유향·유속검층을 이용한 영광지역 해수침투대 균열암반의 지하수 유동 특성화
Heat-pulse Flowmeter Test to Characterize Seawater Intrusion in Fractured Rock, Yeonggwang Area
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A combination of drilling, conventional geophysical well logging and flowmeter was performed to evaluate seawater intrusion through the fractured rock in Baeksu-eup, Yeonggwang-gun, Korea. The test boreholes are drilled in the brackish area interpreted with surface geophysical survey and hydrogeochemcial survey. The geology of the survey area comprises mud, sand, granite and andesite bedrock. Although the drill cores showed several fractures, we didn’t identify the minor fractures using 3-arm caliper logs because of small aperture size of fractures. In order to evaluate the permeable fractures, single hole heat-pulse flowmeter test was conducted in borehole YK-23 and YK-25. Five permeable fractures are detected and transmissivities of each permeable fracture are estimated using Paillet inversion method. To evaluate the hydraulic connectivities between two boreholes, flowmeter test also have been performed during constant pumping about 6.5 ℓ/min at each borehole. Hydraulic flow paths between two boreholes are identified at the depth of 34.5 meters and about 46 meters. These tests also agree with freshwater injection test using double packer and the increasing patterns of electrical conductivity logs in two boreholes. These results indicate seawater intrusion through fractured rocks connected to coast.
Abstract
A combination of drilling, conventional geophysical well logging and flowmeter was performed to evaluate seawater intrusion through the fractured rock in Baeksu-eup, Yeonggwang-gun, Korea. The test boreholes are drilled in the brackish area interpreted with surface geophysical survey and hydrogeochemcial survey. The geology of the survey area comprises mud, sand, granite and andesite bedrock. Although the drill cores showed several fractures, we didn’t identify the minor fractures using 3-arm caliper logs because of small aperture size of fractures. In order to evaluate the permeable fractures, single hole heat-pulse flowmeter test was conducted in borehole YK-23 and YK-25. Five permeable fractures are detected and transmissivities of each permeable fracture are estimated using Paillet inversion method. To evaluate the hydraulic connectivities between two boreholes, flowmeter test also have been performed during constant pumping about 6.5 ℓ/min at each borehole. Hydraulic flow paths between two boreholes are identified at the depth of 34.5 meters and about 46 meters. These tests also agree with freshwater injection test using double packer and the increasing patterns of electrical conductivity logs in two boreholes. These results indicate seawater intrusion through fractured rocks connected to coast.
참고문헌 (24)
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