Abstract: At present,there are 12 development wells altogether in Wenchang13-2 oilfield in western South China Sea,so no empty well groove exists.In order to fully develop oilfield and improve production efficiency,four ?762 mm well grooves are decided to hang on a platform,two-in-one technology is applied,?339.7 mm and ?244.5 mm casing are burrowed into ?762 mm riser by platform 125 t workover rig and cementing operation of two-in-one well is done by ?339.7 mm casing.As a result,horizontal completion operation of two different well structure in a well groove is achieved.In this paper,taking A16h well and A17h in a notch as example,drilling procedure,process features and points for attention in drilling of asymmetric two-in-one well are introduced.The successful application of two-in-one technology in Wenchang13-2 platform gropes a set of successful experience by making full use of spaces of wellhead platform,reducing project cost and development cost.