Reservoir characteristics and productivity analysis of tight sand gas in Upper Paleozoic Ordos Basin China

Abundant tight sands rich in natural gas, as a kind of unconventional energy source, have been discovered in the Ordos Basin, Central-North China, which can contribute greatly to the sustainable supply of natural gas in China. In this paper, the geological and petrophysical characteristics of a typical tight sand gas reservoir in the Upper Paleozoic of the Ordos Basin were investigated and correlated to the productivity of gas wells. Several important petrophysical relationships were revealed based on data from drill cuttings, core, and well logging, including porosity versus permeability, stress sensitivity to permeability, and rock density versus porosity. Their effects on well's productivity were discussed. The productivity of the targeted reservoir was analyzed and classified using a formation capacity method (K.H factor), and was compared with the production data of similar tight sand and low permeability blocks in the region, which can provide good reference for the field development. (C) 2014 Elsevier B.V. All rights reserved.