This comment letter response contains two parts:   

(1) The original submittal from the commenter.

(2) A data base printout of EPA’s response to each point raised by the commenter.

Notes about the response letters:

• The response letters were generated by a data base used to track the content of all public

comment submittals and ensure that the Agency responds to each. Each comment letter

was assigned a Letter ID that corresponds to the last four digits of the docket number of the

original comment (as posted on www.regulations.gov).

• Each response letter includes: comment text; an EPA‐assigned comment code; and an

individual response. These are described and explained below.  

• The data base contains Comment text from the letters submitted by commenters.  

Many hard copy letters were scanned into electronic format for inclusion in the data

base. As a result, there may be some typographical errors attributable to optical

character recognition issues.  However, all original submittals were reviewed in the

process of drafting responses to ensure that the comment content was understood and

appropriately addressed.

• The content of each comment letter was divided into topic areas and assigned a unique

Comment ID.  Additionally, one or more Comment Codes (i.e., unique topic area ID) was

assigned to each discrete point raised by a commenter. This information was added to

the data base. To inform final rulemaking decisions, all comments and information

received on a given topic were reviewed by technical experts in each rule area (e.g., on

construction requirements).  

• Following decisions on the final rule requirements, Individual responses were drafted

by topic area to ensure completeness and consistency of the responses with the final

rule and other responses to similar comments.  Each discrete point made by a

commenter was given a unique response.

• Upon completion of comment responses, all information was entered into the data base.

Each letter response is a compilation of each comment and its individual response,

compiled in the order of the original comment letter.  As a result of this process, there is

repetition in the response text.  The Agency believes this approach ensures completeness

and attention to each comment letter that was submitted.   

• All comments in a topic area were reviewed, evaluated, and responded to concurrently.  

Responses on each topic area are compiled and are also available in the rulemaking docket.
BP Alternative Energy International Limited, a company registered in England and Wales with the company number 1553681, VAT number GB 243 5105 93 and whose registered office is 

Chertsey Road, Sunbury on Thames, Middlesex, TW16 7BP. 

BP Alternative Energy Holdings Limited, a company registered in England and Wales with the company number 2515099, VAT number GB 243 5105 93 and whose registered office is 

Chertsey Road, Sunbury on Thames, Middlesex, TW16 7BP 

BP Alternative Energy Comments to EPA Proposed Rule 

By Mr. Brian Williams 

Well Design Construction and Operations 

EPA Public Hearing, Chicago, Illinois – September 30, 20008 

Docket ID No. EPA-HQ-OW-2008-0390 

INTRODUCTION

 Good morning and thank you for the opportunity to speak here today. My name is 

Brian Williams and I work for BP’s Alternative Energy division in Houston. There I am 

the global CO2 Storage Manager in our Carbon Capture & Storage Technology 

organization. 

 I work in a team that is developing the technological capabilities needed to deliver a 

capability for geologic storage for BP. One of the particular areas where we are 

developing technologies and where we have done specific research and field analysis 

relates to well construction & operational requirements. These are the areas where I’d 

like to direct my comments today. 

RECOGNITION OF CRITICALITY OF WELLS

 EPA has correctly recognized that wells are a fundamental component of a geologic 

storage system that successfully ensures the containment of stored CO2. As such, we 

agree that having appropriate well design, construction & operating requirements are 

critical to the delivery of secure storage of CO2. 

 Oil and gas operators have decades of experience, via past and existing operations, in 

constructing and operating EOR/EGR wells in a safe and secure way. For existing 

EOR projects and wells, Class II requirements have proven to be sufficient at ensuring 

the necessary protection of USDWs, and, therefore, analysis of the experiences and 

performances of these Class II CO2 EOR wells should inform the requirements for 

new Class VI wells. 

 I would like to comment on certain of the incremental requirements in the draft rule, 

including the preamble, around the design, construction & operation of Class VI wells 

that we feel are potentially excessive. 

