Device for the dynamic under balance and dynamic over balance perforating in a borehole

摘要

According to a preferred embodiment, a dynamic underbalance device has a longitudinally extending tool string including an underbalance part. A first overbalance part is above the underbalance part and a second overbalance part below the underbalance part. Upon application of underbalance from the underbalance part and overbalance from the overbalance part, the overbalance and underbalance interact to isolate the underbalance.

主权项

1. A dynamic underbalance device, comprising:
a longitudinally extending tool string including an underbalance part; a first overbalance part above the underbalance part; a second overbalance part below the underbalance part, the first and second overbalance parts each comprising a vented combustion chamber having a cavity with propellant located therein and passages leading from the cavity to outside the overbalance part, wherein the passages of each overbalance part are angled to converge toward a point within the borehole external to the overbalance part; wherein upon application of underbalance from the underbalance part and overbalance from the overbalance parts, the overbalance and underbalance interact to isolate the underbalance.