# High adventure Assessment Methods for Well Integrity during the Hydraulic Fracturing Cycle Washington, D.C. March 11, 2011 James Bolander Vice President – HS&E Southwestern Energy1 

# Protecting Drinking Water Resources



# Well Integrity Is the Key!2 

# Well Integrity Well Construction Standards



# 2 Evaluating Stratigraphic Confinement 

# 1 Evaluating Mechanical Integrity of Well 

# 3 Monitoring Frac Job & Producing Well



# 43 

# Well Integrity Hydraulic Fracturing Life Cycle

• Assessment Methods for Well Integrity during the frac life cycle • Pre-frac Evaluation • Understanding casing and cement integrity • Frac Monitoring • Monitor & record your pressures!! • Post-frac Evaluation • Maintaining well integrity through production 

## Subsurface ConsiderationsCross sectional view FRESH WATER AQUIFER ZONE

SHALLOW PRODUCING ZONE INTERMEDIATE PRODUCING ZONE CONDUCTOR PIPE SURFACE CASING PRODUCTION CASING 

## WELL CONSTRUCTION STANDARDS

TARGET PRODUCING ZONE CEMENT CEMENT

CEMENT

# Pre-Frac Mechanical Integrity of Well
• Internal Mechanical Integrity

– Verify appropriateness of proposed casing program (e.g., size, grade, minimum internal yield pressure, etc.)

– Test casing string to ensure it can withstand maximum stimulation pressure 

### • External Mechanical Integrity

– Verify quality of cement (field blend samples & slurry density)

– Monitor cement job (rates, pressures & returns)

– Identify top of cement

– Test cement job (FIT, CBL, etc.) when operations indicate inadequate coverage 5

# External Mechanical Evaluation Methods • Confirming top of cement (TOC) and quality are keys to protecting drinking water sources

– Monitoring rate and fluid volumes are the first step in evaluating the effectiveness of a cement job

– Mechanical test methods include 

### the following: • Temperature surveys which can determine the top of cement • Cement evaluation tools, such as the Segmented Bond Tool (SBT) which can determine TOC and quality of cement job to confirm zonal isolationFRESH WATER AQUIFER ZONE

SHALLOW PRODUCING ZONE INTERMEDIATE PRODUCING ZONE CONDUCTOR PIPE SURFACE CASING PRODUCTION CASING 

## GOOD MECHANICAL INTEGRITY

TARGET PRODUCING ZONE

## CEMENT CHANNELING PRESSURE BUILDS UP CONDUCTOR PIPE SURFACE CASING PRODUCTION CASING FRESH WATER AQUIFER ZONE

SHALLOW PRODUCING ZONE INTERMEDIATE PRODUCING ZONE TARGET PRODUCING ZONE CASING CEMENT

FORMATION

# Monitoring Frac Job • Monitor surface injection pressure and rate during frac job • Monitor annular pressures during and after frac job • Additional assessment methods include microseismic and use of 

### tracer technology. • Terminate operations and take corrective action if abnormal pressure responses indicate mechanical integrity failure or fracture growth out of target zone 910 Top Morrow Shale

Top Fayetteville Shale Top Hindsville Limestone ~200’

1000’ Cross sectional view 

## Microseismic Evaluation of Stimulation Treatment

# Maintaining Well Integrity

11 • Monitor Flowing and Annular pressures for changes • Monitor gas and fluid rates which could indicate influx from an external sources • Monitor gas and fluid composition which could indicate influx from external source and aid in determining scaling and corrosion tendencies • Perform diagnostic tests to ensure integrity throughout the life of the well: • Use of radioactive tracers and logging • Use of Chemical tracers • Casing Inspection and Production Logging • Take corrective action to remediate well integrity concerns

# Fracture Stimulation Results Tracer Survey Confirms All Zones Effectively Stimulated Near Wellbore

# • During the life cycle of the well, regular maintenance may be required.

– Confirmation of casing integrity 

## by running Casing Inspection Log to determine current condition 13 

# Casing Inspection

## LEAK THROUGH CASING CONDUCTOR PIPE SURFACE CASING PRODUCTION CASING FORMATION CASING FRESH WATER AQUIFER ZONE

SHALLOW PRODUCING ZONE INTERMEDIATE PRODUCING ZONE TARGET PRODUCING ZONE PRESSURE BUILDS UP15 

# Protecting Drinking Water Resources



# Well Integrity 

# Is the Key! Proper Planning, Documentation and Assessment are important keys to maintaining well integrity and environmental protection