Volume 9, Issue 4, April – 2024 International Journal of Innovative Science and Research Technology

ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/IJISRT24APR1423

Chemical Approach to Control Hydrate in Offshore

Gas Production Facilities
Kate Odafe Idolor1 Oluwaseun Francis Owolabi2
1
Madonna University, Nigeria Gateway ICT Polytechnic, Saapade, Nigeria
2

Abstract:- Hydrate formation presents a significant of offshore platforms. The economic ramifications are
operational challenge in offshore oil and gas production, equally severe, with potential losses amounting to millions
primarily due to the potential formation of hydrate plugs of dollars per day due to interrupted production [5].
which obstruct fluid flow, thereby posing serious flow Moreover, traditional methods to manage hydrate formation,
assurance risks. Additionally, these solid, crystalline, ice- such as thermal and mechanical removal, are not only costly
like structures, composed of low molecular weight gases but also pose significant safety risks and environmental
(such as methane, ethane, and propane) encapsulated in concerns [6-8].
hydrogen-bonded water cages, can aggregate into larger
masses capable of damaging or rupturing pipelines. Such Recent advancements in simulation technologies, such
formations typically occur under the high-pressure and as the Prosper software, have revolutionized hydrate
low-temperature conditions prevalent in subsea flowlines management by enabling precise predictions of hydrate
and cold-weather operations. This study employs the formation conditions and optimizing the use of chemical
Prosper simulation software to model these complex inhibitors like Methanol, Monoethylene Glycol (MEG), and
thermodynamic and hydrodynamic conditions and to Triethylene Glycol (TEG) [9-12]. These inhibitors
predict the effective dosages of chemical inhibitors effectively shift the hydrate equilibrium, thus safeguarding
required to prevent hydrate formation. Specifically, our operational conditions from falling within the hydrate
simulations suggest optimal dosages of 35% wt. formation envelope.
methanol (MeOH) and 45% wt. monoethylene glycol
(MEG) for gas stream 1, and 22% wt. MeOH and 33%  Significance of the Study
wt. MEG for gas stream 2. Based on these findings, we This study's significance is anchored in its potential to
advocate the use of Prosper simulation software as a enhance the safety, efficiency, and economic viability of gas
predictive tool for the strategic administration of production operations, particularly in offshore settings. By
hydrate inhibitors in offshore gas production facilities. integrating advanced simulation tools with empirical
This research contributes to the ongoing development of research, this work aims to develop robust chemical
chemical strategies for hydrate management, providing a methodologies for hydrate control, thus minimizing the
basis for improved safety and efficiency in hydrocarbon operational disruptions and hazards associated with hydrate
extraction processes. formations.

Keywords:- Gas Hydrates, Pipeline Corrosion, Hydrate The utilization of chemical inhibitors based on
Management, PVT Analysis, Flow Assurance. simulation-guided strategies represents a critical
advancement in the field. This approach not only helps in
I. INTRODUCTION preempting the formation of hydrates but also contributes to
the broader industry goal of maintaining uninterrupted flow
The formation and management of gas hydrates in the assurance. Flow assurance is crucial in ensuring that
natural gas industry present formidable challenges, traceable hydrocarbons are transported efficiently from the reservoir
to the pioneering work of Hammerschmidt in 1934 [1]. to the point of sale without blockages, thereby optimizing
These hydrate compounds, primarily consisting of gases like production and minimizing downtime.
methane, ethane, propane, isobutene, and carbon dioxide
trapped within a crystalline water structure, manifest under Furthermore, this research aligns with environmental
specific conditions of high pressure and low temperature sustainability goals by reducing the frequency and intensity
commonly encountered in subsea gas pipelines and of interventions required to manage hydrate formations,
processing facilities. Unlike ice, these hydrates have a lower such as the use of pigs or the application of heat. Each of
density and form at temperatures significantly above the these traditional methods carries a carbon footprint and
freezing point of water, behaving as a solid solution where potential ecological impacts, which can be mitigated
gas acts as the solute within a solvent cage of water through the proactive chemical management of hydrates.
molecules without chemical bonding [2-4]
The outcomes of this study are expected to offer dual
The operational challenges imposed by hydrates are benefits: enhancing operational efficiency and reducing
multifold, ranging from the formation of plugs that obstruct environmental impacts in offshore gas production. The
pipeline flow to structural damages threatening the integrity strategies developed herein could serve as a benchmark for

