Gas Processing Capability and Experience



WorleyParsons has designed and constructed over 400 gas processing plants throughout the world that correspond to a total
capacity of over 250 billion SCFD. Locations have ranged from deserts of the Middle East to the frozen wastelands of Prudhoe
Bay in Alaska. The sizes of installations have also varied considerably from small compressor stations to facilities processing over 3,000 MMSCFD of gas. The number of gas processing units of each type designed and built by WorleyParsons is shown below. The table at the end of this section highlights our gas processing experience.



Process Technology

 WorleyParsons has used the MEA, DEA, MDEA, activated MDEA, FLEXSORB, Sulfinol, Selexol, DGA, Purisol, Rectisol, ADIP and Merox processes and promoted hot carbonate acid gas removal/product sweetening processes. Hydrocarbon dewpoint/NGL extraction processes have included: ambient and refrigerated lean oil absorption, mechanical chilling using propane, ethane, ammonia, freon refrigerant and thermal expansion chilling which uses Joule-Thomson expansion valves and expansion turbines. Moisture dewpoint control processes
have used glycols, silica gel and molecular sieves. Processed gas reinjection has been performed for gas cycling, reservoir
pressure maintenance, gas lift, transmission peaking and storage.
 Unique problems of remote locations, hostile environments, extremely sour gas streams and very high injection pressures have all been addressed in WorleyParsons gas projects. A highly experienced cadre of process design engineers at WorleyParsons is custodian of these past process design activities.
 A WorleyParsons-developed computer process simulation package is one tool used by the process engineers to develop heat and material balances for gas processing plants. Other computer programs assist in pipeline sizing, pipeline network optimisation, heat exchanger rating and compressor selection.

North Sea / UK Gas Projects
  On both the East and West Coast of Britain, WorleyParsons London office has designed and managed the construction of the majority of the facilities processing gas produced from both the North Sea and the East Atlantic.
  The most recent of these projects is the Langeled Receiving Facilities, part of the Ormen Lange Project. On reaching the full product rate the Ormen Lange field will meet 20% of the UK’s gas demand. The scope of work included FEED and engineering, procurement and construction services of the Langeled Receiving Facilities in Easington, UK. The facilities were designed to handle 74 MSm3/d. The terminal performs filtration, flow/pressure/temperature control, quality monitoring and metering and is configured into four gas processing trains, each
sized for 25 MSm3/d of gas.
  Another major project carried out by WorleyParsons was the Amoco CATS terminal project at Seal Sands, Teesside. The CATS project scope included the design, procurement, construction and project management of hydrocarbon dewpoint control, mercury removal and gas sweetening units to process gas in two processing trains, each with a capacity of 600MMSCFD. One train operates with a Joule-Thompson (JT) valve and the other with a turbo-expander/generator. The residue gas from the processing trains is delivered to TRANSCO on behalf of the Armada, Erskine and ETAP field shippers.
  The contract for the first of WorleyParsons North Sea gas processing plants (the Phillips plant at Bacton, Norfolk) was awarded in 1968. Since then, WorleyParsons has been involved almost continuously in expansions and additions to the plant. The plant is designed to handle approximately 1.3 BSCFD of gas, of which approximately 50% is sour gas requiring sweetening before NGL extraction for dewpoint control.
  Contracts for a 835 MMSCFD plant for Conoco at Theddlethorpe, Lincolnshire and for a 500 MMSCFD expansion of the Amoco (U.K.) Bacton plant were awarded in 1970. A second contract for installation of an additional 500 MMSCFD dewpoint control train for Amoco's Bacton plant was awarded in 1972.
Gas Receiving and Treating Facilities Bacton, Norfolk, UK

In 1982 WorleyParsons completed a grass roots natural gas and gas liquids facility for Shell UK at St. Fergus Scotland, to treat approximately 1100 MMSCFD of raw natural gas with associated liquids. The facility also extracts and recovers natural gas liquids containing ethane and heavier products as well as producing pipeline quality natural gas. The facility comprised two identical and parallel process trains, each capable of half the total duty. WorleyParsons were responsible for the front end design and the detailed engineering, procurement, project management and construction management of the facilities.

