Borehole Mining
3 Followers
Recent papers in Borehole Mining
Its significant depth, thin mining interval and low ore permeability made the Aqtau sedimentary uranium deposit a mining challenge. Nevertheless, the growing demand for uranium in the former Soviet Union forced construction of a... more
Its significant depth, thin mining interval and low ore permeability made the Aqtau sedimentary uranium deposit a mining challenge. Nevertheless, the growing demand for uranium in the former Soviet Union forced construction of a gargantuan (3km edge-to-edge) open pit. Strip-mining commenced at the shallowest (40m) flank of the ore body. Over the years, the deepening ore layer pushed the strip-ratio higher and higher and about a quarter of a century later, the overburden (caprock) thickness had reached 80m while the ore body "shrunk" to 0.8m, bringing the stripping ratio to 100. The engineers knew that one day the open pit economics would go below the break-even point and all operations would have to cease. It was calculated that some 40% of the entire ore reserves would be extracted by that time and the question "Then what?" remained on the agenda from day one. About 10 years into production, a then-relatively-new geotechnological method Borehole Mining (BHM) [1] came into consideration. If feasible, it could be used to continue operations for the remaining 60% of the reserves and extend the mine life for an additional 18-20 years. That break-even day was projected to occur in the 1980s. This lead time gave the scientists and engineers plenty of opportunity to investigate the feasibility of BHM, develop the technology and then maximize its potential. R&D, lab tests and field trials were begun in the early 70s, and by the late 80s, BHM had reached a pilot-commercial production stage while the strip mine continued its conventional operations. The Chernobyl disaster, the resulting plunge of uranium prices and disintegration of Soviet Union forced the closure of the entire mine in the early 1990s right when the technology reached a new level: application of a second geotechnological mining method-a post-BHM in-situ leaching (ISL) [2] phase which was seen to have the potential to increase future uranium extraction from 60-65% (BHM) to 85-90% (BHM+ISL). While this second phase of geotechnological phase was not initiated, this project became and remains today the longest-lasting and most commercially successful application of borehole mining in the world. Below, the combined BHM+ISL technology is described in detail.
Recent systematic explorations of oil and natural gas by Japan National Oil Corporation and other oil companies revealed that huge volumes of coal seams lie in the depths of Paleogene and Cretaceous sedimentary basins in central... more
Recent systematic explorations of oil and natural gas by Japan National Oil Corporation and other
oil companies revealed that huge volumes of coal seams lie in the depths of Paleogene and
Cretaceous sedimentary basins in central Hokkaido, off the Pacific coast of northeastern Honshu
and northwest of Kyushu. Deep unmineable coal seams and coaly shale layers may provide
possible sink for CO2 sequestration and source for coalbed methane.
Unmineable coal seams deeper than -1,200m and shallower than -3,000m in Japan exceed 300
Gtons that may store 10 Gtons of CO2 and produce 3 Tm3 of coalbed methane. Very deep
unmineable coal seams deeper than -3,000m in Japan are estimated to exceed 3 Ttons, which may
contain 24 Tm3 of coalbed methane. CO2 sequestration potential of very deep unmineable coal
seams deeper than -3,000m are more than 100 Gtons in Japan.
Total volumes of deep unmineable coalbeds exceed tens to hundreds times of the shallow official
coal reserves that are mineable with conventional drift mining or open-cut mining practices. Huge
volumes of deep unmineable coal seams are potential sinks for CO2 and also untapped enormous
energy resources. Injected pure CO2 behaves readily as a supercritical fluid around injection wells
in deep coal seams. By the supercritical CO2-enhanced coal seam gas recovery (EGR) and in situ
fire-free microbial gasification of coal, deep unmineable coal seams may provide CO2–sink and
methane source for the CO2 emission-free closed-circuit power plant. New type of “coal mine” with
borehole mining method is proposed to develop “deep unmineable coalbeds”.
oil companies revealed that huge volumes of coal seams lie in the depths of Paleogene and
Cretaceous sedimentary basins in central Hokkaido, off the Pacific coast of northeastern Honshu
and northwest of Kyushu. Deep unmineable coal seams and coaly shale layers may provide
possible sink for CO2 sequestration and source for coalbed methane.
Unmineable coal seams deeper than -1,200m and shallower than -3,000m in Japan exceed 300
Gtons that may store 10 Gtons of CO2 and produce 3 Tm3 of coalbed methane. Very deep
unmineable coal seams deeper than -3,000m in Japan are estimated to exceed 3 Ttons, which may
contain 24 Tm3 of coalbed methane. CO2 sequestration potential of very deep unmineable coal
seams deeper than -3,000m are more than 100 Gtons in Japan.
