On May 11, 2012, while I was shopping at Wal-Mart, I did a quick price check on different common liquids that most of us will buy, and compare them with the price of crude oil. Below is the graph that shows the price comparison between crude oil and other common liquids in barrel.
Crude Oil VS Other Common Liquids
Not many examples of casing wear are retrieved from field operations. Pulling casing is expensive, and if the damage can be nullified by running and cementing an intermediate casing liner, rather than pulling the damaged string, that will probably be done. As ever, if there are two possible solutions to a field operational problem, the least expensive one will be implemented.
Figure 1: Burst Liner
Figure 1 shows a typical liner failure. Wear is greatest at the top of the liner, and decreases as you progress downward. If wear continues long enough, the liner wall thickness is reduced to the point where the burst strength of the thinned wall is less than the internal pressure. The resulting burst is a tapered opening, largest at the top of the liner, tapering downward.
Figure 2 shows two wear grooves in a liner hanger wear bushing. After inspection revealed the first wear groove, the bushing was rotated 180 degrees before being reinstalled, thus resulting in the formation of the second wear groove.
Casing or riser wear occurs where the borehole either changes direction (dogleg or a flex joint) or diameter (top of a liner).
Dogleg severity can be determined from a directional survey of the well. With dogleg severity and drillstring tension, the lateral load on the casing can be calculated. This allows casing wear as a function of well depth to be calculated.
Where we deal with a change of well diameter – such as at the top of a liner – we have no reliable way to calculate lateral load. Therefore, we assume the worst and install wear bushings at the top of liners.
Figure 2 demonstrates the value of a wear bushing. Better the bushing should wear, rather than the top of the liner hanger.
Figure 2: Wear Groove in Liner Hanger
Figure 3 shows the split resulting from burst failure at the top of a flex joint. This failure occurred in a section weakened by internal wear. Internal view of this split is shown in Figure 4.
Figure 3: Split at the top of Flex Joint
Figure 4 is a view of the split shown in Figure 3, looking from the inside out.
Figure 4: Another View of the Failed Flex Joint
Figure 5: Wear Groove in Upper Element of Flex Joint
Victoria Secret is not really secret, but the Ritz-Carlton Seoul hotel, which I stayed during my recent trip to Korea, does have secret.
After the long flight from San Francisco, I arrived at Incheon. Another hour of limo, I was in Gangnam business district of Seoul. As soon as I stepped into the 5-star hotel, a gentleman greeted me: “Good evening! Mr. Liu?” When I was expecting something like “…, Check in?” Dale Carnegie once said: “A person’s name is the most beautiful sound in the world to them.” And I heard that sound at the farthest place away from home. Skipping the front desk, with a folder in his hand, the same staff even led me directly into my room, which, to my pleasant surprise, was a suite. They upgraded for me with fruits on coffee table, and greeting card from general manager.
During the next couple days, whenever I made phone call to the front desk, or talked with various staff, I always got greeted with my name. One day, I consulted with a lady in Concierge about trip to JeJu Island, she patiently explained to me the attractions and said that she would print some reading material and send to my room. She then asked me my room number. I answered. She immediately said: “Oh, Mr. Liu?” Looking at her puzzled,
I asked: “How can you guys and girls remember guest’s name?” She smiled like a flower:
“It is a secret of the Ritz-Carlton!” She then mentioned that I made reservation through America Express “Luxury Hotel and Resort” program. That might had something to do with it. Regardless, it is a nice secret many wish to have.
Effects of secrets are more powerful than secrets themselves, as illustrated by magicians. I may never find many secrets, but I do enjoy magician shows and my stay in Seoul.
Ritz-Carlton - 1
Ritz-Carlton - 2
First of all, we realized that the data obtained from a casing wear test did not represent a single property of any one of the three elements (casing, tool joint, drilling fluid) of the casing wear system being tested.
The curve of ‘wear groove depth’ vs. ‘test time’, such as that shown in Figure 1, shows the performance of the entire casing wear system under the operating conditions of the test.
