Downhole Dynamometer Card Validation Method

Transcription

1 12 th Annual Sucker Rod Pumping Workshop Renaissance Hotel Oklahoma City, Oklahoma September 27 30, 2016 Downhole Dynamometer Card Validation Method Omar Al Assad, Justin Barton, Kalpesh Singal, Shyam Sivaramakrishnan General Electric

2 Motivation Accuracy of pump card estimation is critical for rod pump control and downhole pump diagnostics Using two different approaches to estimate the pump card offers redundancy that can be used to associate a confidence level to the obtained pump card Pump cards with low confidence level may be used to trigger alarms for operator to check abnormal system behavior such as: 1. Noise in load cell measurement 2. Sticking pump 3. Acute pump speed change 4. Sudden pump fillage drop (intake obstruction) (Patent Pend 2016 Sucker Rod Pumping Workshop 2

3 Downhole Dynamometer Card Validation FS pump card 1 /stroke FD pump card Quasi real-time Norm Distance Pump card Confidence level Pump card validation can be done in real time on well controller to detect any malfunction or abnormal operation leading to different pump card calculation results It can be also considered for offline analysis 2016 Sucker Rod Pumping Workshop 3

4 Down Hole Dynamometer Cards 2 u t = 2 u u 2 a2 c x2 t Acoustic velocity a 2 = 144g ce ρ Damping c = 144c g c ρa Well depth up to feet 2016 Sucker Rod Pumping Workshop 4

5 Sam Gibbs Method - Fourier Series Surface Data Fourier coefficients n=1 Wave equation Analytical solution using Separation of Variable method for taper n n=n+1 Input T n =output T n-1 Last taper? no Inv. FS Transform yes Downhole Data Fourier coefficients Time Domain Frequency Domain 2016 Sucker Rod Pumping Workshop 5

6 Everitt-Jennings Method Finite Difference Discretized rod dynamics model: a 2 1 Δx + u i+1,j u i,j Δx = u i,j+1 2u i,j + u i,j 1 Δt 2 c u i,j+1 u i,j 1 2Δt 1 Δx u i,j u i 1,j Δx Equation recursively solved numerically across all tapers for u i+1,j with surface position and force measurements as inputs. Surface Model Inputs u 0,j = u pr,meas,j u 1,j = Δx EA F pr,meas,j + u 0,j N_ELEMENTS_TOTAL Model Outputs Pump u pump,j and F pump,j 2016 Sucker Rod Pumping Workshop 6

7 Case Studies Test condition Lufkin C Stroke 168 Pump 4,401 Ft Motor Nema B, 60 HP Tubing Anchor 4,052 Diameter Number Installed Total Length Type/Grade Polished Rod D Sucker Rods D Sucker Rods D Sucker Rods Sinker Bars Total Depth 4401 Solver configuration Fourier Series Finite Difference Case Study : 1. Noise in load cell measurement 2. Sticking pump 3. Acute pump speed change 4. Sudden pump fillage drop (intake obstruction) Load Fourier coefficients =14 Position Fourier coefficient = 6 Sampling rate: 200 data pt/stroke Element size x=60 Sampling time t= 20 ms

8 Noise in load cell measurement Base line 1% noise on load measurement 2% noise on load measurement 2016 Sucker Rod Pumping Workshop 8

9 Sticking pump Sticking pump for few strokes due to a build-up Sucker Rod Pumping Workshop 9

10 Acute pump speed change 2 3 Pump Speed up : 2 SPM to 10 SPM Sucker Rod Pumping Workshop 10

11 Acute pump speed change 1 Pump Slow Down 8 SPM to 2 SPM Limited impact on Pump card Sucker Rod Pumping Workshop 11

12 Sudden pump fillage drop (intake obstruction) N-1 Pump fillage drop from 98% to 30% N N Sucker Rod Pumping Workshop 12

13 Conclusions and Perspectives The ability to calculate pump card using different methods on well controller offers opportunity for redundancy to associate a confidence level to the pump card Trigger pump card pattern matching This validation approach can be considered for real-time and offline analysis Deployment of this method on well controller will be considered for future studies on different well sites to analyze the impact of malfunctions on pump card estimation 2016 Sucker Rod Pumping Workshop 13

14 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 14

15 Disclaimer 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 15