James Denton-Brown, Manager of Industrial and Port Planning, Bechtel
Michel Thomet, Manager of Facilities Simulation, Bechtel
2014 World Congress PIANC, San Francisco, USA
Major new discoveries of natural gas in many parts of Africa are leading to the development of a greatly expanded industry—leading some to call Africa the new Middle East of hydrocarbon development. The recent discoveries in Mozambique and Tanzania are particularly significant and raise these countries into the top tier of potential exporters. At the same time, LNG processing and transport costs have rapidly declined, making it possible to sell the fuel at attractive prices to customers thousands of miles away in Europe, Asia and the Americas. As a result, many new and expanded ports are being developed to transport LNG to markets around the world. This paper will examine the state of LNG development in Africa with a focus on the new projects under way.
The share of natural gas in the world’s energy portfolio is increasing rapidly with the discovery and development of large new gas fields. Natural gas has become the favorite among fossil fuels because burning natural gas is cleaner than oil and emits half as much carbon dioxide as coal combustion. In 2012 gas reached 24 percent of the total world energy consumption and is well on its way to overtake coal at 30 percent and even oil at 33 percent in the coming decades.
The technology of LNG liquefaction has progressed rapidly and the cost of building LNG plants has come down significantly through the use of highly efficient engineering and construction. However, many of the largest gas fields are far from major consumption centers and must be moved great distances by ship. The cost of LNG transport has also come down significantly as large capacity tankers have been put into service, enabling a robust worldwide trade to develop.
Africa is emerging as a major supplier of natural gas as new gas discoveries emerge to reshape the world’s energy landscape. This region is rapidly establishing itself as a world-class natural gas producer led by Algeria, Nigeria, Angola, Egypt, and Equatorial Guinea. Recently two new countries have joined them as key players in this African gas renaissance: Mozambique and Tanzania. The newly discovered gas fields of these two countries have put them on par with the reserves of the largest gas suppliers in the world today.
Since 1996, Bechtel has teamed with ConocoPhillips in building LNG plants based on the ConocoPhillips Optimized Cascade® LNG Process, which is designed around a two-train-in-one reliability concept that has been successfully proven in more than four decades of plant operation. Bechtel and ConocoPhillips jointly operate a Product Development Center, which focuses on LNG process, engineering, procurement and construction enhancements.
The LNG product is then pumped into insulated storage tanks before being loaded on refrigerated tanker ships to be transported to LNG import terminals around the world. Gases that continually boil out of the LNG as it warms slightly in the storage tank are captured and returned to the process to be reliquefied. At the receiving terminals the LNG is transferred to storage tanks, regasified and shipped via pipeline to domestic users.
The basic features of this process include progressive cooling using propane, ethylene and methane sequentially. A significant advantage of this process is that, even when a compressor is off line, the plant continues operating at a reduced rate, resulting in very high plant availability to maximize LNG production.
Natural gas is first treated to remove contaminants including CO2, water and mercury before entering the liquefaction section of the plant. The treated gas is then chilled to approximately minus 256 degrees Fahrenheit (minus 160 degrees Celsius) in successively colder heat exchangers using propane, ethylene and methane as refrigerants. Product leaving the methane exchangers is LNG ready for storage.
LNG plants are typically built next to the shoreline on a site with plenty of reserve space for future expansion. The site is built up to protect the plant from high tide, storm surges and ocean rise due to global warming.
Because LNG plants are often in very isolated areas, they also have to be largely self-contained facilities. They start with a pioneer camp for construction start-up, followed by a fully equipped worker camp. Eventually, a community will be built for the operating personnel with a range of residential housing, health facilities, recreational facilities, dining and other amenities to enhance the quality of life.
If available, roads will provide a connection to other cities. Transportation may also be provided by an airfield and small terminal. Cargo ships will provide most of the heavy construction equipment, consumables and maintenance supplies. Air cargo may also be used for higher value and time-sensitive goods.
LNG plants typically also provide their own power supply using gas turbines that run off the feed gas supplying the site.
The LNG site will also have maintenance facilities for all but the most extensive overhauls. Warehouses will store all the needed parts, tools and supplies. Repair and maintenance facilities for the vehicles operated on site will be provided. Fuel farms and gas stations will be provided for local vehicles. Last but not least firefighting capabilities will be provided for the industrial as well as the community facilities. Strict standards of monitoring and control are implemented to minimize impacts to the environment.
Typical LNG plant and ship loading.
