Abstract: American UNOCAL Compeny has been drilling preducing wells in Siam bey for more than 10 years, and more that 560 wells have been completed by now. Ten types of advanced technology were applied in drilling. A world record of completing a 3 272m well only in 3.8l days was set, while drilling costs of every well reduced from over 5 million to 5 million to 1.28 million.It provides valuable experence for us in developing the petroleum resources off shore and onshore.