Method and apparatus for surveying the downhole environment in a steam stimulated well such as a Steam Assisted Gravity Draining well are described. One method comprises interrogating an optic fibre (104) arranged along the path of a well shaft (202, 204) within a steam stimulated well with optical radiation. At least one downhole steam pulse is generated and data gathered from the fibre (104) in response to the steam pulse is gathered and processed to provide an indication of the acoustic signals detected by at least one longitudinal sensing portion of the fibre (104). In some examples, the processed data can be used to determine at least one characteristic of the steam chamber (210).