Abstract:

Based on the nuclear magnetic resonance, mercury penetration measurements, reservoir properties, relative permeability curves and production performance data, the controlling factors of porosity and permeability, pore throat size distribution, bound water saturation, gas height above free water and sweet spots of tight sand reservoirs in Badaowan Formation in Baka gas field were analyzed, and the gas water distribution characteristics and models were summarized. The typical tight sand reservoirs developed  in Badaowan Formation have the following features: the porosity is mostly less than 7% and permeability is less than 02×10-3μm²; the porethroat radius is mainly between 001 and 1 μm; the bound water saturation is relatively high, increasing obviously with porosity decreasing. The height of gaswater transition zone in the study area is approximately 640 m, and favorable reservoirs mostly locate in the gas water transition zone. Reservoirs which have different porosity values and locate in different structural heights have different gaswater production performances. The high porosity reservoirs which locate in high position of the gaswater transition zone are sweet spots for gas production.

Key words: Tuha basin, Baka gas field, tight sands, gaswater distribution, gaswater transition zone