WELL CONSTRUCTION

 Corrosion resistant materials & cement – Based on industry experience and field 

studies, corrosion resistant materials should not be mandated for all projects, and the 

requirement, if there is any, should be made on a site-specific basis. Early field 

studies (by the CO2 Capture Project) indicate that it is the appropriate placement of 

cement, and not the type of cement, that delivers isolation & prevents casing 

corrosion. 
BP Alternative Energy Comments to EPA Proposed Rule 

By Mr. Brian Williams 

Docket ID No. EPA-HQ-OW-2008-0390 

Page 2 

The choice of casing and cement materials should be selected based on planned well 

operating life (i.e., decades), not on the ultimate duration of the storage program. The 

potential for longer term exposure of casing during storage, which might occur after 

injection has stopped, is mitigated by plugging the static well with corrosion-resistant 

material, if it is deemed necessary at that time. 

 Cement across long string casing -- BP does not agree with the requirement for a long 

string from the injection interval to surface or with cementing across that entire 

distance. Allowance should be made for a liner to be set across the injection interval 

when the previous string is set above that zone. Cement should cover the uppermost 

caprock in the Area of Review by a margin of approximately 500 feet, not to surface. 

The ultimate decision for each project should rest with the Director since each is 

unique in the geological intervals of the caprock(s) and injection zone(s) and of the 

position relative to USDW(s). Any expectation to cement in the injection interval 

should permit the use of external casing packers in conjunction with the cementing 

requirements across the caprock. 

WELL OPERATIONS

 No CO2 injection above lowest known USDW -- BP does not subscribe to a blanket, 

artificial constraint that would limit injection only to reservoirs below the USDW. More 

appropriate, given the EPA’s general performance-based approach, would be to place 

containment requirements on the acceptable reservoirs. As long as CO2 can be 

injected and stored securely, with minimal chance for breaching containment (either 

via wellbore or geological features), proximity to USDWs, whether shallower or deeper, 

should not matter. 

 Minimum Injection depth vs. requirement to inject below lowermost USDW – BP 

disagrees with universal mandates for establishing minimum depths for CO2 injection, 

as these should be site-specific based on the containment and capacity parameters of 

the storage site. 

 Standard requirement for downhole shut-in devices -- BP disagrees with the rule to 

include downhole shut-in devices as a standard requirement for injection wells. 

Overpressure protection is best achieved by ensuring compatibility of the casing/tubing 

material design strength with the surface injection (compression) system. Downhole 

shut-in devices may be appropriate, however, for site-specific situations of unique 

potential impact (such as offshore or near airports), but they should not be mandated 

for all injection sites. 
BP Alternative Energy Comments to EPA Proposed Rule 

By Mr. Brian Williams 

Docket ID No. EPA-HQ-OW-2008-0390 

Page 3 

CONCLUSION

 Wells are indeed a fundamental component of a geologic storage system. Having 

appropriate design, construction & operating requirements for these wells is necessary 

to ensure delivery of the secure storage of CO2. 

 Site-specific performance-based guidelines, like the well-related examples I’ve noted, 

will serve the purpose of requiring application of the appropriate technological 

solutions to protect USDWs. 

 Again, I’d like to thank the EPA for providing this opportunity to speak today. 
Letter ID: 0116 

Commenter: Brian Williams 

Organization: BP Alternative Energy 

Letter ID: 0116 Comment ID: 22049 Letter Lines: 30 to 41 

Comment Code: 1320 1.1.3 General comments about GS 

Comment Code: 1940 1.4.4.3 Consultations with Industry; experience with other wells 

Comment: EPA has correctly recognized that wells are a fundamental component of a 

geologic storage system that successfully ensures the containment of stored CO2. 

As such, we agree that having appropriate well design, construction & operating 

requirements are critical to the delivery of secure storage of CO2. 

Oil and gas operators have decades of experience, via past and existing 

operations, in constructing and operating EOR/EGR wells in a safe and secure 

way. For existing EOR projects and wells, Class II requirements have proven to 

be sufficient at ensuring the necessary protection of USDWs, and, therefore, 

analysis of the experiences and performances of these Class II CO2 EOR wells 

should inform the requirements for new Class VI wells. 

Individual Response: EPA recognizes that the oil and gas industry has decades of experience 

injecting CO2 for the purpose of ER, and that sites used for ER may be suitable for GS and may 

be among the first GS sites. Some of the research that informs the final GS rule was conducted at 

ER sites. EPA also recognizes that a by-product of ER activities is that a certain percentage of 

the CO2 is trapped in the receiving formation. 

