• The Journal of Engineering Geology
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• v.8 no.3
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• pp.261-273
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• 1998

Multiple well log analysis technique consisting of geophysical well log and geological core log has been made to analysis the discontinuities of a test borehole-PABH1 located in Pungam sedimentary basin, Sosok, Hongchon-gun, Kangwon Province. Well log methods consist of normal resistivity log, focussed log, single point resistance log, SP log, gamma log, natural gamma log as well as acoustic televiewer log and borehole television log. Core scanning technique was used as an aid for geological core log. The analysis was made by comparing firstly the televiewer and core discontinuities, and then the results from conventional geophysical log analysis were compared to those from core log and acoustic televiewer log. Fractures deduced from the acoustic televiewer log coincide well with discontinuities shown on the core and conventional geophysical logs. Particularly close coincidence could be observed between fractures derived from acoustic televiewer and conventional geophysical log analysis. It has been noted that the geophysical logs such as, caliper, resistivity, density and high resolution gamma gamma curves are effective in delineating the fractures. For example the ratio between density and resistivity (BRD/SHN) provides also an alternative indicator for discerning the fracture condition in the study area.

• The Journal of Engineering Geology
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• v.9 no.3
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• pp.253-265
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• 1999

Physical properties of Paleozoic sedimentary rocks in Gabsan formation in Jechon area were obtained by both geophysical well log methods and core property measurements, and the similarity and difference shown between the well log and core log responses were analyzed. The physical properties obtained are natural gamma, resistivity and density. From the difference in density response between the well log and core measurement, the need of correction for natural gamma effect on density log was strongly suggested. And fairly good correlation was obtained between well log and core properties, and among natural gamma, resistivity and density by applying natural gamma correction on density log. It is noted that shale in Gabsan formation reveals very high density, even higher than the density of adjacent non-porous limestone.

• The Journal of Engineering Geology
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• v.8 no.2
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• pp.163-173
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• 1998

Suite of log analysis techniques consisting of geophysical well log, geological core log, and physical core log have been made to understand the well log responses and to determine the lithology of a test borehole-PABH1 located in Pungam sedimentary basin, Sosok, Hongchon-gun, Kangwon Province. Geological core logging has been precisely made over the cores taken between 64 and 124 meters, and 11 groups of rock types were deduced. Using the core samples divided by 11 groups, geophysical property measurements consisting of resistivity, natural gamma and density were made. Each rock group in the area is shown to have its characteristic physical response from geophysical well log and geophysical core logs. The outstanding physical responses particularly shown from siltstone, coarse sandstone to conglomerate, and granitic gneiss in the area were effectively used as keybeds in correlating the geophysical well logs to the result of geological core logs.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.92-96
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• 2006

Borehole geophysical techniques were adopted for characterizing aquifer properties of crystalline rock formation in Bongmyong borehole test site, Kangwon National University. Specific fractures and/or fracture zones accompanying groundwater flow were delineated well by high resolution flowmeter and dilution measurements, and could be confirmed fromconventional well log methods. These geophysical techniques have been proved to be the most effective in aquifer characterization in crystalline rock formation.

• The Journal of Engineering Geology
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• v.8 no.1
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• pp.87-98
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• 1998

Multiple logging techniques consisting of geophysical logs, care logs, physical property measurements on core samples have been adopted on a test borehole drilled in the Pungam basin ; a small Cretaceous sedimentary basin located in Sosok area, Hongchon-gun, Kangwon Province, Korea. This study has been made to solve the problem of mismatches between the results of geophysical log and core log analyses. And the cause and range of depth errors as well as logging responses were studied. The result shows that the depth error caused by geophysical log is so small that it can be used as a reliable depth criterion in the borehole. The analysis of physical property measurements is also shown as very effective in determining the real depth and the geology of the borehole.

