One of the Largest Oil Fields
Amal Oil Field, Libya, is one of the largest Oil Fields in the Northern African Country. Oil in this field was discovered in the year of 1958, and of all the 81 wells that have been drilled on the 100,000 acre field, 76 are reliable producers of oil (Roberts, 1968). The major source of oil in the field is the Amal Formation that lies about 10,000 feet below the surface.
The Process of Crude Oil Extraction
The process of Crude oil extraction at the Amal Field follows a set of procedures to ensure that high production levels are maintained. Leaving the construction of the wells, manifolds and tanks, the process of extraction will be discussed in current research.
The flow of oil from the producing wells at Amal field is made possible by pumps and injection procedures that improve the rates of flow, as well as maintain them at optimum. All the producer wells at Amal Field have a wellhead to help with the flow and injection of water or gas back into the wells.
From the bottom of the wells, crude oil is pumped to the surface by the help of a pump that is submerged to the bottom of the well. The Electronic Submerged Pump (ESP) is placed into the well and powered by a cable that runs down the well to the motor. The crude oil passes through the tubing, to the surface with the help of anti-gravitational pressure from the ESP system and valves. The ESP System is a reliable force for the oil wells that do not freely flow in Amal Field, Libya.
Speaking about the Oil manifolds, it is essential to mention that these Manifolds bring into one flow several pipes from different oil wells to the separators. They are made to ensure that the flow is not interrupted, even as they take the crude oil into a single flow to the separator tanks. Manifolds are connected to the wellhead that brings flow from the well to the surface. At the Amal Field Production, wellheads connect to the production manifolds, meaning that they carry Crude oil to the separator tanks.
The separator works by gravity letting the water settle at the bottom; gas bubbles out from the top; and the oil gets out through the middle pipe to go on with the rest of the process. Note that the three products are still important for the coming stages.
Moving to the wash tank, the water is separated from the oil and there is no gas allowed into the tank. A degasser is fitted at the entry of the tank only to allow water and oil into the vertical tank. The inlet inflow is from the top of the tank to the bottom with water getting out from the very bottom, while oil floating out from the top due to its lighter density. The wash tank consists of a fluid inlet, degasser, gas outlet, the flume, an oil outlet, spreader apron, bottom spreader and the water outlet from the top to the bottom respectively (Manning & Thompson, 1995).
After oil is let out of the Wash Tank, it is free from air; the water is collected in the Run Tank waiting for the next stage of heating.
The Heater Stage
At the heater stage, in Amal Libya, more impurities, including sand and free flowing water, are removed before the heating is done. Fire tubes are used to heat the flowing oil (Manning & Thompson, 1995).
From the heater, the crude oil passing through the desalting system that removes salt from it. The chlorides of calcium, magnesium and sodium are the most common salts in crude oil. Water is used to help settle and displace salts from the crude oil at the Gravity settler tank.
The Desalting Stage
From the desalting stage, crude is then pumped to a temporary storage facility; then transported via pipes to the lower lying and bigger storage facility at Ras Lanouf Terminal owned and operated by Harouge Company.
From the separators at the Amal Field, gas is processed and then reused for injection into the injection wells to improve the up flow of crude oil. Most of the gas, however, is transferred to the Ras Lanouf Terminal for export in the end.
Reason for Compression of Gas
Reason for compression of gas is to make it transportable via piping systems (Oil and Gas Production Handbook, p.16). When gas is released from the separator, it has a lower pressure than the natural gas, thus, the need for compression. The compression is at 1120 psi at the Amal Field.
The gas is then passed through a vertical scrubber that guides the incoming gas through Glycol. From the vertical scrubber, the gas flows up against a down flow by glycol. The latter absorbs all vapors from the gas letting out dry natural gas from the top of the tank (Oil and Gas Production Handbook, p. 48).
The gas is then injected into the wells to increase the upward flow of crude oil by maintaining pressure in the wells. Remaining gas is transported via pipelines to the low-lying Ras Lanouf Terminal.
It is unfortunate that the effluent water from the processes above is not treated before release into the tank as there is no treatment facility at the Amal Oil Field.
Water, Released into the Environment
Water, released into the environment, gets into natural water reserves and can easily harm the biotic community around or even far off the Oil Wells. With a huge number of 76 producer wells, there is a huge risk facing the environment as the water seeps into ground reservoirs and surface waterways.
It is also noted that there are two sour gas wells at stations 1 and 8, releasing harmful gases into the atmosphere. If nothing is done, the environmental effects and impacts of these gases are going to culminate into an environmental disaster.
- There should be effective water treatment facilities at the Amal Oil field to purify the water before release to the environment;
- For the gas wells at stations number 1 and 8, redirecting the gas to a purifying system would be ideal.