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Bulletin Article

5777
 

The influence of moisture, temperature, coal rank, and differential enthalpy on the methane (CH4) and carbon dioxide (CO2) sorption capacity of coals of different rank has been investigated by using high-pressure sorption isotherms at 303, 318, and 333 K (CH4) and 318, 333, and 348 K (CO2), respectively. The variation of sorption capacity was studied as a function of burial depth of coal seams using the corresponding Langmuir parameters in combination with a geothermal gradient of 0.03 K/m and a normal hydrostatic pressure gradient. Taking the gas content corresponding to 100% gas saturation at maximum burial depth as a reference value, the theoretical CH4 saturation after the uplift of the coal seam was computed as a function of depth. According to these calculations, the change in sorption capacity caused by changing pressure, temperature conditions during uplift will lead consistently to high saturation values. Therefore, the commonly observed undersaturation of coal seams is most likely related to dismigration (losses into adjacent formations and atmosphere). Finally, we attempt to identify sweet spots for CO2-enhanced coalbed methane (CO2-ECBM) production. The CO2-ECBM is expected to become less effective with increasing depth because the CO2-to-CH4 sorption capacity ratio decreases with increasing temperature and pressure. Furthermore, CO2-ECBM efficiency will decrease with increasing maturity because of the highest sorption capacity ratio and affinity difference between CO2 and CH4 for low mature coals.

5776
 

The origin of thermogenic natural gas in the shallow stratigraphy of northeastern Pennsylvania is associated, in part, with interbedded coal identified in numerous outcrops of the Upper Devonian Catskill and Lock Haven Formations. Historically documented and newly identified locations of Upper Devonian coal stringers are shown to be widespread, both laterally across the region and vertically throughout the stratigraphic section of the Catskill and Lock Haven Formations. Coal samples exhibited considerable gas source potential with total organic carbon as high as 44.40% by weight, with a mean of 13.66% for 23 sample locations analyzed. Upper Devonian coal is thermogenically mature; calculated vitrinite reflectances range from 1.25% to 2.89%, with most samples falling within the dry-gas window. Source potential is further supported by gas shows observed while drilling through shallow, identifiable coal horizons, which are at times located within fresh groundwater aquifers. Thermogenic gas detected in area water wells during predrill baseline sampling is determined not only to be naturally occurring, but also common in the region.

Bulletin E P Note

7959
 

The petroleum trap for the Athabasca oil sands has remained elusive because it was destroyed by flexural loading of the Western Canada Sedimentary Basin during the Late Cretaceous and Paleocene. The original trap extent is preserved because the oil was biodegraded to immobile bitumen as the trap was being charged during the Late Cretaceous. Using well and outcrop data, it is possible to reconstruct the Cretaceous overburden horizons beyond the limit of present-day erosion. Sequential restoration of the reconstructed horizons reveals a megatrap at the top of the Wabiskaw-McMurray reservoir in the Athabasca area at 84 Ma (late Santonian). The megatrap is a four-way anticline with dimensions 285 x 125 km (177 x 78 mi) and maximum amplitude of 60 m (197 ft). The southeastern margin of the anticline shows good conformance to the bitumen edge for 140 km (87 mi). To the northeast of the anticline, bitumen is present in a shallower trap domain in what is interpreted to be an onlap trap onto the Canadian Shield; leakage along the onlap edge is indicated by tarry bitumen outliers preserved in basement rocks farther to the northeast. Peripheral trap domains that lie below the paleospillpoint, in northern, southern, and southwestern Athabasca, and Wabasca, are interpreted to represent a late charge of oil that was trapped by bitumen already emplaced in the anticline and the northeastern onlap trap. This is consistent with kimberlite intrusions containing live bitumen, which indicate that the northern trap domain was charged not before 78 Ma. The trap restoration has been tested using bitumen-water contact well picks. The restored picks fall into groups that are consistent both with the trap domains determined from the top reservoir restoration and the conceptual charge model in which the four-way anticline was filled first, followed by the northeastern onlap trap, and then the peripheral trap domains.

