US 11,988,066 B2
Dynamic underbalance sub
Joern Olaf Loehken, Troisdorf (DE); Stefan Purcelean, Troisdorf (DE); Paula Feitoza Nascimento, Troisdorf (DE); and Bernd Fricke, Hannover (DE)
Assigned to DynaEnergetics Europe GmbH, Troisdorf (DE)
Appl. No. 17/920,441
Filed by DynaEnergetics Europe GmbH, Troisdorf (DE)
PCT Filed Jun. 16, 2021, PCT No. PCT/EP2021/066167
§ 371(c)(1), (2) Date Oct. 21, 2022,
PCT Pub. No. WO2021/255058, PCT Pub. Date Dec. 23, 2021.
Claims priority of provisional application 63/079,705, filed on Sep. 17, 2020.
Claims priority of provisional application 63/079,699, filed on Sep. 17, 2020.
Claims priority of provisional application 63/040,979, filed on Jun. 18, 2020.
Prior Publication US 2023/0160279 A1, May 25, 2023
Int. Cl. E21B 34/06 (2006.01); E21B 43/117 (2006.01); E21B 43/1185 (2006.01)
CPC E21B 34/063 (2013.01) [E21B 43/117 (2013.01); E21B 43/11855 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A dynamic underbalance sub for use in a wellbore, the dynamic underbalance sub comprising:
a sub housing;
a first chamber provided in an interior of the sub housing;
an opening extending through the sub housing and configured such that the first chamber is in fluid communication with an exterior of the sub housing;
a second chamber provided in the interior of the sub housing;
a pressure-isolating wall provided between the first chamber and the second chamber; and
a shaped charge positioned to break or perforate the pressure-isolating wall in response to detonation of the shaped charge.