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Volume 9, Issue 4, April – 2024 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/IJISRT24APR1423

the industry, promoting safer and more sustainable practices Full Composition: Yes
across global operations. Allow Lumping: No
Reference Temperature: 60°F
Reference Pressure: 0 psig
Phase detection Method: Advanced
Path to surface – Separator Use Separator Train
Calculation Method:
First stage: 200 psig and 80°F
Second stage: 0 psig and 60°F
Target GOR method: Use Separator fluids

 PVT Data Input

For the simulation, PVT (Pressure, Volume,
Temperature) data is a critical component in assessing the
physical properties and behavior of the gas streams under
Fig 1 Effects of Hydrate Plug on Subsea Pipelines. A. Large various operational conditions. In this study, the PVT data
Gas Hydrate Plug Formed in a Subsea Hydrocarbon Pipeline was entered into the Prosper simulation software by
[1]. B. Corrosion in Subsea Pipelines [2]. accessing a predefined sample directory (Figure 2). This
directory provided baseline data which was then tailored
II. METHODOLOGY according to the specific characteristics of the gas streams
being analyzed, such as whether the gas was predominantly
 Collection of Well Data wet or dry. Adjustments to the PVT data included
The study requires precise well data to manage hydrate modifications based on the gas composition, as well as
formation effectively in offshore gas production facilities, variations in temperature, pressure, and the boiling point
using data from two distinct sources for different gas differential. These changes are essential to accurately model
streams. Data for Gas Stream 1 were sourced from Shell the gas stream's behavior in the pipeline and predict hydrate
Nigeria Limited at the Obigbo gas plants. This data set formation conditions effectively. By fine-tuning the PVT
included operational temperatures, pipeline pressures, and settings to reflect the actual conditions of the gas streams,
the mole percentage composition of the gas. These the simulation can provide more precise and reliable
parameters are critical for assessing the risk of hydrate outputs.
formation and are used to model accurate predictions with
Prosper simulation software [13-15]. For Gas Stream 2, data
were obtained from Nalco Energy Services, encompassing
similar operational parameters such as temperature,
pressure, and detailed gas composition. This information is
crucial for predicting potential hydrate formation under
varying conditions [4].

 Software for Hydrate Simulation

To predict the hydrate forming temperature and
pressure of a gas stream, the Prosper Simulation software
was utilized [16]. The process begins with launching
Prosper from the options menu, which allows for the
selection and setup of the fluid description type. The method
involves configuring the software to accurately represent the
fluid dynamics and chemical properties of the gas stream
being analyzed. This setup is crucial for ensuring that the
simulations reflect real-world conditions and provide
reliable data on hydrate formation risks under various
operational scenarios.

Table 1 Fluid Description Asset-up and iPROSPER

Software Equation of State Model
Fluid description – Type: Retrograde Condensate
Fluid description – Method: Equation Of State
Hydrates: Enable Warning
Calculation type – Model: Enthalpy Balance
EOS Model: Peng Robinson
Optimization Mode: Medium Fig 2 PVT Data of Dry Gas Stream Compisition 1 used in
Optimize Repeat Calculation: Yes Prosper Software

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Volume 9, Issue 4, April – 2024 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/IJISRT24APR1423

III. RESULTS AND DISCUSSION

 Impact of Inhibitor Concentration on Hydrate Formation

Conditions
We generated series of hydrate equilibrium curves,
delineating the predicted hydrate formation temperatures
and pressures for varying concentrations of chemical
inhibitors—specifically methanol and glycol—in Gas
Stream 1. These concentrations ranged from 0% (indicating
no inhibition) to increments of 10%, culminating at 45%.
The resulting data were visually represented across multiple
figures (Figures 4 and Figure 5), illustrating the
progressive shifts in hydrate formation conditions as the
concentration of inhibitors increased.

