Hydraulic fracture initiation and propagation of highly deviated well with oriented perforation completion technique.

In order to investigate the effect of different perforation angles (the angle between the perforation direction and the maximum horizontal principal stress which is also called the preferred fracture plane (PFP)) on the fracture initiation and propagation during the hydraulic fracturing of highly deviated well, laboratory experiments of the hydraulic fracturing of the BZ25-1 oilfield had been carried out on the basis of non-dimensional similar criteria by using 400mm3 cement cubes. We built the geometric model of the hydraulic fracturing fractures which considered the influences of the wellbore azimuth (the angle between the wellbore axis and the PFP), the perforation angle and the well deviation. The results showed that: the perforations in the PFP produce plane fracture; the fractures initiate from the perforations at the upper side of the well hole and then turn to the PFP when the perforation angle is 45°; when the well deviation angle and the perforation angle are both larger than 45°, the fracture initiates difficultly from the perforations at the lower side of the well hole, and multi-fractures easily initiate; when the perforation angle is 90°, multi-fractures initiate, such as twisting fracture, plane fracture, horizontal fracture and T-shape fracture, in addition, the fracture cannot initiate from the perforation tunnels; the larger the well deviation angle is, the easier is the multi-fractures initiation. Moreover, it is easier to result in micro-annulus which makes the fractures more complicated during the hydraulic fracturing of highly deviated well when the perforation angle is not along with the PFP. Oriented perforating technology should be applied in highly deviated well to obtain the big single plane fracture. [ABSTRACT FROM AUTHOR]