Flow Assurance in Pipes
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This report presents an analysis of three natural gas pipeline transmission scenarios through a distance of 342Km, from Escravos to Lagos, given conditions of 70barg Maximum Allowable Operating Pressure (MAOP) at Escravos terminal and a... more
This report presents an analysis of three natural gas pipeline transmission scenarios through a distance of 342Km, from Escravos to Lagos, given conditions of 70barg Maximum Allowable Operating Pressure (MAOP) at Escravos terminal and a minimum delivery pressure of 45barg at Lagos.
To begin, the maximum pipeline capacity at the given operating constraints was estimated from a simple model built with a single pipeline network, process stream properties and other necessary model input parameters. Afterwards, a technical analysis was carried out for the requirements and feasibility of expanding the gas network by an extra 300mmscfd and 600mmscfd with two expansion options: using compressor stations to provide the additional pressure that will be required for the expansion and using pipeline looping to reduce pressure drop along the original pipe such that the 70barg MAOP and 45barg delivery pressure were adhered to. Finally, an economic comparison was made between the two pipeline expansions options mentioned above.
Results showed that a maximum pipeline capacity of 625mmscfd will be required for the first task. Furthermore, the 300mmscf expansion will require one compressor station of 2818.94hp rating or a 243Km length of reinforcement while the 600mmscfd expansion will require two compressor stations of a total rating of 4523hp or a reinforcement pipe length of 335kKm for the use of compressor stations or pipeline looping respectively.
Economic analysis revealed that gas network capacity expansion was found to be significantly more expensive if pipe looping is used relative to the use of compressor stations as the overall cost, for both 300mmscfd and 600mscfd extra gas network expansion by looping exceeds the cost of using compressor stations by £187.62 million.
To begin, the maximum pipeline capacity at the given operating constraints was estimated from a simple model built with a single pipeline network, process stream properties and other necessary model input parameters. Afterwards, a technical analysis was carried out for the requirements and feasibility of expanding the gas network by an extra 300mmscfd and 600mmscfd with two expansion options: using compressor stations to provide the additional pressure that will be required for the expansion and using pipeline looping to reduce pressure drop along the original pipe such that the 70barg MAOP and 45barg delivery pressure were adhered to. Finally, an economic comparison was made between the two pipeline expansions options mentioned above.
Results showed that a maximum pipeline capacity of 625mmscfd will be required for the first task. Furthermore, the 300mmscf expansion will require one compressor station of 2818.94hp rating or a 243Km length of reinforcement while the 600mmscfd expansion will require two compressor stations of a total rating of 4523hp or a reinforcement pipe length of 335kKm for the use of compressor stations or pipeline looping respectively.
Economic analysis revealed that gas network capacity expansion was found to be significantly more expensive if pipe looping is used relative to the use of compressor stations as the overall cost, for both 300mmscfd and 600mscfd extra gas network expansion by looping exceeds the cost of using compressor stations by £187.62 million.
n this experimental study, the phase boundary behaviour of CO2 hydrate is reported in the presence of 1, 5, and 10 wt% of three aqueous ammonium based ionic liquids (AILs) solutions. The T-cycle technique is used to measure the hydrate... more
n this experimental study, the phase boundary behaviour of CO2 hydrate is reported in the presence of 1, 5, and 10 wt% of three aqueous ammonium based ionic liquids (AILs) solutions. The T-cycle technique is used to measure the hydrate equilibrium conditions of AILs + CO2 + H2O hydrate systems within the ranges of 274 – 283 K and 1.80 – 4.20 MPa. All studied AILs inhibited CO2 hydrate with the inhibition effect increasing with AILs concentration. The 10 wt%, TEAOH showed the highest inhibition effect with an average suppression temperature (∆Ŧ) of 1.7 K, followed by TMACl (∆Ŧ = 1.6 K) and then TPrAOH (∆Ŧ = 1.2 K). Furthermore, COSMO-RS analysis is performed to understand the molecular level inhibition mechanism of AILs. In addition, the enthalpies of hydrate dissociation for all studied systems are also determined. The calculated hydrate dissociation enthalpies revealed that all the studied AILs show insignificant participation in CO2 hydrate cage formation at all concentrations, hence, do not form semi-clathrate hydrates.
The heavy crude oil exhibits a non-Newtonian shear thinning behavior over the examined shear rate. The viscosity of the heavy crude oil decreases about 15.6% when the temperature increased from 30 to 60°C. Heavy crude oil was blended with... more
The heavy crude oil exhibits a non-Newtonian shear thinning behavior over the examined shear rate. The viscosity of the heavy crude oil decreases about 15.6% when the temperature increased from 30 to 60°C. Heavy crude oil was blended with the aqueous solution of surfactant and saline water in different volumetric proportions of NaCl, and Na2CO3 solution mixtures. The addition of 50% of the mixture to the heavy crude oil causes a strong reduction in the viscosity, about 67.5% at 60°C. The heavy crude oil fits the Power law model since it has the lowest average absolute percent error of 0.0291. The flow behavior index of the heavy crude oil reaches a value of 0.9305 at a temperature of 30°C and it increases to 0.9373 when the temperature raises 60°C, while the consistence coefficient decreases from 2.8811 to 2.3558.
