A hypervelocity projectile launcher for well perforation

Abstract

Current oil well perforation techniques use low- to medium-velocity gun launchers for completing wells in soft rock. Shaped-charge jets are normally used in harder, more competent rock. A launcher for a hypervelocity projectile to be used in well perforation applications has been designed. This launcher will provide an alternative technique to be used when the conventional devices do not yield the maximum well perforation. It is an adaptation of the axial cavity in a high explosive (HE) annulus design, with the axial cavity being filled with a low density foam material. Two configurations were tested; both had an HE annulus filled with organic foam, one had a projectile. Comparison of the two shots was made. A time sequence of Image Intensifier Camera photographs and sequential, orthogonal flash x-ray radiographs provided information on the propagation of the foam fragments, the first shock wave disturbance, the projectile motion and deformation, and the direct shock wave transmission from the main HE charge. Perforation tests of both device configurations (with and without the pellet) into steel-jacketed sandstone cylinders were made. Static radiographs of the cavities in the sandstone showed similar cavities, however, the perforation of the steel cap was larger in response to the pellet. DYNA2D calculations were made to assist in the interpretation of the experimental records. The preliminary results show promise that a useful perforating tool can be developed. Plans for an extended experimental program are outlined.