## Attachment S

Compressors

John Co rdaway Transcanada

C o r porationResponse to Oil and Gas Sector Compressor White Paper John Cordaway



### 6 .0 C H AR GE Q U EST I O N S F OR R E V I EWE R S

Th ese responses are provided with a practical or o perational point of view. Many well positioned groups and technical data providers will be responding to the charge question s

. S ome questions will not be fully commented given the questions are better addressed by those with a more qualified background in data compilation, assessment of study results, etc.

It seems the quantification of compressor leaks is the end game or focus of the
EPA paper. Assuming that is the case, the following summary is offered as background to the response of the various charge questions.

First and foremost, the GHGRP (Greenhouse Gas Reporting Program) was intended to provide an extensive overview or insight into the fugitive emission picture of several sectors within the oil and gas industry. It is highly
recommended th at EPA allow th e process to work and begin the data mining process. The data mining process should include a partnership with ind ustry sector professionals, advisors and industry trade groups to develop effective regulation. This would both enrich any subsequent requirements and serve to build agreement between operators and regulators.

This partnership would be a key step and wil l be the mechanism to effectively and correctly evaluate the best means to manage GHG ’s from the oil and gas sector. The papers mentioned

, and to some degree summarized by the EPA paper, provide information of areas to target emission reduction but t hose papers have not provided full background into explaining reasons for the differences in the reported fugitive measurements in the study papers

. This context is critical for effective decisions. It is thr ough partnership with industry that will allow the time to fully characterize and substantiate a cooperative go

- forward direction to
reduce GHG emissions.

The partnership discussions will allow the ‘ operational realities ’ to be discussed and adequately considered. The time allowed in this comment peri od limited the opportunity to investigate and document the ‘operational realities’ but the partnership discussions could allow for this documentation to occur. Some ‘operational realities’ are mentioned in the individual charge question response s

.
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### It i s also observed that many companies are already improving their GHG emission footprint due to the GHGRP. For example, operating companies have a desire to operate safely. If an emission source is identified and determined a safety concern, they will be addressed. When it comes to reciprocating compressor packing, operating companies routinely perform reciprocating compressor packing replacement. It is in the best interest of the operating companies to install the best packing so that the activity is not prematurely repeated! It is also critical to note that all companies actively manage their GHG emission footprint as emissions released directly relate to a loss of product to be
marketed. Methane is NOT considered a waste product by industry

.

Lastly, a few operational realities that should be discussed and understood in the joint EPA/Industry disc u ssions:

• Understand the total impact of ‘simple’ actions like modifying vents.

• Understand the degree of ‘typical’ compressor designs before maki ng broad assertions of prevalence

.

• Understand unintended repercussions of installing and operating mitigation
actions.

• A prime example

, and need to conduct joint discussions

, is to understand the impact of wet seals.

o What is the real prevalence of wet seals in the industry?

o What were the wet seal reading sample sizes in the various studies and the characterization of all wet seals from the very limited sample
size?

o Further, the wet seal vents are typically sized by th e manufacturer to be 1 or 1 1⁄2 “ inches in diameter. It is understood large volumes of gas can be emitted but if the manufacture sizes a vent line that small, the likelihood of wet seals being a high emitter is low.

The intended point here is to emp hasize the need to truly understand the data prior to correctly characterize the results from the many studies.

1. P le a se c om m e nt on t he n a t i on a l esti m a tes of met h a ne e m i ss i ons a nd meth a ne e m i ss i on

f

a c tors f o r v e nted c omp r e ssor e m i ss i ons p re s e nt e d in t his pap e r. P le a se c o m m e nt on t he

ac t i vi t y d a ta a nd the m e t hodolo g ies us e d for c a l c ulating e m i ss i on f a c t o rs p re s e nted in

th i s p a p e r.

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### Response to Question 1.

I have limited knowledge in this area and therefore will not provide a

response.

2. Did th i s pa pe r a ppro p ri a t e l y c h a r ac t e ri z e the di f fer e nt s t udies a nd d a ta sou r ce s that

qua n t i f y v e nted e m i ss i ons f r om c ompr e ssors in t h e oil a nd g a s s ec tor?



