Friday, December 16, 2011

Deepwater Horizon - NAE Report

FIGURE 2-7 Uncontaminated cement compressive strength tests (DP = differential pressure). Source: Committee.

The most definitive report yet on the Gulf oil spill has just been released. This long awaited report by the National Academy of Engineering (NAE) on the causes of the Gulf oil spill has been buried like a document dump on the Friday before Christmas. This is the final report by the NAE. It was initially empowered to do this investigation by Interior Secretary Ken Salazar, who then promptly ignored its preliminary findings when he imposed his unilateral drilling moratorium in May 2010. Combined with the juicy news that BP has alleged in federal court that its cement contractor, Halliburton, has engaged in the destruction of physical evidence, a claim Halliburton has denied, this is guaranteed to become a hot button issue. The NAE report provides support for BP's claim and a motive for Halliburton's alleged improprieties. The most important new information is a detailed examination of the nitrified cement that was used. A careful reading of the discussion of Compressive Strength of Foamed Cement and Un-Foamed Cement on pages 22-23 of the report is quite revealing.

The properties of Class H cement are well known. The properties of foamed cement are not well known and not easy to measure because of the compressibility of the foam. In principle, the compressive strength of foamed cement should be less than the compressive strength of unfoamed Class H cement, given the same curing conditions and additives. Testing has shown this to be true. The compressive strength of foamed cement has been shown to be approximately 35 percent of that Class H base cement under the same curing conditions (Gardner 2010). Testing done by Chandler Engineering (Sabens and Maki, Jr 2002) has shown that foamed cement begins to establish compressive strength at about the same time as the base cement (Class H in this case), but the strength of the foam continuously lags that of the base cement as curing time increases. Accepting these trends as representative, the committee created Figure 2-7 to show the compressive strengths of the various cement slurries. The Chevron (protocol 1) and Halliburton base slurry curves are taken from the laboratory testing done on those two un-foamed slurries. The curves for the two foamed cements are not from direct measurement, but assume the foamed cement compressive strength is reduced according to the foam protocol used in the Chevron test software (by a factor of approximately 35 percent). [SNIP]
Figure 2-7 shows the time at which the negative pressure test was started after cement slurries were pumped into the Macondo well. The figure also shows a differential pressure of about 999 psi that was created between the reservoir pressure and the reduced hydrostatic pressure inside the casing during the negative test (see Appendix C for the calculation). Figure 2-7 indicates that the foamed cement using the Chevron data would have just barely established the strength required to resist crushing under the differential pressure imposed by the negative test, assuming that the cement was not contaminated or altered by other events. The foamed cement using the Halliburton base data and the foam algorithm would not have achieved sufficient compressive strength.

In simple English, when the crew of the Deepwater Horizon replaced the drilling mud in the riser above the blowout preventer and upper section of the production immediately below (down to a depth of about 8,300 feet) with lighter sea water, they created a hydrostatic pressure at the very bottom of the well (in the shoe track) that was 999 pounds per square inch less than the pressure of the formation. As you can see in figure 2.7, the Halliburton foam algorithm (HAL Foam Algorithm) line is below that value at the time the test took place (about 900 psi at 16.4 hours after the cement was pumped into place). It is also apparent that allowing more time for the cement to cure had little additional effect. Contrast that to the curve for the un-foamed Halliburton cement (HAL base Cmt). At 16.4 hours the foamed cement has a compressive strength of about 900 psi and is steady but the un-foamed cement is about 2700 psi and rising, peaking at about 23 hours. So experience would have made them expect a compressive strength of 2700 psi when all they had was 900 psi.

It was the failure of the crew to recognize this dramatic reduction in compressive strength that led directly to the blowout. The cement was not strong enough to withstand the 999 psi pressure differential and broke during the negative pressure test. While the transcripts of the Joint Investigative team (JIT) have been hidden behind a firewall making linking impossible, the gist of the testimony by the various witnesses was that none of them had used foamed cement at the depth of this well, 18,000 feet. Combined with an abnormally high percentage of nitrogen in the mix, which resulted in a lower compressive strength, they were in totally uncharted territory. Add in that very few of the men had ever performed a negative pressure test because the standard practice was to wait until the well was being completed, at a later stage of construction, before going to an “underbalanced’ condition and it is no surprise that the crew was confused. They did try to close the blowout preventer after mud was spewing onto the deck, but the gas had risen above the blowout preventer so it had no way to stop the gas that had already flowed past it. The crew’s fate was sealed when the diesel engines sucked in the flammable natural gas/air mixture, over-revved and exploded.

