1. A STUDY ON THE SAFETY OF THE CO2 INJECTION WELL
JONG-RYEOL YOON

2. CONTENTS 1 2 3 4 Review of Standards Well Design Safety Assessment
Summary

3. 1
Review of Standards
CHAPTER 1
1-1. EPA
1-2. API

4. 1-1. EPA (Environmental Protection Agency)
■ EPA (USA)
▷ Operating UIC (Underground Injection Control) Program
▷ Regulation of the construction, operation, permission and closing of injection wells
▷ Classification according to the type and the depth of injected fluid
▷ Addition of CO2 injection well (Class VI) at 2010
Classification
The Characteristics of the Injection Well
Class I
Used to inject hazardous and non-hazardous wastes into deep, isolated rock formations
Class II
Used exclusively to inject fluids associated with oil and natural gas production
Class III
Used to inject fluids to dissolve and extract minerals
Class IV
Shallow wells used to inject hazardous or radioactive wastes into or above a geological formation
Class V
Used to inject non-hazardous fluids underground and dispose of wastes into or above underground sources of drinking water
Class VI
Used for injection of CO2 into underground subsurface rock formations for long-term storage, or geologic sequestration(GS)

5. 1-1. EPA (Environmental Protection Agency)
■ Definition of Class VI wells
『 Class VI wells are used to inject carbon dioxide (CO2)
into deep rock formations. 』
■ Requirements for Class VI wells
① Extensive site characterization requirements
② Injection well construction requirements for materials that are compatible
with and can withstand contact with CO2 over the life of a GS project
③ Comprehensive monitoring requirements that address all aspects of
well integrity, CO2 injection and storage, and ground water quality
during the injection operation and the post-injection site care period
④ Financial responsibility requirements assuring the availability of funds
for the life of a GS project 
⑤ Reporting and record keeping requirements that provide project-specific
information to continually evaluate Class VI operations and
confirm USDW protection 

6. 1-2. API (American Petroleum Institute)
■ API (USA)
▷ Developing petroleum equipment and operating standards
▷ Defining standards of the drilling materials for oil and gas fields
▷ Certificating and supervising of manufacturer maintenance
Certification Code
Objects
API Spec 2B
Structural Steel Pipe
API Spec 5CT
Casing and Tubing
API Spec 5D
Drill Pipe
API Spec 5L
Line Pipe
API Spec 6A
Wellhead and Christmas Tree Equipments
API Spec 6D
Pipeline Valves (Steel Gate, Plug, Ball, and Check Valves)
API Spec 6H
End Closures, Connectors and Swivels
API Spec 10A
Well Cements

7. CHAPTER 2 2 Well Design 2-1. Overview 2-2. Casing Design
2-3. Cementing Design

8. 2-1. Overview Basic Data Mud Design BHA Design Select Casing Sizes
■ Major Design Factor
Basic Data
Mud Design
BHA Design
Geological properties
Exploratory drilling
Rock properties
Fluid type / Density
Additives
Quantity calculation
WOB design
Stabilizer
BHA assembly
Select Casing Sizes
Cement Design
Drilling Parameter
Annular volume
G-Class Cement
T/P condition
Cementing Test
Casing Setting Depth
Casing & Hole Size Selector
buoyancy
WOB/RPM analysis
Calculation of WOB, RPM
Casing Strength
Bit Design
Well Completion
Geological boundaries
Pore/fracture pressure
Casing type and grade
Rock type and strength
Bit Index
Select proper bit
Wellhead
Rig performance
Drilling schedule

9. 2-2. Casing Design ■ Basic Well Design
Multi-stage structure according to Class VI
Ensuring structural safety with international standards
Casing design : KS → API 5CT
• Connection compatibility and sealing
of well head
• Connection type : welding → joint (thread )
• Corrosion resistance
• Connection of FRP casing and sealing

10. 2-3. Cementing Design ■ Basic Well Design G-class cement
Cement Properties
Cement Type : G-class
Specific Gravity : 3.15
Composition
Cement+55%Water+35%Slica +1.25%Retarder(BS200R-2) +0.5%Defoamer(BP-1A)+0.3%RPM
Slurry Properties
Cement slurry density : 1.9g/cm3
Yield : 1.51ft3/sack
■ Basic Well Design
Total Volume
(m3)
Weight (ton)
Total
G class
35% Sand
55% Water
Retarder & Deformer
Amount
24.92
47.42
24.85
8.7
13.67
0.2
Excess (50%)
39.87
75.92
39.75
13.91
21.86
0.4
G-class cement
Sealing the space between the outside of the casing and the rock mass
Prevention of CO2 leakage and the corrosion of the casing

