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Discovering mineral resources
SITE INVESTIGATION:GENERAL 961180 The present-day stress regime in some deep structures of quadrant 25, offshore Norway G. Caillet, R. Deboaisne, B. Mathis & C. Roux, Bulletin Centres de Recherches Exploration-Production Elf Aquitaine, 18(2), 1994, pp 381-390. The present-day stress regime in the north of the quadrant 25, in the Norwegian North Sea, has been investigated using well logs and drilling records. The results of ten wells have been considered as reliable and representative of the area. A regional stress field where oV > oH > oh is probable. The direction of the main horizontal stress, oH, is N 50 in the undeformed Tertiary and Cretaceous formations, and a near isotropic situation characterizes the deep Jurassic structures. Because of the influence of some major faults on the stress distribution, it is not possible to use the orientation of stress to predict the main direction of fluid flow. It would also be difficult to predict preferential directions for hydraulic fracturing. (from Authors)
Measurement of in situ stress 961181 O tensor de teasoes virgens de Serra da Mesa: a sue detenninacao pelo ensaio de fruturamento hidranlico (The virgin stress tensor of Serra da Mesa: its determination utilizing the hydraulic fracturing test) J. A. De Mello Franco & L. A. C. Batista dos Santos, Solos e Rochas, 17(3), 1994, pp 167-180. In this paper a critical review of the techniques for the hydraulic fracturing test interpretation is tentatively presented. The mechanical properties and structural features of the Serra da Mesa's rock mass are presented. Also the concepts of the different rock stress tensors are mentioned. Results are also shown and coupled to the Serra da Mesa lithology. The authors also intend to stimulate the measuring of in situ virgin stress, so that a database is presently composed for utilization in future works in Brazil. (from English summary) 961182 Evaluation of fracture treatments using a layered reservoir description: field examples Z. Rahim, S. A. Holditch, M. D. Zuber & D. Buehring, Journal of Petroleum Science & Engineering, 12(4), 1995, pp 257-267. A practical analysis technique for the determination of actual fracture geometry and proppant profile using a three-dimensional hydraulic fracturing simulator is presented in this paper. A guideline has been presented to properly describe the treatment interval, analyze the fracture treatments using field measured data, and to confirm the results using pressure transient tests and production data analysis. The examples illustrate that detailed description of the reservoir layers is essential to properly evaluate hydraulic fracture treatments. (from Authors) 961183 Evaluation of jetting insertion for the self-boring pressuremeter J. Benoit, M. J. Atwood, R. C. Findlay & B. D. Hilliard, Canadian Geotechnical Journal, 32(1), 1995, pp 22-39. The primary objectives of the self-boring pressuremeter (SPBM) test are to measure, in situ, the horizontal stress and the stress-strain characteristics of soils and soft rocks. A jetting insertion method was introduced and designed to allow a faster rate of insertion using a system that is less equipment intensive and easily adapted to conventional drill rigs. A series of laboratory simulation tests and in situ selfboring pressuremeter tests were carded out in two soft clay deposits to assess the jetting method. The results of this study indicate that, as with the cutting method, the jetting method can be used in soft to medium clays to advance the self-boring pressurerneter with minimum disturbances. (from Authors)
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961184 The influence of constitutive models on self-boring pre~ suremeter interpretation in clay C. N. Pye, Canadian Geotechnical Journal, 32(3), 1995, pp 420-427. A comparison of the elastic-perfectly plastic (EPP) and hyperbolic (HB) theories for interpreting loading and unloading parts of self-boring pressuremcter (SBP) tests in clay is presented. Computer-aided modellilng is used to analyze 60 SBP tests in clay to obtain shear modulus (63 undrained shear strength (S~), and in situ total horizontal geostatic stress (OH0). For both models the inferred horizontal geostatic stresses are identical and comparable to 'lift-off" measurements. A small systematic difference is found between the two models for the undrained shear strength of soft and stiff clays. The shear modulus valves derived from the EPP model are unrelated to the true modulus of the soil There is, however, a semiempirical relationship between the HB model and pressuremeter unload-reload (UR) shear modulus. (from Author)
SITE INVESTIGATION AND FIELD OBSERVATION General 961185 Geoscience 1994 and beyond: thoughts on geology and exploration for world-class ore deposits P. J. Legge, Australian Journal of Earth Sciences, 42(1), 1995, pp 1-10. Australia's income is largely dependent on the mining of world-class ore deposits replenishment of which relies on successful exploration strategies. Exploration strategies are guided by models of ore deposit occurrence and formation derived from both observation and an understanding of geological process. New technology is dramatically affecting geology at all scales and, while the use of tried and proven methods continues, digital data acquisition and analysis, a product of Global Positioning Systems and Geographic Information Systems, amongst others, is becoming integral with geology. A revolution in the electronic storage, retrieval and use of information is taking geology into the world of information cyberspace where publication media are undergoing a paradigm shift. Geology continues to be a resource sector industry advocating the balanced study and sustainable development of minerals for national prosperity but still needs to capture the belief and support of the community. (from Author) 961186 Discovering mineral resources G. M. Brown, Nature & Resources, 30(3-4), 1994, pp 9-20. The aim of this IGCP research is generally to optimize the global or regional information on particular resources and to develop ideas about their further investigation. In many cases, these ideas have led to important new discoveries of economic importance. The eight projects reviewed here include global phosphate deposits; regional base-metal and rare-metal deposits; and global geochemical data-ax'zluisition for economic and environmental purposes. (from Author) 961187 Greece Hcensing round to focus on western sedimentary basins N. Roussos & F. Marnelis, Oil & Gas Journal, 93(10), 1995, pp 58-62. Briefly reviews hydrocarbon exploration activity in Greece. An international licensing round for offshore and onshore areas, mainly in western Greece, is due in the second half of 1995. Geology of eastern and western Greece is outlined and geology and development of the West Katakolon, Prinos and Epanomi fields are described. (J.M.MeLaughlin)
