scholarly journals The Effects of the Length and Conductivity of Artificial Fracture on Gas Production from a Class 3 Hydrate Reservoir

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7513
Author(s):  
Shilong Shang ◽  
Lijuan Gu ◽  
Hailong Lu
Keyword(s):  
Natural Gas ◽  
Gas Hydrate ◽  
Energy Resource ◽  
Gas Production ◽  
Production Performance ◽  
Natural Gas Hydrate ◽  
Conductivity Method ◽  
Fracture Length ◽  
Hydrate Reservoir ◽  
Artificial Fracture

Natural gas hydrate is considered as a potential energy resource. To develop technologies for the exploitation of natural gas hydrate, several field gas production tests have been carried out in permafrost and continental slope sediments. However, the gas production rates in these tests were still limited, and the low permeability of the hydrate-bearing sediments is identified as one of the crucial factors. Artificial fracturing is proposed to promote gas production rate by improving reservoir permeability. In this research, numerical studies about the effect of fracture length and fluid conductivity on production performance were carried out on an artificially fractured Class 3 hydrate reservoir (where the single hydrate zone is surrounded by an overlaying and underlying hydrate-free zone), in which the equivalent conductivity method was applied to depict the artificial fracture. The results show that artificial fracture can enhance gas production by offering an extra fluid flow channel for the migration of gas released from hydrate dissociation. The effect of fracture length on production is closely related to the time frame of production, and gas production improvement by enlarging the fracture length is observed after a certain production duration. Through the production process, secondary hydrate formation is absent in the fracture, and the high conductivity in the fracture is maintained. The results indicate that the increase in fracture conductivity has a limited effect on enhancing gas production.

Nuclear Magnetic Resonance Logging Evaluation of Natural Gas Hydrate Reservoir

2012 ◽  
Vol 482-484 ◽  
pp. 1017-1020
Author(s):  
Xin Li ◽  
Li Zhi Xiao ◽  
Tian Lin An
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Natural Gas ◽  
Gas Hydrate ◽  
Energy Resource ◽  
Natural Gas Hydrate ◽  
Reservoir Evaluation ◽  
Hydrate Reservoir ◽  
Gas Hydrate Reservoir ◽  
Nuclear Magnetic

Natural gas hydrate in ocean bottom and permafrost is a great potential energy resource. Compared to fluids hydrocarbons (oil, water and gas) in conventional reservoir evaluation, natural gas hydrate exists in sedimentary formations in solid form, which should be reconsidered in its reservoir evaluation and global reserves assessment. Nuclear magnetic resonance (NMR) technique plays an important role in natural gas hydrate reservoir evaluation. The recent applications of NMR logging in natural gas hydrate reservoir evaluation including formation porosity-permeability estimation, gas hydrate saturation estimation and growth habits prediction in rock pores are introduced. Finally, the potential combination application of downhole NMR 1H relaxation and 13C spectroscopy in natural gas hydrate reservoir evaluation model is also discussed.

scholarly journals Evaluation and re-understanding of the global natural gas hydrate resources

2021 ◽  
Vol 18 (2) ◽  
pp. 323-338
Author(s):  
Xiong-Qi Pang ◽  
Zhuo-Heng Chen ◽  
Cheng-Zao Jia ◽  
En-Ze Wang ◽  
He-Sheng Shi ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Hydrate ◽  
Oil And Gas ◽  
Material Balance ◽  
Energy Resource ◽  
Resource Assessment ◽  
Future Trend ◽  
Natural Gas Hydrate ◽  
The Future ◽  
Recoverable Resources

AbstractNatural gas hydrate (NGH) has been widely considered as an alternative to conventional oil and gas resources in the future energy resource supply since Trofimuk’s first resource assessment in 1973. At least 29 global estimates have been published from various studies so far, among which 24 estimates are greater than the total conventional gas resources. If drawn in chronological order, the 29 historical resource estimates show a clear downward trend, reflecting the changes in our perception with respect to its resource potential with increasing our knowledge on the NGH with time. A time series of the 29 estimates was used to establish a statistical model for predict the future trend. The model produces an expected resource value of 41.46 × 1012 m3 at the year of 2050. The statistical trend projected future gas hydrate resource is only about 10% of total natural gas resource in conventional reservoir, consistent with estimates of global technically recoverable resources (TRR) in gas hydrate from Monte Carlo technique based on volumetric and material balance approaches. Considering the technical challenges and high cost in commercial production and the lack of competitive advantages compared with rapid growing unconventional and renewable resources, only those on the very top of the gas hydrate resource pyramid will be added to future energy supply. It is unlikely that the NGH will be the major energy source in the future.

Geomechanical Response Induced by Multiphase (Gas/Water) Flow in the Mallik Hydrate Reservoir of Canada

SPE Journal ◽  
2021 ◽  
pp. 1-18
Author(s):  
Yingli Xia ◽  
Tianfu Xu ◽  
Yilong Yuan ◽  
Xin Xin ◽  
Huixing Zhu
Keyword(s):  
Shear Stress ◽  
Shear Failure ◽  
Energy Resource ◽  
Gas Production ◽  
Production Performance ◽  
Reservoir Model ◽  
Hydrate Reservoir ◽  
Maximum Subsidence ◽  
Permeability Anisotropy

Summary Natural gas hydrate (NGH) is regarded as an important alternative future energy resource. In recent years, a few short-term production tests have been successfully conducted with both permafrost and marine sediments. However, long-term hydrate production performance and the potential geomechanical problems are not very clear. According to the available geological data at the Mallik site, a more realistic hydrate reservoir model that considers the heterogeneity of porosity, permeability, and hydrate saturation was developed and validated by reproducing the field depressurization test. The coupled multiphase and heat flow and geomechanical response induced by depressurization were fully investigated for long-term gas production from the validated hydrate reservoir model. The results indicate that long-term gas production through depressurization from a vertically heterogeneous hydrate reservoir is technically feasible, but the production efficiency is generally modest, with the low average gas production rate of 4.93 × 103 ST m3/d (ST represents the standard conditions) over a 1-year period. The hydrate dissociation region is significantly affected by the reservoir heterogeneity and reveals a heterogeneous dissociation front in the reservoir. The depressurization production results in significant increase of shear stress and vertical compaction in the hydrate reservoir. The response of shear stress indicates that the potential region of sand migration is mainly in the sand-dominant layer during gas production from the hydraulically heterogeneous hydrate reservoir (e.g., sand layers interbedded with clay layers). The maximum subsidence is approximately 78 mm and occurred at the 72nd day, whereas the final subsidence is slowly dropped to 63 mm after 1-year of depressurization production. The vertical subsidence is greatly dependent on the elastic properties and the permeability anisotropy. In particular, the maximum subsidence increased by approximately 81% when the ratio of permeability anisotropy was set at 5:1. Furthermore, the potential shear failure in the hydrate reservoir is strongly correlated to the in-situ stress state. For the normal fault stress regime, the greater the initial horizontal stress is, the less likely the hydrate reservoir is to undergo shear failure during depressurization production.

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