A detailed analysis focused particularly on the

conditions with 35% and 45% inhibitor concentrations.
These scenarios were graphically superimposed onto the
curve representing 0% inhibition (as displayed in Figure 4),
to highlight the significant shift in the hydrate formation
region. The comparative visualization clearly demonstrated
that the presence of chemical inhibitors effectively alters the
thermodynamic landscape of hydrate formation.
Specifically, with increasing concentrations of methanol and
glycol, the hydrate formation region is displaced to lower
Fig 3 PVT Data of Dry Gas Stream Compisition 2 used in temperatures and higher pressures, thereby reducing the risk
Prosper Software of hydrate formation under typical operational conditions.
This shift is indicative of the inhibitors' efficacy in
 Hydrate Curve Generation and Analysis modifying the gas stream's thermodynamic environment,
In the PVT analysis phase within Prosper, a hydrate making it less conducive to hydrate formation. The results
curve was generated to visually represent the potential for underscore the importance of selecting appropriate inhibitor
hydrate formation under various conditions. This curve was dosages to optimize flow assurance while mitigating the
then stored within the Prosper file for further reference and risks associated with hydrate blockages in pipeline systems
analysis. During the simulation process, Prosper actively as also pointed out by Bavoh et al [14].
monitored the operating conditions—specifically pressure
and temperature—to determine if they fell within the
hydrate formation danger zone. The temperature range
employed for the analysis spanned from 33°F to 80°F, with
the simulation adjusting the temperature at each of the 10
incremental steps. This methodical variation allowed for a
detailed examination of how temperature fluctuations
influence hydrate stability within the specified range. The
resulting hydrate curve is visualized in the output, providing
a clear graphical representation of the conditions under
which hydrates are likely to form. This visual tool is crucial
for identifying critical thresholds and planning appropriate
operational strategies to avoid hydrate-related
complications.

 Validation with Historical Data

We validated the simulation model against historical
data is crucial for ensuring its accuracy and reliability. This
step involves comparing the hydrate formation predictions
made by the Prosper simulation with actual instances of
hydrate occurrence documented during past operations. By
doing so, discrepancies can be identified and the model can
be calibrated to better reflect real-world conditions. This Fig 4 Hydrate Equilibrium Curves Delineating the Predicted
validation process enhances the confidence in the simulation Hydrate Formation Temperatures and Pressures for Varying
outputs, making them more actionable for operational Concentrations of Methyl Ethly Glycol (MEG) Chemical
planning and risk management. Inhibitor for Gas Stream 1

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Volume 9, Issue 4, April – 2024 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/IJISRT24APR1423

 Hydrate Management Through Inhibitor Modeling in

Prosper Software.
The Prosper simulation software was employed to
assess hydrate formation under specific operational
conditions for gas stream 1, defined by a pressure of 1500
psi and a temperature of 40°F. At this high pressure, the
hydrate equilibrium temperature without inhibitors was
predicted to be 70°F, placing the system within the hydrate
formation region. Initial modeling efforts using varying
concentrations of inhibitors—10% to 30% of methanol and
10% to 45% of MEG (monoethylene glycol)—were
conducted. However, these concentrations proved
insufficient, as indicated by the results displayed in Figure 5
for methanol and Figures 4for MEG, which showed that the
system remained within the hydrate-prone conditions.

To safely operate outside the hydrate formation region,

higher concentrations of inhibitors were needed. Injecting
35% wt. of methanol shifted the hydrate curve significantly
to the left (Figure 5), aligning the operating conditions to
the right of the hydrate equilibrium curve, thus moving out
of the hydrate forming region. The new hydrate equilibrium
temperature at 1500 psi was adjusted to 37°F, comfortably Fig 6 Hydrate Equilibrium Curves with and without
below the operating temperature. Similarly, injecting 45% Chemical Inhibitors for Gas Stream 1
wt. of MEG shifted the hydrate equilibrium to a new low of
40°F, ensuring operational safety. The same simulation strategy was applied to gas
stream 2 under identical operating conditions of 1500 psi
and 40°F, which also initially placed the system within the
hydrate formation region. Modeling with lower inhibitor
concentrations of 0%, 10%, and 30% methanol and 10% and
20% MEG (Figure 7) did not achieve the desired shift in
hydrate formation conditions. Ultimately, a 30%
concentration of MEG and 30% methanol (Figure 7) were
required to effectively move the hydrate formation
conditions outside of the critical region.

