Through laboratory tests, high quality formula of C12 foam mud was optimized, which made the drilling construction successful in serious fracture leakage formation. Time effect increased 0.24m with foam mud than with common mud, average footage of working group increased 0.77m; mud cost decreased 4.71 Yuan/m3, average mud cost of working group decreased 20.95 Yuan. There was no leakage while drilling with foam mud with borehole collapsing solved. The paper also put forward the points for attention of C12 foam mud application.