The most obvious lessons learned ought to be:

1) If no one has done the procedure before, get qualified technical experts to teach you how before attempting to do it! Ask questions!!
2) Never use a nitrified cement with such a high percentage of nitrogen in it a pressure barrier!
3) If you have never done a negative pressure test before, you have never actually confirmed the quality of the cement job in the shoe track. This is why the prevalent cement failure mode is an annular blowout, negative pressure tests were quite rare and by the time you unbalance a completed well you want the gas to flow, so it matters not whether the flow is through perforations in the production casing or U-tubing up through the shoe track.
4) A huge amount of effort was wasted on the expectation that this was an annular blowout, when it was a “wet shoe” blowout. A timely attempt at a “top kill” would have succeeded and stopped the flow of oil into the Gulf in mid-May.

Saturday, December 10, 2011

Impeachment? Eric Holder's Next Big Problem

Remember President Obama dispatching attorney General Eric Holder to be the enforcer during the BP oil spill. The kind of guy who would “kick ass”, or in Interior Secretary Ken Salazar’s phrase keep a “boot on the throat” of BP? Well it seems there is a little tiff developing in federal court in New Orleans between BP and the left’s favorite bête noir Halliburton. The Wall Street Journal reports

BP’s alleging that Halliburton co. destroyed evidence in the weeks following the Deepwater Horizon explosion in 2010 that demonstrated that the cement formula the firm used on the drilling operation was flawed. The claim, made Monday in a federal civil-court filing in New Orleans, is the latest in a continuing volley of accusations between the companies as they face potentially huge civil and criminal penalties stemming from the 2010 accident in the Gulf of Mexico that killed a total of 11 people and led to the largest offshore oil spill in the U.S. history.
Halliburton has previously said that it believes the cement mix it recommended that BP use on the well was stable. It has argued that the well failed because of poor engineering and design choices made by BP.

Destruction of evidence, Oh My!!! Reading through the article you will discover that BP is alleging that Halliburton destroyed test samples meant to replicate the exact mixture of the cement used in the ill-fated Macondo well. This would seem to be the perfect opportunity for a grown-up to intercede. And the logical candidate would be Attorney General Holder as he is supposed to have in his possession the fragments of the actual cement used in the shoe track of the well. Those fragments ended up on the deck of the support vessel, the Damon Bankston, which played such a critical role in the rescue of the crew of the Deepwater Horizon, fragments of the actual failed cement job from a total depth of 18,000 feet, below one mile of ocean and two and one half miles of solid rock! What a key piece of evidence that must be!

Now one is inclined to marvel at the “target rich” environment Mr. Holder finds himself in. But, like a confused bluefin tuna approaching a shoal of baitfish, will he become confused, decide to lead from behind and go hungry? (As an aside the WSJ also reports that the bluefin tuna population survived the spill).

As AT’s publisher Thomas Lifson asked me, wouldn’t this seem to be a heaven sent opportunity for Eric Holder to add Halliburton to the demonization list of evil corporations? While at first glance that might seem to be the case, but the test results proving that the mixture of cement and nitrogen was a little “thin” is confirmation of the observations that I made in my August 4, 2011 blog post here on AT.

Given that the chief counsel to the president's commission on the oil spill agrees that the blowout occurred through the cement in the shoe track, it is unacceptable that no administration official has yet commented on what the commission's own researchers have discovered. Here's the link to the Halliburton experts on nitrified cement who state in their last paragraph "Typically, only 2 1/2 to 5 % of gas by volume is required downhole to produce enough compressibility to help prevent gas entry into the cement column." Per Halliburton's OptiCem program, Macondo was allegedly
going to suffer "severe gas flow potential" at 19% gas by volume!
Even a novice ought to be able to imagine what the consistency of the cement would be with about four times too much gas in the mixture!

Oh the humanity!!! All those $1000 per hour litigators, government regulators, mainstream media reporters and other elitists failed to find a problem that is obvious to a fifth grader. And they do not like to lose when playing Are You Smarter Than a Fifth Grader?

