Chevron U.S.A. Production- Carter Creek Gas Plant - Executive Summary
FACILITY DESCRIPTION |
The Carter Creek Gas Plant (CCGP) is owned and operated by Chevron U.S.A. Production Company. The gas plant, located in the Whitney Canyon / Carter Creek gas field (approx. 35 miles North and East of Evanston Wyoming), was designed to process 150 mmscfd of natural occurring hydrocarbon gas and natural gas liquids
Chevron has approximately 85 employees, and contractors working for the Asset. Consisting of Operations, Maintenance and support staff
ACCIDENTAL RELEASE PREVENTION AND RESPONSE POLICIES
It is the policy of Chevron USA Production Company to conduct its business in a socially responsible and ethical manner that protects safety, health and the environment. The CCGP Emergency Preparedness and Response Policy involves assessing the hazards and risks of an unplanned incident; developing a plan for managing those hazards and risks; communicating relevant information to employees, contractors and appropriate agencies; and conducting emergency exercises.
Process 1- Well Stream separation and stabilization
The well stream separation area is designed to handle about 150 MMCF maximum of gas per day. Approximately 3000 barrels of hydrocarbon condensate will be recovered from this gas.
The well stream enters the plant as a three-phase stream: gas, hydrocarbon condensate, and free water. The gas and liquid is separated in the V-1101 (Slug Catcher). The gas is then filtered and treated. The hydrocarbon condensate is depressured, stripped of H2S, and stabilized. The free water is degassed of H2S and sent to sour liquids blowdown.
Process 2- NGL and moisture extraction
The treated high pressure gas that meets pipeline H2S specification is sent to Process 2 for NGL extraction and dew point control before being routed into the N.G.L. sales pipeline.
Treated high pressure gas is chilled to -20F chiller operating temperature which is controlled to ensure that the sales gas hydrocarbon dew point requirement of 15F and water
content specification of 7 lb/MMSCF are met, and also to maximize liquids production to be sold as stabilized N.G.L. product. Chilling is supplied by a propane refrigeration system
Hydrocarbons condensed and collected in the V-1301 (Glycol Separator) during chilling are used as feed stock for the N.G.L. system where the natural gas liquids are stabilized (de-methanized) and then shipped to the N.G.L. sales pipeline.
Process 3- H2S removal and Sulfur recovery
The H2S Removal system is designed to remove H2S from the naturally occurring hydrocarbon gases from the Plant inlet. The gas streams are fed to high, medium, and low pressure Absorbers for contacting with DEA solution. H2S is absorbed into the DEA.
The DEA is regenerated to produce a gas stream containing H2S and water vapor (steam), which is further processed for conversion to elemental sulfur. The regenerated DEA is recirculated to the H2S Absorbers.
The H2S liberated from the DEA is reacted and converted to elemental su
lfur utilizing the Claus Sulfur Recovery process (SRU) and the Beavon Stretford Sulfur Recovery Process (BSRP)
The tail gas from the Plant is then heated and lofted to the atmosphere at or below Wyoming State DEQ permitted levels for emission components.
REGULATED SUBSTANCES ABOVE THRESHOLD QUANTITIES AT CCGP
There are three RMP defined processes with threshold quantities of regulated substances at CCGP including:
Inlet flows and quantities of flammable, naturally occurring hydrocarbon mixtures of methane, ethane, propane, butane and pentane. The total quantities found in the process vessels, process piping and equipment of 590,000 lbs.
Flammable hydrocarbon mixtures of methane, ethane, propane, butane, pentane associated with NGL removal from the sales gas stream and propane refrigeration systems. The total quantities in the process vessels, process piping and equipment of 130,000 lbs.
Hydrogen Sulfide (H2S) associated with the naturally occur
ring hydrocarbon mixture of natural gas entering the Gas Plant and the associated SRU systems used to remove the H2S from the gas and convert the H2S to elemental Sulfur. The total quantities of H2S in the process vessels, process piping and equipment is 15,000 lbs.
