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(CBS/ AP) The tricky process of sealing an offshore oil well with cement - suspected as a major contributor to the Gulf of Mexico oil spill disaster - has failed dozens of times in the past, according to an Associated Press investigation.
Yet federal regulators give drillers a free hand in this crucial safety step - another example of lax regulation regarding events leading up to the April 20 explosion on the Deepwater Horizon oil rig.
Federal regulators don't regulate what type of cement is used, leaving it up to oil and gas companies. The drillers are urged to simply follow guidelines of the American Petroleum Institute, an industry trade group.
An AP review of federal accident and incident reports on offshore wells shows that the cementing process has been implicated at least 34 times since 1978. Many of the reports, available from the U.S. Minerals Management Service that regulates offshore wells, identify the cause simply as "poor cement job."
In a November 2005 accident where the Deepwater Horizon was positioned above another well in the Gulf, faulty cement work allowed wall-supporting steel casing to come apart. Almost 15,000 gallons (56,800 liters) of drilling fluid spilled into the Gulf.
Just a week later in a nearby well at another platform, cement improperly seeped through drilling fluid. As a result of an additive meant to quicken setting time, the cement then failed to block a gas influx into the well.
When the crew finally replaced heavy drilling fluid with lighter seawater, as they also did last month before the blowout at Deepwater Horizon, the well flowed out of control and much of the crew had to be evacuated.
Cementing was identified by federal investigators as a glaring cause of an August 2007 blowout, also off Louisiana. They said, "The cement quality is very poor, showing what looks like large areas of no cement."
...Oil companies test the thickness and strength of cement in wells by shooting sound waves into the cement. This kind of test, called a sonic logging test, wasn't run on April 20 at Deepwater Horizon. A Halliburton manager said it's the most realistic way of testing the quality of the cement bond, but a BP manager said pressure tests are better and log tests are used only if there's already a sign of a problem.
Either way, these tests are not 100 percent reliable. Sometimes, oil companies don't discover a bad cementing job until it fails.
There can be early warning signs, though. Federal regulators have known for years that a condition called sustained casing pressure - usually gas caught between the casing and well wall - is a major problem that typically signals bad cement work.
In the August 2007 blowout, investigators cited tests showing high casing pressures that could have indicated suspect cement work. The platform owner reported a problem to federal regulators, but nothing was done before the blowout, the report said.
More than 8,000 of the 22,000 offshore wells on federal leases, most of them in the Gulf, show sustained pressure, according to government reports.
This month, in a move in the works long before the Deepwater Horizon explosion, regulators wrote in the Federal Register that the oil and gas industry in the Gulf has "suffered serious accidents as a result of high sustained casing pressure, and the lack of proper control and monitoring of these pressures."
New rules take effect June 3. But they take a conservative watch-and-wait approach and demand only routines already carried out around the industry: a management program with monitoring and diagnostic testing. If operators discover sustained pressure, they must notify MMS of plans to fix it.
There are no new record-keeping or reporting requirements in the new rules, which are backed by industry. In the rule-making documents, regulators - long accused of being too cozy with the industry - said the regulations would cost the entire industry only $5 million, compared with the "impracticable and exceedingly costly" $2 billion alternative of fixing the wells outright.
"Unfortunately, this is yet another crisis in a long line of accidents caused by cementing problems in drilling," said U.S. Rep. Diana DeGette of Colorado, a member of the Energy Committee looking into the cause of the blowout.
...Here's what the American Petroleum Industry says about cementing procedures and cement types.
Class A: Intended for use from surface to 6,000 feet (1830 m) depth* when special properties are
not required. Available only in ordinary type (similar to ASTM C 150, Type I).**
Class B: Intended for use from surface to 6,000 feet (1830 m) depth, when conditions require
moderate to high sulfate-resistance. Available in both moderate (similar to ASTM C 150,
Type II) and high sulfate-resistant types.
Class C: Intended for use from surface to 6,000 feet (1830 m) depth, when conditions require high
early strength. Available in ordinary and moderate (similar to ASTM C 150, Type III) and
high sulfate-resistant types.
Class D: Intended for use from 6,000 feet to 10,000 feet (1830 m to 3050 m) depth, under
conditions of moderately high temperatures and pressures. Available in both moderate
and high sulfate-resistant types.
Class E: Intended for use from 10,000 feet to 14,000 feet (3050 m to 4270 m) depth, under
conditions of high temperatures and pressures. Available in both moderate and high sulfate-
Class F: Intended for use from 10,000 feet to 16,000 feet (3050 m to 4880 m) depth, under
conditions of extremely high temperatures and pressures. Available in both moderate
and high sulfate-resistant types.
Class G&H: Intended for use as a basic well cement from surface to 8,000 feet (2440 m) depth as
manufactured or can be used with accelerators and retarders to cover a wide range of
well depths and temperatures. No additions other than calcium sulfate or water or both,
shall be interground or blended with the clinker during manufacture of Class G or H well
cement. Available in moderate and high sulfate-resistant types.
.....so Halliburton should have used G or H type cement....now...let's go back to the above article for a second...
" In the first sign of trouble, though, the well then failed a negative pressure test, where internal fluid pressure is reduced, according to congressional testimony from a BP PLC executive. It showed different pressures in two areas, indicating an unseen leak somewhere in the well. "
" Oil companies test the thickness and strength of cement in wells by shooting sound waves into the cement. This kind of test, called a sonic logging test, wasn't run on April 20 at Deepwater Horizon."
" Oil companies test the thickness and strength of cement in wells by shooting sound waves into the cement. This kind of test, called a sonic logging test, wasn't run on April 20 at Deepwater Horizon. A Halliburton manager said it's the most realistic way of testing the quality of the cement bond, but a BP manager said pressure tests are better and log tests are used only if there's already a sign of a problem.
...........ok....so they knew since February that there were problems...
...........on April 20th, they ran pressure tests and discovered a leak.
...........the next decision was to not perform a " sonic logging test ".....on the same day...
...........that's only because they knew it was too late.
...........pressure loss testing indicating a leak in the section of the casing made it obvious to those on-site.
............moving on....the type of test they preformed on the cement job in the Horizon well.
Pressure Testing Method
" Reliance on the weight indicators may or may not be accurate at 15,000 psi "
..........that means the well pressure is definitly above 15k psi...
Originally posted by apacheman
I will be contacting my congresscritters to demand more inspections immediately, and an independent task force to review all documentation regarding cement jobs at offshore drilling sites to determine priorities for inspection and shutdowns.
We can't afford anymore blowouts, and we can't trust the oil companies, MMS, or the Coast Guard to tell the truth.