The 1

st

Member of Xiashihezi Formation(H1)of Daniudi gas field is a typical low permeability reservoir in Ordos Basin.In order to clearly understand the stress sensitivity of H1

13 core samples of different types were chosen for stress sensitivity tests.The experimental results show that the core samples from H1 commonly show stress sensitivity and permeability hysteresis

indicating that the cores experience plastic deformation with the increasing of net stress.Analysis of the experimental data with internal stress sensitivity index method shows that the type Ⅰ reservoirs with better physical properties has a relatively low stress sensitivity

while the type Ⅱ and Ⅲ reservoirs have low to moderate stress sensitivity.The averaged internal stress sensitivity index of these 13 core samples is 0.086

indicating that the overall stress sensitivity is low.We built numerical simulation models of multi-stage fracturing of horizontal wells for Ⅰ-Ⅲ type reservoirs

into which the relationship between dimensionless permeability and the formation pressure was incorporated.Under a constant gas production rate scheme in the numerical model

the effects of stress sensitivity on horizontal well performance were investigated.The numerical simulation results show that the stress sensitivity has very little effect on gas rate during stable production period for type Ⅰ reservoir

which only decreased by 1.6% in comparison with that without stress sensitivity case.For type Ⅱ and Ⅲ reservoirs

the gas rate during stable production period decreased by 11.2% and 23.6%

respectively.Therefore

production allocation and management should be strengthened for type Ⅱ and Ⅲ reservoirs to guarantee well performance.