Gas hydrate saturation and distribution in the Kumano Forearc Basin of the Nankai Trough

2017 ◽  
Vol 48 (2) ◽  
pp. 137-150 ◽  
Author(s):  
Jihui Jia ◽  
Takeshi Tsuji ◽  
Toshifumi Matsuoka
Keyword(s):  
Gas Hydrate ◽  
Nankai Trough ◽  
Forearc Basin ◽  
Hydrate Saturation

Comparison of Simplistic and Geologically Descriptive Production Modeling for Natural-Gas Hydrate by Depressurization

SPE Journal ◽  
2019 ◽  
Vol 24 (02) ◽  
pp. 563-578 ◽  
Author(s):  
Yilong Yuan ◽  
Tianfu Xu ◽  
Yingli Xia ◽  
Xin Xin
Keyword(s):  
Gas Hydrate ◽  
History Matching ◽  
Nankai Trough ◽  
Flow Behavior ◽  
Test Site ◽  
Gas Production ◽  
Production Test ◽  
Hydrate Reservoir ◽  
Hydrate Saturation ◽  
Production Modeling

Summary Marine-gas-hydrate-drilling exploration at the Eastern Nankai Trough of Japan revealed the variable distribution of hydrate accumulations, which are composed of alternating beds of sand, silt, and clay in sediments, with vertically varying porosity, permeability, and hydrate saturation. The main purposes of this work are to evaluate gas productivity and identify the multiphase-flow behavior from the sedimentary-complex hydrate reservoir by depressurization through a conventional vertical well. We first established a history-matching model by incorporating the available geological data at the offshore-production test site in the Eastern Nankai Trough. The reservoir model was validated by matching the fluid-flow rates at a production well and temperature changes at a monitoring well during a field test. The modeling results indicate that the hydrate-dissociation zone is strongly affected by the reservoir heterogeneity and shows a unique dissociation front. The gas-production rate is expected to increase with time and reach the considerable value of 3.6 × 104 std m3/d as a result of the significant expansion of the dissociation zone. The numerical model, using a simplified description of porosity, permeability, and hydrate saturation, leads to significant underestimation of gas productivity from the sedimentary-complex hydrate reservoir. The results also suggest that the interbedded-hydrate-occurrence systems might be a better candidate for methane (CH4) gas extraction than the massive hydrate reservoirs.

Mechanical Response of Reservoir and Well Completion of the First Offshore Methane-Hydrate Production Test at the Eastern Nankai Trough: A Coupled Thermo-Hydromechanical Analysis

SPE Journal ◽  
2018 ◽  
Vol 24 (02) ◽  
pp. 531-546 ◽  
Author(s):  
Jun Yoneda ◽  
Akira Takiguchi ◽  
Toshimasa Ishibashi ◽  
Aya Yasui ◽  
Jiro Mori ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Mechanical Response ◽  
Nankai Trough ◽  
Water Pressure ◽  
Compressive Force ◽  
Gas Production ◽  
Production Test ◽  
Frictional Stress ◽  
Well Completion ◽  
Hydrate Saturation

Summary During gas production from offshore gas-HBS, there are concerns regarding the settlement of the seabed and the possibility that frictional stress will develop along the production casing. This frictional stress is caused by a change in the effective stress induced by water movement caused by depressurization and dissociation of hydrate as well as gas generation and thermal changes, all of which are interconnected. The authors have developed a multiphase-coupled simulator by use of a finite-element method named COTHMA. Stresses and deformation caused by gas-hydrate production near the production well and deep seabed were predicted using a multiphase simulator coupled with geomechanics for the offshore gas-hydrate-production test in the eastern Nankai Trough. Distributions of hydrate saturation, gas saturation, water pressure, gas pressure, temperature, and stresses were predicted by the simulator. As a result, the dissociation of gas hydrate was predicted within a range of approximately 10 m, but mechanical deformation occurred in a much wider area. The stress localization initially occurred in a sand layer with low hydrate saturation, and compression behavior appeared. Tensile stress was generated in and around the casing shoe as it was pulled vertically downward caused by compaction of the formation. As a result, the possibility of extensive failure of the gravel pack of the well completion was demonstrated. In addition, in a specific layer, where a pressure reduction progressed in the production interval, the compressive force related to frictional stress from the formation increased, and the gravel layer became thin. Settlement of the seafloor caused by depressurization for 6 days was within a few centimeters and an approximate 30 cm for 1 year of continued production.

