Schlumberger

Case Study: TDDirect CD Casing-While-Drilling Service Saves 52 Hours in Lobo Field, South Texas

Casing while drilling reduces lost-circulation NPT to
1 hour

Challenge: Drill three intervals to TD while reducing NPT associated with stuck BHAs and lost circulation.

Solution: Use TDDirect CD casing-while-drilling service with retrievable BHAs and underreamers for two intervals, and use a nonretrievable bit with a TDDirect casing-drilling and liner-drilling technology bit release tool.

Result: Cased while drilling three intervals to TD, reducing NPT by 52 hours.

Excessive NPT hinders operator’s progress

An operator using a conventional drilling assembly to drill multi-interval wells in Lobo field, South Texas, was dealing with stuck pipe, lost circulation, forced shut downs to build mud volume, and mechanical and cementing problems. The operator wanted to drill a planned three-interval well more efficiently and reduce lost circulation, stuck pipe, and other NPT-related incidents.

Integrated drilling approach matches application demand

Schlumberger recommended the TDDirect CD casing-while-drilling service with retrievable BHAs and underreamers to case while drilling the first two intervals. Following this, a nonretrievable bit and aTDDirect technology bit release tool would be used to case while drilling the third interval.

The first interval was drilled with a pilot bit and a 12 1/4-in underreamer on a 9 5/8-casing string. Upon reaching TD, the TDDirect CD service BHA was retrieved through the casing prior to cementing. The intermediate section was drilled with a TDDirect CD service using a 6 1/4-in PDC pilot bit, 8 7/8-in underreamer on 7-in casing. After reaching TD, the BHA was retrieved and the casing was cemented.

The 4 1/2-in production section was cased while drilling using a nonretrievable 4 1/2-in bit with a TDDirect technology bit release tool . Upon reaching TD, a rat hole was drilled and the casing landed. A ball drop activated the bit release tool, releasing the bit into the rat hole. After which, the 4 1/2-in casing was cemented.

Casing-while-drilling service substantially reduces NPT

When recounting previous well drilling times in the field by conventional assemblies, from spud to release, the operator determined that 300 hours was the best time in which a three-interval well was drilled. The TDDirect CD service and TDDirect technology tools cased while drilling a well with the same number of intervals in 248 hours and reduced NPT caused by lost circulation to one hour. During the project, the retrievable BHA design was successfully run and retrieved 95 times with no delays.


Download: TDDirect CD Casing-While-Drilling Service Saves 52 Hours in Lobo Field, South Texas (0.59 MB PDF)

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