Fig 5 Hydrate Equilibrium Curves Delineating the Predicted

Hydrate Formation Temperatures and Pressures for Varying
Concentrations of Methanol Chemical Inhibitor for
Gas Stream 1

Fig 7 Hydrate Equilibrium Curves Delineating the Predicted

Hydrate Formation Temperatures and Pressures for Varying
Concentrations of MEG (Upper Panel) and Methanol
Chemical (Lower Panel) Inhibitor for Gas Stream 2

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Volume 9, Issue 4, April – 2024 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/IJISRT24APR1423

This enhanced modeling approach demonstrates the wonderful contribution to the success of this research. We
importance of accurately determining and applying also wish to thank the staff and management of Shell
sufficient inhibitor concentrations to ensure that the Nigeria Limited and Nalco service Company for their
operational conditions in gas pipelines are maintained safely wonderful contribution towards the success of this research.
outside the hydrate formation thresholds. Our appreciation goes to Eng. Mrs. Ahamefule for the
critical analysis and constructive criticism.
IV. CONCLUSION
REFERENCES
This study has thoroughly evaluated the efficacy of
different hydrate inhibitors in offshore gas processing [1]. Hammerschmidt, E. G. Formation of Gas Hydrates in
facilities using Prosper simulation software. Monoethylene Natural Gas Transmission Lines. Ind. Eng. Chem.
glycol (MEG) emerged as the most effective inhibitor when 1934, 26(8), 851−855.
compared to methanol and NaCl, owing to several [2]. Nashed, O.; Sabil, K. M.; Lal, B.; Ismail, L.; Jaafar,
significant advantages. Firstly, MEG can be regenerated and A. J. Study of 1-(2-Hydroxyethyle)3-
reused, which contrasts sharply with methanol that lacks this Methylimidazolium Halide as Thermodynamic
capability. This feature of MEG not only aligns with Inhibitors. Appl. Mech. Mater. 2014, 625, 337−340.
sustainable practices but also renders it economically [3]. Pavlenko, A. M.; Koshlak, H. Intensification of Gas
advantageous despite its higher initial cost. Furthermore, Hydrate Formation Processes by Renewal of
MEG poses lower health, safety, and environmental risks, Interfacial Area between Phases. Energies 2021, 14,
making it the preferred choice in the Exploration and 5912.
Production (E&P) industry where safety is paramount. [4]. Chen, J.; Zeng, Y.; Liu, C.; Kang, M.; Chen, G.;
Deng, B.; Zeng, F. Methane Hydrate Dissociation
The analysis determined that the optimal dosages of from Anti-Agglomerants Containing Oil Dominated
inhibitors for effective hydrate control are 35% methanol Dispersed Systems. Fuel 2021, 294, 120561.
and 45% MEG for Gas Stream 1, and for Gas Stream 2, the [5]. Ul Haq, I.; Qasim, A.; Lal, B.; Zaini, D. B.; Foo, K.
dosages are 30% methanol and 30% MEG. These findings S.; Mubashir, M.; Khoo, K. S.; Vo, D. V. N.; Leroy,
underscore the necessity of selecting appropriate inhibitor E.; Show, P. L. Ionic Liquids for the Inhibition of Gas
concentrations to balance efficacy and economic Hydrates. A Review. Environ. Chem. Lett. 2022, 20,
considerations in hydrate management. 2165.
[6]. Song, G.; Li, Y.; Wang, W.; Jiang, K.; Shi, Z.; Yao, S.
RECOMMENDATIONS Hydrate Formation in Oil-Water Systems:
Investigations of the Influences of Water Cut and
Our study recommends the implementation of Gas Anti-Agglomerant. Chin. J. Chem. Eng. 2020, 28(2),