### Response to Question 2.

The paper did provide a reasonable list of the key industry studies and the

results . What would have been beneficial is a characterization of the study

results from the view of the EPA

. What is needed is to characterize or

explain the reason for key differences in the results of each paper. For

example, the time span of the dif ferent studies can affect the ‘apparent’

results. The type of material of construction or component design changes

may have changed from one study to the next and therefore could be the

source for the varying readings. The key differences in the studies must be

understood before comparing the results to other studies. When comparing

studies, there are countless data quality considerations that if not

addressed, will provide a mischaracterization. For example, s ample size,

component construction or type, etc.

3. Did th i s pa pe r c a ptu r e t h e f ull ra n g e o f t ec hnol o g i e s av a i l a ble to r e du c e v e nted e m i ss i ons

f r om r e c i p ro c a t i n g c om p r e ssors a nd w e t se a l c e nt r ifu g a l c ompr e ssors a t o i l and g a s

f

a c i l i t ie s ? I n p a rticul a r, a r e the r e o t h e r options for r e du c i n g e m i ss i ons a t e x is t ing

r e c i p r o ca t i n g or ce ntrif u g a l c ompr e ssors? F or e x a mp l e , the E P A is a w a r e of “ low e m i ss i ons

p ac ki n g ” f o r r e c ipr o ca t i n g c ompr e ss o r s but h a s no d e tailed in f o r m a t i on on th i s te c hnolo g y

.

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### Response to Question 3.

Companies are incentivized to reduce fugitive emissions and many have

conducted various internal or operational studies on, for example, Low

Emissions Packing. (LEP) LEP is an area of promise that has seen some very
positive results in reducing fugitive emissions

. The operational reality is LEP

may not be promising in all sectors or situations. Operational realities may

call for different packing to operate in different gas quality environments. For

example, s ome gas stream s have a bit more dirt or entrained liquids that

must be addressed with different types of packing. As companies further

review and understand the GHGRP results, operators will more fully

understand and the improvements needed to support the LEP operation

, machining of the packing cups, maintaining proper packing clearances, and

understanding compressor rod qualities leading to extending reciprocating

packing operational life.

4. Did th i s pa pe r a ppro p ri a t e l y c h a r ac t e ri z e the e m i ss i ons r e du c t i ons ac hie v a ble f rom

the e m i ss i ons mi t i g a t i on te c hnolo g ies discuss e d for re c ipro ca t i n g c omp r e ssors a nd

w e t se a l ce ntrif u g a l c ompr e ssors?



### Response to Question 4.

Overall, the paper does not appropriately characterize the reductions.

The results are snap shots of various studies performed for various

reasons and various goals . The take away should be that the papers are

directing the focus of additional detailed study. For example, some

companies understand how to properly repair and/or install

reciprocating com pressor packing. If studies were conducted with a goal

to determine the best reciprocating packing solution, a different result

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### would likely occur when compared to the reductions characterized in the

paper.

5. Did th i s pa pe r a ppro p ri a t e l y c h a r ac t e ri z e the ca pi t a l and op e r a t i ng c osts f or the

t ec hnol o g ies discuss e d for r e du c t i on o f v e nted e m i ss i ons f r om r ec ipro c a t i ng c ompr e ssors

a nd w e t se a l ce ntrif u g a l c ompr e ssors?



### Response to Question 5.

The operating costs referenced in the paper are an order of magnitude low.

In today ’ s operational environment, the cost to modify an existing facilities

design is quite high. Additional cost considerations include :

Something as ‘simple’ as conducting a design review requires a large

amount of manpower. Securi ng a company design engineer to review

existing drawings to verify equipment, site visits are required, as

- built

drawings from a draftsman, p rocurement of pipe, valves and fittings , etc.
are all additional cost considerations for many ‘simple’ vent modific ations.

6. I f the r e a r e e m i ss i ons m i t i g a t i on opt i ons for r ec ip r o ca t i ng a nd c e ntrif u g a l c o mpr e ssors

that w e re not d i s c ussed in th i s pa pe r, pl e a se c om m e nt on the p r os a n d c ons of t hose

opt i ons. P le a se discuss the e f fi c ac y , c ost a n d fe a sib l y f o r b oth new a nd e x is t ing

c o mpr e ssors.


### Response to Question 6.

I am not aware of other mitigation options.

7. A r e the r e te c hn i ca l l i m i t a t i ons th a t m a ke the re pl a ce ment of w e t s e a ls with d r y

s ea ls i m p rac t i ca l at c e rt a in e x is t ing ce ntrif u g a l comp r e ssors?

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### Response to Question 7.

