Optimization Strategies of Production Parameters to Prevent Hydrate Reformation in Marine Gas Hydrate Production System

2021 ◽  
Author(s):  
Zheng Liu ◽  
Baojiang Sun ◽  
Zhiyuan Wang ◽  
Jianbo Zhang

Abstract In recent decades, the development of natural gas hydrates has become a research hotspot of scholars all over the world. However, the decomposed gas and water in marine gas hydrate production system may regenerate gas hydrates due to the low-temperature and high-pressure environment in seafloor. In this study, a transient temperature and pressure calculating model was established to predict the risk of hydrate reformation in production pipelines during offshore natural gas hydrate development. Using the proposed model, the region of hydrate reformation in gas hydrate production wells were predicted quantitatively. Meanwhile, the hydrate reformation management strategies through optimization of production design parameters in combination with hydrate inhibitor injection were proposed and discussed in detail. The results indicate that the risk of hydrate reformation is the highest in the drainage pipeline (DP); however, the flow in gas-water mixed transportation and gas production pipelines (MTP and GPP) basically does not satisfy the hydrate formation condition. In the process of production well design, adding additional the EH and ESP can fully eliminate the hydrate reformation risk in the DP without using the hydrate inhibitor.

2016 ◽  
Vol 50 (6) ◽  
pp. 58-68 ◽  
Author(s):  
Narayanaswamy Vedachalam ◽  
Sethuraman Ramesh ◽  
Arunachalam Umapathy ◽  
Gidugu Ananda Ramadass

AbstractNatural gas hydrates are considered to be a strategic unconventional hydrocarbon resource in the Indian energy sector, and thermal stimulation is considered as one of the methods for producing methane from gas hydrate-bearing sediments. This paper discusses the importance of this abundantly available blue economic resource and analyzes the efficiency of methane gas production by circulating hot water in a horizontal well in the fine-grained, clay-rich natural gas hydrate reservoir in the Krishna-Godavari basin of India. Analysis is done using the electrothermal finite element analysis software MagNet-ThermNet and gas hydrate reservoir modeling software TOUGH+HYDRATE with reservoir petrophysical properties as inputs. Energy balance studies indicate that, in the 90% hydrate-saturated reservoir, the theoretical energy conversion ratio is 1:4.9, and for saturations below 20%, the ratio is <1. It is identified that a water flow of 0.2 m3/h at 270°C is required for every 1 m2 of wellhead surface area to dissociate gas hydrates up to a distance of 2.6 m from the well bore within 36 h.


2008 ◽  
Vol 130 (3) ◽  
Author(s):  
M. Uddin ◽  
D. Coombe ◽  
D. Law ◽  
B. Gunter

Numerical modeling of gas hydrates can provide an integrated understanding of the various process mechanisms controlling methane (CH4) production from hydrates and carbon dioxide (CO2) sequestration as a gas hydrate in geologic reservoirs. This work describes a new unified kinetic model which, when coupled with a compositional thermal reservoir simulator, can simulate the dynamics of CH4 and CO2 hydrate formation and decomposition in a geological formation. The kinetic model contains two mass transfer equations: one equation converts gas and water into hydrate and the other equation decomposes hydrate into gas and water. The model structure and parameters were investigated in comparison with a previously published model. The proposed kinetic model was evaluated in two case studies. Case 1 considers a single well within a natural hydrate reservoir for studying the kinetics of CH4 and CO2 hydrate decomposition and formation. A close agreement was achieved between the present numerical simulations and results reported by Hong and Pooladi-Darvish (2003, “A Numerical Study on Gas Production From Formations Containing Gas Hydrates,” Petroleum Society’s Canadian International Petroleum Conference, Calgary, AB, Jun. 10–12, Paper No. 2003-060). Case 2 considers multiple wells within a natural hydrate reservoir for studying the unified kinetic model to demonstrate the feasibility of CO2 sequestration in a natural hydrate reservoir with potential enhancement of CH4 recovery. The model will be applied in future field-scale simulations to predict the dynamics of gas hydrate formation and decomposition processes in actual geological reservoirs.


