Abstract: Core stress sensitivity test in lab generally use Change Outside Pressure & Keep Inside Pressure Test method at present, which is not accord with actual gas field development process that overburden pressure do not change while fluid pressure decrease. This paper put forward Change Inside Pressure & Keep Outside Pressure Test method and use Sulige gas field low permeability core do Change Outside Pressure & Keep Inside Pressure Test and Change Inside Pressure & Keep Outside Pressure Test at the condition of formation temperature. Study indicate that core stress sensitivity of Change Inside Pressure & Keep Outside Pressure Test is little than Change Outside Pressure & Keep Inside Pressure Test, core stress sensitivity become more little even tend to a limit with multiple stress sensitivity times. This provides experiment accordance for gas well dynamic analysis and has very important meaning for study on stress sensitivity character of low permeability gas reservoir relative high、medium、low permeability core during multiple stress rise and drop process.

Key words: low permeability gas reservoir, stress sensitivity, permeability lag effect, permeability damage, effect pressure