The oil and gas industry is essential for our everyday needs. This is why it’s important for the pipe flow to be in well working order. Read more below.
Pipe flow in the oil and gas industry is always a flow in a closed conduit. And the increase in the demand for energy makes researchers and scholars to seek after knowledge for many years to understand the complexity of flows in pipes and rings used in the oil and gas industry.
The industry is classified to three divisions; upstream, midstream and downstream sector. Fluid flow in pipes is more of importance in the upstream division, which covers the exploration and production of crude oil underground or underwater fields.
It is arguably true that the upstream sector of the oil and gas is risky and complex but if the piping, oil flow, and pressure are well fixed, there would be continuous growth of the other sectors of the industry – midstream and downstream.
Pipe flow for oil and gas is an aspect of fluid mechanics and hydraulics branch and it is confined within closed conduit. It does not exert direct atmospheric pressure, but exerts hydraulic pressure on the conduit.
How Does Fluid Flow in a Pipe?
There are essentially two ways in which fluid flows through a pipe. One of the approaches is to tilt the pipe so that the flow is downhill which converts gravitational kinetic energy into kinetic energy. The second method is to make the pressure higher at one end of the pipe than at the other. A difference in pressure is like a net force, which produces acceleration of the fluid in pipes.
As long as the fluid flow is steady, and the fluid is non-viscous and incompressible, the flow can be regarded in Bernoulli’s equation.
Any fluid, either gas or liquid, passes through a pipe wall. This pipe wall has a surface roughness, which is the finely spaced micro-irregularities on the surface texture. The amount of roughness of the pipe affects the drag of the fluid in the pipe. For a smooth pipe, there will be a higher velocity compared to a pipe of higher micro-irregularities.
To further understand how fluid flows in a pipe, it is necessary to fully understand the concept of friction and density effects. Fluids have different flow characteristics. The density of a fluid affects its velocity and this makes fluid with more mass per unit volume to be heavier and shear less easily. The temperature rise of a fluid in a pipe decreases the viscosity and density of such liquid.
If elbows, reducers, nipples, flanges and bends are not mentioned in the study of how fluid flows, then it is incomplete. When there is a forced change in the direction of how fluid flows, eddies are produced and this adds additional pressure loss in the pipe.
Oil and Gas Underwater Piping Challenges
There are lot of challenges affecting the upstream sector of the oil and gas industry. In traditional pipeline design, though this involves several factors, pipe flow is typically controlled by the need to withstand an internal pressure. When pressure in the pipe is low, it makes products to be slow, hence the shortage of supply to other streams of the sector. The higher the pressure of how products can be transferred down the line, the higher the rate of flow and the greater the potential for revenues. Critical factors for deep water pipelines, however, become dominated by the need to withstand external pressure, particularly during construction.
It is saddening that the waves and tides of the oceans also largely affect the underlying of oil and gas pipes. There are different types of pipes that could be buried underground. It can be categorized into segmented pipelines such as the jointed concrete cylinder pipelines, cast iron pipelines and the continuous pipelines such as steel pipelines with welded slip joints.
Another pressing challenge is tow-in pipeline installation. Just as it sounds, tow-in installation of oil and gas pipelines is the suspension of pipes in water with the use of buoyancy modules and with one or two tug boats, which precisely submerge the pipe in place.
In the following paragraphs, I will share a few potential solutions that would help in making the oil and gas sector become a better one.
Potential Solutions
If root of a problem is known, the answers to such a problem is not farfetched. This makes Det Norske Veritas (DNV), a free standing, autonomous and independent foundation whose purpose is to safeguard life, property and the environment says the acceptability of a pipeline design for a given water depth is determined by means of standard equations, that measure the relationship between wall thickness, pipe shape, and material compressive strength.
- Pipe shapes
The shape of pipes goes a long way in solving oil and gas pipeline problems. It is as well very important to note that a finished pipe shape is optimized by balancing the manufacturing parameters, pipe compression, and expansion.
The combination of crimp, U-press, and O-press ensures that the pipe size is controlled, often beyond most offshore specifications. Improved pipe roundness, wall thickness, and diameter tolerance removes uncertainty in the design and production stages and allows pipe wall thickness optimization.
- Compressive strength
The compressive strength is a function of many factors, which most times include mix design, curing process, cementitious material and manufacturing. Pipe manufactured by the UOE process – a method used for production of longitudinally welded large diameter pipes, undergoes various strain cycles, both tensile and compressive. The combination of tensile and compressive cycles affects the overall behavior of the material in compression.
Conclusion
With all these lingering problems, the rigorous study of fluid mechanics and dynamics, water waves and pipeline distribution should be widely encouraged among engineers. This is one of the methods to truly preserve the falling oil sector, which has been affecting the economy of many petroleum producing countries.
All these longing problems make the oil and gas sector to lag. There is call for scientists and researchers to put in the work in getting solutions. Even though there has been a headway in the sector, there could still be better ways.