Measurement of in situ stress 961181 O tensor de teasoes virgens de Serra da Mesa: a sue detenninacao pelo ensaio de fruturamento hidranlico (The virgin stress tensor of Serra da Mesa: its determination utilizing the hydraulic fracturing test) J. A. De Mello Franco & L. A. C. Batista dos Santos, Solos e Rochas, 17(3), 1994, pp 167-180. In this paper a critical review of the techniques for the hydraulic fracturing test interpretation is tentatively presented. The mechanical properties and structural features of the Serra da Mesa's rock mass are presented. Also the concepts of the different rock stress tensors are mentioned. Results are also shown and coupled to the Serra da Mesa lithology. The authors also intend to stimulate the measuring of in situ virgin stress, so that a database is presently composed for utilization in future works in Brazil. (from English summary) 961182 Evaluation of fracture treatments using a layered reservoir description: field examples Z. Rahim, S. A. Holditch, M. D. Zuber & D. Buehring, Journal of Petroleum Science & Engineering, 12(4), 1995, pp 257-267. A practical analysis technique for the determination of actual fracture geometry and proppant profile using a three-dimensional hydraulic fracturing simulator is presented in this paper. A guideline has been presented to properly describe the treatment interval, analyze the fracture treatments using field measured data, and to confirm the results using pressure transient tests and production data analysis. The examples illustrate that detailed description of the reservoir layers is essential to properly evaluate hydraulic fracture treatments. (from Authors) 961183 Evaluation of jetting insertion for the self-boring pressuremeter J. Benoit, M. J. Atwood, R. C. Findlay & B. D. Hilliard, Canadian Geotechnical Journal, 32(1), 1995, pp 22-39. The primary objectives of the self-boring pressuremeter (SPBM) test are to measure, in situ, the horizontal stress and the stress-strain characteristics of soils and soft rocks. A jetting insertion method was introduced and designed to allow a faster rate of insertion using a system that is less equipment intensive and easily adapted to conventional drill rigs. A series of laboratory simulation tests and in situ selfboring pressuremeter tests were carded out in two soft clay deposits to assess the jetting method. The results of this study indicate that, as with the cutting method, the jetting method can be used in soft to medium clays to advance the self-boring pressurerneter with minimum disturbances. (from Authors)
23A
961184 The influence of constitutive models on self-boring pre~ suremeter interpretation in clay C. N. Pye, Canadian Geotechnical Journal, 32(3), 1995, pp 420-427. A comparison of the elastic-perfectly plastic (EPP) and hyperbolic (HB) theories for interpreting loading and unloading parts of self-boring pressuremcter (SBP) tests in clay is presented. Computer-aided modellilng is used to analyze 60 SBP tests in clay to obtain shear modulus (63 undrained shear strength (S~), and in situ total horizontal geostatic stress (OH0). For both models the inferred horizontal geostatic stresses are identical and comparable to 'lift-off" measurements. A small systematic difference is found between the two models for the undrained shear strength of soft and stiff clays. The shear modulus valves derived from the EPP model are unrelated to the true modulus of the soil There is, however, a semiempirical relationship between the HB model and pressuremeter unload-reload (UR) shear modulus. (from Author)
SITE INVESTIGATION AND FIELD OBSERVATION General 961185 Geoscience 1994 and beyond: thoughts on geology and exploration for world-class ore deposits P. J. Legge, Australian Journal of Earth Sciences, 42(1), 1995, pp 1-10. Australia's income is largely dependent on the mining of world-class ore deposits replenishment of which relies on successful exploration strategies. Exploration strategies are guided by models of ore deposit occurrence and formation derived from both observation and an understanding of geological process. New technology is dramatically affecting geology at all scales and, while the use of tried and proven methods continues, digital data acquisition and analysis, a product of Global Positioning Systems and Geographic Information Systems, amongst others, is becoming integral with geology. A revolution in the electronic storage, retrieval and use of information is taking geology into the world of information cyberspace where publication media are undergoing a paradigm shift. Geology continues to be a resource sector industry advocating the balanced study and sustainable development of minerals for national prosperity but still needs to capture the belief and support of the community. (from Author) 961186 Discovering mineral resources G. M. Brown, Nature & Resources, 30(3-4), 1994, pp 9-20. The aim of this IGCP research is generally to optimize the global or regional information on particular resources and to develop ideas about their further investigation. In many cases, these ideas have led to important new discoveries of economic importance. The eight projects reviewed here include global phosphate deposits; regional base-metal and rare-metal deposits; and global geochemical data-ax'zluisition for economic and environmental purposes. (from Author) 961187 Greece Hcensing round to focus on western sedimentary basins N. Roussos & F. Marnelis, Oil & Gas Journal, 93(10), 1995, pp 58-62. Briefly reviews hydrocarbon exploration activity in Greece. An international licensing round for offshore and onshore areas, mainly in western Greece, is due in the second half of 1995. Geology of eastern and western Greece is outlined and geology and development of the West Katakolon, Prinos and Epanomi fields are described. (J.M.MeLaughlin)