Abstract:

         It is important to study the natural gas’s enrichment of well Shaan 200 area in Jingbian gasfield, Ordos Basin, which has potential gas reserves. The configuration of ancient valleys and fractures has different influence on natural gas’s enrichment.The natural gas from the Upper Paleozoic migrates into the Lower Paleozoic vertically through the ancient valleys,and into the fifth member of Majiagou Formation laterally through its fractures. The more ancient valleys or/and fractures develop,the more natural gas enrich. The gas saturations of Ma_5(1) and Ma_5(2) formations are greater than that of Ma_5(4-1) with only fractures for their dual-action of ancient valleys and fractures.

Key words:  Ordos Basin, Jingbian gasfield, natural gas, carbonate palaeogeomorphology, fractured reservoir