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.Document ID: EPA

- HQ

- OW

- 2008

- 0390

- 0237

Last Name: Fesmire

First Name: Mark E.

Title: Director

Organization: New Mexico Oil Conservation Division (NMOCD)

City: Santa Fe

State: NM

Zip Code: 87505

Phone Number: 505.476.3440

Fax Number:

Country Code:

Email Address:

Current Category Code: 250

Comment:

U.S. ENVIRONMENTAL PROTECTION AGENCY’S

PROPOSED FEDERAL REQUIREMENTS UNDER THE UNDERGROUND

INJECTION CONTROL PROGRAM FOR CARBON DIOXIDE GEOLOGIC

SEQUESTRATION WELLS

DOCKET ID NO. EPA

- HQ

- OW

- 2008

- 0390

December 24, 2008

The New Mexico Oil Conservation Division (OCD) is the New Mexico state agency

that is responsible for regulating all aspects of the oil, gas and geothermal

industries in New Mexico. It is also the lead agency with primacy for the

Underg round Injection Control program of the Safe Drinking Water Act and is the

agency that will regulate the geologic sequestration of carbon dioxide in New

Mexico.

After review of the proposal, the OCD is pleased to present the following

comments on the proposed requirements and thanks the EPA for the opportunity to

make these comments.

1. General Comments

A. The OCD has participated in preparing, and is generally supportive of, the

comments presented by the Interstate Oil and Gas Compa ct Commission (IOGCC) and

the Ground Water Protection Council (GWPC).

B. The OCD applauds the inclusion of computational modeling to establish the

Area of Review (AOR) as much more representative of reservoir conditions than

fixed radius AOR’s currently in use in the UIC program.

C. The proposed regulations do not seem to adequately address the detrimental

thermal effects on well integrity caused by near well bore phase changes. It ishighly probably that pressure losses thru perforations of injected superc ritical

fluid during early phases of a sequestration project in a depleted oil or gas

reservoir (where the pressure is below the supercritical pressure) will result

in phase changes at the perforations that will have a thermal effect on

mechanical integrit y of the casing cement system.

2. Specific Comments

In addition to the comments presented by the IOGCC and the GWPC, the OCD

is pleased to present the following specific comments.

A. Section 144.55 "Corrective Action"

- The question arises whether the analysis

of the wells in the area of review should include those wells that not only

penetrate the injection zone, but also those that penetrate the confining zone

also.

B. Section 146.86 "injection well construction"

- sub section (B)(2) requires a

sufficient number of centralizers, but does not establish the objective of the

centralizer placement. It is suggested that this section require a "sufficient

number of centralizers to insure an adequate cement bond to prevent fluid

communication under inje ction pressures."

Mark E. Fesmire, PE JD

Director, NMOCDLetter ID: 0237

Commenter: Mark E. Fesmire

Organization: New Mexico Oil Conservation Division (NMOCD)

Letter ID: 0237 Comment ID: 23208 Letter Lines: 39 to 41

Comment Code: 1200 1.1 General comments about the rulemaking

Comment: A. The OCD has participated in prepar ing, and is generally supportive of, the

comments presented by the Interstate Oil and Gas Compact Commission (IOGCC) and

the Ground Water Protection Council (GWPC).

Individual Response: EPA acknowledges the comment. Pleas e see the remainder of EPA's

responses to this comment and comments from IOGCC and GWPC for further details. For

additional information on EPA's fina l regulatory approach, please se e the final rule and preamble

as well as the rulemaking docket.

Letter ID: 0237 Comment ID: 23209 Letter Lines: 42 to 44

Comment Code: 3310 2.2.1.1 Comments in favor of requiring computational models to

delineate the AoR (seeking comment)

Comment: B. The OCD applauds the inclusion of co mputational modeling to establish the

Area of Review (AOR) as much more repres entative of reservoir conditions than

fixed radius AOR’s currently in use in the UIC program.

Individual Response: EPA acknowledges the commenter’s s upport and agrees that predicting

the complex multiphase, buoyant flow of the CO 2, co-injectates, and compounds that may be

mobilized due to injection requires the sophistica tion of computational models, as required at

§146.84(c)(1). Models can predict CO2 fate and tr ansport, as well as changes in formation

pressure, in three dimensions, as a function of ti me in order to delineate the subsurface storage

site and the AoR. Models can account for site-specific and predicted operating conditions as well

as geologic heterogeneities a nd potential migration through fau lts, fractures, and artificial

penetrations.

Letter ID: 0237 Comment ID: 23210 Letter Lines: 45 to 51

Comment Code: 3860 2.3.3 Well component degradation

Comment: C. The proposed regulations do not seem to adequately addre ss the detrimental

thermal effects on well integrity caused by near well bore phase changes. It is

highly probably that pressure losses thru perforations of inj ected supercritical

fluid during early phases of a sequestrati on project in a depleted oil or gas

reservoir (where the pressure is below the supercritical pressure) will result

1in phase changes at the perforations that will have a thermal effect on

mechanical integrity of the casing cement system.

Individual Response: Injection depth will be a vital consideration if formations designated to

receive supercritical CO2 are of su ch low pressure that supercritic al CO2 reverts to its gas phase

upon entry. This could result in thermal shock if expansion of gaseous CO2 causes a drop in

temperature (the Joule-Thomson effect). Therma l shock is a common cause of cracking in many

types of pressure equipment, and repeated expo sure to such stresses could compromise the

integrity of the injection well's tubular compone nts. EPA believes that the continuous pressure

monitoring required at §146.85, which can detect ear ly effects of thermal shock, along with the

construction requirements at §146.86 and the te sting and monitoring requirements at §146.90,

provide a multiple barrier approach to pr otecting USDWs from endangerment. See the

discussion of Class VI well constr uction requirements in the preamble to the final GS rule for

additional information. Additionally, EPA is deve loping guidances on the construction of Class

VI wells and testing and monitoring for GS projec ts. These guidances will be available on EPA’s

website at http://water.epa.gov/type/gr oundwater/uic/wells_se questration.cfm.

Letter ID: 0237 Comment ID: 23211 Letter Lines: 58 to 61

Comment Code: 3440 2.2.2.2 Evaluation of wells in the AoR (e.g., types of data to be

reviewed)

Comment: A. Section 144.55 "Corrective Action" - The question arises whether the analysis

of the wells in the area of review shoul d include those wells that not only

penetrate the injection zone , but also those that pene trate the confining zone

also.

Individual Response: The final rule leaves §144.55 unchanged from the existing UIC

requirements; i.e., Class VI wells are not addressed in this pr ovision. Based on its evaluation of

all public comments and input on the proposed rule and NODA a nd Request for Comment, EPA

has made many revisions to the GS Rule. See th e final rule and preamble for further discussion

on EPA's final approach.

Letter ID: 0237 Comment ID: 23212 Letter Lines: 62 to 66

Comment Code: 3820 2.3.1 Well construction procedures

Comment: B. Section 146.86 "injection well construc tion" - sub section (B)(2) requires a

sufficient number of centralizers, but doe s not establish the objective of the

centralizer placement. It is suggested th at this section require a "sufficient

number of centralizers to insure an adequate cement bond to prevent fluid

communication under injection pressures."

Individual Response: EPA clarifies that centralizers serve to keep the casing centered in the

23 wellbore during drilling and cementi ng. If the casing is not centere d, it can be difficult to remove

the drilling mud and the cement job may not be eve n. This can lead to an inadequate cement job.