Total volumes of deep unmineable coalbeds exceed tens to hundreds times of the shallow official
coal reserves that are mineable with conventional drift mining or open-cut mining practices. Huge
volumes of deep unmineable coal seams are potential sinks for CO2 and also untapped enormous
energy resources. Injected pure CO2 behaves readily as a supercritical fluid around injection wells
in deep coal seams. By the supercritical CO2-enhanced coal seam gas recovery (EGR) and in situ
fire-free microbial gasification of coal, deep unmineable coal seams may provide CO2–sink and
methane source for the CO2 emission-free closed-circuit power plant. New type of “coal mine” with
borehole mining method is proposed to develop “deep unmineable coalbeds”.
The importance of an accurate geomechanical model for borehole stability assessment is increasing in the petroleum industry due to the growth in the number of drilling operations in unconventional reservoirs. These reservoirs are thin... more
The importance of an accurate geomechanical model for borehole stability assessment is increasing in the petroleum industry due to the growth in the number of drilling operations in unconventional reservoirs. These reservoirs are thin layered, naturally fractured with high clay content; the presence of clay minerals in particular, make their behavior to be unpredictable and also make the rocks to become chemically active with the drilling fluid. Thus, wellbore stability analysis is crucial and challenging; In addition a good understanding of elastic and physiochemical properties of the formation would be necessary for better field development to avoid future financial losses. For this study elastic, petrophysical and physicochemical properties of the shaly Bakken Formation were tested and reported from a several number of core plugs in different wells drilled in the Williston basin, North Dakota. We measured and reported various poro-mechanical, petrophysical and physiochemical properties of the Bakken shale along with the chemical properties of the drilling mud. The direction and the magnitude of the horizontal principal stresses were measured in the field with the data acquired from advanced logging tools in several wells. All of these values are coupled and used as input parameters in a time-dependent chemo-thermo-poroelastic constitutive model to calculate in-situ stresses and pore-pressure variations around the borehole. Changes in radial and hoop stresses were also plotted in the vicinity of the well. Mohr-Columb failure criterion was applied to the model to evaluate the deformations and failure occurrences around the borehole. Finally probabilistic risk assessment was carried out to understand the sensitivity of the results to the uncertainties in the input data.
In this paper an information management system used in Attica Greece that combines modeling with the integrated management of water, sewerage and storm water infrastructure is presented. From this information management system there are... more
In this paper an information management system used in Attica Greece that combines modeling with the integrated management of water, sewerage and storm water infrastructure is presented. From this information management system there are proposed certain public works that are grouped in two categories, i.e. works that are needed for the entire Attica district and have a general character for the whole region (1 st category works) and then, works that are specifically needed for every particular and individual municipality (2 nd category works).
Successful engineering works often benefit from a clear and better understanding of the nature of soil and rock below ground. In the absence of extensive trenching and excavation and to complement noninvasive geophysical exploration... more
Successful engineering works often benefit from a clear and better understanding of the nature of soil and rock below ground. In the absence of extensive trenching and excavation and to complement noninvasive geophysical exploration techniques, borehole investigations can be carried out, including the analysis and characterization of the soil and rock recovered. Such investigations allow the identification of the soils or rocks present, as well as an understanding of their physical properties on the basis of field and laboratory tests. Borehole investigations allow practitioners to determine the nature and location of the different soil/rock layers, collect samples, carry out in situ tests and permeability tests, and, if necessary, install piezometers and other...
In order to increase the productivity from the Three Forks Formation, drilling horizontal well and multilateral ones in particularl seems inevitable. A multilateral well is defined as a single well with one or more wellbore branches... more
In order to increase the productivity from the Three Forks Formation, drilling horizontal well and multilateral ones in particularl seems inevitable. A multilateral well is defined as a single well with one or more wellbore branches radiating from main vertical borehole. A successful multilateral well that replaces several vertical wellbores will not only increase production but also reduces overall drilling and completion costs and allows more efficient hydraulic fracturing operations. Reducing surface impoacs while developing a field is a major benefit of such drilling plan. Well placement and design to have enough stability where in-situ stresses are disturbed dramatically due to short well spacing and stress shadowing is a crucial task, which should be studied prior to any drilling operation. Instability problems in multilateral wells results from stress interplay among nearby wellbores. In this study, stability and stress variation around horizontal section of the high density pad desing also known as pad drilling which is a growing trend in the Bakken and Three Forks operation is studies. Focusing on the Three Forks Formation, mechanical properties of this rock unit such as Poisson's ratio, Young's modulus and Unconfined Compressive Strength (UCS) have been extensively studied and reported through filed data and lab experiments. Next step was to input these parameters plus the calculated in-situ stress for instability analysis and geomechanical modeling into numerical simulation software. Flac 2D was used for this analysis. As the final result, considering the suggested well spacing between two horizontal wells with respect to the direction of the principal horizontal stresses stress perturbation along with failure zones in the horizontal section is presented.
Related Topics