Singular Integral Equations. By N.I. Muskhelishvili. Translated fromthe 2nd Russian edition by J.R.M. Radok. Pp. 447. F1. 28.50. 1953. (Noordhoff, Groningen)

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A User’s Guide

The validity of the cubic law for laminar flow of fluids through open fractures consisting of parallel planar plates has been established by others over a wide range of conditions with apertures ranging down to a minimum of 0.2 µm. The law may be given in simplified form by Q/Δh = C(2b)3, where Q is the flow rate, Δh is the difference in hydraulic head, C is a constant that depends on the flow geometry and fluid properties, and 2b is the fracture aperture. The validity of this law for flow in a closed fracture where the surfaces are in contact and the aperture is being decreased under stress has been investigated at room temperature by using homogeneous samples of granite, basalt, and marble. Tension fractures were artificially induced, and the laboratory setup used radial as well as straight flow geometries. Apertures ranged from 250 down to 4µm, which was the minimum size that could be attained under a normal stress of 20 MPa. The cubic law was found to be valid whether the fracture surfaces were held open or were being closed under stress, and the results are not dependent on rock type. Permeability was uniquely defined by fracture aperture and was independent of the stress history used in these investigations. The effects of deviations from the ideal parallel plate concept only cause an apparent reduction in flow and may be incorporated into the cubic law by replacing C by C/ƒ. The factor ƒ varied from 1.04 to 1.65 in these investigations. The model of a fracture that is being closed under normal stress is visualized as being controlled by the strength of the asperities that are in contact. These contact areas are able to withstand significant stresses while maintaining space for fluids to continue to flow as the fracture aperture decreases. The controlling factor is the magnitude of the aperture, and since flow depends on (2b)3, a slight change in aperture evidently can easily dominate any other change in the geometry of the flow field. Thus one does not see any noticeable shift in the correlations of our experimental results in passing from a condition where the fracture surfaces were held open to one where the surfaces were being closed under stress.

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VALIDITY OF CUBIC LAW FOR FLUID FLOW IN A DEFORMABLE ROCK FRACTURE - eScholarship

The flow of homogeneous fluids through porous media: analogies with other physical problems

The present invention relates to engineered multivalent and multispecific binding proteins, methods of making, and specifically to their uses in the prevention, diagnosis, and/or treatment of disease.

Dual variable domain immunoglobulins and uses thereof

The Zagros Basin, which extends in a NW-SE orientation across southwestern Iran, is a large tectonically disturbed sedimentary basin that is oil-rich and which has an elevated natural seismicity level. Much of the region appears to be close to criticality, and anthropogenic perturbations can lead to triggering of seismic activity. This article assesses the baseline seismic rate and induced seismicity linked to oil and natural gas development activities in the reservoir structures in the Zagros Basin in the south and southwest of Iran. According to the location analyses of the earthquake data and the b-values map, some reservoirs have a particularly high b-value and these sites of concentrations of induced earthquakes were selected for further analyses. Among these selected reservoirs, Field B, one of the biggest producing oil fields located in the southwest of Iran, was studied. The injection and production history of the field is compared with the annual seismicity recorded for the field and a good correlation was found. The data are discussed in the context of criticality in the natural stress field. A few simple calculations of injection and depletion effects suggest that the seismicity field represents a valuable data source for improved geomechanics management of oil and gas production activities in critically stressed cases.

Induced seismicity risk in Irani oil and gas fields

Optimization of the mining sequence in terms of economics (maximizing net present value) often leads to multi-front mining methods generating pillars. Significant resources are tied up in these pillars, but mining them is often challenging. In order to improve our understanding of rock mass behaviour while extracting these pillars, an extensive monitoring program has been designed and implemented at Vale’s Coleman mine (Sudbury, Canada). The program focuses on existing and new technologies that have potential for monitoring deformation and rock mass property changes. It includes both active and passive methods: gravimeters, multi-point borehole extensometers, fiber optic strain meters, fixed and portable three-component seismic arrays, borehole imaging and sonic logging, and, repeated LiDAR surveys. This paper reports results from an initial project phase, when only a small amount of mining has taken place. The goal was to test and compare technologies in order to assess their sensitivity, accuracy, repeatability and suitability for underground mining conditions. Value is gained by having a broad range of monitoring devices running side by side, enabling comparisons and benchmarking.

Rock mass change monitoring in a sill pillar at Vale's Coleman mine (Sudbury, Canada)

SEGS Reservoir Behavior, Western Canada Sedimentary Basin Case Study

One-dimensional Thermal Conductivity Measurements In Quartz-illite And Smectitic Shales

Differential subsidence after resoiling is observed on reclaimed Canadian prairie strip mines. The overburden consists largely of Cretaceous smectitic clay shales and silts, and is disaggregated on mining, casting and windrow levelling. Hydrocompaction on rewetting causes settlement to occur, mainly in the valley areas of the original spoil windrows. Curing the problem is necessary to achieve a better land use value. Several means are postulated, but remain to be field tested. It is essential to devise rapid field means of estimating efficacy of compactive effort in these smectitic materials so that the mining companies can implement them.

Maurice B. Dusseault

Papers

Induced seismicity risk in Irani oil and gas fields

Rock mass change monitoring in a sill pillar at Vale's Coleman mine (Sudbury, Canada)

SEGS Reservoir Behavior, Western Canada Sedimentary Basin Case Study

One-dimensional Thermal Conductivity Measurements In Quartz-illite And Smectitic Shales

Swelling Clays and Post-reclamation Mine Subsidence in Alberta