Severe Mud Losses While Drilling

Reservoir: Cardium Basin, Alberta, Canada

Bottom-hole Temp: 131°F - 140°F (55°C - 60°C)

Products Deployed: CemVert+ D535 Flakes

Problem: 

An operator was drilling a well using an invert mud system when between 2723 – 2887 ft depth (4920 ft target depth) they lost complete mud circulation.  Mud losses were estimated at 60 bbl/h.

Attempted Solution: 

Operator first attempted to squeeze in a cement pill across the zone, sending a viscous pill down.  The cement plug was successfully placed, and drilling operations resumed.  Immediately after drilling through the plug, losses of 4.7 bbl/h were encountered at an injection rate of 6.3 bpm.  After 20 min, circulation losses returned to 60 bbl/h. 

DiverterPlus Solution:

The operator contacted DiverterPlus, whom recommended a procedure and delivered diverter to location via a local service company. 

1.      A pill of 200lb of CemVert+ D535 in 20bbl of mud was deployed.  Upon landing, circulation was reestablished at 7 bpm while losses were 3 bbl per hour. 

2.      The operator then ran a sequence of 3 pills of CemVert+ D535, each 100lbs in 20bbl of mud with 30bbl mud spacers between the pills.  Losses were completely eliminated after landing the pills and circulating rate was increased to 8.1 bpm.  No losses were seen at the increased rate, so drilling was resumed. 

3.      At 3937ft depth, losses of 12 bbl/h were seen, so pipe was pulled up 30ft and two pills of CemVert+ D535 (each 100lbs in 20bbl of mud) were deployed at an injection rate of 8bpm.  Once the pills cleared the end of the drill pipe 70 psi of squeeze pressure was applied to prevent circulation of the diverter to surface.  A circulating pressure increase of 145 psi was seen, indicating seating of the diverter, so the squeeze pressure was relieved and drilling operations resumed. 

Result: 

The operator was able to reach their target depth with no additional losses while maintaining 8.1 bpm circulating rates as well as run casing and a precision liner with successful cementing without further interference from loss zones.

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