gas lift surveillance using welltracer tm...

34th Gas-Lift WorkshopSingapore

February 7 - 11, 2011

This presentation is the property of the author(s) and his/her/their company(ies).It may not be used for any purpose other than viewing by Workshop attendees without the expressed written permission of the author(s).

Gas Lift Surveillance using WellTracerTM

TechnologyMariana Jamil, Firdaus Abdullah, Anupam Konwar, Dk Adline Pg Hj T (Brunei Shell Petroleum, BSP)

Jayant Sadare (Weatherford International)

Larry Peacock (AppSmiths)

Feb. 7 - 11, 2011 2011 Gas-Lift Workshop 2

Outline

• WellTracer (WT) Technology• WellTracer Video• WellTracer Project Workflow Details• Summary of the results• Benefits to Client• Three example wells


WellTracer Technology Overview

• CO2 is injected into the gas lift injection line andits concentration is recorded at the well head

• Injected CO2 travels through the tubing-casingannulus into the tubing through injection point/s

• Travel velocities inside tubing and casing areused to back calculate operating lift depth/s


WellTracer Technology Overview

• WellTracer™ offers a low cost effective method to quickly and reliably determine lift gas entry points in the well.

Detect operating lift depth

Detect multiple points of injection

Detect tubing leaks

Identifies lift gas rate through each injection point

Identifies how much lift gas goes to each string of a dual completion well


WellTracer Video


WellTracer Workflow Set up• 26 wells pilot was run in 2009. Following workflow was

established for smooth & successful operation.

• Job Preparation WT analyst, PT’s, and Gas Lift focal point identifies the well

candidates for WT survey

WT analyst and PT prepare WinGLUE models and verify all the information in the models for the selected wells

WT analyst run the WinGLUE model and create procedure with estimated return times for the job

WT coordinator add selected wells to WT schedule (i.e. Well testing, and logistics) during IAP (Integrated Activity Planning)


WellTracer Workflow Set up• Field Operations Workflow Notify WT field crew about scheduled survey date

Arrange site survey for the following things well in advance– Making sure all the casing/tubing thread connections are compatible

– Ensure Sump, Platform Crane, and Electricity available

WT field crew runs WT survey

• WT Analysis/Reporting WT analyst and PT review the well test data from Programmer and

confirm the quality of the data

WT analyst conduct the analysis in WinGLUE program and discuss the results with PT

WT analyst generate report and submit recommendations to PT


WellTracer Summary of Results• Total 56 wells (63 strings) surveyed

• 29 (52%) wells were found to be lifting from single point

• 27 wells (48%) were found to be multi-pointing, majority of which were not identified during normal FTS

• 4 wells identified for the potential tubing leaks

• It is estimated that 750,000 m3/day of gas is being over injected over calculated optimum gas injection rate

• The potential oil gains are estimated at 400 m3/day

• WT analysis identified that the improvement needed with injection gas allocation and metering

• Average WT survey time was 4-6 hrs.


WellTracer Summary of Results• Tracer Returns were pretty quick for very high injection gas

rates wells (Ex. 10 mins, 18 mins, 23 mins, and 33 mins)

• Average amount of CO2 injected was 30-40 lbs

• Shot fluid level’s to determine the fluid level in casing – Noise from wet gas made it less reliable

– Recommended to shut-in gas injection for future determination

• Clamp-on Gas flowmeter will be introduced – There is no real time gas injection measurements available

– Will help to reduce the survey run time

– Pin-point the tubing leaks more accurately

• Overall teamwork between WT team, gas lift foal point, PT’s and field operations was excellent


WellTracer Summary of Results

• Most common parameters causing over-injection and loss in production for the problem wells. Port erosion from the wet gas (to be confirmed after GLV change

out) and higher differential across the operating valves

Choking back the wells

Multi-pointing

No surface control

Leaky valves

Tubing leaks

Oversized Tubing


Benefits to Client using WT Technology• Frees up wireline to focus on other important

surveillance/integrity tasks.

Static Pressure surveys

Zone changes

• Improve surveillance in well reservoir management workflow by allowing wells to be reviewed each year

It was identified that some of the wells were not surveyed for few years and taking lot of gas

More surveillance will increase production, save injection gas, compression and maintenance costs


Benefits to Client using WT Technology• WT does not require any well intervention and will

virtually eliminate any costs related to fishing and production loss due to downtime

• Team members comprising of WT analyst, PT, Gas Lift focal point, and reservoir engineer can look at all the aspects of Nodal Analysis for problematic wells fairly quickly and put together proper recommendations to optimize the wells production. It allows everyone involved to utilize their time efficiently to focus on problematic wells.


