Abstract: Liuhua4-1 Oilfield is located in deeper waters, in order to improve operating efficiency of surface casing, ensure the stability of deep water surface casing wellhead, the surface casing run by spray mode.The key technology of spray mode is to determine the setting depth of surface casing and choose the drilling pressure and displacement parameters of drilling process. A capacity profile of surface casing is established by analying load bearing capacity data of the seafloor earth in Liuhua4-1 Oilfield,and a reasonable driving depth of surface casing is determined according to size of surface casing and load distribution in Liuhua4-1 Oilfield. Based on comprehensive analysis on process characteristics of the surface casing and construction features of string combination,the drilling pressure and displacement parameters of surface casing are optimized,and the surface casing running in construction by spray mode is given. Surface casing setting depth computation method can provide good technical information and guidance for the domestic deep water the surface casing setting in by jetting.