Update on Sandia Downhole Dynamometer Testing

Transcription

1 10 th Annual Sucker Rod Pumping Workshop Renaissance Hotel Oklahoma City, Oklahoma September 16-19, 2014 Update on Sandia Downhole Dynamometer Testing (Data Collected in 1996) Lynn Rowlan Echometer Company

2 Introduction Electronic Downhole Load Cells (DHLC) was used to measure rod loading DHLC was developed by Glen Albert Engineering. DHLCs were usually located between two rod tapers DHLC data collected while the well is operating SANDIA coordinated collecting data using the DHLC on six (6) different types of wells. Industry provided wells and paid to run the DHLC. SANDIA collected, de-coded and presented the data. NABLA and others provided the surface Dynamometer measurements at the same time as the DHLC in wells. Sept , Sucker Rod Pumping Workshop 2

3 SANDIA Test AHC SSAU /04/96 10:00 AM Rod String: -Size--Description Length Ea.--Number--Cum. Depth 1.5" Polished Rod 30' 1 0' 1.0" API Grade 'D' Steel 4' 1 4' 1.0" API Grade 'D' Steel 2' 1 6' 1.0" API Grade 'D' Steel 6' 1 10' 1.0" API Grade 'D' Steel 25' ' DHLC Tool #5 2' ' 0.875" API Grade 'D' Steel 25' ' DHLC Tool #4 2' ' 0.75" API Grade 'D' Steel 25' ' DHLC Tool #3 2' ' 1.5" Sinkerbars 25' ' DHLC Tool #2 2' ' Flexbar Stabilizer 4' ' 2 Pump 24' 5060' Well Depth: 5278' w/ Casing of 5.5" to 5090' Tubing: 2.875" to 5060', seating nipple 5060', tubing anchor ' Sept , Sucker Rod Pumping Workshop 3

4 Lateral Acceleration Measured by DHLC: Large lateral accelerations occurred at some points along the trace. Correlation of large lateral accelerations with negative effective loads Could be used to identify where buckling of the rod string would occur Sept , Sucker Rod Pumping Workshop 4

5 Position Determined form Integration of Accelerometer Data Inch - In/Sec - In/Sec^2 200 Pump Card Vs Time (2x5i03.csv) 150 Acc. (in/s/s) Vel. (in/s) Pos. (in) /04/96 10:00:00 AM -- Tool #2 ~ Above 4995 Time (sec) Sept , Sucker Rod Pumping Workshop 5

6 Loads Determined from ID of DHLC Tube 08/04/96 10:00:00 AM -- Tool #2 ~ Above 4995 Sept , Sucker Rod Pumping Workshop 6

7 Pressure, Po, and Load Acquired at Tool 08/04/96 10:00:00 AM -- Tool #2 ~ Above 4995 Sept , Sucker Rod Pumping Workshop 7

8 Diagnostic Pump Card from Surface Dyno Sept , Sucker Rod Pumping Workshop 8

9 SANDIA Test AHC SSAU /04/96 10:00 AM Sept ,

10 Diagnostic Wave Down VS DHLC SANDIA Wave Down Pump Stroke Length ==> Inch Sept , Sucker Rod Pumping Workshop 10

11 Velocity Ft/Sec Diagnostic Wave Down VS DHLC Max. Polished Rod Velocity ==> 4.60 Ft/Sec Min. Polished Rod Velocity ==> Ft/Sec Time Per Pump Cycle ==> 9.2 Seconds Sept , Sucker Rod Pumping Workshop 11

12 Diagnostic Wave Down VS DHLC Sonic Velocity = 16,300 Ft/Sec Depth to Pump = 4995 Ft Time for Pressure Wave to reach Pump = 0.3 Sec. Sept , Sucker Rod Pumping Workshop 12

13 SANDIA DHLC Cards Initially Reported With Very Negative Loads DHLC Ao of 0.75 Rod Pump Cards Displayed using True load ~ we think compression is very very high (BUT compression could be nothing or zero) DHLC Loads initially shifted by PoAo Sept ,

14 Comparison of Effective Load Pump Card to SANDIA DHLC Card Robert Sosa: Review of Downhole Dynamometer Testing, 43 rd SWPSC: "Example output from predictive and diagnostic programs available on the market show different negative loads on the downstroke. We have measured pump cards with the DHLC that shows very little negative loads. Why can't industry get together and consistently show the same type of pump card." Sept , Sucker Rod Pumping Workshop 14

15 True Load Does Not Cause Buckling Effective Load Solved Wave Eq. without gravity term True Load No Buoyancy Effective on Dynamic Pump Loads Pump Card 1226 Lb Buoyancy Force loads shifted down below True Load = Dynamic Load - Buoyancy Force the zero load line. Predicting Behavior Sucker Rod Systems, S. Gibbs, SPE588, July 1963 Sept , Sucker Rod Pumping Workshop 15

16 True Load Calculate Using Different Technique Effective Load True Load - PoAo True Load = Effective Load - PoAo Ao is the rod cross sectional area Po is the hydrostatic Ao Constant Diameter Rod String Interpretation of Calculated Forces on Sucker Rods, J.F.Lea, SPE25416, Feb 1995 Sept , Sucker Rod Pumping Workshop 16