Lithological features of hydrate-bearing sediments and their relationship with gas hydrate saturation in the eastern Nankai Trough, Japan

2015 ◽  
Vol 66 ◽  
pp. 368-378 ◽  
Author(s):  
Takuma Ito ◽  
Yuhei Komatsu ◽  
Tetsuya Fujii ◽  
Kiyofumi Suzuki ◽  
Kosuke Egawa ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Nankai Trough ◽  
Hydrate Saturation ◽  
Hydrate Bearing Sediments

scholarly journals Multiphase Flow Behavior of Layered Methane Hydrate Reservoir Induced by Gas Production

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Yilong Yuan ◽  
Tianfu Xu ◽  
Xin Xin ◽  
Yingli Xia
Keyword(s):  
Multiphase Flow ◽  
Gas Hydrate ◽  
Methane Hydrate ◽  
Nankai Trough ◽  
Flow Behavior ◽  
Gas Production ◽  
Production Performance ◽  
Heterogeneous Structure ◽  
Hydrate Saturation ◽  
Hydrate Reservoirs

Gas hydrates are expected to be a potential energy resource with extensive distribution in the permafrost and in deep ocean sediments. The marine gas hydrate drilling explorations at the Eastern Nankai Trough of Japan revealed the variable distribution of hydrate deposits. Gas hydrate reservoirs are composed of alternating beds of sand and clay, with various conditions of permeability, porosity, and hydrate saturation. This study looks into the multiphase flow behaviors of layered methane hydrate reservoirs induced by gas production. Firstly, a history matching model by incorporating the available geological data at the test site of the Eastern Nankai Trough, which considers the layered heterogeneous structure of hydrate saturation, permeability, and porosity simultaneously, was constructed to investigate the production characteristics from layered hydrate reservoirs. Based on the validated model, the effects of the placement of production interval on production performance were investigated. The modeling results indicate that the dissociation zone is strongly affected by the vertical reservoir’s heterogeneous structure and shows a unique dissociation front. The beneficial production interval scheme should consider the reservoir conditions with high permeability and high hydrate saturation. Consequently, the identification of the favorable hydrate deposits is significantly important to realize commercial production in the future.

Numerical Analysis of the Behavior of Gas Hydrate Layers After Cementing Operations

2021 ◽  
Author(s):  
Sukru Merey ◽  
Tuna Eren ◽  
Can Polat
Keyword(s):  
Numerical Simulations ◽  
Gas Hydrates ◽  
Gas Hydrate ◽  
Cement Hydration ◽  
Nankai Trough ◽  
Heat Of Hydration ◽  
Production Test ◽  
Hydrate Saturation ◽  
Gas Channeling ◽  
Heat Released

Abstract Since the 2000s, the number of gas hydrate wells (i.e., exploration wells, production test wells) has increased. Moreover, in the marine environment, gas hydrate zones are drilled in conventional hydrocarbon wells. Different than conventional hydrocarbon wells, the heat released with cement hydration cannot be ignored because gas hydrates are heat sensitive. In this study, by analyzing different cement compositions (conventional cement compositions and novel low-heat of hydration cement), it is aimed to investigate the effect of the heat of cement hydration on gas hydrate zones near the wellbore. For this purpose, numerical simulations with TOUGH+HYDRATE simulator were conducted in the conditions of the Nankai Trough gas hydrates. According to the numerical simulations in this study, if the increase in temperature in the cemented layer is above 30°C, significant gas hydrate dissociation occurs, and free gas evolved in the porous media. This might cause gas channeling and poor cement bond. The heat released with cement hydration generally affects the interval between the cemented layer and 0.25 m away from the cemented layer. Within a few days after cementing, pressure, temperature, gas hydrate saturation, and gas saturation returned to almost their original values.

GAS HYDRATE SATURATION ESTIMATED FROM ACOUSTIC IMPEDANCE IN THE ANDAMAN SEA, INDIA

2014 ◽  
Vol 33 (2) ◽  
pp. 163-168
Author(s):  
Xiujuan WANG ◽  
Jiliang WANG ◽  
Wei LI ◽  
Nittala Satyavani ◽  
Kalachand Sain
Keyword(s):  
Gas Hydrate ◽  
Acoustic Impedance ◽  
Andaman Sea ◽  
Hydrate Saturation

INTERPRETATION OF GAS HYDRATE PROSPECT IN THE MIYAZAKI-OKI FOREARC BASIN, JAPAN

2017 ◽  
Author(s):  
Makoto Tanaka ◽  
◽  
Tetsuya Fujii ◽  
Than Tin Aung ◽  
Naoya Wada ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Forearc Basin
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