EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 1 of 22 – Well Integrity Narrowly Defined as the Prevention of Fluids Migration into Protected Water

During Drilling

During Completion (includes HF)

Well Integrity “WI” During Drilling

WI During Completion (includes hyd fracturing)

WI During Operations (includes re-fracturing)

WI During Plug and Abandonment

Full Life Cycle View

Discuss Jurisdiction, Regulations, Best Practices

Consider Failure Categories, Modes, Relative Rates

Development Phase: Well Specific Economics

Exploration Phase: Determine Commercial Value

Basis of Design for a Development Well

Consider a Time Line Perspective

Case Study not unlike Marcellus and Eagle Ford
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 2 of 22 – Jurisdiction

Federal and State Environmental Laws

State Mineral Law (Federal if BLM, BIA Minerals)

State Mineral Law (Federal if BLM, BIA Minerals)
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 3 of 22 – Natural Separation of Protected Water and Hydrocarbons, in most cases

Natural Separation of Protected Water and Hydrocarbons

Protected water = USDW < 10,000 mg/l TDS

Will not discuss the natural migration of gas, oil, brine
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 4 of 22 – Spud well with conductor pipe (driven, augered or drilled) no impact on Protected Water

Structural, not always needed

Does not penetrate the base of protected water

Typically installed before the rig arrives
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 5 of 22 – Well is drilled to a prescribed depth below Protected Water

Drilled to a prescribed depth

Drilled in less than a day – Open for a short period only

Typically drilled with air or water based system
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 6 of 22 – Surface casing is run

Primary barrier from wellbore fluids when drilling the next interval

Never optional; Extensive regulatory requirements

Significant body of industry best practices for running and testing casing

Failure categories: materials, connections, handling, mechanical, corrosion 

External corrosion is most common failure mode 

Remedies may include external coatings, cement, cathodic system

Surface casing is run the same day the surface hole is drilled 
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 7 of 22 – Surface casing is cemented and tested

Cement is the primary barrier for vertical migration of fluids into USDWs

The first attempt aka „primary cement job‟ is most critical for well integrity

All other attempts aka “remedial cement jobs” have lower success rates

Prescriptive regulatory requirements apply to this cement job

Failure to comply triggers agency notification and remedial actions

Significant body of industry guidance and best practices for cementing

Cement sets-up, then casing and cement float equipment is tested together

Failure categories; insufficient volume, low bond strength, sheath damage

Remedies include: pumping in, top job, perforate the casing and squeezing 

Strong correlation between poor cement sheath & external casing corrosion 

Strong correlation between poor cement sheath & gas / fluid migration 

Surface casing on our case study well is cemented at the end of day #2
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 8 of 22 – Surface casing shoe and formation are integrity is tested

The FIT tests the casing shoe and adjacent formation together

Assessment of well‟s ability to withstand pressure to the next casing point 

Not a leak-off test, it does not establish a limit

For our case study well we are now at the end of day #3
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 9 of 22 – Next section of hole is drilled

Depth for the next hole section is not prescribed, as for the surface casing 

Safe drilling operations and not wasting minerals are the general guidelines

For our case study well this section takes a week, now at end of day #10 
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 10 of 22 – Intermediate string of casing is run

Safe drilling operations and not wasting minerals are the general guidelines

For our case study well this section takes a week, now at end of day #11 
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 11 of 22 – Intermediate casing is cemented and tested

Cement is the primary barrier for vertical migration of fluids

The first attempt aka „primary cement job‟ is most critical for well integrity

All other attempts aka “remedial cement jobs” have lower success rates

Less prescriptive regulations than for the surface casing cement job

Cement sets-up, then casing and cement float equipment is tested together

Failure categories; insufficient volume, low bond strength, sheath damage

Remedy is to perforate the casing and squeeze 

Strong correlation between poor cement sheath and external casing corrosion 

Strong correlation between poor cement sheath and gas / fluid migration 

Intermediate casing on case study well is cemented by the end of day #12
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 12 of 22 – Intermediate casing shoe and formation integrity are tested

The FIT tests the casing shoe and adjacent formation together

Not a leak-off test, it does not establish a limit

Assessment of well‟s ability to withstand pressure to the next casing point 

For our case study well we are now at the end of day #13
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 13 of 22 – Next section of hole is drilled

Depth for the next hole section is not prescribed, as for the surface casing 

Safe drilling operations and not wasting minerals are the general guidelines

For our case study well this section takes 2 weeks, now at end of day #27 
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 14 of 22 – Production casing is run

Safe drilling operations and not wasting minerals are the general guidelines

For our case study well,this takes 2 days, now at end of day #29 
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 15 of 22 – Production casing is cemented, Drilling phase is done

Cement is the primary barrier for vertical migration of fluids

The first attempt aka „primary cement job‟ is most critical for well integrity

All other attempts aka “remedial cement jobs” have lower success rates

Less prescriptive regulations than for the surface casing cement job

Failure categories; insufficient volume, low bond strength, sheath damage

Remedy is to perforate the casing and squeeze 

Strong correlation between poor cement sheath and external casing corrosion 

Strong correlation between poor cement sheath and gas / fluid migration 

Production casing on our case study well is cemented by the end of day #30

Drilling operations are done, Well Integrity is pretty much determined
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 16 of 22 – Completion phase: perforate, hydraulically frac, flowback, production begins

Frac flowback period varies from days to weeks, Completion ops are done

Monitor all annulus pressures 

Production casing and cement float equipment are tested together

Completion phase begins

Production phase begins, basically this is how it looks for next 30 years

The production casing is perforated & frac‟ed stage by stage, “toe” to “heel”

After the final frac stage is pumped, drill out the isolation plugs

During the frac monitor injection pressures, rates, and annular pressures
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 17 of 22 – Refrac and Adjacent Well Frac Scenarios

Squeeze cement, frac string, wellhead saver can protect weak components 

Well integrity during a refrac is all about planning, pressures, and rates

Refracs require well specific analysis to identify potential weak links 

Hydraulic fracturing activity on this well might impact our adjacent 

case study well if our well‟s cement is absent or not sufficient to 

withstand the conditions imposed on it 

Monitor all annulus pressures 
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 18 of 22 – Plug and Abandonment begins, producing zone is plugged and tested

30 years later, all the reserves have been produced, P&A begins

A cement plug is the primary barrier for isolating the hydrocarbon zone
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 19 of 22 – Casing is cut or perforated near the surface casing shoe

Production casing is cut, bridge plug is set in the intermediate casing
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 20 of 22 – Cement plug is set across the surface casing shoe and tested

A cement plug set across the surface casing shoe
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 21 of 22 – Shallow surface plug is set and tested

A cement plug set near the surface
EPA Hydraulic Fracturing Study Technical Workshop #2 March 10-11, 2011

Well Integrity Case Study by Lloyd H. Hetrick 

Slide 22 of 22 – Pipe cut-off, cap welded, well ID marker, backfill 

All strings are cut and capped, well ID marker, then backfilled with soil