There are rich gas deposits in southwestern mountainous area of China

and with the increasing scale of development

the gas exploitation are moving from plain to mountain areas where have adverse geological environment conditions.This paper takes a gas well in southwestern mountainous area as a primitive type

and based on explanation of the geological environment of the well site

firstly

we made a general assessment and analysis of the mined-out region

then chose the software Flac-2D of finite difference method to analyse the stress and deformation of foundation influenced by the load of well site before and after its construction.Simulation analysis chose two models

including double holes and mined-out area.Simulated results indicate that maximum displacement of foundation in direction y is 2 mm and tension stress appears in the part site of the foundation

but which is steady in general.Research conclusions may give a reference to the optimum layout and the lectotype of the well site foundation.