LNG is natural gas that has been cooled into liquid form at a temperature of minus 256 degrees Fahrenheit (minus 160 degrees Celsius). As a liquid it takes up to 600 times less volume, allowing great quantities of it to be transported in LNG tankers to re-gasification terminals around the world. A typical LNG plant is shown above; major elements include:
- Inlet gas feed from on-shore or off-shore sources supplied via a gas collection network
- Feed gas metering station and gas chromatograph
- Gas treatment to remove contaminants such as water, mercury and sulfur
- Liquefaction using the ConocoPhillips Optimized Cascade® LNG Process through sequential cooling
- Air fin coolers to remove excess heat from the compression process
- Transfer pump to shift LNG to storage
- LNG storage tanks maintained at minus 256 degrees Fahrenheit (minus 160 degrees Celcius)
- Boil off gas compressor to recover gases from tanks
- LNG tanker ship loading LNG facility process
LNG is a relatively light liquid (0.45 t/m3) and even the largest tankers do not have a draft deeper than about 43 feet (13 meters). However, depending on the local bathymetry, a transfer trestle will often have to extend several miles (several kilometers) into the open sea to reach waters of adequate depth. If the loading berths are in exposed waters, the berths will have to be protected with a breakwater.
The number of berths needed will be determined by the frequency of the ship calls and their sizes. The largest LNG tankers to date are the Q-Max ships that operate from Qatar.
The Mozah, one of the larget LNG tankers in operation today, has the following characteristics:
- Length overall: 1,132 feet (345 meters)
- Beam: 176.5 feet (53.8 meters)
- Draft: 39 feet (12 meters)
- Air draft: 114 feet (34.7 meters)
- Power: 21,770 kilowatts
- Capacity: 9.4 million cubic feet (266,000 cubic meters)
Today the LNG site will in general include a pioneer dock (if necessary), a multipurpose dock, a material offloading facility (MOF), a marine services facility (MSF), a multiproduct berth (if necessary), a dredged navigation channel, and a turning basin(s). Future expansion will require additional berths and backland.
The MOF is designed to support the unloading of aggregate, plant materials and equipment plus large plant modules from a range of Ro/Ro ships, self-fear heavy lift cargo ships, and barges during the construction phases of the project as required by contractors. Aggregates may also be received at the MOF for the construction of subsequent terminals.
The MSF is designed to accommodate some or all of the following: tractor tugs, pilot boats, security/patrol boats, line handling boats, oil skimmer boats, standard tugs and multi-cat vessels. A multi-level marine operations building (MOB) may also be provided with offices on the first floors and a marine control tower on the top level. The marine radar tower can be placed adjacent to the MOB. An emergency response warehouse, wash-down pad and sump will also be part of the MSF as well as a combination marine warehouse-machine shop for maintenance of the support craft.
African natural gas fields
As mentioned earlier, several major gas field discoveries have turned Africa into a potential new ―Middle-East for gas production. Even the old workhorse of African gas production, Algeria, has added two new LNG plants for exports at Arzew and Skikda which are producing more than 9 MTPA.
There is a recent LNG plant at Idku Egypt producing 3.6 MPTA since 2005 and at Damietta another LNG plant is scheduled to start producing 5 MTPA in 2015. Continuing to Equatorial Africa, the Soyo LNG plant in Angola, built by Bechtel, has recently started producing 5.2 MTPA. Further north, the Malabo plant, on Bioko Island in Equatorial Guinea has been producing since 2007 and has a capacity of 3.7 MTPA.
Nigeria, rich with an estimated 5300 bcm of gas and rising investments in gas production, is well on its way to becoming the world's second-largest liquefied natural gas supplier, after Qatar. One of the largest new additions is the LNG plant built by Bechtel on Brass Island which will have a capacity of 9.9 MTPA and start producing in 2015.
In East Africa very large offshore gas fields have been discovered near the common border of Tanzania and Mozambique. Based on initial estimates, international oil and gas companies have recently discovered 3400 to 4000 bcm of gas reserves in offshore Mozambique (a figure expected to grow to 6000 to 7000 bcm in the very near future) and around 630 bcm in offshore Tanzania. Given this huge bonanza, LNG projects are already rapidly advancing both in Mozambique and Tanzania, with a major target market in Asia.
Further information and relevant data for these gas developments are discussed below.
