History of Slim Hole Coupling Derating Factors ...· 8th Annual Sucker Rod Pumping Workshop...

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Transcript of History of Slim Hole Coupling Derating Factors ...· 8th Annual Sucker Rod Pumping Workshop...

  • 8th Annual Sucker Rod Pumping Workshop

    Renaissance HotelOklahoma City, Oklahoma September 25 - 28, 2012

    History of Slim Hole Coupling Derating Factors &

    Application to Special High Strength Rods

    by

    Norman W. Hein, Jr., P.E.NPS Norris/AOT

  • 09/25-28/2012 2012 Sucker Rod Pumping Workshop 2

    Content Origin of Derating Factors by Mr. F. W. Gipson Modifications by Mr. D. Hermanson Extension of D Grade Rod Strength to Special

    High Strength Rods Conclusions and Recommendations

  • HF Design, selection, clearances table

    09/25-28/2012 2012 Sucker Rod Pumping Workshop 3

  • Gipson & Swaim Green Book

    The first discussion that provides derating factors for slim hole couplings was published in the 1969 by Gipson & Swaim in the Conoco Green Book

    09/25-28/2012 2012 Sucker Rod Pumping Workshop 4

  • Green Book (first published 1969) Although not discussed was why the derating was

    required other than field failures were occurring. Looking back into the production time of the

    fields, it is assumed that waterflood response was occurring, wells were able to produce more fluids, and prior rod string installations were inadequate to handle the required, applied loads/stresses.

    Normally, if higher loads were being applied, rod body cross sectional area would still be the weak link and the body should fail first.

    This may be occurring again w/new, deeper wells09/25-28/2012 2012 Sucker Rod Pumping Workshop 5

  • Development of Derating Factors T Class Couplings

    Gipson first compared full sized cross sectional area to associated rod body area.

    Established the following area relationship:

    09/25-28/2012 2012 Sucker Rod Pumping Workshop 6

    Nominal Coupling Size (in)

    (OD area)2-

    ID area)2(in)2

    Rod Body Area(in)2

    (Delta Coupling

    Area)/ Rod Area

    5/8 1.0508 0.307 3.42283/4 1.1579 0.442 2.61977/8 1.4398 0.601 2.39571 2.2342 0.785 2.8461

    1- 1/8 2.4694 0.994 2.4843

  • 09/25-28/2012 2012 Sucker Rod Pumping Workshop 7

    Based on rod body to coupling areas, with the coupling area 2.4 to 3.4 times associated rod body area, the rod body is the weakest link.

    If couplings are properly made up to required connection preload, and then installation properly operated, you should never see a connection or coupling failure

    Derating (cont)

  • Slim Hole Coupling Area Comparison

    09/25-28/2012 2012 Sucker Rod Pumping Workshop 8

    Similar coupling to rod area comparison made. A derating of the slim hole (SH) coupling could

    be made for all sizes but response from the field said 1 SH couplings were not failing.

    The derating was modified to normalize the factors to account for the non-failures of 1SH couplings

  • Normalized SH Coupling Deratings

    Nominal Coupling Size (in)

    Delta Coupling Area (in)2

    (Delta Area)/ Rod Body Area

    Normalized Derating (prior column)/2.0606

    0.3234 1.6471 0.79935/8 0.5109 1.6642 0.807 0.8510 1.9253 0.93437/8 0.9337 1.5536 0.75401 1.6176 2.0606 1.000

    09/25-28/2012 2012 Sucker Rod Pumping Workshop 9

  • Rod Strength vs. Coupling Strength

    Rod Grade Tensile Range (ksi)

    Coupling Tensile (ksi)

    C &K 90 to 115 90 minAll 3 D 115 to 140 (56 to 62 HRa)

    Special HS 140 to 150 (155; 160)