Figure 1: Wear Groove Depth VS Elapsed Test Time
Next, we learned that casing grade, such as K-55, N-80, C-95, was not a good indicator of wear properties. Wear factors for various samples of N-80 casing were uncertain to ± 50%. Often there would be a significant difference in the wear factors obtained from casing samples cut from opposite ends of a 40 foot casing joint. Later tests showed a remarkable lack of correlation between wear factor and just about everything else associated with the composition of the casing alloy.
Every casing wear system should be regarded as unique and individual, and probably not related to any other casing wear system.
The Maurer ‘Wear Factor’, shown in Figure 2, has been shown to predict the performance of casing wear systems encountered in drilling operations with an uncertainty that is consistent with the uncertainty of the field measurements.
What is important in estimating casing wear to be expected during drilling operations is whether the casing wear factor will be 0.2 (oil based mud), 1.0 (some of the new hardbanding alloys), 5 to 8 (unprotected tool joints), or as high as 50 or 70 (X-80 as used in riser pipes).
Remember that we said that casing grade was no indicator of casing wear rate? I make an exception for X-80, a line pipe, often used as the basis for 21 inch riser pipes. At first, we didn’t believe our own results, but, yes, it was true. This explains the severity of riser wear adjacent to the flex joint at the wellhead.
Figure 2: Casing Wear Groove Volume VS Work Done by Tool Joint
The result of extremely high casing wear rate is shown in Figure 3. The tool joint was hardbanded with rough tungsten carbide, as shown in Figure 1 of Casing Wear Series – 1: How we got here?.
Figure 3: Extremely High Casing Wear Rate
This is why rough, field applied Tungsten Carbide has largely been abandoned as a means to protect tool joints during drilling operations. It does protect the tool joints, but is a bit hard on the casing.
We bought a glamour dollhouse for my 6-year-old daughter for Christmas. It finally arrived a couple of days after new year of 2012.
Yesterday evening, I set up a time to assemble it with my daughter, thinking that I could demonstrate how easy the assembly would be if we read the instructions and work together. However, the installation turned out to be a trial-n-error process. At one time, I thought I had finished the dollhouse, only to find that the top floor (one of the 3) was installed upside down with unpainted side facing up. The problem was not only about aesthetic, I also couldn’t install the partition into the slot on the floor, which was the last step. In other words, I wasn’t be able to identify the problem until the last step.
It was a major frustration, because I had to uninstall half of the dollhouse to be able to flip the floor. One can argue that I am not a handyman, which I agree, but the assembly instruction, being in black and white, doesn’t differentiate some subtle differences. And what is the worst is that any mistakes during the installation do not stop one from continuing.
My daughter had to go to bed without seeing it get done for school has started. Right before she left for her room she comforted me by saying: “We could do it tomorrow.” The installation was finally completed, after 2 hours. I felt good and now I am a semi-expert in dollhouse assembly.
This morning, my daughter’s eyes sparkled when she saw this 5-ft dollhouse standing, just as the 1st time she played “Angry Bird” in iPad a few months ago. But at that time, none of our family read user’s manual of iPad. My 6-year-old learnt to play with it almost as quickly as I did.
It is an industry norm that almost anything we buy today, from glamour dollhouse or drilling software, comes with an instruction or manual. But in reality, people seldom read manual because they do not have time and/or they expect the device or software friendly enough to be figured out. Steve Jobs once commented: “The manual for WordStar, the most popular word-processing program, is 400 pages thick. To write a novel, you have to read a novel – one that reads like a mystery to most people.”
Many people do not want to spend time reading instructions. The best manual is probably the carefully designed structure and graphical user interfaces for software. If technical background is a necessity, by all means have it in user’s manual, but the explanation of how to operate software should be kept minimal for intuitive design.
For drilling software, if roughnecks on the rig and engineers in the office can both run them without going through user’s manual, one of our goals is achieved.