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Oil and gas industry operations cannot control all of the trials and tribulations that may come with exploration and drilling activities. As we will demonstarte below, there are always issues that the industry will face including, among other problems, drill pipe issues. Operators can, however, anticipate common problems and issues and be prepared for them with the necessary equipment and support in case something bad does occur. What types of drill pipe issues and drilling issues may companies encounter?
Below, MSI Pipe Protection Technologies shares information on eight common issues that both land-based and offshore drilling operations face today.
Drilling operations may encounter several different types of drill pipe issues and failure. These include the following:
While it may be impossible to totally eliminate drill pipe issues and failure, there are steps that can be taken to minimize the occurrence and magnitude. For example, fatigue-based failures can be mitigated by reducing cyclic stresses and managing the drilling environment to be less corrosive. Proper handling and inspection of the drill string can also help to prevent drill pipe failures.
Fig. 1 Failure Analysis of Drill Pipe: A Review
Source: DirectScience.com
Cyclic stress occurs in directional wells because the drill string is both compressed and stretched simultaneously. This happens when the drill string is bent along the curvature of the well, so that one side experiences compression and the other tension. This type of structural stress can dramatically shorten a drill pipe&#;s life expectancy.
To reduce cyclic stress, operators should minimize the severity of any doglegs, thus providing a straighter path for the drill string. It&#;s also important to try to control drill string vibrations that can exacerbate the structural stress.
Drill pipe corrosion is caused by a variety of chemicals in the drilling mud that then interact with the metal in the drill pipe. The most harmful of these chemicals include oxygen, carbon dioxide, and hydrogen sulfide. Dissolved salts and organic acids can also cause corrosive damage to metal drill pipes.
To reduce corrosion, operators can employ corrosive scavengers and work to control the mud pH levels when hydrogen sulfide is present. Changing the chemical composition of drill pipe fluid to remove corrosive chemicals is also advised.
Pipe sticking occurs when a pipe can&#;t be freed and pulled out of the hole without damage. There are two types of pipe sticking issues.
Differential-pressure pipe sticking occurs when some or all of the drill string becomes embedded in mud-cake. To free this type of stuck pipe, operators can try diluting or gasifying the mud weight with nitrogen to reduce the mud-hydrostatic pressure in the annulus. Operators can also apply oil spotting around the stuck drill string.
Mechanical pipe sticking typically occurs when drilled cuttings from the annulus are not fully removed or when borehole instabilities appear. To free mechanically stuck pipe, the cause of the problem needs to be corrected. For example, if the borehole has narrowed, increasing mud weight or circulating fresh water may free the pipe.
Fig. 2 &#; Differential Sticking. Oilfield Glossary
Drill pipe threads can become damaged due to operator error, faulty manufacturing, or adverse drilling conditions. Proper care, use, and inspection of the drill pipe threads are necessary to prevent this type of issue. It&#;s also necessary to ensure the correct rig alignment and avoid over torque.
Care should also be taken when storing and transporting drill pipe, including using thread protectors and similar products offered by MSI Pipe Protection Technologies.
As noted, over torque can cause significant drill pipe thread damage. Over torqueing typically occurs when the drill pipe under torqued before its run down the hole. In these conditions the pipe continues tightening down the hole and can easily be over tightened.
The simple solution to this problem is to always properly tighten the connections to their designated levels &#; at the table. This requires doing the proper math to determine the optimum make-up torque, but will minimize the risk of over torque and damage to the drill pipe threads.
Borehole instability describes a hole that does not consistently maintain its size, shape, or structural integrity. An unstable or collapsed borehole is typically caused by overburden or pore pressure, earth movement, or water absorption or dispersion. Unstable boreholes can cause other problems, including stuck pipe, bridges and fill-up, the enlargement of wellbores, and difficulties in logging.
To minimize the risk of borehole instability, drilling operators should use the appropriate borehole fluid and hydraulics, select the right mud weight, determine the proper hole trajectory, and spend the minimal time necessary in the open hole.
Lost circulation describes the uncontrolled flow of drilling mud into a formation. This typically occurs when the pressure exerted against the formation exceeds the formation&#;s total pressure. This can happen when formations are cavernous and open fissured, coarse and permeable, naturally or easily fractured, or depleted. Lost circulation can result in an increased mud expense and can even cause subsurface blowouts.
Operators can reduce circulation loss by maintaining the proper mud weight, minimizing annular-friction pressure losses, avoiding restrictions in the annular space, and using appropriate formation pressure and facture gradients. Mud can also be treated with lost-circulation materials.
In the event of lost circulation, operators need to seal the affected zone. This can be done by mixing lost-circulation materials into the mud. In severe cases plugs can be used to seal the zone.