The new Egyptian LNG plant is located on approximately 408 acres (165 hectares) of land some 2 miles (3 kilometers) away from the town of Idku and 40 kilometers east of Alexandria on the Egyptian Mediterranean coast. The Idku LNG plant is the third grassroots ConocoPhillips Optimized Cascade project built by Bechtel and consists of two trains. Each train was built to produce 3.6 MTPA using GE Frame 5D gas turbines. EPC work for train 2 started in November 2005, and the first LNG was produced in November 2005, nine months ahead of schedule
The latest estimate of Tanzania's offshore gas reserves, by the international oil and gas companies active in the country, amounts to 630 bcm. According to the USGS there are still some 1990 bcm to be found (mean estimate) and USGS estimates this figure still at 1050 bcm with a 95 percent probability, though there might be some overlap with the very recent gas finds. Commercial frameworks to allow LNG exports have been agreed and the operators are evaluating options for such a development. However, it seems that more gas needs to be discovered to support a separate two-train onshore LNG development for both partnerships (BG-Ophir; Statoil-Exxon). Given that both partnerships do not currently have sufficient gas volume to justify individual projects, a joint LNG project could be an alternative development option.
With an estimated amount of 3400 to 4000 bcm of recently discovered natural gas reserves, Mozambique has become a major player of the African gas revolution. According to the USGS there are still some 5100 bcm to be found (mean estimate) and it estimates these additional reserves to be found at 2860 bcm with a high probability (95 percent) of occurrence and 8100 bcm with a low probability (5 percent). Considering this unprecedented opportunity, Mozambique's government is speeding-up the drafting of a master plan for the gas sector. The plan will cover the whole value chain, with the aim to maximize the economic and social benefits that the gas could bring to the country. Designed by the National Oil Institute, the plan will cover the various uses to which the gas can be put and it will also cover institutional reforms in the public and private sector, and the development of gas infrastructure. Since 2004 Mozambique has been exporting about 2 to3 bcm/yr of natural gas to South Africa through a 637-mile (865-kilometer) transport pipeline, which Sasol Petroleum International, the South African government, and the government of Mozambique own through a joint venture. The pipeline has a peak capacity of 5 bcm/y of natural gas and was part of a $1.2-billion natural gas project started in 2004.
The Angola LNG built by Bechtel, will gather, process, sell and deliver 5.2 million tons per year of LNG—plus natural gas, propane, butane and condensate - from its plant in Soyo, Angola, one of the world's most modern LNG processing facilities. The Angola design utilizes GE Frame 6 and Frame 7 compressor drivers in a unique way that delivers cost improvements while still maintaining the operating advantages of the two-trains-in-one reliability. It also utilizes an integrated solution for NGL and LPG recovery in a liquefaction facility reducing even further the capital cost. During its 30 years expected lifetime, an average of 70 ship calls per annum will be processed.
The plant's train 1 has a capacity of 3.7 MTPA. Several systems are in places such as feed gas metering, liquefaction, refrigeration, ethylene storage, boil off gas compression, product transfer to storage and LNG product metering. The EG LNG plant utilizes the ConocoPhillips Optimized Cascade LNG Process and was built by Bechtel. It delivered its first LNG cargo in 2007. In August 2006 a frontend engineering and design (FEED) contract was awarded to Bechtel for the second LNG train. The scope of the FEED work for the potential 4.4 MTPA. Train 2 LNG project includes feed gas metering, liquefaction, refrigeration, ethylene storage, boil-off gas compression, product transfer to storage and LNG product metering.
Brass Island, Nigeria
The Brass LNG project located in Brass Island, Bayelsa State, Nigeria, is designed to produce 10 MTPA. The Nigerian National Petroleum Corporation (NNPC) holds 49 per cent equity in the project, while United States-owned oil company, ConocoPhillips, along with French oil giant, Total, and Italian company ENI hold 17 per cent stakes each in the Brass LNG Ltd. The project is waiting on investment issues to be resolved and the government to issue a Final Investment Decision (FID). An important hurdle facing the Brass LNG project is the resolution of issues surrounding availability of associated gas derived from crude oil operations to provide an assured supply for the plant.
As large new LNG development occurs in remote parts of Africa, major new infrastructure in processing and port facilities must be built to take advantage of the opportunities. Governments, in partnership with international oil and gas companies, will have to work together to achieve an equitable distribution of costs and benefits. Despite these challenges, the future is bright for African LNG as a growing part of the world’s energy picture. Gas, as a more environmentally friendly fuel compared to oil and coal, will play an important role in the reduction of greenhouse gases and emissions while simultaneously leading to economic and social development in the producing countries. The new Middle East in Africa is well on its way to achieving its potential as a major energy provider.