Correlation And Water-Transmitting Properties Of Fractures

Abstract

Marine, I. Wendell, (In cooperation with the US Atomic Energy Commission) US Geological Survey, Aiken, S.C. Publication Rights Reserved This paper was to be presented at the 40th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Denver, Colorado, October 3–6, 1965, and is considered to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of the Journal of Petroleum Technology or the Executive Secretary. Such abstract elsewhere after publication in the Journal of Petroleum Technology or Society of Petroleum Engineers Journal is granted on request, providing proper credit is given that publication and the original presentation of the paper. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Water-transmitting fractures in crystalline rock beneath the Savannah River Plant, near Aiken, South Carolina, were located most reliably by packer tests and in-hole tests using radioactive iodine. Connectivity of some fractures was determined by pumping packed-off sections of one hole while making in-hole tracer tests in another. A previously made estimate of the maximum mean ground-water velocity based on hydraulic parameters is being tested with a between-holes tracer test using tritium. At the Savannah River Plant near Aiken, South Carolina, as at other locations where there are chemical separations plants for the processing of nuclear fuels, most of the radioactive waste is stored in steel and concrete tanks buried just beneath the surface of the ground. This waste is of such activity and of such longevity that it cannot be dispersed to the environment but must be contained for periods of time at least into hundreds of years. An investigation conducted from 1961 to 1963 at the Savannah River Plant has indicated the technical feasibility and safety of storing this waste in unlined tunnels excavated in crystalline rock about 1500 feet beneath the surface. This investigation was sponsored by the U. S. Atomic Energy Commission and participated in by the Du Pont Company, the U. S. Geological Survey, and the U. S. Army Corps of Engineers. The Savannah River Plant is located on the Atlantic Coastal Plain about 20 miles southeast of the Fall Line where the crystalline rocks of the Piedmont province crop out as shown on figure 1. It is on the Savannah River, which forms the boundary between South Carolina and Georgia. The area of intensive investigation for bedrock waste storage is an area of 3 square miles near the central part of the plant. At the site of the investigation the crystalline basement rock is overlain by about 1000 feet of unconsolidated sands and clays characteristic of the Coastal Plain as shown on figure 2. These sediments thin toward the Piedmont province to the northwest and thicken toward the Atlantic Ocean to the southeast. The crystalline rock beneath the sediments is composed of chlorite-hornblende schist and hornblende gneiss with lesser amounts of quartzite. The schistosity or foliation strikes generally northeast and dips an average of 55 degrees to the southeast.