Liquid-solid flows, in both heterogeneous and saltation regimes, are critical in the transport of suspended solid particles in pipelines prone to particles settling and accumulating on the bottom of the pipe, eventually blocking the flow... more
Liquid-solid flows, in both heterogeneous and saltation regimes, are critical in the transport of suspended solid particles in pipelines prone to particles settling and accumulating on the bottom of the pipe, eventually blocking the flow and risking flow assurance. Numerical simulation of a statistically developed and steady two-phase liquid-solid flow in a horizontal pipe is performed by solving Reynolds-Averaged Navier-Stokes (RANS) equations within an Eulerian-Eulerian framework to predict the complex interaction among particles and between particles and their transporting fluid and surrounding walls. Particles are treated as a secondary fluid phase with viscosity determined using the Granular Kinetic Theory (GKT), including its three potential contributions, i.e., frictional, collisional and kinetic interactions. A case study for a horizontal pipe flow with mono-disperse and bi-disperse liquid-particle mixtures, at different flow velocities and particle-bulk concentration, is presented. Particles concentration for statistically steady heterogeneous and saltation regimes without a fixed bed are presented. Governing equations for each phase are solved numerically using ANSYS-Fluent platform which is based on the finite volume method to integrate the equations about each control volume and turning the problem into a system of algebraic equations. A second-order spatial discretization is implemented across the model. Bulk concentrations of solid particles in water were considered in percentage of 10% and 20%. Solid particles of 0.125mm and 0.440mm in diameter were used in the study, while bulk velocities of 1m/s, 2m/s and 3m/s were prescribed.
The present study investigated the wax deposition tendencies of a light Malaysian crude oil (42.4° API), and the wax inhibiting potential of some surfactants and their blends with nanoparticles. With the knowledge that the majority of the... more
The present study investigated the wax deposition tendencies of a light Malaysian crude oil (42.4° API), and the wax inhibiting potential of some surfactants and their blends with nanoparticles. With the knowledge that the majority of the wax inhibition research revolved around polymeric wax inhibitors, which cause environmental issues, we highlighted the potential of surfactants and their blend with SiO 2 nanoparticles as wax deposition inhibitors. Different surfactants including oil-based, silane-based, Gemini and bio-surfactants were considered as primary surfactants. The primary surfactants and their respective blends at a concentration of 400 ppm were screened as wax inhibitor candidates using cold finger apparatus. The screening results showed a significant influence on the paraffin inhibition efficiency on wax deposition by using 400 ppm of silane-based surfactant, which decreased the wax deposition up to 53.9% as compared to that of the untreated crude oil. The inhibition efficiency among the silane-based surfactant (highest) and bio-surfactant (lowest) revealed an appreciable difference up to 36.5%. Furthermore, the wax from the treated sample was found to deposit in a thin gel-like form, which adhered inadequately to the surface of the cold finger. A further investigation by blending the 400 ppm silane-based surfactant with a 400 ppm SiO 2 nanoparticle suspension in a load ratio of 3:1 found that the wax inhibition decreased up to 81% as compared to the scenario when they were not added. However, we have shown that the synergy between the silane-based surfactant and the nanoparticles is influenced by the concentration and load ratio of surfactant and nanoparticles, residence time, differential temperature and rotation rate.
Liquid-solid two-phase flows are found in numerous operations in the chemical, petroleum, pharmaceutical and many other industries. In numerous cases, the mixture or slurry that flows is composed by a suspension of solid particles... more
Liquid-solid two-phase flows are found in numerous operations in the chemical, petroleum, pharmaceutical and many other industries. In numerous cases, the mixture or slurry that flows is composed by a suspension of solid particles (dispersed phase) transported by a liquid (continuum phase). However, the large number and range of variables encountered in slurry flows, in the case of pipelines, cause the flow behavior of these slurry systems to vary over a wide range of conditions, and consequently, different approaches have been used to describe the behavior of different flow regimes. Therefore, there are numerous studies of particular cases that cover limited ranges of conditions. In consequence, the experimental approach is necessarily limited by geometric and physical scale factors. For these reasons, Computational Fluid Dynamics, CFD, constitutes an ideal technique for predicting the general flow behavior of these systems. CFD models in this area can be divided in two different c...
In this experimental work, the phase boundaries of TMAOH + H2O + CH4 and TMAOH + H2O + CO2 hydrates are measured at different concentrations of aqueous TMAOH solution. The temperature-cycle (T-cycle) method is applied to measure the... more
In this experimental work, the phase boundaries of TMAOH + H2O + CH4 and TMAOH + H2O + CO2 hydrates are measured at different concentrations of aqueous TMAOH solution. The temperature-cycle (T-cycle) method is applied to measure the hydrate equilibrium temperature of TMAOH + H2O + CH4 and TMAOH + H2O + CO2 systems within the ranges of 3.5-8.0 MPa and 1.8-4.2 MPa, respectively. Results reveals that, TMAOH acts as a thermodynamic inhibitor for both gases. In the presence of 10 wt% of TMAOH, the inhibition effect appears to be very substantial for CO2 with an average suppression temperature (∆Ŧ) of 2.24 K. An ample inhibition influence is observed for CH4 hydrate at 10 wt% with ∆Ŧ of 1.52 K. The inhibition effect of TMAOH is observed to increase with increasing TMAOH concentration. Confirmed via COSMO-RS analysis, the TMAOH inhibition effect is due to its hydrogen bonding affinity for water molecules. Furthermore, the calculated hydrate dissociation enthalpies in both systems revealed that TMAOH does not participate in the hydrate crystalline structure.
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