WellTracer Analysis- Example 1Well has valve interference– Lift gas has lower CO2 concentration than produced gas

– As injection rate fluctuates, the CO2 concentration baseline fluctuates

– Valves change out completed after WT survey and well is producing an additional 75 m3/day of oil

Concent

ration (%

)

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

Time (hh:mm:ss)

0:00:00 0:33:20 1:06:40 1:40:00 2:13:20 2:46:40 3:20:00 3:53:20 4:26:40 5:00:00

WellTracer Concentration vs Time (C vs. T) Well: [GLUE] WORK,EXAMPLE,EXAMPLE 1,23 24-Jan-

CO2 Concentration

Total Transit 1 (1381 MD - Dummy - Dummi


Total Transit 3 (3604 MD - Weatherford R

Top 2 Dummy Valves

3rd WFT RF-1BL Valve (3/16”): 45%

4th WFT RF-1BL (3/16”): 43%

5th Orifice Valve (3/16”): 12%


WellTracer Analysis- Example 1De

pth (m

eters)

-0

200

400

600

800

1000

1200

1400

Pressure (kPag)

-0 1000 2000 3000 4000 5000 6000

Depth vs Pressure (D vs. P) Well: [GLUE] WORK,EXAMPLE,EXAMPLE 1,23 24-Jan-2011 19:28:22

Production Pressure Model: MMSM

Measured Injection Pressure Model

Measured Valve Opening Pressure

Measured VPC Valve Begin Flow Pressure

LIQUIDS (m3/day) GAS (m3/day)Oil 196.70 Form 15,000.00Water 148.35 Inj. 12,000.00Total 345.05 Total 26,600.00

Pressure(kPag) G/L Ratio (m3/m3)THP 670 Form GOR 76.26CHP 6,033 Total GLR 77.09

Gradient plot shows valve interference during the WT

survey.

Changed 4th PPO valve to 3/16” orifice valve and oil rate

increased by 75 m3/day.


WellTracer Analysis- Example 2Co

ncen

tratio

n (%)

3.4

3.2

3.0

2.8

2.6

2.4

2.2

2.0

1.8

1.6

1.4

1.2

1.0

Time (hh:mm:ss)

0:00:00 0:33:20 1:06:40 1:40:00 2:13:20 2:46:40 3:20:00 3:53:20 4:26:40

WellTracer Concentration vs Time (C vs. T) Well: [GLUE] EXAMPLE,EXAMPLE,EXAMPLE 2,23 24-J

CO2 Concentration



Total Transit 3 (3337 MD - Weatherford R

Example 2:

Top 2 Dummy Valves

3rd WFT RF-1BL Valve (8/64”): 34%

4th Orifice Valve (12/64”): 66%

Bottom 2 dummy Valves



pth (m

eters)

-0

200

400

600

800

1000

1200

1400

1600

1800

Pressure (kPag)

-0 1000 2000 3000 4000 5000 6000 7000 8000 9000






Example 2:

Oil Rate= 108 m3/day

Water Rate= 186 m3/day

Formation Gas= 8,500 m3/day

Injection Gas= 23,000 m3/day


WellTracer Analysis- Example 2Ga

s Rate

(m3/d

ay)

18000

16000

14000

12000

10000

8000

6000

4000

2000

-0

Pressure (kPag)

-0 1000 2000 3000 4000 5000 6000

Injection vs Pressure (I vs. P) Well: [GLUE] WORK,EXAMPLE,EXAMPLE 2,23 24-Jan-2011 19:19:36

Valve 3 Weatherford RF1-BL 3/16 T/C

Valve 4 Camco BKO-3 3/16 VPC

Operating Points

Design Operating Points


WellTracer Analysis- Example 3Co

ncen

tratio

n (%)

5.0

4.5

4.0

3.5

3.0

2.5

2.0

Time (hh:mm:ss)

0:00:00 0:33:20 1:06:40 1:40:00 2:13:20 2:46:40 3:20:00 3:53:20 4:26:40

WellTracer Concentration vs Time (C vs. T) Well: [GLUE] WORK,EXAMPLE,EXAMPLE 3,23 24-Jan-

CO2 Concentration


Total Transit 2 (2615 MD - Camco BKR-5 3

Total Transit 3 (3625 MD - Camco BKR-5 3

Example 3:

6 GL valves

Dummy Valve in 1st and 5th Mandrel

Unloading in 2nd, 3rd, 4th Mandrel

Orifice in 6th Mandrel



pth (m

eters)

-0

200

400

600

800

1000

1200

1400

1600

1800

Pressure (kPag)

-0 1000 2000 3000 4000 5000 6000







Any Questions ??


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