Perforating gun for isolated zone wells integrated into production string which does not puncture the string when fired

摘要

It is known to establish wells with multiple production zones (451) isolated by packers (462, 470), wherein the isolation is further maintained by having separate production strings (452,454) for each zone. It is also known to attach the perforating gun (480) for the upper zone to the lower zone production string to simplify completion. However in the past these guns have been bulky arrangements clamped on to the side of the string (see figure 1). The invention lies in integrating the gun into centralising fins (478) on the production string. This allows the perforating charges to be placed on a complete 360{ arc around the string if required. The perforating charges can be oriented in the fins to fire tangentially (see Fig. 12) or radially (see Fig. 17), but it must be ensured that the production string is strong enough to survive the firing without rupturing.