Abstract: The underground gas storage will be constructed in Yong-21 block that is abandoned gas poor in Shengli oil-gas area for the purpose of working in domestic gas long-transmission pipe line network construction, meeting the demand for natural gas from Shandong region and ensuring the safe and steady gas supply for city and town of the region. At present, the gas pool reservoir of Yong-21 block has been watered out, it’s difficult to restore to initial water saturation by gas injection process. Therefore gas-water two-phase flow exists during construction or operation of underground gas storage, and along with the change of operation cycle, the water saturation changes unceasingly, the gas well’s deliverability can also unceasingly change. In this paper, the gas well’s deliverability equation for Yong-21 block in condition of water free using the well test and production test data from old gas wells is presented. Based on the result of gas-water displacement physical simulation experiment study, the equation between gas relative permeability and injection-production multiple of Yong 21 block is presented. Through revision of gas relative permeability of the deliverability formula, the gas well’s deliverability equations in different operation cycles are also given. These have solved the difficult problems of gas well’s deliverability calculation in underground gas storage with water production.

Key words: Yong'an oilfield, depleted gas reservoir, water flooded gas reservoir, underground gas storage, deliverability