Flags/Fulmar Projects at St. Fergus, Scotland

  The year 1985 saw the start of a new onshore terminal for BP Petroleum. Designed for an initial throughput of 500 MMSCFD, the facility was built at a green field site at Dimlington, approximately 1km from the existing West Sole gas processing plant at Easington (also extensively revamped by WorleyParsons).
  The terminal is designed for the reception, processing to contract specification and metering of the gas prior to delivery through an underground pipeline to the nearby British Gas Corporation facilities. In addition, the condensate produced is stabilised, metered and transferred via an underground pipeline to tie-in to the existing Easington to Salt End pipeline. The terminal was expanded to increase the gas processing capacity of the facility in 1987. This expansion increased the capacity of the terminal by 450 MMSCFD, principally for the treatment of gas from the Ravenspurn North Field.
  Pre-assembled process modules were used to improve constructability of the new plant and minimise disruption to the operation of the commissioned unit. In 1988, WorleyParsons was awarded the Mobil SAGE Onshore Gas Terminal Project. The project, released in two phases, has a total installed cost of approximately $600 million.
  The SAGE Onshore Gas Terminal Located at St. Fergus, Scotland, receives and conditions raw dense phase gas from the Beryl, Brae and Scott fields. The terminal exports sales gas to BGC and NGL to Shell and BP.

Mobil SAGE Gas Terminal  at St. Fergus, Scotland

  The project philosophy was for phased construction of the terminal. The product separation unit of the first train (Phase A) operated initially only on sweet Beryl gas at 500 MMSCFD although it is designed to process 575 MMSCFD or Beryl/Brae feed gas. The Phase B project modified the Phase A separation train, added a second identical separation train, added two gas treating trains and other facilities to allow the terminal to process 1150 MMSCFD of a range of sour feed gas mixes.
  Gas processing includes the removal of water, heavy hydrocarbons and acid gases to meet the sales gas specifications. Extracted hydrocarbons in the form of NGL are stabilised, treated and exported by separate pipelines as liquid by-products to Shell and BP. The project incorporated extensive use of pre-assembled units (PAUs) which significantly reduced skilled labor demands at the St. Fergus jobsite. Approximately 75 PAUs were utilised to complete the project.
  In May 1993 BHP Petroleum Limited awarded WorleyParsons a contract for the process design, engineering and procurement services for the Onshore Terminal located at Point of Ayr, in Clwyd, North Wales. The terminal was designed to treat approximately 300 MMSCFD of feed gas to remove sulphur compounds, condensates and moisture. The treated sales gas flows from the terminal via a 27 km, 24 inch pipeline to the power station at Connah's quay.
  The major process units, including vessel type slug catcher, acid gas treating, dew point control and sulphur recovery, are similar to the numerous facilities designed and built by WorleyParsons associated with the development of North Sea gas reserves. This facility, however, is unique in the UK in that it incorporates a tail gas unit on the sulphur recovery unit to further reduce sulphur emissions from the facility. This yields a total recovery of sulphur of 99.9+% and limits the gaseous emission from the facility to less than 250 ppmv of sulphur.
  The terminal design also incorporates a significant amount of civil landscape enhancement to help blend the facility into the surrounding countryside and comply with the conditions laid down by the Clwyd County Council in the Planning Consent.
  The majority of the United Kingdom onshore gas terminals processing gas from the North Sea have been designed by WorleyParsons (see map on following page). These plants have ranged in size from small compression stations to the large terminal at St. Fergus, processing gas from the Brent Field. WorleyParsons has also designed and built many gas processing facilities outside the United Kingdom with capacities over 3,000 MMSCFD.
  WorleyParsons has extensive experience in the design, procurement and construction of all the types of processing units and offsite facilities involved in a modern gas processing plant including:
 
• Inlet facilities
 
• Dehydration
 
Cryogenic extraction
  • Liquids treatment
 
• Associated utilities
 
• Gas sweetening and sulphur recovery
 
• NGL fractionation
 
•  NGL storage
 
• Sales gas compression
 
Gas gathering

  Compression of natural gas has been a feature of many of our projects. BP West Sole, Karanj Gas Injection, Phillips Bacton and Shell St. Fergus projects involved substantial compression facilities.
 