The Courage to Make a Decision

Regular readers of the American Thinker know that I was employed by Grumman Aerospace during the summer of 1969 when the corporation’s Lunar Excursion Module Eagle carried Neil Armstrong and Buzz Aldrin to the Sea of Tranquility and then re-inserted them into lunar orbit to begin the journey home, in JFK’s immortal phrase “return them safely to the Earth”. So it shouldn’t come as any surprise that I like to watch the original videos of the Apollo 11 mission. I recently found one on YouTube that brilliantly illustrates what we have lost since those days. It only lasts 9 minutes and 50 seconds, but it is a real time record of decision making at its finest.

To get the context of what you will see it is necessary to become familiar with the story of Jack Garmin. Here is the relevant history taken from his Wikipedia page

In 1966 at the age of twenty-one Garman was hired by NASA. He chose to specialize in onboard computing and was assigned to the Apollo Guidance Program Section where he worked with MIT, supervising the design and testing of the Apollo Guidance Computer.
During the Apollo missions Garman worked in a support role, advising flight controllers in Mission Control on the operation of spacecraft computer systems. A few months before the Apollo 11 mission he suggested that simulation supervisors at Mission Control test how flight controllers might react to a computer error code. Guidance officer Steve Bales responded to the simulated error by calling an abort, which was found to be a needless reaction for that particular code. As Garman later recounted, "Gene Kranz, who was the real hero of that whole episode, said, 'No, no, no. I want you all to write down every single possible computer alarm that can possibly go wrong.'" Garman made a handwritten list of every computer alarm code that could occur along with the correct reaction to each of them and put it under the plexiglass on his desk.
An error in procedural protocol went undetected during simulations and during the final descent of Apollo 11. This led to a switch in the lunar landing module (LM) being set to the wrong position. As a result, (and unknown to anyone at the time), the onboard guidance computer was needlessly processing data from the rendezvous radar. Then, as the LM descended, its separate landing radar acquired the lunar surface. Now processing data from two radars instead of only one as intended, the computer's duty cycle grew heavier than expected and a series of "1202" and "1201" alarms began signalling an executive overflow, meaning that the computer did not have enough time to execute all tasks so lower priority tasks were being dropped. Several seconds after the first alarm Neil Armstrong, with some concern apparent in his voice said, "Give us a reading on the 1202 program alarm." Meanwhile, given his knowledge of the computer systems, Garman had already advised Steve Bales the computer could be relied upon to function adequately so long as the alarms did not become continuous.[1] Bales, who as guidance officer had to quickly decide whether to abort the mission over these alarms, trusted Garman's judgement and informed flight director Kranz. Within seconds this decision was relayed through CAPCOM to the astronauts, Apollo 11 landed successfully and Garman received an award from NASA for his role in the mission.
Bales later recalled, "Quite frankly, Jack, who had these things memorized said, 'that's okay', before I could even remember which group it was in".[2]

As you watch the video you will get the first hint of an anomaly at 0:45

“We’ve got data dropouts. You’re still looking good.”

The 1202 program alarm appears at 1:58

“Give us a reading on the 1202 program alarm.”

Steve Bales gives them the “reading” they need at 2:04!

“We’re go on that alarm.”

The alarm re-appears at 2:24.

“Same alarm and it appears to come up when we have a 1668.”

Having isolated the problem Neil Armstrong tries to go back to automatic control at 3:22.

“Okay, I’m still on slew. So we may tend to lose as we gradually pitch over. Let me try auto again now and see what happens. Okay looks like she’s holding.”

Houston answers at 3:34

“Roger we’ve got good data.”

Contrast that to a President who wants to wait for all the data to come in before he begins to mull over his options and do the polling before making a decision. I know that Tom Brokaw likes to call the World War II generation, “The Greatest Generation”. I’m satisfied being a part of the Apollo Generation, a junior thermodynamicist for Grumman at age 20 during the Summer of ’69. And I am also certain that there is a succeeding generation soon to arrive from the Association of Independent Technological Universities.

Thursday, December 01, 2011

Sirius Thinks That's Interesting, Wait 'Til He Sees Fukushima on TheOiIDrum

Sirius made a positive comment about my post "Plagiarism Masquerading as Leading From Behind" below

Now that the real facts about the Fukushima Nuclear crisis are starting to come out in the Wall Street Journal , he ought to read the various Fukushima threads on The Oil Drum site!

Start here

It will be worth the effort!!!!

EDIT - 12/3/11 - The Wall Street Journal has a column today about Tepco's internal investigation of the accident. They obviously STILL don't get it! So read my comment to their article for more info