seismic exploration from the mid-1960s onwards showed a thick Tertiary/Cretaceous sequence draped unconformably over tilted fault blocks of unknown age. In 1971, coincident with the opening of the 4th Round, Shell’s 211/29–1 pioneered drilling in the area with a major oil discovery, the Brent Field in Middle Jurassic deltaic sandstones. The 4th Round resulted in allocation of almost all the remaining blocks. Between 1972 and 1978, 32 discoveries were made in the UK sector of which 17 are currently in production and a further 7 in the pre-development stage; thereafter only minor reserves have been added, the area now being relatively mature. The exploration history in Norway has been similar although delayed by a few years; it is also less mature as several blocks have still to be explored. Total reserves for the province now approximate to 15 billion barrels of oil equivalent.

Depositional framework and hydrocarbon resources of the early Miocene (Fleming) episode, northwest Gulf Coast Basin

The Fleming Group and its basinward equivalents constitute deposits of a major Cenozoic depositional episode of the northern Gulf Coast Basin. The facies complex is bounded above by the Amphistegina B Shale and below by the Anahuac Shale. Initially, early Miocene (Oakville) progradation built across the broad, submerged shelf platform constructed during the earlier Frio depositional episode. At the Frio paleocontinental margin the rate of outbuilding slowed as large-scale growth faulting created a narrow early Miocene expansion zone. The later part of the episode was characterized by a stable to retreating shoreline and consequent aggradational to retrogradational deposition (Lagarto Formation). The lower Miocene depositional framework includes, in South Texas, the Santa Cruz fluvial system and the North Padre delta system. The bedload fluvial complex fed a wave-dominated delta, which constructed a broadly convex deltaic headland across the foundered Frio Norias delta system. Extensive wave reworking and longshore transport of sand and mud nourished a broad barrier/lagoon and strandplain complex that extended along the central and much of the northeastern Texas coast. This well-known Matagorda barrier/strandplain system was bounded updip by a coastal plain traversed by numerous small intrabasinal streams. Near the present Sabine River westernmost deposits of a continental-scale, mixed-load fluvial and equivalent delta system extend beneath the Texas Coastal Plain and shelf from the Miocene depocenter in Louisiana. Here, the initial phase of early Miocene progradation was also complicated by the incision and filling of numerous submarine gorges. Lower Miocene reservoirs have produced nearly 500 million tonnes (4 billion barrels of oil equivalent (BOE)) of hydrocarbons from nine identified plays in the Texas Coastal Plain and shelf. The most prolific play, the salt domes of the Houston Embayment, accounts for nearly all the oil and more than two-thirds of the total production from the sequence. Four offshore plays offer greatest room for discovery of substantial new reserves, primarily of gas. To date, however, the yield per volume of reservoir sandstone for Miocene plays remains low relative to more prolific units, such as the Frio Formation.

Forecasting petroleum discoveries in sparsely drilled areas: Nigeria and the North Sea

Decline function methods for projecting future discoveries generally capture the crowding effects of wildcat wells on the discovery rate. However, these methods do not accommodate easily situations where exploration areas and horizons are expanding. In this paper, a method is presented that uses a mapping algorithm for separating these often countervailing influences. The method is applied to Nigeria and the North Sea. For an amount of future drilling equivalent to past drilling (825 wildcat wells), future discoveries (in resources found) for Nigeria are expected to decline by 68% per well but still amount to 8.5 billion barrels of oil equivalent (BOE). Similarly, for the total North Sea for an equivalent amount and mix among areas of past drilling (1322 wildcat wells), future discoveries are expected to amount to 17.9 billion BOE, whereas the average discovery rate per well is expected to decline by 71%.

Future of Petroleum Exploration in the United States

The decline of United States oil and natural gas reserves could be moderated by increasing exploratory drilling. During each of the past three years, 1978-1980, the United States produced approximately 3.0 billion barrels of crude oil, 0.7 billion barrels of natural gas liquids, and 20 trillion cubic feet of natural gas, for a total of more than 7 billion barrels of oil equivalent. In contrast, discoveries have been more than 2 billion barrels of oil equivalent. Annual estimates of ultimate recovery (past production plus reserves) are calculated for each year since 1920 by the American Petroleum Institute and the American Gas Association. To each of these estimates, we must add an estimate of future reserve growth resulting from revisions, extensions, new pool discoveries, in-field drilling, and enhanced recovery. From the derived quantities of oil and natural gas discovered each year and from the estimates of the footage drilled annually in new field wildcat wells, the oil and natural gas discovered per foot are estimated. In the late 1940's, the average discovery per foot was more than 350 barrels of oil equivalent. By the late 1970's, the average discovery per foot had dropped to approximately 50 barrels of oil equivalent. Projections of t ese decline curves determine the number of feet of new field wildcats needed to find 2 billion barrels of oil equivalent per year, a limited rate of discovery in the United States. Projecting the average drilling depth permits calculation of the number of needed wildcats per year. The 1979-1990, 12-yr total is 388,514 wells, which is 5 times the drilling rate of recent years. Estimated discoveries are 7% oil and 8% natural gas. The projected increases in drilling and completion costs from 1979 to 1990, in inflated dollars indicate a total cost of $179 billion. Lease, geological and geophysical, development well, and overhead costs are not included. A projected increasing role of natural gas and natural gas liquids in the total energy mix is due to the relatively large proportion of natural gas, on a Btu-equivalent basis, being discovered per foot of new field wildcat drilled. At the present finding rates it is not possible to replace the production of more than 7 billion barrels of oil equivalent. The projected costs are so large that attaining these limited goals, 2 billion barrels of oil equivalent per year, does not seem possible. The total cost of the necessary new field wildcats, $179 billion, is of the same order of magnitude as the estimated federal income from the 'windfall' profits tax for 1980-1990. Total exploration costs, however, would be more than one trillion dollars, $50 per barrel of oil equivalent discovered. In any case, estimates of available oil and natural gas resources indicate that it is possible to moderate the decline in reserves and production.