• Journal of the Korean Geophysical Society
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• v.4 no.2
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• pp.95-102
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• 2001

As a basic study of characterizing fracture condition in bore hole, conventional geophysical well log data consisting of sonic, gamma-gamma and resistivity logs were compared with geological core log and acousic televiewer log in limestone geology. Discontinuities shown on the acoustic televiewer log and the core log show fairly good correlation. The conventional Geophysical log is also shown to bi effective in locating discontinities in limestone geology; sonic log shows the best result and resistivity shows the worst. Particularly, the combination method of density and sonic logs is shown to be the most effective in delineating discontinuities.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.55-71
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• 2005

Jeju Island is mainly composed of basaltic lava flows and subordinate amounts of volcaniclastic sedimentary rocks. Jeju Province operates the monitoring wells for seawater intrusion problems around Jeju Island to evaluate of groundwater resources in coastal area. Various surveys and monitoring have been performed in boreholes, and also conventional geophysical well loggings conducted to identify basalt sequences and assess seawater intrusion problems. Various conventional geophysical well logs, including radioactive logs, electrical log, caliper log, and temperature and conductivity log and heat-pulse flowmeter log were obtained in 29 boreholes. The results of geophysical well loggings for saturated rocks are interesting and consistent. Natural gamma logs are useful in basalt sequences to sedimentary interbeds, unconsolidated U formation, and seoguipo formation with higher natural gamma log regardless of saturated or unsaturated basalts. Neutron logs are very effective to discriminate among individual lava flows, flow breaks, and sedimentary interbeds in saturated formation. In hyalocastite, porosity is high and resistivity is low, and we think that hyalocastite is a major pathway of fluid flow. In trachybasalt, porosity has a wide range and resistivity is high. In sedimentary interbeds, unconsolidated U formation and seoguipo formation, porosity is high and resistivity is low. The temperature logs in eastern area in Jeju are useful to interpret the hydrogeological unit and evaluate seawater intrusion in Suan area.

• Journal of the Korean earth science society
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• v.30 no.4
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• pp.401-408
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• 2009

We carried out the Suspension PS log and gamma-gamma log in andesite and sedimentary rocks distributed near the area of Myodo-dong, Yeosu. The main purpose of this study was to find out the distribution of seismic velocities and densities and to analyze the correlation of the two rocks by comparing their geophysical well logs with rock cores. The distributions of P and S-wave velocities for two rocks represented in the study area showed a difference of about 2,000 m/sec and 1,500 m/sec with depth, respectively, while the distributions of densities had a discrepancy of about $0.35g/cm^3$ with depth. However, the results of geophysical well logs analysis were similar to the two rocks. Consequently, it is clear that these results are interpreted as a difference due to weathering rather than rock type. In particular, the RQD values showed a good correlation to geophysical well log data.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.432-436
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• 2003

Geophysical well logging techniques which are useful for delineating permeability of geological formation have been reviewed. A new technique for obtaining permeability using conductivity log technique has been discussed. This conductivity logging technique has been tested by monitoring the conductivity change within the model hole using borehole environment water and incoming-outgoing water of different salinity with constant flow rate by maintaining balance between inflow and outflow. Conductivity variation features depended mainly on flow rate, density contrasts due to salinity and temperature contrasts between fluid within the hole and incoming-outgoing fluid. The results of the experiment show uniform change of fluid conductivity within bore hole with time, and a fairly good correlation between the flow rate and the conductivity change rate. This conductivity logging technique is expected to be an efficient tool for determining permeability.

• Economic and Environmental Geology
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• v.21 no.1
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• pp.85-96
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• 1988

Geophysical well logging at various coal fields were carried out to study the characteristic response of domestic coal seams. Also a computer program is developed for quantitative analysis of coal logging data. Most coal seams penetrated by the drill holes, where the well logging were carried out, showed poor thickness and quality, and were severely altered. Therefore, majority of log data are inadequate for detailed quantitative analysis. The logs show, however, typical characteristics with related to coal seams, but interpretation should be made with caution because certain log response of demestic coals, mostly anthracite, are quite different to those of foreign coals, mostly bituminous. The developed comuter program has been proved as an effective one for identification of coal seams and lithology anslysis, and is expected to be succesfully used for coal quality analysis in cases of more diversified log data of good quality being obtained.