Validating Vertical-Hole Diagnostic Models with Measured Sandia Data

Transcription

1 12 th Annual Sucker Rod Pumping Workshop Renaissance Hotel Oklahoma City, Oklahoma September 27 30, 2016 Validating Vertical-Hole Diagnostic Models with Measured Sandia Data Victoria Pons, Ph.D. Weatherford

2 Introduction In an effort to address technical problems identified by the U.S. petroleum industry, the Department of Energy s National Gas and Oil Technology Partnership contracted SANDIA National Laboratory to coordinate a series of field tests, and create the Downhole Dynamometer Data Base (DDDB) The Downhole Dynamometer Data Base contains data for 6 wells, which were picked for specific downhole or pumping conditions The Downhole Dynamometer Data Base is available on CD The results of these tests were presented by Waggoner in Waggoner, J. R.: Insights from Downhole Dynamometer Database, Southwestern Petroleum Short Course in Sucker Rod Pumping Workshop 2

3 Introduction In 1986, Glenn Albert developed an electronic downhole dynamometer Glenn Albert is the founder of Albert Engineering (Longmont, Colorado) The Sandia National Laboratory compiled a series of test data collected with a set of five downhole tools built by Albert Engineering under contract to Sandia National The necessary memory tools were deployed in the sucker rod string and equipped with sensors that were capable of measuring pressure, temperature, load and acceleration The position was calculated by integrating the acceleration twice, yielding a load versus position downhole dynagraph 2016 Sucker Rod Pumping Workshop 3

4 Introduction Up until the study, it was common practice to rely on load versus position information measured at the surface to infer stresses on the sucker rod string downhole Primarily, the motivation behind this research was to try to minimize sucker rod failures, which represent a significant cost to the oil recovery industry The downhole dynamometer is a 12-inch-long cylindrical steel probe Along each probe's surface is a collection of sensors including strain gauges, an accelerometer, and pressure and temperature gauges Several tools are deployed downhole for each well at specific key depths All these measurements are taken as the wells are pumping 2016 Sucker Rod Pumping Workshop 4

5 Wave Equation Solution vs. SANDIA The Downhole Dynamometer Data Base contains data for 6 wells, which were picked for specific downhole or pumping conditions Results from the current Modified-Everitt-Jennings algorithm and from the Gibb s method are compared to actual dynamometer readings from SANDIA data The Modified Everitt-Jennings uses finite differences to solve the wave equation while the Gibb s method uses Fourier Series and separation of variables For each well, the surface card is displayed as well as the MEJ calculated card (solid), the Gibb s card (dashed) and SANDIA measured downhole card (dotted) 2016 Sucker Rod Pumping Workshop 5

6 Test Data 1 This well has a depth of 2700 ft. with a 0.75 in. API Grade 'C' steel rod string and a 1.5 in. RWA pump in in. tubing. The pumping speed is 11 SPM with a 86 in. surface stroke. The dynamometer tools were installed in the rod string as follows: 1) below the pump 2) above the pump at 2708 ft. 3) at 2456 ft. 4) at 1004 ft. 5) at 2 ft Sucker Rod Pumping Workshop 6

7 Test Data 1 This well was chosen for its normal operating characteristics, representative of a fairly large number of wells Waggoner includes dynagraph cards from the bottom of the well when the pump is full at 9:07 AM (SX1c03, 5X1c07 and 2X1c07) and when the well pumps off at 10:47 AM (SX1c05, 5X1c13 and 2X1c13) Cards were taken from data gathered at the surface, right below the polished rod and right above the pump at 2708 ft. Data representing a full pump and a pumped off condition at 1004 and 2056 ft. are also available for the comparison 2016 Sucker Rod Pumping Workshop 7

