Abstract: Developing with slim-cluster well can cut down the drilling cost of shallow reservoirs, while the improvement of auxiliary technology is also necessary. Study has been carried out on slim directional well and cluster well drilling technology since 1998 in Changqing Oilfield, and a set of drilling technologies have been developed. Basing on the formation and reservoir characteristics, together with the analyzing of casing program and borehole profile, and combining with the special techniques needed for slim directional well, the suitable drilling equipment and tools are proposed. It focuses on slim hole trajectory control, effects of BHA selection on hole deviation and azimuth, and the selection of drill bits for slim hole. The optimum drilling parameters are also investigated.