Abstract: Bohai P Oilfield is a complex fault block reservoir with multi fault blocks,having small sizes and irregular shapes in the plane. The fluid properties and oil-bearing area of each fault block vary greatly,and the oil-water relationship is very complex. In vertical,inter layers’ properties are quite different. Among these layers,the L50^U formation is characterized by large reservoir thickness,good continuities and high crude oil viscosity,which is suitable for horizontal well development,but the small faults,strike-slip faults and local micro-structure are staggered distributed inside the oilfield,resulting in that the conventional horizontal well pattern is not applicable to this oilfield. This study considers the actual condition in oilfield development and production and breaks through traditional mechanism model research methods. The well points and seismic attributes are combined to characterize the horizontal and vertical distribution and variation of sandstones in L50^U formation,interpreting the complex secondary faults distribution of Bohai P Oilfield. Based on the three-dimensional model of seismic model,geologic model and numerical model,the drilling limits of horizontal wells are systemically optimized,and the theoretical curves are formed to guide the integrated development of horizontal wells in L50^U formation of Bohai P Oilfield. At present,this technology has successfully guided the implementation of three horizontal production wells in Bohai P Oilfield. The daily oil production per horizontal well at the initial stage is about three times of the directional one,greatly improving the development effect of this old oilfield.

Key words: complex fault block, heavy oil, thin inter bed, horizontal well, integrated development