THE WORST CASE SENARIOS
Worst-case scenario (WCS) for would be a loss of containment of the V-1101 (Slug Catcher) vessel contents, releasing the entire vessel volume (310,000 lbs.), resulting in a vapor cloud explosion. Although Chevron has numerous controls to prevent such releases and to manage their consequences, no credit for administrative controls or passive mitigation measures was taken into account in evaluating this scenario. While the calculated maximum distance to endpoint (1 psi overpressure) for the WCS of Process 1 is beyond the plant boundaries, there are no public receptors within that calculated radius due to the remote location of the gas plant
Worst-case scenario (WCS) for wou
ld be a loss of containment of the V-1301 (Glycol Separator) vessel contents, releasing the entire vessel volume (30,500 lbs.), resulting in a vapor cloud explosion. Although Chevron has numerous controls to prevent such releases and to manage their consequences, no credit for administrative controls or passive mitigation measures was taken into account in evaluating this scenario. While the calculated maximum distance to endpoint (1 psi overpressure) for the WCS of Process 1 is beyond the plant boundaries, there are no public receptors within that calculated radius due to the remote location of the gas plant
Worst-case scenario (WCS) for would be a loss of containment of the V-1101 (Slug Catcher) vessel contents to the atmosphere. This resulting in the entire volume of H2S (7,500 lbs.) being released at the rate of 700 lbs per minute over a period of ten minutes. Although Chevron has numerous controls to prevent such a release and to manage their consequences, no credit
for administrative controls or passive mitigation measures was taken into account in evaluating this scenario. While the calculated maximum distance to the toxic endpoint (0.042 mg/L; Basis ERPG-2) for the WCS of Process 3 is beyond the plant boundaries, there are no public receptors within that calculated radius due to the remote location of the gas plant
GENERAL ACCIDENTAL RELEASE PREVENTION PROGRAM
Chevron encourages employees to participate in all facets of process safety management and accident prevention. Examples of employee participation range from updating and compiling technical documents, operating procedures, job safety analyses and compiling chemical information to participating as a member of a process hazard analysis team.
Employees have access to all information created as part of the CCGP accident prevention program element.
The CCGP keeps a variety of technical documents that are used to help maintain safe operation of the processes. These documents address chem
ical properties and associated hazards, limits for key process parameters and specific chemical inventories and equipment design basis/configuration information. Chemical-specific information, including exposure hazards and emergency response/exposure treatment considerations, is provided in material safety data sheets (MSDSs).
Chevron ensures that the processes are designed, constructed, operated and maintained within specifications, standards and limits set and accepted by the industry and (or) Company
The processes are controlled and monitored using instruments, highly trained personnel and protective systems (e.g. distributive control systems, automated detection, emergency shutdown systems, closed blowdown systems, pressure relief valves, pressure control valves, remotely located flare systems, etc.).
CCGP has a comprehensive program to help ensure that hazards associated with the various processes are identified and controlled. Within this program, each process is systematic
ally examined to identify hazards and that adequate controls are in place to manage these hazards.
CCGP maintains written procedures that address various modes of process operations such as (1) unit startup, (2) normal operations, (3) temporary operations, (4) emergency shutdown, and (5) normal shutdown.
To complement the written procedures for process operations, Chevron has implemented a comprehensive training program for all employees involved in operating CCGP
CCGP uses Management of Change processes to control and track Facility changes
Mechanical Integrity programs including on-line equipment testing (e.g. ultrasonic thickness testing, corrosion coupons, etc.), chemical inhibition to control corrosion, equipment preventative maintenance and the regularly scheduled comprehensive internal equipment inspection and repair.
THE FIVE YEAR ACCIDENT HISTORY
No accidental releases have occurred at this Facility in the past 5 years
EMERGENCY RESPONSE PROGRAM
To maintain a safe, e
nvironmentally sound and profitable plant process is the number one priority of this facility.
Chevron actively participates on the Uinta County LEPC and Fixed Facilities Group to plan and practice for emergency response issues in the area.
The CCGP Emergency Response Organization consists of between 20 to 30 trained individuals. These individuals will be able, and required to respond to related emergencies at the CCGP
The training these individuals receive is in the area of Incident Command System, Emergency Response, Confined space Response, Basic Emergency Care, P.P.E., and basic Rescue Techniques. They have training that insures they know how to respond to all Areas and processes of the facility, and know how to deal with the different hazards associated with those Areas and processes.
Basic training shall be conducted either in house, at the Fire Training Ground, the Safety Building or other approved locations. All practices sessions will be held in approved plant Areas. Meet
ings will be held in the Control Room Conference Room, to help accommodate plant processing needs for quick response to operational problems.
Additional training will occur outside the area at approved training sites. It is well understood that the practice sessions and drills are an extremely important portion of this training.
The equipment coordinators will help insure that the proper equipment and materials are made available to the Team Members.
The Carter Creek Emergency Response Team is a voluntary organization made of Chevron Employees who work full time at the CCGP
The team will respond to any emergency or plant/field upset that they are called upon. Their response will not exceed the available resources and will not exceed their training levels.
The E.R.T. consists of two major branches:
1. The incident Command Staff.
2. Response Teams. (Rescue, First Aid, Fire Advisory and Hazmat Advisory).
All teams are required to inventory, control and replace all materials req
uired to meet the response they're trained to perform.
The E.R.T. is organizationally structured to respond to emergencies efficiently, safely and to meet corporate regulatory guidelines and regulations.