Sweetening Processes. In facilities where acid gases like 369−377.
H2S and CO2 are present, gas sweetening processes should [7]. Robinson, D. B.; Ng, H. J. Hydrate Formation and
be implemented. These gases contribute to the potential for Inhibition in Gas or Gas Condensate Streams. J. Can.
hydrate formation; therefore, removing them from the gas Pet. Technol. 1986, 25(4), 26−30.
stream significantly reduces this risk. Our study also [8]. Johal, K. S. Flow Assurance Technology Options For
emphasizes continuous monitoring of production parameters Deepwater & Long Distance Oil & Gas Transport.
is crucial. Real-time data acquisition and analysis can help Offshore Mediterranean Conference and Exhibition,
in predicting and preventing conditions conducive to hydrate March 28, 2007; p OMC-2007-071.
formation, thus ensuring uninterrupted gas flow and [9]. Bavoh, C. B.; Lal, B.; Osei, H.; Sabil, K. M.;
operational efficiency. Mukhtar, H. A Review on the Role of Amino Acids in
Gas Hydrate Inhibition, CO2 Capture and
To further mitigate the risk of hydrate formation, Sequestration, and Natural Gas Storage. J. Nat. Gas
dehydration of natural gas is recommended. Removing Sci. Eng. 2019, 64, 52.
moisture from the gas stream effectively lowers the [10]. Lv, Y. N.; Jia, M. L.; Chen, J.; Sun, C. Y.; Gong, J.;
probability of hydrate formation, enhancing the reliability of Chen, G. J.; Liu, B.; Ren, N.; Guo, S. Di; Li, Q. P.
pipeline operations. While kinetic inhibitors and anti- Self-Preservation Effect for Hydrate Dissociation in
agglomerates offer potential benefits in managing hydrates, Water+ Diesel Oil Dispersion Systems. Energy Fuels
their limitations must be thoroughly evaluated to ensure they 2015, 29(9), 5563−5572.
are feasible for production scenarios. This includes [11]. Koh, C. A.; Sloan, E. D.; Sum, A. K.; Wu, D. T.
considerations of cost, environmental impact, and their Fundamentals and Applications of Gas Hydrates.
integration into existing treatment systems. Annu. Rev. Chem. Biomol. Eng. 2011, 2, 237−257.
[12]. Zerpa, L. E.; Aman, Z. M.; Joshi, S.; Rao, I.; Sloan,
ACKNOWLEDGMENT E. D.; Koh, C.; Sum, A. Predicting Hydrate
Blockages in Oil, Gas and Water-Dominated
The Authors acknowledge the staff and management of Systems. Paper presented at the Offshore Technology
Federal University of petroleum resources, Effurun, Warri Conference; Houston, Texas, USA, April 2012.
and also to the staff and management of Federal University DOI:10.4043/23490-MS.
of Science and technology Owerri, Imo state for their

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Volume 9, Issue 4, April – 2024 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/IJISRT24APR1423

[13]. Farhang, F.; Nguyen, A. V.; Hampton, M. A.

Influence of Sodium Halides on the Kinetics of CO2
Hydrate Formation. Energy Fuels 2014, 28(2),
1220−1229.
[14]. Bavoh, C. B.; Lal, B.; Osei, H.; Sabil, K. M.;
Mukhtar, H. A Review on the Role of Amino Acids in
Gas Hydrate Inhibition, CO2 Capture and
Sequestration, and Natural Gas Storage. J. Nat. Gas
Sci. Eng. 2019, 64, 52−71.
[15]. Wang, Y.; Fan, S.; Lang, X. Reviews of Gas Hydrate
Inhibitors in Gas-Dominant Pipelines and
Application of Kinetic Hydrate Inhibitors in China.
Chin. J. Chem. Eng. 2019, 27(9), 2118−2132.

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