{In Archive} Re: Information Request - ExxonMobil MCU j ennifer.wilder to: Shaheerah Fateen 07/08/2004 01:04 PM

From: j ennife r .wilder@exxonmobil.com
To: Shaheerah Fateen/R9/USEPA/US@EPA, History: This message has been forwarded.

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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

Field Process_McElmo.docA. Field Process
McElmo Creek unit is a CO2 flood designed to enhance oil recovery. CO2 is delivered to the unit via pipeline (KinderMor gan 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/Al ternating/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 we ll 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 satellit e, several wells are directed straight into a Battery. (see flow diagrams for more detail)

Oil is sold at the LACT unit at each Cent ral 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 Plan t is to receive pr oduced gas through a gathering system, pressure the gas up to a su itable 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 tim e, the Plant inlet vol ume can vary between 10 and 18 million standard cubi c 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 r eceiver which collects free liquids. The gas then passes through f ilter vessels which collect any incoming solids.

Compression. The Plant consists of four hi gh-speed electrically-d riven 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 si ngle 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.