Validating Vertical-Hole Diagnostic Models with Measured Sandia …€¦ · Validating Vertical-Hole Diagnostic Models with Measured Sandia Data Victoria Pons, Ph.D. Weatherford

12th Annual Sucker Rod Pumping

WorkshopRenaissance Hotel

Oklahoma City, Oklahoma

September 27 – 30, 2016

Validating Vertical-Hole Diagnostic Models with Measured Sandia Data

Victoria Pons, Ph.D.

Weatherford

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 1997

Sept. 27 - 30, 20162016 Sucker Rod Pumping Workshop 2

• 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

Introduction


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


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)


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 2.875 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.


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


Test Data 1


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 1.125 in. Norris fiberglass rods

– 3200 ft. of 1 in. API Grade ‘D’ steel rods

– 1.5 in. insert pump in 2.875 in. tubing

• The dynamometer tools were installed in the rod string as

follows:

1) below the pump


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.


Test Data 2

• Well production at 8.2 SPM with a 144 in. surface

stroke:

– 29 BOPD, API = 40

– 210 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


Test Data 2


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 0.875 in., a 2.25 in. diameter tubing pump, and 2.875 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:


2) at 1 in. rods at 9089 ft.

3) in 1 in. rods at 8787 ft.

4) at the lower 0.875 in. rod/1 in. rod crossover at 7660 ft.

5) in the 0.875 in. rods at 7508 ft.


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


Test Data 3


Test Data 3


Test data 4

• This well has a depth of 3100 ft. with an API Grade 'D' steel

rod string consisting of 0.875 in. and 0.75 in. rods, with

1.25 in. sinker bars, a 1.25 in. insert pump and 2.875 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


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.


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


Test data 4


Test data 4


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?


Vertical vs. Deviated


???

DeviatedVertical

QUESTIONS?


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Validating Vertical-Hole Diagnostic Models with Measured Sandia …€¦ · Validating Vertical-Hole Diagnostic Models with Measured Sandia Data Victoria Pons, Ph.D. Weatherford