F.J. BROWN & ASSOCIATES, INC.

MEMORANDUM TO: Hubert Young

FROM: Murphy J. Hebert
DATE: March 12, 2002
SUBJECT: Shale Inhibition-Main Pass Block 35

I recommend the use of Contone for inhibition of shale’s in pressure transition intervals or any shale’s that are not water wet; not for gumbo. I currently use Contone in lieu of Soltex for wells that I plan for clients in the Gulf Coast region. It has been my experience that Contone will stabilize a well bore better than any competitive product when the problem is associated with unstable shale’s.

My first use of Contone was on a deep well for Chevron in Main Pass Block 35 and it was on this well that I observed the most dramatic results. While drilling a 61/2” hole below 12,000’ the gas units were high and the amount of shale across the shaker was considerably more than drilled cuttings. Periodic increases in mud density resulted in short term decreases in gas units but the volume of shale continued to be excessive. During a logging run, the caliper on the logging tool was fully extended and Indicated a hole size too large to measure. Obviously, Chevron’s Geology Group were displeased with the hole size and Chevron’s Drilling Superintendent decided to add Contone, a new product at the time, to the mud. The remaining 61/2” hole, several hundred feet, was in perfect gauge.

As a well site-drilling engineer, I was amazed with the results. But had no idea why this dramatic result occurred. Because of a production engineering assignment, I forgot about Contone. Upon returning to a drilling assignment, I found the industry using blown asphalt, Soltex, for shale inhibition. Although the results with Soltex were good on all wells I was associated with, there was none to compare with the results obtained with Contone. Contone does not go into solution as readily as Soltex, which explains the more favorable results from Contone. If the material has to seal the micro-fractures, the last soluble-the better the results.

Some of our well site supervisors are high on Contone as a lubricant and recommend it for decreasing torque and drag. However, I do not use it for that purpose, but accept the fact that there is an additional benefit.

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