No abstract available

[en] We initially hypothesized that a nuclear detonation below the water table in a high porosity medium will preferentially compact the void space above and along the water table, which may result in a broad early-time subsidence at the surface. Ground motion measurements show rapid compaction above such events. Hydrodynamic calculations are presented, which provide some insight into these subsidence phenomena. The work is in progress and conclusions are still tentative

[en] Mine layouts, new machines and techniques, research into problem areas of ground control and so on, are highlighted in this report on extending mine life. The main resources taken into account are coal mining, uranium mining, molybdenum and gold mining

[en] This is the most advanced computed technique on Terra Mod software for interpretation of tectonic subsidence and hydrocarbon generation. This techniques is used for the first time for a Pakistani geological basin. The actual subsurface data of 6-wells of the Offshore Indus Basin of Pakistan were used for this study. The results were found very useful, as this study negated the earlier concept of existence of immature or partially mature hydrocarbon source rock in this basin. The results of this interpretation may help to attract the oil companies to re-consider Offshore Indus Basin for investment in hydrocarbon exploration. (author)

[en] Subsidence in Burgan oil field of Kuwait has been studied by Interferometric technique using Synthetic Aperture Radar data. Repeat pass Interferometry is applied to the study area that accounts for infinitesimal changes in the topographic elevations. Subsidence of about 27 mm over a period of 3 years was estimated in Burgan oil field area. The study is significant since continued subsidence may result in reduction of porosity of host formation and may activate the sub-surface geological structures, which can compromise the integrity of the reservoir seal, leading to migration of hydrocarbons to other formations and areas

[en] A bullet containing the radioactive source is propulsed through the formation by explosives. Beside means to reduce velocity inside the soft formation are provided preferentially by bracing to control penetration of the formation. The radioactive source allows subsidence measurement

[en] In the oil and gas sector, onshore buried steel pipelines are the principal means used for transportation and distribution. However, in mining areas, ground deformation can increase the pipeline's failure probability and this has to be taken into account in pipeline design, construction and operation. The aim of this paper is to propose a mechanical model of oil and gas pipeline in areas where there is mining subsidence. Numerical simulations were carried out on X70 grade oil pipes with different wall thicknesses, outside diameters and buried depths and the deformation characteristics were analyzed. Results showed that wall thickness is the parameter which has the greatest impact on strains; buried depth has a greater impact than outside diameter, except in creeping state. This study highlighted the impact of wall thickness, outside diameter and buried depth on pipeline strains and provided guidance for design, route selection and operation of pipeline in areas where there is mining subsidence.

[en] A single-axis sodar system, with off-line Doppler analysis, has been operated in the month of january 1987 at the italian antarctic base near Terra Nova bay. The instrument was installed in complex terrain at a distance of approximately 1 km from the shore-line. During the campaign the area around the station, for a width of about 2-3 km from the shore, was completely deglaciated and exposed to periods of direct solar irradiation. The measurements were carried out almost continously with the antenna pointing to the zenith or at zenith angles of 20 and 30 in the NE direction. From a preliminary analysis of the data, the main phenomena observed were as follows: a) very intense convection during periods of insolation with vertical velocities up to 4 m/s. b) Evidence of layering and Kelvin-Helmholtz instabilities. c) Strong subsidence

[en] A review of the application of existing subsidence prediction methods available is presented. A brief description of all the three methods - empirical, functional and mechanistic - is given and merits and demerits of each method are discussed. A review of the applications of each method in different parts of the world and recommendations for research on further improvements in each method are given for the state of the art of subsidence prediction. Methods using the functional approach, especially those of influence function, are found, at present, to be the most reliable and practicable; however there is still scope for improvements in this approach, to incorporate the effects of various subsidence-inducing parameters by the use of complementary functions. 31 refs., 13 figs

[en] Adequate monitoring and proper intervention can significantly increase a pipeline's chances of surviving the strains of soil subsidence in an area of longwall mining. The first part of this article on the effects of longwall mining on underground pipelines presents a technique for monitoring those effects. The concluding part examines intervention options and discusses the benefits of exposing pipelines in longwall mining areas. Longwall mining can constitute a threat to the integrity of a pipeline by way of surface subsidence and soil strains. The usual effects on a pipeline of mining-induced subsidence are increased axial and flexural strains affecting its longitudinal strength. In the presence of severe circumferentially oriented defects and added tensile strain, a rupture is possible. In the presence of added compressive strain, buckling of the pipe may occur. Pipeline operators can use available predictive methods and geophysical data to estimate the potential effects of longwall mining, and they can monitor their pipelines and intervene if necessary to prevent a pipeline failure due to subsidence