Buried-hill carbonate reservoir is typically fractured and caved in Chengdao Oil Field.Several periods of faulting and denudation were undergone during some tectonic movements in Chengdao area, which results in good condition for hydrocarbon accumulation. The buried hill can be divided into three structural units, all of which converge in brush to the south end of the arch where some sub-structural units meet and also the structural stress is concentrated. In Chengdao Oilfield, there are three common types of reservoir spaces, that is, intercrystal pores, solution caves and fractures.