water resource issues in the marcellus shale region · an approach to well integrity assessment:...

An Approach to Well Integrity Assessment: Best Management Practices in the

Marcellus Shale Region

J. Daniel Arthur, P.E., SPEC, ALL Consulting

David Alleman, ALL Consulting

SPE Workshop

Reducing Environmental Impact of

Unconventional Resource Development San Antonio, TX

April 23-25, 2012

Outline

• What is well mechanical integrity?

• Why is it important?

• What are the components?

• Best Practices for assessing mechanical integrity – Processes & methods

4/23/2012 ALL Consulting, April 2012 2

Mechanical Integrity

Well Integrity Considerations

• Internal Integrity – Tubing and casing

integrity

– Packers, plugs, perfs

• External Integrity – Cement, mud, annular

fluids

– Gas/Fluid intrusion • Via micro-annulus

• Via cement channels

• Through cement pores

• Fracture systems

Other Integrity Considerations

• Tanks • Trucks • Pipelines • Pumping equipment • Valves and

connections • Well pad pits or

impoundments • Wellheads • Geologic system and

confinement • Other

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Why do Integrity testing? • To assure objectives are achieved

and to avoid unwanted or unauthorized releases/failures.

• Integrity testing serves to confirm that our physical and mechanical systems are functioning as designed.

• Integrity testing and analysis is used in multiple areas:

pressure testing before fracturing – injection well integrity – pipelines – casing and cementing for protection of groundwater – assessing possible

behind pipe integrity (e.g., methane intrusion) – impoundments/tanks to avoid releases


Provided by ALL Consulting

Well Integrity Evaluation: Process

• Well integrity analysis requires a holistic approach.

• Key testing methods include pressure testing and vent rate testing if gas is a consideration.

• Well construction, well history timelines, and other application information requires reviews/analysis.

• Build-up pressure is used as an important indicator, but is not the sole basis for making well integrity determinations or recommendations for remedial action.

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Step 1

• Assess Pressures on Annular Spaces

• Pressures serve as indictors/screening

Step 2

• Perform BU test (continuous recorder) • Vent Rate Testing & Site Safety Assessment

Step 3

• Analyze results and associated data • Proceed to Step 4 as prompted by analysis

Step 4

• Perform Temp & Noise Logging/Assess EMI • Expand data collection if required

Step 5 • Perform Remedial Action as Necessary (e.g., venting, remedial cementing, other)

Step 6 • Conduct post remedial testing as justified to affirm external integrity

ALL Consulting, April 2012 4/23/2012

WELL INTEGRITY ANALYSIS DETAILS

The following slides summarize and describe some of the methods and processes used to assess well integrity using a holistic approach.


Well Evaluation Methods • Well activity timeline analysis

• Pressure build-up and fall-off testing on well casings and annulus spaces – Including signature of pressure

build-ups

• Vent Rate Testing

• Geologic/Hydrogeologic analysis

• Well construction/completion details

• Analysis of casing and cementing program

• Noise/Temperature Logging


Well Activity Timeline Analysis

• Used to identify issues applicable to well integrity analysis: – Drilling and completion

history

– Previous testing

– Prior logging

– Prior remedial actions

– Potential correlations between well activity and residential complaints

– Etc.

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Source: Exco Resources

4/23/2012 ALL Consulting, April 2012

Pressure Testing

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Pressure transducer for BU testing

Data logger for BU testing


Common Low/Zero Pressure Signatures

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Continuous tracking of pressure testing allows confirmation of results and also

trend analysis. Even for tests where the final result is “zero”, having a complete

pressure test signature provides confirmation that the test is accurate.


Example Pressure Signature Curves


Annular Vent Rate Testing

• Where gas intrusion is an issue, used to measure gas venting volumes.

• Measured in inches of water using a U-tube manometer.

• Balloon tests are completed when manometer readings are too low to measure.


Casing and Cementing • EPA: In the EPA Underground Injection Control (UIC)

Program, wells are constructed with performance

standards such that they must be cased and cemented

to prevent fluid movement into or between USDWs (EPA

Program Guidance #38).

• States: State regulations are generally focused similarly,

including requirements to protect usable quality type

groundwater, isolate zones from inter-zonal

communication, and to generally be protective of the

environment and resources being recovered.

• Industry: Many standards existing within the industry as

well, including those from API, ASTM, and others.

• Facts: Casing and cementing is key to the effective and

environmentally protective nature of any oil & gas well!

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Radial Cement Bond Logging

• Provides a technically sound and cost-effective method to assess bonding of the cement exterior to the well’s casing.

• Can be conducted over entire length of the wellbore or over specific cement intervals.

• Used in conjunction with other logs and information throughout the well integrity analysis process.

• Critical component for wells requiring remedial cementing.


Source: www.bridge7.com

Cement Bond Long Interpretation

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Good Cement

• Low Amplitude

• Strong VDL

No Cement

• High Amplitude

• VDL Straight

• Collars

“Ringing”

Partial Cement

• Varied

Amplitude

• Varied VDL

Microannulus • Varied Amplitude

• Varied VDL

• Pressured/No

Pressure


Noise/Temperature Logging • Noise and temperature logging are

effective methods for assessing external well integrity.

• Wells are water filled and allowed to stabilize prior to logging.

• Logging is performed in accordance with standard procedures. *

• Tests are commonly conducted using multiple configurations of casing and annular spaces open or closed.

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Hypothetical noise

logging results


* ALL maintains standard procedures for integrity testing.

Temperature Log Interpretation

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Recorded Temperature

Temperature Gradient





Fluid Entrance from

Formation

Fluid Entrance &

Downward Fluid

Movement

Gas Intrusion


Noise Logging • First described by Arco in ~1955

as a “quantitative “ tool, but utility was questionable.

• In 1973, Dr. McKinley (Exxon) started pointing out the utility of noise logging and ultimately worked with EPA and published a document on MI.

• For identification of gas movement behind pipe, noise logging can be crucial.

• Typically run with a temperature log and interpreted using other logs and data for the subject well.

• Unfortunately, interpretation is not always as straightforward as you might think!

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Considerations… • A combination of testing methods and

analyses can be used effectively to assess well integrity.

• Regulatory Agencies tend to seek tests and analysis methods that provide a black & white answer (e.g., Standard Annulus Pressure Test).

• Most testing methods do not offer an absolute and definitive answer regarding well integrity. Interpretation is often required to account for various interferences.

• Sometimes the BEST remedial approach can be the simplest (e.g., monitoring, venting, etc.). Intrusive actions are not always Necessary.


Proper Drilling & Completion

Effective use of Standards and Regulatory Requirements

Quality Data Collection

Use Holistic Well Integrity Approach

Document Well Integrity Findings if Positive

Use Results to Determine Remedial Path Forward

Contact & Citation Information

J.D. Arthur, P.E., SPEC

ALL Consulting

[email protected]

Special Appreciation for Contributions:

David Alleman, ALL Consulting; David Cornue, P.G., CHMM, ALL Consulting; B. Greg Casey, P.E., ALL Consulting; Jeff Kennedy, ALL Consulting; Preston Wilson, ALL Consulting

Citation: Arthur, J.D., ALL Consulting and Alleman, D., ALL Consulting. “An

Approach to Well Integrity Assessment: Best Management Practices in

the Marcellus Shale Region”. Presented at the Society of Petroleum

Engineers’ Advanced Technology Workshop (ATW) on Reducing

Environmental Impact of Unconventional Resource Development, April

23-25, 2012.

water resource issues in the marcellus shale region · an approach to well integrity assessment:...

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