摘要
An innovative perforation method of interlaced fixed perforation was put forward based on the analysis of the characteristics of fractures in various periods of perforation and conventional perforation modes.By conducting a large-scale perforation shooting experiments,we investigated the morphology,propagation mechanism and propagation law of the near-wellbore fractures generated during perforating processes under different fixed angle and interlaced angle combinations,and discussed the control method of near-wellbore fractures in different types of unconventional oil and gas reservoirs.The experimental results show that:(1)The interlaced fixed perforation strengthens the connectivity between the perforation tunnels not only in the same fixed plane but also in adjacent fixed planes,making it likely to form near-wellbore connected fractures which propagate in order.(2)Three kinds of micro-fractures will come up around the perforation tunnel during perforation,namely typeⅠradial micro-fracture,typeⅡoblique micro-fracture and typeⅢdivergent micro-fracture at the perforation tip,which are interconnected into complex near-wellbore fracture system.(3)Different types of perforation bullets under different combinations of fixed angles and interlaced angles result in different shapes of near-wellbore fractures propagating in different patterns.(4)By using the interlaced perforation on fixed planes,arranging fixed planes according to the spiral mode or the continuous"zigzag"shape,the desired near-wellbore fractures can be obtained,which is conducive to the manual control of main fractures in the fracturing of unconventional or complex conventional reservoirs.
An innovative perforation method of interlaced fixed perforation was put forward based on the analysis of the characteristics of fractures in various periods of perforation and conventional perforation modes. By conducting a large-scale perforation shooting experiments, we investigated the morphology, propagation mechanism and propagation law of the near-wellbore fractures generated during perforating processes under different fixed angle and interlaced angle combinations, and discussed the control method of near-wellbore fractures in different types of unconventional oil and gas reservoirs. The experimental results show that:(1) The interlaced fixed perforation strengthens the connectivity between the perforation tunnels not only in the same fixed plane but also in adjacent fixed planes, making it likely to form near-wellbore connected fractures which propagate in order.(2) Three kinds of micro-fractures will come up around the perforation tunnel during perforation, namely type Ⅰ radial micro-fracture, type Ⅱ oblique micro-fracture and type Ⅲ divergent micro-fracture at the perforation tip, which are interconnected into complex near-wellbore fracture system.(3) Different types of perforation bullets under different combinations of fixed angles and interlaced angles result in different shapes of near-wellbore fractures propagating in different patterns.(4) By using the interlaced perforation on fixed planes, arranging fixed planes according to the spiral mode or the continuous "zigzag" shape, the desired near-wellbore fractures can be obtained, which is conducive to the manual control of main fractures in the fracturing of unconventional or complex conventional reservoirs.
基金
Supported by the China National Science and Technology Major Project(2017ZX05009-003).