DL Abstract

3102
 

Challenges for global gas shale production include infrastructural and geological with the Marcellus providing an analogue for both. (Infrastructural) The production from the Marcellus gas shale presents unique challenges that include issues associated with leasing, geology, landowners, virtually no deep disposal wells, state governments without a severance tax, several river basin commissions, an infrastructure designed for shallow gas production, an emotional group of environmentalists, and one state that has yet to permit horizontal well stimulation.

3082
 

Using examples from shale reservoirs worldwide, I demonstrate the diversity of shale-hosted fracture systems and present evidence for how and why various fractures systems form. Core and outcrop observations, strength tests on shale and on fractures in core, and geomechanical models allow prediction of fracture patterns and attributes that can be taken into account in well placement and hydraulic fracture treatment design. Both open and sealed fractures can interact with and modify hydraulic fracture size and shape. Open fractures can enhance reservoir permeability but may conduct treatment fluids great distances, in some instances possibly aseismically.

Explorer Article

8490
 

If you want to know about the Eagle Ford play in Texas, AAPG member Art Donovan is a man you want to be talking to.

8486
 

Robert G. Loucks, a senior research scientist at the Bureau of Economic Geology, University of Texas at Austin, is one of this year’s Robert R. Berg Outstanding Research Award winners. 

8473
 

Shale formations can confound even the savviest geoscientist when it comes to determining the inner workings of the rock. After expert evaluation, even the most attractive prospecting deal can be a tough sell. And there’s almost always a new piece to each of these puzzles that requires some sophisticated high-tech explaining.

8045
 

Oklahoma! As-yet unlocked SCOOP and STACK plays have plen’y of room for maturation and development.

Explorer Division Column EMD

3800
 

Every six months, chairs of the Energy Minerals Division committees convene and report on developments in the areas they cover. In this column, we highlight important observations from these recent reports.

Field Seminar

Great Falls Montana United States 08 September, 2014 13 September, 2014 150
 
Great Falls, Montana, United States
8-13 September 2014

The seminar will utilize traverses to examine multiple thrust sheets exposed in Sun River Canyon, the famous Teton Anticline, and an outstanding example of an exposed fractured reservoir along a fault‐propagated fold in Mississippian carbonates as Swift Reservoir. Participants will examine the mechanics of fracturing, folding, and faulting in thrust belt terrains, identify and discuss new ideas regarding the geometry and kinematics of the development of thrust belts, compare seismic interpretation with outcrop examples, and analyze stratigraphic concepts which are essential in the exploration of thrust belt targets.

Short Course

Austin Texas United States 29 April, 2014 01 May, 2014 1518
 
Austin, Texas, United States
29 April - 1 May 2014

The overall goal of this course is to provide tools for efficient and effective re-exploration and development. It uses a two-part approach. First it uses petrophysical analysis to understand all that can be derived from examination of standard open-hole logs. This is followed by integrated approaches to discover key factors controlling oil and gas distribution in carbonate reservoirs in the greater Midcontinent USA. Methodologies and workflows reviewed include geosteering and evaluation of horizontal wells and optimizing carbon storage utilization and management.

Workshop

Muscat Oman 20 October, 2014 22 October, 2014 8553
 
Muscat, Oman
20-22 October 2014

This three-day workshop will be dedicated to sharing knowledge, ideas, and workflows pertaining to exploration for stratigraphically trapped hydrocarbon accumulations in the Middle East. The workshop will emphasize case studies involving both carbonates and clastics — in order to help focus explorationists in their search for these types of traps. 

Dubai United Arab Emirates 21 September, 2014 24 September, 2014 8548
 
Dubai, United Arab Emirates
21-24 September 2014

Leveraging from global analogues, the workshop aims to apply lessons worldwide to the Middle East Shale Gas setting. Additionally, the workshop will explore several distinct features in the region. We anticipate rich discussions to further understand these new potential reservoirs. 

Rio de Janeiro Brazil 14 May, 2014 15 May, 2014 1502
 
Rio de Janeiro, Brazil
14-15 May 2014

Join the discussion with leading operators in Latin America and Africa. Gain greater understanding of geological and geophysical attributes of stratigraphic traps in deep water settings. Learn more from equatorial margin exploration analogues.

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