Buy API 11BR: RECOMMENDED PRACTICE FOR THE CARE AND HANDLING OF SUCKER RODS from SAI Global. Find the most up-to-date version of API RP 11BR at Engineering Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at  API RP 11BR, Recommended Practice for Care and Handling of Sucker.
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Carrying out the various procedures described in this section can greatly reduce operating costs and make production more efficient and economical.
An SPE paper by Powers  considers the factors that enter into the decision about when to replace the entire rod string after sustaining the calculated number of failures.
Fatigue of rods also was considered in The primary factor in determining the proportion of each size of rod in the rod string is the size of the pump. The API does not specify the minimum yield strength for sucker rods. Society of Petroleum Engineers. If any of the strands furnished the weight that was required to help open the traveling valve, the strands immediately above the sinker bars failed in short order because of the compressive forces.
In such cases, corrosion-fatigue failures occur frequently in the rod string.
The weak point in the string is this rod. Approximately 40 years ago, a top steel manufacturer experimented with the use of plastic-coated wire cable instead of sucker rods. A detailed discussion and development of these formulas is provided by Zaba. However, the ID of the seating nipple determines 11gr fluid load that must be lifted to unseat the pump.
This hardness is normally accomplished by the spray-metal process. This is calculated as a static load.
RP 11BR Archives – Production Technology
Usually, wells of the same type in a field can be grouped together and the necessary calculations do not have to be performed for each well. The three main grades 111br steel rods follow:. Regardless of what method or program is used to predict loads, once the equipment is installed and the well has stable production and fluid levels, it is recommended that a dynamometer 11r be run with a load-capable dynamometer attached to the polished rod.
The first column of Table I in this reference contains the rod-string size designation. However, a high tubing-casing-annulus fluid level decreases the load on the rod string when attempting to unseat a pump. In a noncorrosive environment, the endurance limit of steel is primarily determined by the maximum stress, the range of stresses, and the number of stress reversals.
These rods have a special heat treatment that should put the surface in a compressive set. There has been a apii history of work trying to model or design sucker-rod strings. Thus, when placing the rod string with new suckers, new pony rods should be used. This enables operators to run 1-in.
API RP 11BR Revisions on Sucker Rod Makeup
The advantage of this rod is its ability to pull the entire rod string in one piece with a special pulling unit. A hand-tight position is attained when full shoulder abutment is made and a 0.
The sucker-rod string is often highly stressed and usually fails because of the repeated load reversals. This method correlates strain guage readings in the laboratory versus the applied torsional load during makeup and the resulting movement of the coupling to provide the required 11gr preload stress. The predicted loads should be compared to the actual loads and the associated fluid production.
These variables include, but are not limited to: The use of the API taper lengths, of course, saves the time of a detailed string design, but the wide availability of personal computers today has eliminated the need to resort to such a shortcut method.
Preload no axial load 3 2. The Sponsoring Organizations cannot and do not warrant the accuracy of these 11bt beyond the source documents, although we do make every attempt to work from authoritative sources.
Using four or 11bg sizes of rods in a taper is not normally recommended. Thus, a full economic analysis should be conducted and good operating records obtained to determine if use of these rods is cost effective.
The diameter of the pump plunger determines the fluid load lifted during the pumping cycle. This type of rod string was less expensive than a normal API steel string and was found useful for unloading gas wells.
This is impractical, not only because of the manufacturing difficulties involved, but also because the lower rods must have sufficient stiffness to support the entire string in the tubing if failures occur high up in the string. Old pony rods normally should not be used in the load-carrying part of a new rod strings.
A number of manufacturers have developed higher-strength steel rods to compete with other specialty rods.
API RP 11BR Revisions on Sucker Rod Makeup
This includes the original work from Slonneger  and Mills  on vibration effects of rod strings. Chemical inhibition may not prevent embrittlement. This allows pumps to be run deeper than would be possible if just one size of rod was run. The taper percentages published in RP 11L were calculated from the Neely,  procedure by assuming several parameters like pumping speed, polished rod stroke length, etc.
Corrosion, scale, and paraffin deposits may accelerate such failures. Adjustments to the predictions should be made for future troubleshooting and any further zpi changes. Proper running, handling, and makeup procedures should be followed to secure maximum service from a rod string. Subsurface equipment for sucker-rod lift. Typically, the rod-string section ap be replaced after two or three failures, while the entire rod string may be replaced after three or four failures.
Further work by Hermanson  using the area relationships and allowable strength of the different grades of 11hr rods resulted in different derating factors, which are included in API RP 11BR.