Abstract: Qinhuangdao 32-6 oilfield is a typical offshore low-amplitude bottom-water heavy oil field. Oil reservoirs with the thickness of less than 10 m account for 22% in respect of reserves due to the low amplitude. To produce the reserves in these reservoirs efficiently, based on the interlayer logging identification and core analysis, this paper carries out a study on the influences of interlayer on development and the limits for horizontal well deployment by using numerical simulation method. According to the study results, interlayer can effectively block the rapid coning of bottom water when the interlayer permeability to matrix permeability ratio is 0.01. Bottom water can be diverted to flow around and the producing degree of reserves can be maximized when the interlayer area is 2~3 times the oil drainage area in horizontal wells. The coning of bottom water can be effectively slowed down and the swept volume of waterflooding be expanded when the interlayer is located at the position with the distance of 3/4 reservoir thickness to the reservoir top. Taking the cumulative oil production of 5×10⁴ m³ as the lower economic limit for horizontal well deployment, the lower limit of reservoir thickness for horizontal well deployment in offshore low-amplitude heavy oil reservoirs with bottom water should be 5 m. These conclusions have been proved by pilot tests, and they provide technical support for horizontal well deployment in low-amplitude heavy oil reservoirs with bottom water.

Key words: Qinhuangdao 32-6 oilfield, reservoir with bottom water, heavy oil reservoir, interlayer, reservoir thickness, horizontal well deployment, pilot test