Study On Crack Propagation And Induced Stress Field Of Tight Oil Reservoir In Kong 2 Member

The oil resources of the second member of Kong 2 in Dagang Oilfield are rich in lithology, heterogeneity and heterogeneity. Non-sandstone rocks dominated by transitional rocks, and developed a series of bedding and natural fractures. Reservoir spaces include fractures and pores. The reservoirs are poor in physical properties, mainly in the medium-low porosity-ultra-low permeability reservoirs. Due to the unfavorable extension of fracture initiation, lead to the Fracture morphology complexity is not high and the Reservoir reconstruction effect is poor?Therefore, it is necessary to improve the complexity of the hydraulic fractures. With the support of the "Key Technology of Exploration and Development of the Great Oil and Gas Fields in Dagang Oilfield". A project aimed at the artificial fracture conduct in-depth study on in-situ stress interference problem. This paper discusses the process of forming complex cracks by using ground stress, and provide the theoretical basis for the formation of suitable dense oil reservoir fracturing process technology, so as to promote the effective exploration and development of the second oil. In this paper, through experiments, theoretical research and field application analysis, the following conclusions and understanding:(1) Kong 2 formation of Dagang oilfield is a typical tight oil reservoir with porosity ranges from 6.4% to 11.1%, permeability ranges from 0.01 mD to 0.89 mD. Hence, complex hydraulic fractures are need to effectively develop these reservoirs.(2) Simulation results show that horizontal stress difference, pumping rate and fluid viscosity have a large influence on stress interference and natural fracture extension. The smaller stress difference is, the higher pumping rate is and the higher fluid viscosity is, the easier to generate stress interference and natural fracture propagation.(3) Induced stress analysis shows that the man-made fracture has an effect on reducing reservoir stress difference and increase the complex fracture geometry. The stress difference reduce is not obvious when it is more than two times hydraulic fracturing. Hence, the secondary fracturing was selected to reduce the stress difference.(4) The higher net pressure, the higher induced stress. Horizontal stress difference coefficient decreases with the fracture spacing and then increases with the fracture spacing. And the optimum fracture spacing is selected as 50m?60m.(5) Numerical simulation of horizontal well clusters shows that it is much easy to generate uniform propagation when the cluster spacing is bigger than 30 m. And when the spacing is less than 40 m, it is much easier to generate complex fractures. Based on the induced stress and fracture extension, the recommended cluster is 30 m to 40 m.(6) The secondary fracturing in vertical wells and segmented cluster fracturing techniques in horizontal wells show a good test results in Kong 3 tight oil reservoir which could offer a technical support for the development of this type reservoir.