In addition, EPA is using an adaptive approach to regulating GS under the UIC Program. Even 

after finalization of the GS regulation, the Agency plans to collect and review data every six 

years on GS projects to determine whether the appropriate amount and types of information and 

appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Letter ID: 0116 Comment ID: 22050 Letter Lines: 42 to 53 

Comment Code: 3862 2.3.3.1 Use of corrosion-resistant construction materials (seeking 

comment) 

Comment Code: 3864 2.3.3.2 Use of corrosion-resistant cements (seeking comment) 

Comment: I would like to comment on certain of the incremental requirements in the draft 

rule, including the preamble, around the design, construction & operation of 

Class VI wells that we feel are potentially excessive. 

1
WELL CONSTRUCTION 

Corrosion resistant materials & cement - Based on industry experience and field 

studies, corrosion resistant materials should not be mandated for all projects, 

and the requirement, if there is any, should be made on a site-specific basis. 

Early field studies (by the CO2 Capture Project) indicate that it is the 

appropriate placement of cement, and not the type of cement, that delivers 

isolation & prevents casing corrosion. 

Individual Response: EPA agrees that proper cement placement is extremely important to the 

integrity of a Class VI well. However, even proper cement placement cannot compensate for an 

improper type of cement. It is also important that the cement type be appropriately CO2 

compatible and corrosion-resistant, and suitable to both the CO2 stream and formation fluids. 

Data from research and the field show that various cement designs are subject to chemical 

alteration when exposed to CO2 (e.g., Barlet-Gouedard et al., 2006; Kutchko et al., 2007; Carey 

et al., 2007). The rule does not specify materials to be used; rather, it provides owners or 

operators with the flexibility to choose, as long as the materials used in Class VI wells are 

compatible with fluids with which they may come into contact and meet or exceed standards 

developed for such materials by API or ASTM International, or comparable standards approved 

by the Director, as provided at §146.86(b)(1). 

See the discussion of Class VI well construction requirements in the preamble to the final GS 

rule for additional information. Additionally, EPA is developing guidance on the construction of 

Class VI wells. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0116 Comment ID: 22051 Letter Lines: 55 to 59 

Comment Code: 3862 2.3.3.1 Use of corrosion-resistant construction materials (seeking 

comment) 

Comment Code: 3864 2.3.3.2 Use of corrosion-resistant cements (seeking comment) 

Comment: The choice of casing and cement materials should be selected based on planned 

well operating life (i.e., decades), not on the ultimate duration of the storage 

program. The potential for longer term exposure of casing during storage, which 

might occur after injection has stopped, is mitigated by plugging the static 

well with corrosion-resistant material, if it is deemed necessary at that time. 

Individual Response: EPA disagrees that the casing, cement, or other materials should only be 

designed for the period of the injection process, rather than the life of the sequestration project. 

GS projects are anticipated to have long life spans in comparison to other types of deep injection 

wells. Not only must Class VI wells be able to function safely and properly over the lifespan of 

the GS project, but they must be constructed such that USDWs remain protected after well 

plugging. The requirements at §146.86 will ensure that the well can maintain integrity 

throughout the proposed life span of the project, including after the injection well is plugged and 

2
through the post-injection site care period and beyond. While the risk profile of a GS site will 

decrease following cessation of injection, EPA believes that Class VI wells must be designed to 

protect USDWs from endangerment for the life of the project. Furthermore, rigorous casing and 

cementing help ensure that the Class VI well will not serve as a conduit for movement of fluids 

associated with future injection operations. 

Letter ID: 0116 Comment ID: 22052 Letter Lines: 61 to 71 

Comment Code: 3824 2.3.1.2 Cementing of long-string casing (seeking comment) 

Comment: Cement across long string casing -- BP does not agree with the requirement for a 

long string from the injection interval to surface or with cementing across that 

entire distance. Allowance should be made for a liner to be set across the 

injection interval when the previous string is set above that zone. Cement 

should cover the uppermost caprock in the Area of Review by a margin of 

approximately 500 feet, not to surface. The ultimate decision for each project 

should rest with the Director since each is unique in the geological intervals 

of the caprock(s) and injection zone(s) and of the position relative to USDW(s). 

Any expectation to cement in the injection interval should permit the use of 

external casing packers in conjunction with the cementing requirements across 

the caprock. 

