Casing Damage Caused by Jet Perforating

Abstract

Abstract This investigation has confirmed and extended the work by Bell and Shore, on casing damage by perforating. Perforating with the hollow carrier jet causes only slight deformation and, does not damage the casing. The expendable jet causes more deformation and possible damage in the form of cracks and possible damage in the form of cracks and splits. Tests under down-hole conditions show that expendable jets do not cause damage to (1) high-strength casing without flaws even when nonsupported, or (2) high-strength casing with flaws (laps and seams) that is well supported. The decreasing trend of casing deformation with increasing strength factor continues to hold through the high-strength P-110 and V-150 casing. The casing deformation P-110 and V-150 casing. The casing deformation decreases as the cement support changes from non- to semi- to well-supported. In scaled model test, 6 or fewer perforations/ft do not reduce the collapse resistance of casing significantly. In the field, we recommend that the hollow-carrier jet gun be used for perforating low-strength, poorly supported or old, corroded casing. Expendable jet guns with nominal charges will not cause damage if the casing strength factor is high and the casing is well supported. Introduction Casing damage caused by gun perforating has been investigated by several authors. Their reports have not agreed entirely and of course their work could not be comprehensive enough to cover every field condition. The work by Bell and Shore is the most complete. Our work was undertaken to check and extend the study by Bell and Shore and thereby extend our knowledge of casing damage by jet perforating.