8 Test Data Sucker Rod Pumping Workshop 8

9 Test Data 2 This well has a depth of 7600 ft. with a mixed fiberglass and steel The rod string composition is: 4408 ft. of in. Norris fiberglass rods 3200 ft. of 1 in. API Grade D steel rods 1.5 in. insert pump in in. tubing The dynamometer tools were installed in the rod string as follows: 1) below the pump 2) above the pump at 7616 ft. 3) 75 ft. above the pump in the 1 in. rods at 7539 ft. 4) at the fiberglass/steel crossover at 4412 ft. 5) 75 ft. above the crossover at 4335 ft Sucker Rod Pumping Workshop 9

10 Test Data 2 Well production at 8.2 SPM with a 144 in. surface stroke: 29 BOPD, API = BWPD GOR = 1620 Because the tubing anchor was set at 6168 ft. and the seating nipple at 7655 ft., 1487 ft. of tubing below the anchor was subject to stretch The rods parted in the shallow section of the well, terminating the test after one downhole test period and corresponding surface measurement 2016 Sucker Rod Pumping Workshop 10

11 Test Data Sucker Rod Pumping Workshop 11

12 Test Data 3: Rotaflex unit This well has a depth of 9300 ft. with an API Grade 'D' steel rod string consisting of 1 in. and in., a 2.25 in. diameter tubing pump, and in. tubing The well operated at 3.9 SPM with a surface stroke of 306 in. During the tests, the variable frequency drive was run at 3.8, 3.5, 2.9 and 2.4 SPM The tools were installed in the rod string as follows: 1) above the pump at 9231 ft. 2) at 1 in. rods at 9089 ft. 3) in 1 in. rods at 8787 ft. 4) at the lower in. rod/1 in. rod crossover at 7660 ft. 5) in the in. rods at 7508 ft Sucker Rod Pumping Workshop 12

13 Test Data 3 This well was chosen in an effort to observe the dynamics of the Rotaflex pumping unit at different pumping speeds and the dynamics of the rod string affected by the rapid direction changes during operation Waggoner observed that the loads and shape of the cards were similar Waggoner also observed that the downhole stroke length was about 5% longer at the faster pumping speed 2016 Sucker Rod Pumping Workshop 13

14 Test Data Sucker Rod Pumping Workshop 14

15 Test Data Sucker Rod Pumping Workshop 15

16 Test data 4 This well has a depth of 3100 ft. with an API Grade 'D' steel rod string consisting of in. and 0.75 in. rods, with 1.25 in. sinker bars, a 1.25 in. insert pump and in. tubing Tests were conducted using pump speed of 8.8, 6.7 and 4.6 SPM with a surface stroke of 168 in. The tools were installed in the rod string as follows: 1) below the pump 2) above the pump at 3010 ft. 3) at the sinker bar/0.75 in. rod crossover at 2708 ft. 4) at the 0.75 in. rod/0.875 in. rod crossover at 1006 ft. 5) below the polished rod at 7508 ft Sucker Rod Pumping Workshop 16

17 Test data 4 This well was chosen to explore the effects of both different pumping speeds and varying pump fillages on the dynamics of the sucker rod string Waggoner observed that the dynagraph data at the slower speed yields more regular downhole cards Waggoner also remarked that the downhole tools and the surface tools were not synchronized to record data at the same time The effect of this was that the strokes during this interval were not consistent. It was observed that even though the surface card showed about 15% pump fillage, the downhole cards at Tool #2 and Tool #1 showed pump fillages of 30% and 50%, respectively 2016 Sucker Rod Pumping Workshop 17

18 Test data Sucker Rod Pumping Workshop 18

19 Test data Sucker Rod Pumping Workshop 19

20 Conclusions Even though the objective of the SANDIA testing was to reduce failures in reciprocating rod lift, it provided a way to prove the effectiveness of the wave equation solution Solving the wave equation with appropriate damping provides an accurate and reliable way to compute downhole cards For the above results, the damping had to be adjusted manually since the required inputs for the iteration on damping were not available The data collected for the Sandia experiment only represents vertical wells. What about deviated wells? 2016 Sucker Rod Pumping Workshop 20

21 Vertical vs. Deviated Vertical Deviated??? 2016 Sucker Rod Pumping Workshop 21

22 QUESTIONS? 2016 Sucker Rod Pumping Workshop 22

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