11. CHAPTER 3 3 Safety Assessment 3-1. Casing 3-2. Cementing 3-3. Wellhead
3-4. Foundation of Storage Tank

12. 3-1. Casing ■ Casing Size ■ Safety Factor of API ■ Casing Strength
Section
Original design
Modified design
Drilling
Casing
Grade
Conductor (0~30 m)
16″
14″
KS D3562
Surface (0~535 m)
12″
10″
12¼″
10¾″
K-55
Intermediate (0~803 m) 8″
9⅞″
8⅝″
Monitoring (803~1100 m) -
Open hole
7⅞″
3.5”
Strength
Design safety factor
Burst
(from internal pressure)
1.1
Collapse
(from external pressure)
1.125
Tension and Joint strength
1.8
■ Casing Strength
Depth
10 ¾ inch K-55
8 5/8 inch K-55
3.5 inch FRP
Burst
Pressure
(psi)
Collapse Pressure
Weight
(1000lb)
Surface (0~535m)
3,130
1,580
629 -
Intermediate (0~800m)
2,950
1,370
381
inner (790~1,090m)
2,500

13. 3-1. Casing
Not considering the buoyancy : Designing casing strength with worst condition
Burst Pressure=Max. Pore PressureⅩSafety Factor(1.1)
Collapse Pressure=0.052ⅩMW(13 ppg)ⅩDepth(ft)ⅩSafety Factor (1.125)
FRP Casing : Collapse Pressure 17.9 Mpa ← Satisfying designed pressure (14 Mpa)
K-55 grade : Yield strength 379~552 MPa / tensile strength > 655 MPa (minimum elongation: 15%)
■ Corrosion
Upper steel casing :13 CR
Lower FRP casing : Aliphatic Amine Cure Epoxy

14. Bottom Hole Static Temperature (BHST)
3-2. Cementing
■ Gravel Packing
Collaboration with Canada Veriperm Co. ← Satisfying Class VI regulation
Temperature monitoring using fiber optic sensor
Cementing Depth : 913 m
■ Cementing Test
Cementing test according to API Standard
Water sampling from nearby rivers that are actually used for cementing
Determining test condition considering actual physical conditions of injection well
UCS of hardened cement slurry after 72 h : 23.6 MPa
Bottom Hole Static Temperature (BHST)
45 ℃
Bottom Hole Circulating Temperature(BHCT)
30 ℃
Bottom Hole Pressure(BHP)
2,308 psi
Mud Weight
1.16 g/cm3
Item
Cement
Density [g/cm3]
1.9
72h UCS (MPa)
23.6
Initial consistency (Bc) 12
100Bc Thickening time (min)
150

15. 3-3. Wellhead ■ Completion and Pressure Test
Control of Pressure and Sealing
Pressure Welding Standard (API 2B) and Manufacturer’s welding standard (StreamFlo EB )
Casing Pressure Test (max=14 Mpa] : test of sealing status
Sealing of the control Line after installing the casing hanger
• Stainless Line : Swagelok fitting
• Polyurethane Line : Conax fitting
Wellhead Pressure Test

16. 3-4. Foundation of Storage Tank
■ Mat Foundation of Storage Tanks
Seismic Design of Foundation: Korea Building Code (Ministry of Land, Infrastructure and Transport, 2016)
Designed Foundation : Resistant to Intensity VII and Magnitude 6.1 ← Occurred Mag. < Designed Mag.
Visual inspection and Level Survey : No Abnormality Sign
Level survey of CO2 Tank Anchor
Visual inspect of foundation crack
Structure
Front Level
Back Level
Difference
Result
Foundation
113 cm
113.5 cm
0.5 cm
For rainwater drainage – Clear
Tank Anchor
106 cm
0 cm
Clear

17. 4
Summary
CHAPTER 4

18. 4. Summary
■ Application of international standards for safety and reliability of the injection well
▷ No standardized domestic regulation related to the CO2 storage
▷ No domestic standard of the aseismic design for the CO2 injection well
▷ Design and completion according to the EPA Class VI and the API standards
■ Casing and cementing designs applied conservative standards and safety factor
■ Confirming sealing status of the wellhead by pressure test
■ Foundation construction based on the domestic standard of seismic design (KBC)
■ The status of the Janggi CO2 storage site after the Pohang Earthquake
▷ No detailed crack or settlement of mat foundation
▷ No pressure change of DTS sensor → borehole stability
■ Additional investigation for the completed monitoring well

19. Thank You !