Experimental Investigation On Hydraulic Fracture Propagation And Stress Shadow Of Multistage Fracturing In Tight Reservoir

Horizontal well segmentation fracturing is a fairy efficient method for exploiting tight oil and gas by which the drainage area between the wellbore and the formation raised through forming multiple transverse fractures.The influence of stress generated by the early fractured fractures will affect the form that subsequent fractures develop and in turn the overall effect of fracturing process.This essay apply the numerical simulation method in indoor large-scale physical simulation experiment to research the influence of reservoir conditions(horizontal stress influence),construction parameters(net pressure,perforation depth,perforation spacing and cement job quality)and other factors on the fracturing.The result shows: With high horizontal stress differences,small fracture distance and shallow perforation depth makes it easy for fractures to merge after expanding for some length.And by increasing the perforation depth,the break down pressure could be lowered and enables each fracture to extend along the main stress direction.With the increase of fluid net pressure in the early fractured fractures,the starting pressure increases and forces later fractures to turn from perpendicular to the horizontal wellbore towards along it.In addition,when the horizontal well cementing quality is poor,the fractures will most likely to extend along the horizontal well instead of forming multiple transverse hydraulic fracture.While there is angle between the wellbore and the direction of the minimum principal stress and the hydraulic fracture is tension and shear mixed,the extension direction deflects in a positive correlation with the angle.The second and third fracture will both deflect in sequential fracturing;in Texas two-step fracturing,the width of middle crack is small and the extension form is straight by the influence of symmetrical stresses on both sides.