| EXAMPLE WELLS: |
| Example 1: |
Chevron False River Field, Louisiana
Reported by Andy Mayeux |
Well: Paul O. Bourgeois #1 |
Added 4 ppb Contone while drilling the interval 12,145’-12,280’ immediately above the Midway Shale. The entire Midway Shale section was drilled with some minimal sloughing through the first 100’ and none thereafter. The Contone concentration was maintained throughout the drilling of the Midway Shale.
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| Example 2: |
Chevron False River Field, Louisiana
Reported by Bo Billeaud |
Well: P.S. Dorgan #1 |
Soon after entering the Midway Shale section at 13,000’, the drill string encountered severe torque problems associated with sloughing shale fouling the BHA, often requiring the back reaming of one or more joints before successfully completing a new connection. Connection time averaged 1 to 2 hours each. Four ppb of Contone was added to the 10.0 lb/gal gel-water based mud and the first subsequent connection required 30 minutes. The Contone concentration was increased to 6 ppb and mud density was increased to 10.2 lb/gal. Thereafter, connections were made with no problems and no obvious torque/drag problems attributable to sloughing shale were experienced. The Contone concentration was maintained with daily additions of ¼ ppb.
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| Example 3: |
Exxon Mobile Bay Block 111, Alabama State Lease. 536 #1
Reported by K.A. Richardson |
While tripping from 18,725’, the drill string became stuck, with the bit at 15,965’ and the BHA across an in-gage section of sandstone below a reactive shale interval at 15,500-15,800. The interval 15,900-16,200 had been “tight” on previous trips.
Sidetracked the fish. Contone was added to the seawater based gel mud system @ 4.2 ppb concentration
while kicking off the cement plug @ 14,980’ (above the reactive shale). Immediately after adding Contone the rotating torque decreased from 22,000 Ft.-Lbs to 14,500 Ft.-Lbs. The HTHP filtration rate of the 10.6 lb/gal mud decreased from 16.2-14cc. A proprietary program used to predict drilling drag and torque indicated that the coefficient of friction for this sidetrack hole was the lowest COF of any of the 9 directional Mobil Bay wells drilled by Exxon at that time. The 4-arm caliper showed the reactive shale interval @ 15,500-15,800’ to be uniform in size with an average diameter of 9 ½ “(8 ¾” bit). Caliper logs in this same shale from offset Mobile Bay wells drilled with seawater gel based mud ranged from 27” to “off-scale” in diameter.
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