Quantitative studies of hydrocarbon loss of the Silurian bitumen sandstone in the Tarim Basin

Abstract

The evolution of Tarim Basin experienced several tectonic movements, of which Caledonian movement caused a serious damage to reservoirs of Silurian. The earlier reservoirs size and the later hydrocarbon loss are two key factors to exploration prospect of Silurian. On the basis of net thickness of bituminous sandstone and recovery coefficient of crude oil converting to bitumen, the scale of the hydrocarbon loss of palaeo-accumulation in bitumen sandstone of Silurian was calculated (86.30×108t). The determination of net thickness of bitumen sandstone was completed mainly by several methods, such as physical property demarcation, observing lithology, grains with oil inclusion (GOI) technology, and quantitative grains fluorescence (QGF) technology. The samples of black sandstone and white sandstone were collected and compared by means of the methods mentioned above. The results showed that there was little hydrocarbon, or none, in the white sandstone. The recovery coefficient was obtained by the analyses of plentiful physical parameters of crude oil and bitumen sandstone, based on the hypothesis that nonhydrocarbon compounds and bitumen were invariable in the process of bitumen forming. The calculated result, which is more scientific and actual, indicates the exploration prospect is more promising in Silurian of the Tarim Basin.