Individual Response: The final GS rule at §146.86(b)(3) requires that the long-string casing 

extend to the injection zone and be cemented by circulating cement to the surface in one or more 

stages. It does not, however, specify how cementing would be accomplished, and gives 

flexibility to the owner or operator to propose alternate methods to provide a sufficient amount 

of cement to meet the standard that USDWs are protected from endangerment, subject to the 

approval of the Director. EPA adds that, under §146.86(b)(4), the Director may approve an 

alternative method of cementing in cases where the cement cannot be recirculated to the surface, 

provided the owner or operator can demonstrate by using logs that the cement does not allow 

fluid movement behind the wellbore. 

The construction requirements at §146.86 offer flexibility to the owner or operator to propose 

well construction procedures that are appropriate to the site-specific conditions of the project. 

With their permit applications, operators must submit well construction procedures, as specified 

at §146.82(a)(12), that demonstrate that the well as constructed will prevent unacceptable fluid 

movement; allow the use of appropriate testing devices and workover tools; and allow 

continuous monitoring of the annulus space between the injection tubing and long-string casing, 

as specified at §146.86(a). The Director will evaluate the proposed well construction procedures 

in the context of other data about the site. EPA has evaluated the cementing requirements for 

other well classes and believes that flexibility can be afforded while ensuring that USDWs are 

protected. 

See the discussion of Class VI well construction requirements in the preamble to the final GS 

rule for additional information. Additionally, EPA is developing guidance on the construction of 

3
Class VI wells. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0116 Comment ID: 22053 Letter Lines: 75 to 81 

Comment Code: 4324 2.4.4.1.2 Comments opposed to requiring injection below the lowermost 

USDW 

Comment: No CO2 injection above lowest known USDW -- BP does not subscribe to a blanket, 

artificial constraint that would limit injection only to reservoirs below the 

USDW. More appropriate, given the EPA’s general performance-based approach, 

would be to place containment requirements on the acceptable reservoirs. As long 

as CO2 can be injected and stored securely, with minimal chance for breaching 

containment (either via wellbore or geological features), proximity to USDWs, 

whether shallower or deeper, should not matter. 

Individual Response: EPA acknowledges that there are limited circumstances where injection 

above the lowermost USDW can be performed in a manner that protects USDWs from 

endangerment, as long as appropriate protections are in place. The final GS rule at §146.95 

establishes a process by which owners or operators can seek a waiver of the Class VI injection 

depth requirements for injection into non-USDW formations above and/or between USDWs. The 

final rule also establishes limited circumstances under which expansions of the areal extent of 

aquifer exemptions may be granted for owners or operators of Class II EOR/EGR wells 

transitioning to Class VI injection for GS. Additionally, the final GS rule does not categorically 

preclude or prohibit injection into any type of formation. 

EPA believes that these requirements will ensure USDW protection while providing flexibility to 

UIC program Directors and owners or operators who undertake CO2 injection for GS. The 

Agency believes this approach: 1) responds to concerns about local and regional geologic storage 

capacity limitations imposed by the proposed injection depth requirements; 2) allows for a more 

site-specific assessment of injection depth for GS projects; 3) accommodates injection into 

different formation types; 4) allows for injection of CO2 for GS into non-USDWs above and/or 

between USDWs when appropriate and where it can be demonstrated that USDWs will be 

protected; and 5) responds to concerns about the use of aquifer exemptions for GS. Finally, 

EPA’s approach to addressing injection depth variability through a waiver process responds to 

concerns about future drinking water resource availability and the need to ensure that high 

quality water remains available in sufficient quantities to supply drinking water needs. For 

additional information on the waiver approach and aquifer exemptions for Class VI wells, please 

see the final rule and preamble, as well as EPA's responses to comments on the Notice of Data 

Availability and Request for Comment. 

Letter ID: 0116 Comment ID: 22054 Letter Lines: 83 to 86 

Comment Code: 4344 2.4.4.2.2 Comments opposed to setting a minimum injection depth 

4
Comment: Minimum Injection depth vs. requirement to inject below lowermost USDW - BP 

disagrees with universal mandates for establishing minimum depths for CO2 

injection, as these should be site-specific based on the containment and 

capacity parameters of the storage site. 

Individual Response: EPA agrees that it is not appropriate to set a minimum injection depth for 

GS projects and the Agency believes that a determination of site-suitability for GS (i.e., that 

subsurface formations will receive and confine injected CO2) should be made on a site-specific 

basis. The GS rule, at §146.82, requires the owner or operator to provide extensive site- and 

project-specific information to the Director to demonstrate that the site meets the minimum site 

criteria at §146.83, that the CO2 will be contained within the injection formation, and that 

USDWs will be protected from endangerment. 

