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A New Continuous‐Sampling Wireline System for Acquisition of Uncontaminated, Minimally Disturbed Soil Samples
Author(s) -
Clark Robert R.
Publication year - 1988
Publication title -
groundwater monitoring and remediation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 47
eISSN - 1745-6592
pISSN - 1069-3629
DOI - 10.1111/j.1745-6592.1988.tb01104.x
Subject(s) - barrel (horology) , drilling , tube (container) , drill , sampling (signal processing) , casing , geology , insert (composites) , drilling fluid , core (optical fiber) , geotechnical engineering , engineering , materials science , petroleum engineering , electrical engineering , mechanical engineering , composite material , detector
A new wireline system has been developed to alternately full‐hole drill or continuously sample soil in a variety of soils. Those samples recovered by the system are complete, relatively undisturbed, and minimally affected by drilling fluids. The system, which includes an outer barrel, center‐bit insert tube and a spring‐retract‐sampler inner barrel, can be used with either a core or rotary‐type drill. The system's outer barrel and bit act as a casing advancer to prevent hole collapse in unstable soils. The outer barrel and bit remain in the hole while either the center‐bit‐insert tube or the soil‐sampler inner barrel are wirelined in and out of the outer barrel and drill rod column. When the center‐bit insert is wirelined into place, it combines with the outer barrel and bit to become a full‐hole drilling tool. When this center‐bit insert is replaced with the soil‐sampler inner barrel, the system is capable of continuous soil sampling to depths ranging from several hundred to several thousand feet. The spring of this soil‐sampler inner barrel is designed to extend the drive‐shoe some 6 to 8 inches ahead of the outer‐barrel bit and the circulating fluids. Therefore, the sample is not in continuous contact with the circulating fluids during the sampling process. As the sample enters the soil‐sampler tube, those circulating fluids inside the tube are forced up and out through the inner barrel's fluid bypass. The result is a sample relatively free of contamination or washing by drilling fluids. Because the soil‐sampler tube comes in contact with the circulating fluid as it travels into sampling position, there is a film coating the recovered sample. Similarly, the fluid also coats either end of the sample. However, that film is easily scraped away before analysis. Should additional protection be required, a liner can be inserted inside the sampler tube. Sample contaminants can be totally eliminated through the use of filtered‐air circulation. In field use, negligible tearing or amalgamation of the samples has been experienced, because the soil‐sampler tube and retract‐spring are suspended from dual bearings, which prevent inner barrel rotation.