Abstract: The ?152.4 mm slim hole drilling technique can effectively enhance EOR and overall economic performance of oilfield development. Slim hole drilling was tested first in the third drilling section of Well Xushen 9-Ping 4 in the Xushen Gasfield of Daqing Oilfield, but the ROP was lower than expected, failing to fulfill ROP enhancement and cost reduction in drilling deep gas wells. Taking the on site ?152.4 mm slim hole drilling as an example, reservoir features, footages drilled per bit, pure drilling time and ROP have been analyzed, and based on the universal ROP equation, features of reservoir formations in the Xushen Gasfield, and experiences in drilling slim hole, factors affecting ROP in slim holes have been figured out, and problems encountered during drilling of such slim holes have been analyzed, which can provide basis and guideline for slim hole drilling in deep gas development of the Daqing Gasfield.