Gas hydrates are solid crystalline structures in which water molecules trap small guest gas molecules and encage them through hydrogen bonding. Gas hydrates are known to be problematic in flow assurance applications as they can form plug inside the pipelines during oil and gas production, transportation and processing. In order to inhibit hydrate formation thermodynamically, various chemicals including some alcohols e.g. methanol (MeOH), mono- ethylene glycol (MEG) are used as thermodynamic hydrate inhibitors (THIs). In this paper, a simulation study is performed using PVTsim software wherein it predicts the hydrate formation for pure CO2 solution mixture and CO2 -MEG solution mixture systems using different equation of states. These equations of states include Soave-Redlich-Kwong (SRK), SRK-Peneloux, Peng- Robinson (PR) and Peng-Robinson Peneloux. The simulation results obtained using these equation of states were validated with the experimental data and PRPenelouxEoS was found to be in better agreement. The hydrate formation regions are determined in between the pressure range of 10 to 110 bara for natural gas mixture containing high percentage of CO2 in it. The inhibitors are used in 5, 10 and 20 wt% concentrations. The hydrate inhibition efficiency increased with the increase in concentration. Simulation results showed that methanol performed better in comparison to the other inhibitors at all concentrations.


2021 ◽  
Vol 12 (1) ◽  
pp. 312
Author(s):  
Dávid Hečko ◽  
Milan Malcho ◽  
Pavol Mičko ◽  
Nikola Čajová Kantová ◽  
Zuzana Kolková ◽  
...  

For countries with limited access to conventional hydrocarbon gases, methane hydrates have emerged as a potential energy source. In view of the European Union’s requirements to reduce the energy intensity of technological processes and increase energy security, it appears promising to accumulate natural gas and biomethane in the form of hydrate structures and release them if necessary. Storing gas in this form in an energy-efficient manner creates interest in developing and innovating technologies in this area. Hydrates that form in gas pipelines are generated by a more or less random process and are an undesirable phenomenon in gas transportation. In our case, the process implemented in the proposed experimental device is a controlled process, which can generate hydrates in orders of magnitude shorter times compared to the classical methods of generating natural gas hydrates in autoclaves by saturating water only. The recirculation of gas-saturated water has been shown to be the most significant factor in reducing the energy consumption of natural gas hydrate generation. Not only is the energy intensity of generation reduced, but also its generation time. In this paper, a circuit diagram for an experimental device for natural gas hydrate generation is shown with complete description, principle of operation, and measurement methodology. The natural gas hydrate formation process is analyzed using a mathematical model that correlates well with the measured hydrate formation times. Hydrates may become a current challenge in the future and, once verified, may find applications in various fields of technology or industry.


2012 ◽  
Vol 462 ◽  
pp. 221-224 ◽  
Author(s):  
Xian Guo Yang ◽  
Ming Ju Qin

On the worldwide basis, gas hydrate is about two times the total carbon in coal, oil and conventional gas in the world. The enormous size of this resource, if producible to any degree, has significant implication for worldwide clean energy supplies and global environmental issues. This paper deals with the potential of gas hydrates as a source of energy which is widely available in permafrost and oceanic sediments. It discusses methods for gas production from natural gas hydrates. Many questions remain to be answered to determine if any of this potential energy resources technically and economically viable to produce.


2021 ◽  
Vol 2021 (2) ◽  
pp. 43-55
Author(s):  
Andrey Vitalievich Makagon

The article considers the modern problems and prospects of the development of technologies of transporting the natural gas by sea due to the fact that gas hydrate deposits are found on the bottom of Lake Baikal, the Black Sea, the Caspian Sea and the Okhotsk Sea. It has been stated that despite the proved gas hydrate deposits the fields have not been explored yet. Introducing the technology for transporting gas by sea in gas hydrate form is being substantiated. Comparative analysis of LNG, CNG and NGH technologies for sea transportation of natural gas proved that the transport component of the NGH technological chain has significant advantages over LNG and CNG technologies. The process of converting thermal energy of the ocean has been proposed to use for increasing the energy efficiency of methane production from subsea gas hydrate deposits in the gas hydrate cycle, which can save 10-15% of the produced methane for electricity generation. A schematic and technological solution of a gas production complex is presented, according to which carbon dioxide is introduced into the gas hydrate layer to extract methane from gas hydrates. To improve the kinetics of replacing methane with carbon dioxide in gas hydrates it is proposed to recycle a portion of CO2. Due to the specific and diversified geographic, economic, political and other conditions the conventional technologies for pipeline transportation of gas and LNG cannot fully meet the requirements of gas export and production projects. It has been inferred that NGH technology is most suitable for solving the problem of diversifying natural gas supplies from the Arctic regions, the Black Sea and in the development of offshore gas and oil fields.


