US 12,305,456 B2
Monobore drilling methods with managed pressure drilling
Elvin Mammadov, Calgary (CA); Shawn Cody, Calgary (CA); and Ahmad Alizadeh, Calgary (CA)
Assigned to Opla Energy Ltd., Calgary (CA)
Filed by Opla Energy Ltd., Calgary (CA)
Filed on Jun. 25, 2024, as Appl. No. 18/753,570.
Application 18/753,570 is a continuation of application No. 17/226,763, filed on Apr. 9, 2021, granted, now 12,055,001.
Claims priority of provisional application 63/007,873, filed on Apr. 9, 2020.
Prior Publication US 2024/0344412 A1, Oct. 17, 2024
Int. Cl. E21B 21/08 (2006.01); E21B 21/16 (2006.01); E21B 47/06 (2012.01); E21B 37/00 (2006.01)
CPC E21B 21/082 (2020.05) [E21B 21/16 (2013.01); E21B 47/06 (2013.01); E21B 37/00 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method of killing a wellbore, the wellbore having:
a weak zone having a weak zone depth;
a heel downhole from the weak zone, the heel having a heel depth;
a horizontal section downhole from the heel; and
a drill string extending therein, the drill string having a proximal end, a distal end, a wall having an inner surface defining an inner bore extending between the proximal and distal ends, and a circulation sub provided between the proximal and distal ends,
the drill string and an inner surface of the wellbore defining an annulus therebetween,
the method comprising:
cleaning the wellbore by circulating a light mud from the proximal end to the distal end via the inner bore, and out of the distal end into the annulus;
opening the circulation sub to allow fluid communication between the inner bore and the annulus through the circulation sub;
introducing, from the proximal end, an initial volume of heavy mud, via the inner bore to the circulation sub, and out of the circulation sub into the wellbore, the heavy mud having a mud weight greater than that of the light mud;
pulling the drill string uphole;
periodically introducing additional volumes of the heavy mud as the drill string is pulled uphole;
upon determining that the circulation sub is at the top of the heavy mud or that the heavy mud is backing up the inner bore, closing the circulation sub to restrict fluid communication between the inner bore and the annulus via the circulation sub; and
pulling the drill string out of the wellbore.