17 1 Effective Load vs 3 or 5 True Loads? Effective Load Pump Card True Load Pump Card Effective Load Mechanical Load the Pump applies to the Rod String. True Load (1) (Po = 1673 Ao = area ¾ rod) DHLC Tool True Load (2) (No Buoyancy 1226 Lbs) True Load (3) (Po = 1673 Ao = area 1.5 rod) Weight Bar Sept , Sucker Rod Pumping Workshop 17

18 SANDIA Added True Load Options Display Effective Load OR True Load Any Rod Diameter can be Entered for True Load Option Only 1 Effective Load VERSUS Infinite Number of True Loads Sept , Sucker Rod Pumping Workshop 18

19 Why are Negative Pump Card Loads Important Negative Load supposed to mean Compressive Load True Load confuse when displayed as pump card loads Different techniques used to calculate True Load PoAo does not equal a Force or Load You cannot measure True Load with Dynamometer. True Load does not reduce the life of sucker rod strings (Goodman) True Load does not exert a mechanical force on the rods (does not cause buckling) Effective Compressive Loads can cause slender columns to BUCKLE Sept , Sucker Rod Pumping Workshop 19

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26 50% of SANDIA Pump Cards Show Negative Effective Loads 1. Critical buckling load for a long slender column (like sucker rods) is almost zero. 2. If any compressive load is applied to the rods by the pump, then the very long slender sucker rod column begins to buckle; and would buckle to failure if intermediate support were not provided by the tubing. 3. Buckling to failure does not occur in sucker rod strings, because the mode of buckling increases to cause the critical buckling load of the long column to be greater due to intermediate support to the rods by the tubing. 4. Bracing by the tubing prevents buckling to failure by the sucker rods. 5. Bracing of the tubing increases the critical buckling load above any compressive force applied to the rod string. Sept , Sucker Rod Pumping Workshop 26

27 Sinker Bars Reduce Deep Failures Caused by Rod on Tubing Wear Rod strings behave as a slender Euler column. Buckling occurs under small Effective Compressive Load. Notice: 25 Lbs. Buckles > 25 feet of 5/8 Inch Dia. Rod 50 Lbs. Buckles > 25 feet of 3/4 Inch Dia. Rod 200 Lbs. Buckles > 50 feet of 1 ½ Inch Dia. Rod Sept , Sucker Rod Pumping Workshop 27

28 Negative Effective Loads are Difficult to ID, Due to Friction and Damping Negative load in the pump card? Seems like there is more to the problem than negative loads. Changes in inertia, momentum, and rod velocity (acceleration) may result in up-hole rod buckling. If the ¾ rods touch the tubing is 3 places due to bucking, when the compressive force on the rods is 200 lbs. The pump card does not usually show this negative load. This small negative load is difficult to see. When the rods buckle then the tubing supports/absorbs the compressive load, this results in increased rod on tubing contact. When weight bars are ran, then the pump loads appear the same. But the hole in tubing goes away, why? Tubing has the same force on tubing from rods, but weight bars spread force out over more area of contact and reduce wear. Sept , Sucker Rod Pumping Workshop 28

29 Summary Plots of True Load Pump Cards are confusing. Discussed the true/effective load argument for display of downhole dynamometer data. Dynamometer data measured at each of the rod tapers was presented as in Windows XP software operating system is required to display and export the SANDIA data XP is no longer supported and dynamometer files must be in EXCEL and.dyn format. Sept , Sucker Rod Pumping Workshop 29

30 Copyright Rights to this presentation are owned by the company(ies) and/or author(s) listed on the title page. By submitting this presentation to the Sucker Rod Pumping Workshop, they grant to the Workshop, the Artificial Lift Research and Development Council (ALRDC), and the Southwestern Petroleum Short Course (SWPSC), rights to: Display the presentation at the Workshop. Place it on the web site, with access to the site to be 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 use of this presentation is prohibited without the expressed written permission of the author(s). The owner company(ies) and/or author(s) may publish this material in other journals or magazines if they refer to the Sucker Rod Pumping Workshop where it was first presented. Sept , Sucker Rod Pumping Workshop 30

31 Disclaimer The 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 Sucker Rod Pumping Web Site. The Artificial Lift Research and Development Council and its officers and trustees, and the Sucker Rod Pumping 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 Sucker Rod Pumping 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. Sept , Sucker Rod Pumping Workshop 31

32 Free ends like the sucker rod pump are allowed in the calculation of the critical buckling load Sept , Sucker Rod Pumping Workshop 32

33 Intermediate Support Mode of Buckling Tubing provides bracing and increases the critical bucking load. Catastrophic buckling of the sucker rods does not occur. Tubing catches the rods and provides intermediate support. Mode of buckling of the sucker rod increases due to intermediate support from tubing. Shorter and shorter critical length of the sucker rod buckling mode occurs; until the dynamic force that caused the buckling is held by the tubing. Tubing provides intermediate support and prevents catastrophic bucking, then the tubing (the intermediate support) fails due to rod on tubing wear. Sept , Sucker Rod Pumping Workshop 33