Abstract: The lithologic combination of the reservoir interlayers in a certain area of Xinjiang Oilfield is complex, showing prominent thin-interbedding occurrence characteristics. The study of the judgment conditions of combined and separated pressure is beneficial to improve the fracturing efficiency, enhance the production degree of the reservoir and the effect of post-pressure reconstruction. The behavior of hydraulic fracture penetration and fracture propagation in thin interbeds is affected by the geological characteristics of thin interbeds and fracturing operation parameters. Based on this, fracturing experiment on thin interbed physical model was carried out to study the influence of bedding interface cementation, rock layer distribution, rock layer thickness, fracturing fluid viscosity and injection volume on the vertical propagation of hydraulic fractures in thin interbeds. The experimental results show that the stratigraphic characteristics of thin interbeds, bedding interface cementation and rock distribution are the main controlling factors for the vertical propagation of hydraulic fractures. The influence of bedding interface cementation strength on fracture vertical propagation behavior is stronger than that of rock distribution. Due to the existence of weak cemented bedding interface, the direction of hydraulic fracture can be deflected when it propagates vertically through the bedding, which can inhibit the vertical propagation of fracture. The increase of fracturing fluid viscosity and injection volume is beneficial to the vertical propagation of hydraulic fractures in thin interbeds.

Key words: thin interbeds, fracture height expansion, physical simulation of hydraulic fracturing, bedding interface, rock distribution