Bulletin Article
Umiat field in northern Alaska is a shallow, light-oil accumulation with an estimated original oil in place of more than 1.5 billion bbl and 99 bcf associated gas. The field, discovered in 1946, was never considered viable because it is shallow, in permafrost, and far from any infrastructure. Modern drilling and production techniques now make Umiat a more attractive target if the behavior of a rock, ice, and light oil system at low pressure can be understood and simulated.
The Umiat reservoir consists of shoreface and deltaic sandstones of the Cretaceous Nanushuk Formation deformed by a thrust-related anticline. Depositional environment imparts a strong vertical and horizontal permeability anisotropy to the reservoir that may be further complicated by diagenesis and open natural fractures.
Experimental and theoretical studies indicate that there is a significant reduction in the relative permeability of oil in the presence of ice, with a maximum reduction when connate water is fresh and less reduction when water is saline. A representative Umiat oil sample was reconstituted by comparing the composition of a severely weathered Umiat fluid to a theoretical Umiat fluid composition derived using the Pedersen method. This sample was then used to determine fluid properties at reservoir conditions such as bubble point pressure, viscosity, and density.
These geologic and engineering data were integrated into a simulation model that indicate recoveries of 12%–15% can be achieved over a 50-yr production period using cold gas injection from five well pads with a wagon-wheel configuration of multilateral wells.
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American Association of Petroleum Geologists (AAPG)
Added on 28 February, 2014
Bulletin Article
Organic-carbon–rich shales of the lower Marcellus Formation were deposited at the toe and basinward of a prograding clinothem associated with a Mahantango Formation delta complex centered near Harrisburg, Pennsylvania. Distribution of these organic-carbon–rich shales was influenced by shifts in the delta complex driven by changes in rates of accommodation creation and by a topographically high carbonate bank that formed along the Findlay-Algonquin arch during deposition of the Onondaga Formation. Specifically, we interpret the Union Springs member (Shamokin Member of the Marcellus Formation) and the Onondaga Formation as comprising a single third-order depositional sequence. The Onondaga Formation was deposited in the lowstand to transgressive systems tract, and the Union Springs member was deposited in the transgressive, highstand, and falling-stage systems tract. The regional extent of parasequences, systems tracts, and the interpreted depositional sequence suggest that base-level fluctuations were primarily caused by allogenic forcing—eustasy, climate, or regional thermal uplift or subsidence—instead of basement fault reactivation as argued by previous workers. Paleowater depths in the region of Marcellus Formation black mudrock accumulation were at least 330 ft (100 m) as estimated by differences in strata thickness between the northwestern carbonate bank and basinal facies to the southeast. Geochemical analysis indicates anoxic to euxinic bottom-water conditions. These conditions were supported by a deep, stratified basin with a lack of circulation.
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American Association of Petroleum Geologists (AAPG)
Added on 28 February, 2014
Search and Discovery Article
In recent years, artificial intelligence techniques, and neural networks in particular, have gained popularity in solving complex nonlinear
problems. Permeability, porosity and fluid saturation are three fundamental characteristics of reservoir systems that are typically distributed in a
spatially non-uniform and non-linear manner. In this context, porosity and permeability prediction from well log data is well-suited to neural
networks and other computer-based techniques. The present study aims to estimate formation porosity and permeability from digital well log
data using an artificial neural network (ANN) approach. A representative case study from the Alberta Deep Basin is presented. Five well log
responses (Gamma Ray Log (GR), Deep Resistivity (RD), Formation Density (DEN), Neutron Porosity (PHIN) and Density Porosity (PHID))
are used as inputs in the ANN to predict porosity and permeability. Core porosity and permeability are used as target data in the ANN to test
the prediction. The accuracy of the ANN approach is tested by regression plots of predicted values of porosity and permeability with core
porosity and permeability respectively. Excellent matching of core data and predicted values reflects the accuracy of the technique. ANN is a
fast and accurate method for the prediction of reservoir properties and could be applied in reservoir modeling and characterization.
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American Association of Petroleum Geologists (AAPG)
Added on 25 February, 2014
Energy Policy Blog
By Edith Allison
Witnesses stated that BLM policies create unnecessary obstacles to oil and gas activities on federal lands at a recent House Natural Resources, Energy and Mineral Resources subcommittee hearing: “Energy in America: BLM’s Red-Tape Run Around and its Impact on American Energy Production”
American Association of Petroleum Geologists (AAPG)
Added on 24 February, 2014
Explorer Policy Watch
By Edith Allison
Oil and natural gas production continued to grow in the United States in 2013 even as progress on new federal laws and regulations stalled – but local opposition to shale gas and oil development increased.
American Association of Petroleum Geologists (AAPG)
Added on 01 February, 2014
Explorer Emphasis Article
By Brian Ervin
Icebreaking vessels are the key to navigating the Arctic, and so are in high demand as oil producers set their sights on the vast oil reserves at the top of the world.
American Association of Petroleum Geologists (AAPG)
Added on 01 February, 2014
Explorer Emphasis Article
By Louise Durham
Oil spills are a potential challenge in any corner of the world, but the Arctic brings its own set of challenges to oil production and transportation, and so it needs its own dedicated technologies for meeting them.
American Association of Petroleum Geologists (AAPG)
Added on 01 February, 2014
Explorer Emphasis Article
By David Brown
Arctic pioneers will relate their lessons and experiences from exploring and producing in the frozen north at the third annual Arctic Technology Conference this month in Houston.
American Association of Petroleum Geologists (AAPG)
Added on 01 February, 2014
Explorer Emphasis Article
By Louise Durham
The Final Frontier: The Arctic Circle’s vast, untapped treasures of oil and gas resources beckon explorers to boldly go, despite the daunting technical, political and environmental challenges.
American Association of Petroleum Geologists (AAPG)
Added on 01 February, 2014
Explorer Article
By Jeff Ottmann,Kevin Bohacs
'Breakthrough elegance': ExxonMobil geologists Jeff Ottmann and Kevin Bohacs shared their highly-coveted knowledge on sweet spots and producibility thresholds at a recent Geosciences Technology Workshop on Unconventional Reservoir Quality.
American Association of Petroleum Geologists (AAPG)
Added on 01 February, 2014