 
 

  Western Canada Projects
  From the mid-1950s to the mid-1970s, WorleyParsons designed and built a substantial percentage of the high-pressure sour gas processing plants in Alberta. They are still operating today. Overall, they represent over 2.25 BSCFD of gas processed, 100,000 BPSD of liquids recovered and 13,200 LTPD of sulphur produced. In July 1980, WorleyParsons gas processing technology section undertook the process design for the Gulf Canada Resources, Inc., natural gas and liquids processing plant located in the Hanlan/Robb area of Alberta. This facility processes 300 MMSCFD of natural gas and recovers 250 BPSD of NGL and 1,150 LTPD of sulphur.
  The map below shows WorleyParsons’ major Western Canadian projects.

 
Major Western Canadian Gas Processing and Sulphur Recovery Projects

Middle East Projects
WorleyParsons’ work in the Middle East began in 1965 with the award of an 86 MSCFD NGL and sulphur recovery project in Iraq.
Our company’s experience has included some of the region’s largest gas processing and sulphur recovery projects. These include some recent projects for such as:
 
• Uthmaniyah project for Saudi Aramco – 1,200 MMSCFD of gas, DGA and TEG treating and two 600 LTD sulphur recovery units
 
•  Hawiyah project for Saudi Aramco – grass roots facilities including 1,600 MMSCFD of gas, DGA, TEG and three 500 LTD sulphur units
 
Kuwait Oil projects – restoration and upgrade of gathering facilities for 100 MMSCFD and 170 MMSCFD
The map on the next page presents WorleyParsons’ major gas processing and sulphur recovery projects in the Middle East



Alaska Projects
WorleyParsons’ Alaskan work includes the 1986 completion of the central gas facility at Prudhoe Bay, three subsequent expansions
and the 1987 completion of the Endicott offshore production facilities. WorleyParsons Alaskan North Slope experience began with Increments 1, 2 and 3 of the oil/gas separation and gas reinjection facilities for the eastern half of the Prudhoe Bay field for ARCO-Exxon. This project lasted for five years (1973-1978)  and it pioneered the modular construction approach.
  The project involved:
 
• Process equipment module fabrication in the lower 48 states (some modules weighed as much as 3,000 tons).
 
• Seagoing barged transportation to Prudhoe Bay.
 
• Inland module movement to production and plant site locations using heavy-duty crawler transporters (up to 1,200-ton capacity).
 
Module installation on pile foundations.

Module Transport through the Panama Canal for ARCO Alaska Project

These facilities included three multi-train oil/gas separation and conditioning centers (flow stations), each designed to handle up to 360,000 BPSD of oil and 500 MSCFD of gas and a central reinjection gas compressor plant designed to compress 1.7 BSCFD of gas for reinjection. The central compressor plant featured twelve 22,500-hp gas turbine driven compressors that compressed the gas in two stages to 4500 psig.
  In 1978, WorleyParsons completed a comprehensive study and report, commissioned by Atlantic Richfield Company (study coordinator) and 17 other interested producing and gas transmission companies. We evaluated several potential processes for conditioning the Prudhoe Bay field gas to stringent pipeline quality specifications and prepared preliminary designs and cost estimates for the candidate processes. In all, WorleyParsons screened seven acid gas removal processes and examined three (Sulfinol, Selexol and Propylene Carbonate) in
detail. Simultaneously, WorleyParsons reviewed various hydrocarbon dewpoint control (NGL extraction) processes to determine the optimum process and processing conditions for the Prudhoe Bay field gas.
  In early 1979, WorleyParsons received authorisation from Atlantic Richfield Company (operator - eastern area) to continue work on the Prudhoe Bay Unit Development program in the eastern operating area. This program extended through 1985 and it included engineering, procurement, lower-48 states fabrication and North Slope facility installation required to maintain production rates in the eastern half of the Prudhoe Bay field. The scope of work included gas lift facilities, produced water handling and reinjection, central compressor plant expansion, addition of low-pressure oil/gas separation equipment at the three-flow stations (gas/oil/water separation plants) in the eastern area, drill site expansions, additions to the field fuel gas system, additions to the operating center and installation of additional large diameter flow lines from the expanded drill sites to the flow stations. As in the initial project phase, modular design was employed extensively to minimise the amount of installation labour required at Prudhoe Bay.
  In 1980, Northwest Alaskan Pipeline Company selected WorleyParsons to perform design and engineering services for a natural gas conditioning plant on the North Slope. The plant was designed to condition 2.7 BSCFD of raw gas. It was prepared for shipment to the lower-48 states via the Alaskan natural gas transportation system, a 4,800-mile pipeline constructed across Alaska, Canada and several northern states through the Midwest to the West Coast. In its final form, the project included three gas conditioning trains, each of which was, at the time, one of the largest single-train gas plants in the world.
  The Central Gas Facility (CGF) at Prudhoe Bay is the world's largest gas processing plant. Built for the consortium of 11 leaseholding
companies led by ARCO Alaska, Inc., ExxonMobil and Standard Oil, the CGF had an original design capacity of 3.3 BSCFD. Subsequent expansions have increased the capacity to 7.5 BSCFD. The Miscible Injectant Expansion (MIX) project, currently being completed by WorleyParsons, will further increase capacity to 8.1 BSCFD.
  WorleyParsons served as prime contractor for design, procurement and construction for the first phase of the CGF, which was completed in December 1986. Total elapsed time from initial conceptual studies to startup was less than 4 years. This was a significant achievement considering the magnitude of the project and the logistics of North Slope construction. Seventeen modules were fabricated in Tacoma, with certain specialised equipment also assembled at Korean and Japanese sites. The most complex facility ever completed and delivered in
a single sealift year, the CGF was the major portion of the 1986 sealift, which was the largest ever attempted since the start of modular transport in 1975.

