A new technique for sampling water and gas from deep drill holes

Abstract

A new technique for sampling water and gas from deep (500–1500 m) drill holes is described. The principle of the technique is to raise a continuous column of water inside a thin polyamide tube with a back-pressure valve at the lower end and with shutoff valves every 50 m. The equipment is easily assembled from standard parts. Sampling can be performed by three people without mechanical apparatus. Descent to 1000 m takes 2 hours and retrieval 1 hour. The method makes it possible to obtain a practically undisturbed continuous water profile from a drill hole. Dissolved gases remaining inside the tube can be sampled at the surface. To demonstrate the efficiency of the technique, selected results from the deepest drill hole in Finland, having a vertical depth of 1100 m, are presented.