{In Archive} Fw: Information Request - ExxonMobil MCU

Shaheerah Kelly to: christopherjlee, mohanrasthana, 

morrismuskett 07/18/2005 08:57 AM

From: Shaheerah Kelly/R9/USEPA/US

To: christopherjlee@navajo.org, mohanrasthana@navajo.org, morrismuskett@navajo.org, 

Archive: This message is being viewed in an archive.

Shaheerah Kelly

Air Division, Permits Office

U S EPA Region IX

75 Hawthorne Street

San Francisco, CA 94105

Phone: 415-947-4156

Fax: 415-947-3579

----- Forwarded by Shaheerah Kelly/R9/USEPA/US on 07/18/2005 08:56 AM -----

jennifer.wilder@exxonmobil.c

om

07/08/2004 01:02 PM

To Shaheerah Fateen/R9/USEPA/US@EPA

cc

Subject Re: Information Request - ExxonMobil MCU

Shaheerah

I have attached a quick summary of the plant. I am still working on the

lease breakdown.

one comment - The dehydration unit is mainly used to dry gas that is

compressed by HOS 6 (compressor). There is a small stream of the dried gas

that is used for heater treaters in the field and for the firebox at the

plant. Water is removed to preserve the integrity of the compressor as

well as keep the flow lines dry and avoid freezing as gas is re-injected.

 (See attached file: Field Process_McElmo.doc)

I am faxing the GRI GLYCalc over right now.

Jennifer Wilder Baird

Compliance Engineer

ExxonMobil Production Company

Office: (281) 654-1135 Fax: (281) 654-1147

jennifer.wilder@exxonmobil.com
A. Field Process 

McElmo Creek unit is a CO2 flood designed to enhance oil recovery. CO2 is 

delivered to the unit via pipeline (KinderMorgan gas plant from the Shell Dome). The 

dome is approximately 25 miles north of the McElmo Creek Unit. The method used 

to flood the unit is Water/Alternating/Gas (WAG) sytem. 

McElmo Creek Unit Oil Production: 3700 BOPD 

 Water Production: 26,000 BWPD 

 CO2 Purchased: 12KCF 

 Gas Re-injection 23KCF 

Approximately 90 producing wells send full well stream, (oil, gas and water) to either 

a satellite of one of 4 batteries. There are 11 satellites that function as testing facilities 

for producing wells. As stated above, not all wells go into a satellite, several wells are 

directed straight into a Battery. (see flow diagrams for more detail) 

Oil is sold at the LACT unit at each Central Tank Battery to Giant Refinery through 

Running Horse Pipeline (owned & operated by Navajo Nation) 

Water is separated and re-injected via the water injection station. Gas is sent to the 

Plant and processed as described below. 

B. Plant and Process Overview 

The McElmo Creek Compression Plant serves tertiary recovery operations for the 

McElmo Creek Field. The goal of the Plant is to receive produced gas through a 

gathering system, pressure the gas up to a suitable working pressure then re-inject the 

gas to maintain reservoir pressure. The natural gas is injected with produced water in a 

dual injection system. Due to varying water injection demands in the field, and to the 

number of wells being serviced at any time, the Plant inlet volume can vary between 

10 and 18 million standard cubic feet per day (MSCFD). 

To describe the plant process in more detail, the gas is processed in three main steps: 

inlet separation, compression and re-injection. 

Inlet Separation. The inlet separation consists of an inlet slug receiver which collects 

free liquids. The gas then passes through filter vessels which collect any incoming 

solids. 

Compression. The Plant consists of four high-speed electrically-driven reciprocating 

compressors which utilize 6300 Brake Horsepower (BHP). Each compressor consists 

of four stages which raise the pressure of the incoming gas from 40 psig to 2900 psig. 

Each stage has a dedicated aerial cooler and liquid scrubber vessel. On the largest 

compressor, inter stage dehydration takes place to remove water for corrosion 

mitigation. 
Re-Injection. The four units discharge into a single header, where purchased CO2 is 

co-mingled to achieve a daily injection goal of 24 MSCFD. The gas is then distributed 

to the field. During Plant upsets, additional CO2 is purchased to meet the daily 

injection goal.