    09/25-28/2012 2012 Sucker Rod Pumping Workshop 10

  • 09/25-28/2012 2012 Sucker Rod Pumping Workshop 11

    Dean Hermansons Extension

    API Rod Size (in) Normalized Derating Factor5/8 0.81 0.937/8 0.751 1.0

    API Rod Size (in)

    API Grade K API Grade C API Grade D

    5/8 na 0.97 0.77 na na 0.867/8 0.93 0.88 0.691 na na 0.89

  • Special High Strength Rod T Class Derating Extension for SH & FS

    09/25-28/2012 2012 Sucker Rod Pumping Workshop 12

  • Conclusions

    Gipsons mathematical comparison of areas originally resolved connections failing; but this compared nominal C versus coupling T grade.

    Hermanson said that if D grade rod used versus T grade couplings, then SH deratings may need to be further reduced.

    Extending strength comparison to special HS rods says deratings need further reduction not only for SH, but also FS.

    09/25-28/2012 2012 Sucker Rod Pumping Workshop 13

  • Rod string designs need to consider the potential need to apply the SH derating factor or at least provide to the operator that a failure potential may exist

    If dont want or cant derate rod string, then operator needs to run the correct sized tubing in the length requiring SH couplings

    This can be run as full length or tapered tubing string

    Or could consider running special HS couplings09/25-28/2012 2012 Sucker Rod Pumping Workshop 14

    Recommendations

  • Precaution

    Many rod strings have been installed w/o excessive failures even though SH couplings included

    Some believe there is not a need to derate; but there has been recent rash of coupling failures high in the string

    Operators may want to consider running a pilot string w SH couplings w/o derating to see if there are operational problems/failures then take the risk

    09/25-28/2012 2012 Sucker Rod Pumping Workshop 15

  • 09/25-28/2012 2012 Sucker Rod Pumping Workshop 16

  • 09/25-28/2012 2012 Sucker Rod Pumping Workshop

    CopyrightRights to this presentation are owned by the company(ies) and/orauthor(s) listed on the title page. By submitting this presentation to the Gas Well Deliquification Workshop, they grant to the Workshop, the Artificial Lift Research and Development Council (ALRDC), and the Southwestern Petroleum Short Course (SWPSC), rights to:

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    as directed by the Workshop Steering Committee. Place it on a CD for distribution and/or sale as directed by the

    Workshop Steering Committee.Other uses of this presentation are prohibited without the expressed written permission of the company(ies) and/or author(s) who own it and the Workshop Steering Committee.

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  • 09/25-28/2012 2012 Sucker Rod Pumping Workshop

    DisclaimerThe following disclaimer shall be included as the last page of a Technical Presentation or Continuing Education Course. A similar disclaimer is included on the front page of the Gas Well Deliquification Web Site.The Artificial Lift Research and Development Council and its officers and trustees, and the Gas Well Deliquification Workshop Steering Committee members, and their supporting organizations and companies (here-in-after referred to as the Sponsoring Organizations), and the author(s) of this Technical Presentation or Continuing Education Training Course and their company(ies), provide this presentation and/or training material at the Gas Well Deliquification Workshop "as is" without any warranty of any kind, express or implied, as to the accuracy of the information or the products or services referred to by any presenter (in so far as such warranties may be excluded under any relevant law) and these members and their companies will not be liable for unlawful actions and any losses or damage that may result from use of any presentation as a consequence of any inaccuracies in, or any omission from, the information which therein may be contained.The views, opinions, and conclusions expressed in these presentations and/or training materials are those of the author and not necessarily those of the Sponsoring Organizations. The author is solely responsible for the content of the materials.The Sponsoring Organizations cannot and do not warrant the accuracy of these documents beyond the source documents, although we do make every attempt to work from authoritative sources. The Sponsoring Organizations provide these presentations and/or training materials as a service. The Sponsoring Organizations make no representations or warranties, express or implied, with respect to the presentations and/or training materials, or any part thereof, including any warrantees of title, non-infringement of copyright or patent rights of others, merchantability, or fitness or suitability for any purpose.

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