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.
Added on 28 February, 2014
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”
Added on 24 February, 2014
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.
Added on 01 February, 2014
Sandstone pressures follow the hydrostatic gradient in Miocene strata of the Mad Dog field, deep-water Gulf of Mexico, whereas pore pressures in the adjacent mudstones track a trend from well to well that can be approximated by the total vertical stress gradient. The sandstone pressures within these strata are everywhere less than the bounding mudstone pore pressures, and the difference between them is proportional to the total vertical stress. The mudstone pressure is predicted from its porosity with an exponential porosity-versus-vertical effective stress relationship, where porosity is interpreted from wireline velocity. Sonic velocities in mudstones bounding the regional sandstones fall within a narrow range throughout the field from which we interpret their vertical effective stresses can be approximated as constant. We show how to predict sandstone and mudstone pore pressure in any offset well at Mad Dog given knowledge of the local total vertical stress. At Mad Dog, the approach is complicated by the extraordinary lateral changes in total vertical stress that are caused by changing bathymetry and the presence or absence of salt. A similar approach can be used in other subsalt fields. We suggest that pore pressures within mudstones can be systematically different from those of the nearby sandstones, and that this difference can be predicted. Well programs must ensure that the borehole pressure is not too low, which results in borehole closure in the mudstone intervals, and not too high, which can result in lost circulation to the reservoir intervals.
Added on 31 January, 2014
January 8 the Environmental Protection Agency (EPA) issued a new rule on offshore hydraulic fracturing that takes effect on March 1. The rule adds additional effluent limits and monitoring requirements. Operators would be required to maintain an inventory of chemicals used in drilling operations and report any released into surrounding waters. The new EPA rule applies only to existing development and production platforms, and new exploratory drilling operations in federal waters off the Santa Barbara coast. There are 23 existing production platforms in California federal waters.
Added on 13 January, 2014
Peer-reviewed research from the ongoing EPA hydraulic fracturing study is available, well ahead of the final report that is expected at the end of 2014.
Added on 06 January, 2014
The request to speak at a Florida Legislature Energy Briefing on hydraulic fracturing came from Edie Allison, AAPG’s GEO-DC director, one week before the event.
Added on 01 January, 2014
The presence of natural gas in Kansas was known in pre-territorial time, as it was escaping from “oil springs” in Miami County in the region’s northeast part – there is some evidence that it was collected and used by local American Indians before any easterners settled in what would become the Sunflower State.
Added on 01 December, 2013