Volume II of the Petroleum Engineering Handbook provides a wealth of resourceful information on resolving the eight issues we&#;ve discussed. However, Chapter 10 of the handbook offers even more detail on how to fix some of the drilling issues that operators face. Learn more below.
If you want to learn more, please visit our website Threaded Water Well Drill Pipe.
PEH: Drilling Problems and Solutions &#; Chapter 10
Operators can also protect their drill pipes and other drilling equipment with the wide range of Guardian&#; drill pipe protection products from MSI. Our top-quality products include durable plastic and steel pipe protectors, bumper rings, pipe chocks, and Rhino tubular handling systems. Our products primarily help prevent issues like pipe thread damage, corrosion, and certain pipe failures.
You can conveniently discover more information online. Give us a call toll-free at 1-877-276-. MSI Pipe Protection Technologies is an NOV/Tuboscope Company, and we&#;re proud to help you deliver all day, every day.
Sometimes we just don&#;t know.
In the early s, we received a complaint of thread problems from an Oklahoma customer. After a month or two of drilling, the threads had become damaged and unusable. The customer ran 2&#;&#; flush joint drill pipe a Schramm T64. They hoped to strike oil at around 1,100 feet.
We asked for a sample and examined it, only to find no definitive causes of the problem. Since our customer was one of our best OEM accounts, we offered to replace the drill pipe. We took extra care in manufacturing the replacements &#; especially double-checking our threads. We sent out the replacements only to get a call a few weeks later that it was happening again. We planned a trip to visit the rig.
Typically, a manufacturer&#;s thread issue appears very quickly, perhaps in the first couple of holes. However, given I had no experience running a drill rig, I had limits to my technical experience and troubleshooting. I hired a former Schramm start-up man named Jones (I cannot recall his first name). Jones had been all around the globe starting up new Schramm rigs, including a stint in Africa where he slept in an empty 55-gallon drum for two weeks.
One concern I had centered on the drill pipe having a 2&#;&#; FEDP (Failing Exploration Drill Pipe) connection to the 2&#;&#; OD flush joint. I thought this a poor choice of connections. The 2&#;&#; FEDP had an oversized thread for this diameter of drill pipe. You may hear people describe the imbalanced connection as &#;box weak&#; or &#;pin strong.&#; In this case, I brushed aside the concern because we had an OEM print. Certainly, the OEM&#;s engineers verified that this combination was OK.
I met Jones in Oklahoma City and headed out to the rig in southern Kansas the next morning. Once there, I observed the crew adding new drill pipe. I could see aspects like alignment, ease of make-up and care taken. Jones watched the operator, to see if he did anything that might contribute to the issue. Every so often, we inspected the connections.
Before I left for this trip, I checked the weather and thought I had packed well. But, I had under estimated that Kansas wind and it was downright cold. While waiting for drill rod changes, I spent a lot of time near the rig&#;s exhaust, trading inhaled diesel emissions for heat. That night on the way back to the hotel, we stopped so I could buy warmer clothes.
On site the next day, my heart sank as I observed the beginnings of thread damage on some connections. Jones saw nothing abnormal in the operation of the rig. Now what? I do not know who was more disappointed with the dry hole: me or the property owner.
What were my options?
Try another replacement string? We tried everything with the replacement string we sent, so we could probably expect similar results with any replacement string.
Tell the driller that the problem is not ours. We took extra care and conducted thorough inspections on the replacement pipe, so the problem must lie elsewhere. Remember, however, that the sale went through a good OEM customer. Taking this route would transfer the problem to the OEM, potentially damaging our relationship with that company.
I opted to bite the bullet. We would refund the money and take back our drill pipe. Although the OEM was not exactly pleased, they understood the situation. Since we could not solve the problem, they could work with another source.
While this did take us out of the picture, I hoped it would resolve the problem for the contractor. Of course, I can&#;t deny wondering, in back of my mind, if the new supplier would face the same problems we did.
I still think about this. Applying today&#;s experience, was our information on the 2&#;&#; FEDP connection correct? We did not have an official print, which meant we reversed engineered the connection. Did we have a hardened ground thread gage, or did we use a &#;size piece&#;?
Was the problem a torque issue relating to the fact that the 2&#;&#; FEDP was an oversized connection for the 2&#;&#; OD tool joint? Being somewhat naive at that time, I never considered it. Now I would try to determine if that damage was due to under or over torquing. I should have gone to a thread consultant for their opinion. Maybe then, the problem could have been resolved and I could have learned something new.
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Sometimes the problem lies in not knowing what we do not know. I did not know about make-up torque and balancing connections, so I did not consider them issues. Without that knowledge, these aspects went uninvestigated. I should have sought expert advice.
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