2017 ◽  
Vol 10 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Eric Broni-Bediako ◽  
Richard Amorin ◽  
Cornelius B. Bavoh

Background:Gas hydrates are considered as a major threat to the oil and gas flow assurance industry. At high pressure and low temperature conditions, gas hydrates form in pipelines and production facilities leading to pipeline blockages, high removal cost, environmental hazards and loss of lives. For a successful prevention of gas hydrate formation, predicting the hydrate formation phase boundary of hydrocarbon fluid composition becomes very necessary.Objective and Method:In this study, computer simulation software called PVTSim was used to predict hydrate formation phase boundary of synthetic natural gas composition of the Keta basin of Ghana at pressure and temperature ranges of 43.09 bar - 350 bar and 12.87 °C - 27.29 °C respectively. The effect of changes in natural gas composition (N2and H2S) and the presence of four commonly used thermodynamic gas hydrate inhibitors (methanol, ethanol, diethylene glycol and monoethylene glycol) on the hydrate formation phase boundary is also discussed. Prior to the study, the accuracy of PVTSim was validated with the hydrate formation phase data in literature.Results and Conclusion:Results suggested that the hydrate formation phase boundary decreased with increasing N2composition and increased with increasing H2S composition, suggesting that, the presence of H2S increases the threat of hydrate formation. However, a reduction in hydrate formation threat was observed in the presence of all four commonly used gas hydrate thermodynamic inhibitors with methanol demonstrating the highest inhibition effect.


2019 ◽  
Vol 28 (3) ◽  
pp. 395-408
Author(s):  
V. Bondarenko ◽  
K. Sai ◽  
M. Petlovanyi

The actuality has been revealed of the necessity to attract the gas hydrate depos- its of the Black Sea into industrial development as an alternative to traditional gas fields. This should be preceded by the identification and synthesis of geological and thermobaric peculiarities of their existence. It was noted that the gas hydrates formation occurs under certain thermobaric conditions, with the availability of a gas hydrate-forming agent, which is capable of hydrate formation, as well as a sufficient amount of water necessary to start the crystallization process. The gas hydrate accumulation typically does not occur in free space – in sea water, but in the massif of the sea bed rocks. The important role in the process of natural gas hydrates formation is assigned to thermobaric parameters, as well as to the properties and features of the geological environment, in which, actually, the process of hydrate formation and further hydrate accumulation occurs. It was noted that the source of formation and accumulation of the Black Sea gas hydrates is mainly catagenetic (deep) gas, but diagenetic gas also takes part in the process of gas hydrate deposits formation. The main component of natural gas hydrate deposits is methane and its homologs – ethane, propane, isobutane. The analysis has been made of geological and geophysical data and literature materials devoted to the study of the offshore area and the bottom of the Black Sea, as well as to the identification of gas hydrate deposits. It was established that in the offshore area the gas hydrate deposits with a heterogeneous structure dominate, that is, which comprises a certain proportion of aluminosilicate inclusions. It was noted that theBlack Sea bottom sediments, beginning with the depths of 500 – 600 m, are gassy with methane, and a large sea part is favourable for hydrate formation at temperatures of +8...+9oC and pressures from 7 to 20 MPa at different depths. The characteristics of gas hydrate deposits are provided, as well as requirements and aspects with regard to their industrialization and development. It is recommended to use the method of thermal influence on gas hydrate deposits, since, from an ecological point of view, it is the safest method which does not require additional water resources for its implementation, because water intake is carried out directly from the upper sea layers. A new classification of gas hydrate deposits with a heterogeneous structure has been developed, which is based on the content of rocks inclusions in gas hydrate, the classification feature of which is the amount of heat spent on the dissociation process.


2014 ◽  
Vol 14 (1) ◽  
pp. 45
Author(s):  
Peyman Sabzi ◽  
Saheb Noroozi

Gas hydrates formation is considered as one the greatest obstacles in gas transportation systems. Problems related to gas hydrate formation is more severe when dealing with transportation at low temperatures of deep water. In order to avoid formation of Gas hydrates, different inhibitors are used. Methanol is one of the most common and economically efficient inhibitor. Adding methanol to the flow lines, changes the thermodynamic equilibrium situation of the system. In order to predict these changes in thermodynamic behavior of the system, a series of modelings are performed using Matlab software in this paper. The main approach in this modeling is on the basis of Van der Waals and Plateau's thermodynamic approach. The obtained results of a system containing water, Methane and Methanol showed that hydrate formation pressure increases due to the increase of inhibitor amount in constant temperature and this increase is more in higher temperatures. Furthermore, these results were in harmony with the available empirical data.Keywords: Gas hydrates, thermodynamic inhibitor, modelling, pipeline blockage


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