EPA acknowledges that there are limited circumstances where injection above the lowermost 

USDW can be performed in a manner that protects USDWs, as long as appropriate protections 

are in place. The final GS rule at §146.95 establishes a process by which owners or operators can 

seek a waiver of the Class VI injection depth requirements for injection into non-USDW 

formations above and/or between USDWs. The waiver approach requires the submission of 

extensive, site-specific information (in conjunction with the permit application submission) to 

demonstrate that injection of CO2 into a non-USDW that is above or between USDWs can be 

done in a manner that is protective of USDWs. The requirements are designed to ensure that the 

owner or operator, the Director, and the Regional Administrator consider, on a site specific basis, 

the implications, benefits, and challenges associated with GS and ensuring water availability and 

USDW protection. For additional information on the waiver approach, please see the final rule 

and preamble, as well as EPA's responses to comments on the Notice of Data Availability and 

Request for Comment. 

Letter ID: 0116 Comment ID: 22055 Letter Lines: 88 to 94 

Comment Code: 4200 2.4.2 Down-hole shut-off valves in GS wells (seeking comment) 

Comment: Standard requirement for downhole shut-in devices -- BP disagrees with the rule 

to include downhole shut-in devices as a standard requirement for injection 

wells. Overpressure protection is best achieved by ensuring compatibility of the 

casing/tubing material design strength with the surface injection (compression) 

system. Downhole shut-in devices may be appropriate, however, for site-specific 

situations of unique potential impact (such as offshore or near airports), but 

they should not be mandated for all injection sites. 

Individual Response: EPA agrees that proper design of the well, including appropriate materials 

and emplacement of casing and tubing, is essential to proper operation of the well. Such design, 

however, does not eliminate the possibility of failure, e.g., due to over-pressurization as 

suggested by the commenter. EPA believes that a multiple-barrier approach, which includes 

appropriate well design as required at §146.86, suitable injection pressure limits as required at 

§146.88(a), and automatic shut-off systems, as required at §146.88(e), is necessary to ensure 

protection of USDWs from endangerment from the risks associated with CO2 GS. 

5
After evaluating the risks and benefits of down-hole shut-off systems and considering additional 

research, EPA will not require automatic down-hole shut-off devices for onshore Class VI wells 

since it is not necessary in all cases to ensure protection of USDWs from endangerment. Instead, 

the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells 

install automatic surface shut-off devices. The rule affords Director's discretion to mandate 

automatic down-hole shut-off devices in onshore situations that may warrant their use. However, 

the Agency agrees with the commenter that offshore Class VI wells present unique construction 

and operational conditions, including isolation from shorelines and the need to construct wells 

through the water column and the subsurface, which may delay response time in the event of 

well difficulties. The rule requires, at §146.88(e)(3), that owners or operators of offshore wells 

within State territorial waters install automatic down-hole shut-off systems. EPA believes that 

these requirements at §146.88(e) ensure that proper precautions are taken to prevent subsurface 

fluid movement and ensure protection of USDWs. 

Letter ID: 0116 Comment ID: 22056 Letter Lines: 98 to 104 

Comment Code: 1250 1.1.1.4 Flexibility is needed (performance-based standards) 

Comment: Wells are indeed a fundamental component of a geologic storage system. Having 

appropriate design, construction & operating requirements for these wells is 

necessary to ensure delivery of the secure storage of CO2. 

Site-specific performance-based guidelines, like the well-related examples I’ve 

noted, will serve the purpose of requiring application of the appropriate 

technological solutions to protect USDWs. 

Individual Response: The Agency believes that the Class VI requirements balance site-specific 

flexibility with USDW protection. Rather than setting performance or technology-based 

standards for GS projects, EPA is adopting a flexible approach, where operators of GS projects 

would develop and implement site-specific plans for delineating the AoR, testing and monitoring 

the site, performing corrective action, and post-injection site care. EPA believes that the plans—

which would be reviewed and approved by the Director and periodically updated throughout the 

life of the project—promote an ongoing dialogue between the operator and the Director that will 

encourage use of the most appropriate technologies for a particular project. 

6