The fracture development features of the Bashijiqike Formation in Keshen gasfield were studied by making full use of core observation and micro-resistivity image logging interpretation. The image logging results collected in oil-based mud for Well Keshen2-2-12 were compared with those in water-based mud，then the differences between water-and oilbased mud in the effect of fracture recognition were summarized. The results show that large aperture fractures can be identified. However，some small aperture fractures are difficult to be seen in the oil-based mud image logging. Generally，the high-angle fractures are easily to be seen，while the low-angle fractures cannot be detected，and the lost of cross bedding information are serious in the oil-based mud imaging. The oil-based mud image logging results can be calibrated with core observations，the caliper logging，acoustic logging and array acoustic logging，and the accuracy of fracture recognition and interpretation will be improved in this way.