Open spaces in epithermal veins of the Bohemia mining district, Oregon, USA, filled with sediments during hydrothermal activity. These sediments consist mainly of chalcedony, rock fragments, and vein quartz fragments. In addition, hematite is deposited during stage three of the vein development. Observed sedimentary features include draping laminae, erosion surfaces, slumping, and graded beddin...

Some of the most difficult coal mine roof in the United States can be found in the Illinois Basin. Factors contributing to the high roof fall rate include weak, moisture-sensitive roof rock; high horizontal stress; and limited longwall mining. The depth of cover ranges from 27 to 300 m (90 to 1,000 ft), and roof damage from horizontal stress can be severe. Moisture-sensitive roof rock, which co...

Abstract As a commonly used and effective technology for increasing the permeability of coal–rock reservoirs, hydraulic fracturing has been widely in engineering sites to realize efficient exploitation utilization gas resources reservoirs. The core is initiation, propagation, path cracks. In this paper, combination true triaxial physical test numerical simulation study influence coal bedding ch...

Coalbed Methane (CBM) is an unconventional form of natural gas which self-generated and self-stored in coal seams. In order to realize the effective exploitation CBM Zhengzhuang block, microstructure, wettability, permeability, rock mechanics in-situ stress were studied this research. It found that high rank anthracite characterized by vitrinite content low inorganic mineral content, abundant C...

The study of rock fractures is essential in evaluating stability of underground structures, understanding earthquakes, and assessing storage and transport of oil and gas in rock formations. Geophysical monitoring techniques, particularly compressional and shear wave propagation, can probe the internal structure of rock and fractures remotely and nondestructively and can provide insight into fra...

We present results of a life cycle assessment (LCA) of Marcellus shale gas used for power generation. The analysis employs the most extensive data set of any LCA of shale gas to date, encompassing data from actual gas production and power generation operations. Results indicate that a typical Marcellus gas life cycle yields 466 kg CO2eq/MWh (80% confidence interval: 450-567 kg CO2eq/MWh) of gre...

In order to solve the bit front rake angle parameter selection problem of under different coal rock, it is proposed in polycrystalline diamond compact no core bit as the research object, and established a bit compact two-dimensional stress model of cutting teeth. The result shows that the front rake angle is the factor of cutting force and the drilling efficiency. Application of Solid Works sim...

By way of introduction, the general invariant integral (GI) based on the energy conservation law is presented, with mention of cosmic, gravitational, mass, elastic, thermal and electromagnetic energy of matter application to demonstrate the approach, including Coulomb's Law generalized for moving electric charges, Newton's Law generalized for coupled gravitational/cosmic field, the new Archimed...

Hydrocarbon wells drilled vertically through longwall coal pillars are vulnerable to severe deformation and potential failure as a result of underground coal mining. The lithology of the host rocks play a critical role in well stability. In this study, a two dimensional finite element method is employed to investigate the horizontal shear offset, vertical delamination, and compression at the we...