Yes. Given t he technical limitation is the focus of the question and

therefore cost will not be mentioned, the lead driver s are likely

availability of very clean gas or electrical power. For example, some

installations are limited by availability of power to drive an air

compressor for the dry seals. In other situations, the gas quality

(presence of micro solids or entrained liquids) can be low enough that

f

iltration cannot be relied on to provide 100% clean gas to the dry

seal. A seal failure is very costly and never timely. Theoretically, one

c ould say that if enough money was spent on the filtration, the proper

quality can be achieved but such is not known and therefore this

statemen t would not be a reasonable response. The risk to shutting

in production and suffering contractual implications is also a resulting

impact that is an operational reality. Even with dual filtration

systems, an operator will be challenged to determine the risk of

shutting a unit down and stopping production. In remote or offshore

applications, this would be extremely difficult to address.

8. A r e the r e te c hn i ca l r e a s o ns w h y a n op e r a tor w ou l d use a w e t s e a l c e ntr i f u g a l

comp re ssor without a g a s r e c o v e r y s y ste m ?



### Response to Question 8.

Potentially, y es.

1. There must be a lower pressure source for the wet seal gas to be

routed and used.

2. If the lower pressure gas source can potentially introduce a higher

pressure on the wet seal vent, the seal may no operate properly. Today,

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### Operators can be resistant to deal with that type of issue. Technically, the

issue can probably be resolved but wi ll require quite a few dollars to

address.

9. A r e the r e te c hn i ca l l i m i t a t i ons th a t m a ke the inst a l l a t i on of g a s ca ptu r e s y s t e ms at

c e r t a in r e c ipr o ca t i n g c ompr e ss o r s i m p rac t i ca l?



### Response to Question 9.

Yes. Some limitations include :

• A fuel burning source of lower pressure gas must be available.

• As the gas is captured, time must be available for the amount of

trapped gas to ‘bleed’ into the lower pressure fuel source. Time is not

always available. Example: M any facility safety requ irements state a

facility must provide pressure relief within a certain time frame.

• Gas capture ‘venturi tubes’ may not be technically limiting but could

have a high operation cost due to the loss of the driving gas.

10. P le a se c om m e nt on t he p r e v a le n c e of t h e dif f

e r e nt e m i ss i on m i t i g a t i on opt i ons in t he f ield.



### Response to Question 10.

Many companies employ or utilize Low Emissions Packing. Since LEP is considered an emission mitigation option, it is suggest ed that operators implement this op tion, but in varying degrees. P ersonal knowledge has observed the success of LEP but this technology should be further and properly documented for broader understanding

.

Additionally, m any companies already have unit blow down recovery systems. Eff ectiveness of the blow down systems can be influenced by the daily operation of the unit, other equipment on site and other issues. Quantification of the recovered gas can at times be challenging given wide variance of operation.

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11. Giv e n the substantial b e n e fits of d r y s e a l s y stems ( e

. g ., lo w e r e m i ss i ons, l e s s maint e n a n ce ,

a nd hi g h e r ef f ici e n c y ), a r e y ou a w a re of situations wh e re n e w w e t se a l c e ntrifug a l

c ompr e ssors a re b e i n g i n stalled in the f ield? I f so, a re th e re sp e c ific a ppl ica t ions t h a t

r e quire w e t se a l comp r e ssor s ?



### Response to Question 11.

It is not known if a general industry philosophy exists where wet seals are

replaced by dry seals. Given the extreme high cost of the dry seals and the

potential to require other facility modifications to support the dry seals, it is

unlikely any operator much less a general philosophy exists to replace the

wet seals. If an exis ting engine/compressor unit is equipped with wet seals

and is overhauled, the general phil osophy is to return the unit with the wet

seals. As previously stated, there may be times operation conditions suggest

a need to keep wet seals in service. If a new unit is purchased and installed,

dry seals are likely the choice.

12. A r e the r e o n g oi n g or pl a nn e d studies that w i l l sub s tantial l y i m p r ove the c u r re nt

und e rst a ndi n g of v e nted V O C a nd meth a ne e m i ss i ons f r om r ec ipr o ca t i n g a nd

ce ntrif u g a l c ompr e ssors a nd a v a i l a b l e te c hniques f o r in c r ea s e d p r odu c t r e c ov e r y a nd

e m i ss i ons r e du c t i ons?



### Response to Question 12.

E

fforts to data mine the GHGRP information are underway by the various oil and gas trade groups who are better suited to respond to this question.

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