Alaskan Central Gas Facilities (CGF) Project

Processing the total flow of gas from the Prudhoe Bay field, the CGF originally yielded more than 40,000 bpd of NGLs, to be blended with produced crude. The subsequent expansions to the facility have increased NGL recovery substantially. The second product is miscible injectant (MI), a blend of natural gas and NGL. MI is injected into selected zones of the sandstone reservoir, where it increases reservoir permeability and permits additional recovery of crude that otherwise would remain trapped in the sandstone. (CGFs MI capacity currently makes it the largest individual enhanced oil recovery facility.) Following NGL and MI extraction, the remaining lean gas is recycled into the reservoir both for storage and maintenance of the gas cap pressure.
  In mid-1983, Standard Oil selected WorleyParsons to perform design and engineering services for the development of the Endicott Field located in the shallow waters of the Beaufort Sea about 20 miles northeast of the Prudhoe Bay field. The WorleyParsons scope of services for this billion-dollar project included detailed design, procurement, construction management support, commissioning support and project management services.
The Endicott facilities are located about two miles offshore on two manmade gravel islands connected to the shore by a gravel causeway. Surface processing facilities were designed to: produce 100,000 bpd of crude oil product; reinject 200 MSCFD of produced gas; and recover NGL from the produced gas. The facilities also compressed 200 MSCFD of artificial lift gas, treated and reinjected 150,000 bpd of produced water, as well as heated and injected 140,000 bpd of seawater. Utility systems such as power generation, fuel gas, heating and cooling medium, instrument and process air, flare and chemical storage were also included. The latest techniques in modular construction were used in this project. The main processing facilities were built into five multistory super modules, ranging up to 5,000 tons with shipping dimensions of up to 195-feet long, 95-feet wide and 115-feet high. This was more than twice the size and weight of the Prudhoe Bay modules.

Endicott  Gravel Island Production Facilities

  In 1989, WorleyParsons was awarded the detail, procurement and construction services for British Petroleum's (BP) gas handling expansion project (GHX-1). In early 1991, ARCO Alaska, Inc. awarded WorleyParsons a solesource contract for engineering and support services for the second phase of the gas-handling expansion project (GHX-2). Total installed cost was $1.1 billion. This project increased the
production of crude oil and natural gas liquids by 100,000 bpd (or as much as 450 million barrels during the life of the field). The GHX-2 project installed facilities that increased the annual average total Prudhoe Bay field gas offtake capacity from 5.2 billion SCFD to 7.5 billion SCFD.

GHX-2 Module

WorleyParsons continuing role on the North Slope includes engineering activities to support further ongoing enhancements to the CGF including the aforementioned MIX project. In 1987 ARCO nominated WorleyParsons to assume a lead role on other North Slope projects, including follow-up work on the Lisburne and Kuparuk oil and gas processing facilities. At Kuparuk, WorleyParsons also designed and procured the equipment for an MI project. Tie-in of the new MI facility to existing Kuparuk equipment occurred in mid-1988.



Representative Natural Gas Processing Projects
(Click on the picture to zoom in and once again to reduce)