Stress Characteristics near Wellbore and Prevention Casing Deformation for Fracturing Horizontal Wells

Aiming at the problem that casing deformation can easily occur in tight oil horizontal well fracturing, based on rock mechanics experiments and probability statistics, distribution characteristics law of near-wellbore stress field reservoir STH M56 were solved analyzed by using finite element modeling numerical method. The research shows (1) max/min ratio is 1.2, difference less than 8 MPa, this characteristic condition more conducive to formation complex fracturing network during fracturing. (2) In M56, Mises isoline near borehole symmetrically distributed. Stress concentration has four dangerous points (30°, 150°, 210° 330°); a sector-shaped high zone formed along points. As pumping pressure increases, vertical first increases then decreases, while decreases increases. max-Mises wall linearly positively correlated with uniformity coefficient. When 80 exceeds safe limit casing. A 70 MPa for (3) It found 90° 270° fixed plane perforations avoid zone, increasing decreasing injection flow rate pump step ( step pressure ≤ 5 MPa ) start stop stages fracturing; control whole process within which prevent deformation.