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Collaborating Authors
Results
Gas-Hydrate-Associated Carbonates and their Implications in the Qilian Mountain Permafrost
Lu, Zhengquan (Oil & Gas Survey, China Geological Survey) | Cai, Junjun (Chinese Academy of Geological Sciences) | Sun, Qing (National Research Center for Geoanalysis) | Wang, Ting (Oil & Gas Survey, China Geological Survey) | Tang, Shiqi (Oil & Gas Survey, China Geological Survey) | Tan, Panpan (Oil & Gas Survey, China Geological Survey)
Abstract It is a universal phenomenon for gas hydrate associated carbonates in subsurface sediments, but it is rarely reported in the permafrost. Based on microscopic observations and mineral analyses on carbonates associated with gas hydrate, mineral species and occurrence modes of carbonates are determined in the Qilian Mountain permafrost:white thin-layered carbonate; smoky rhombic crystal calcite aggregates, darkish gray thin crust-like carbonate, sparsely disseminated calcite or carbonate. Among these carbonates, typed II carbonates is rich in large calcite aggregates, and is abound in a certain amount of aragonite and strawberry-like pyrite. For the typed II carbonates, element concentrations are generally very low, and particularly some element concentrations and elemental ratios are obviously different from other typed carbonates. For example concentrations of Sr, Ba and Eu are abnormal in the typed II carbonates and its Chemical Index of Alteration (CIA) is the lowest among the four types of carbonates. The values of ฮดCV-PDB โฐ range from -6~-0.8 โฐ while the values of ฮดOV-PDB โฐ range from -17.7~-15.2 โฐ in the typed II carbonates, appearing relatively independent of other three types. Hence the typed II carbonates are indicative of association with gas hydrate decomposition. Namely they possibly form from carbonated reworking after gas hydrate dissociation in the geological history in the Qilian Mountain permafrost.
- Asia (0.74)
- North America > United States > Alaska (0.28)
- Geology > Rock Type > Sedimentary Rock (1.00)
- Geology > Mineral > Carbonate Mineral > Calcite (0.69)
- Geology > Mineral > Silicate (0.69)
- Geology > Structural Geology > Tectonics > Compressional Tectonics > Fold and Thrust Belt (0.47)
Abstract In offshore gas transmission pipeline systems, typically gas and water are produced under high pressure and low temperature conditions causing the formation of gas hydrates blocking pipelines. Thermodynamic modeling is necessary to understand the phase stability of hydrate in the presence of green solvents namely, ionic liquids (ILs). In this work, the thermodynamic models are based on the computation of fugacity of hydrate phase using Van der Waals and Platteeuw solid solution theory combined with Peng - Robinson equation of state (PR-EoS) for fugacity of hydrate former in the gas phase and the computation of fugacity of aqueous water phase using activity coefficient models such as the non - random two - liquid (NRTL) model and Pitzer - Mayorga model. The model results are compared with available experimental data from open literature and observed to be in good agreement with the reported literature. Finally, the hydrate suppression temperature due to ILs on methane hydrate is calculated to know the inhibition effectiveness of IL on methane hydrate formation in offshore pipeline system. The overall accuracy of Pitzer-Mayorga model is found to be 5.8 % while NRTL model's accuracy was 6.3 % for various ILs and methane hydrate system. Model results further indicated that ILs with shorter alkyl chain length exhibit better inhibition effect. The model developed in this work shows potential application in the determination of hydrate phase stability using green solvent for offshore oil field applications.
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Oil & Gas > Midstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.81)
A lot of data and parameters have Huge amount of methane hydrates worldwide exist at offshore and been obtained to make the following computational modules needed for onshore areas, particularly in reservoirs of marine sediments. Because the simulator, such as the permeability module, the dissociation rate the development of methane hydrates is of great interest for future estimation module, and the consolidation module. MH21 national energy of natural gas, a lot of R&D projects have been undertaken to project has three phases for the complete target of commercial achieve the whole system including geological survey, exploration, production. In the first phase we focus on fundamental properties of production and enhanced recovery technologies. Japanese program hydrate-bearing sand layers and simulator development based on MH21 has promoted the own R&D, focused on the production of laboratory experiments and simulations.
Abstract The unexpected formation of gas hydrates during production and transportation processes in petroleum industries has caused serious problems, blocking oil and gas pipelines with safety hazards. To cope with this trouble, the gas hydrate community has searched for hydrate inhibitors that have great performance and cost effectiveness. Recently, the ionic liquids (ILs) have been suggested as novel hydrate inhibitors that are able to act in both thermodynamic and kinetic ways which are designated as dual-function inhibitors. In this study, we suggest a non-ionic liquid compound, morpholine as a dual-function inhibitor. We observed that this inhibitor shifts the hydrate phase equilibrium curve and reduces the hydrate formation rate as well. The formation kinetics of gas hydrates in the presence of morpholine was found to be better than two comparators of 1-ethyl-3-methylimidazolium tetrafluoroborate and polyvinylpyrrolidone. In addition, a series of microscopic analyses (powder X-ray diffraction, solid-state C NMR and Raman spectroscopy) were adopted to identify their crystal structure and molecular behavior during hydrate formation. Such inhibition effects of morpholine are thought to be mainly attributed to the nucleophilicity of the ring compound forming hydrogen bonds between surrounding water molecules. Moreover, it can be speculated that the more energy is required to form the structure II hydrate in the presence of morpholine instead of the structure I CH4 hydrate with milder formation conditions.
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.95)
Exploration and Identification of Gas Hydrate in Muli Permafrost
Wen, Huaijun (Qinghai Bureau of Coal Geology) | Wei, Liyang (Shenhua Qinghai Energy Development Co. Ltd.) | Guo, Jinning (Qinghai Bureau of Coal Geology) | Wang, Jinping (Shenhua Qinghai Energy Development Co. Ltd.) | Li, Yonghong (Qinghai No.105 Coal Geological Exploration Team) | Chen, Xin (Shenhua Qinghai Energy Development Co. Ltd.) | Zhang, Shaolin (Qinghai No.105 Coal Geological Exploration Team) | Wang, Weichao (Qinghai No.105 Coal Geological Exploration Team) | Fan, Haijun (Shenhua Qinghai Energy Development Co. Ltd.)
Abstract Compared with marine gas hydrate, continental gas hydrate in Muli permafrost Qilian Mountain has a discontinuous vertical distribution and bad horizontal relativity, in addition, no BSRs or other reliable marks can be used. So gas hydrate exploration methods of permafrost have obvious difference with that of ocean. According to recent exploration works in Sanlutian study area, Muli permafrost, core observation, test analysis, well logging, seismography, drilling, gas logging, geochemistry and other methods are used to summarize the gas hydrate identification characteristics. Each method has its reliability level and fineness, so comprehensive researches must be conducted to improve the exploration level.
- Phanerozoic > Mesozoic (0.68)
- Phanerozoic > Paleozoic (0.48)
- Geology > Rock Type > Sedimentary Rock (1.00)
- Geology > Geological Subdiscipline (0.70)
- Geology > Structural Geology > Tectonics > Compressional Tectonics > Fold and Thrust Belt (0.70)
- Geology > Sedimentary Geology > Depositional Environment > Marine Environment (0.69)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying (0.97)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Non-Traditional Resources > Gas hydrates (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
Natural Thermoluminescence Prospecting of Gas Hydrate in the Qilian Mountains Permafrost, Qinghai
Sun, Zhongjun (Chinese Academy of Geological Sciences) | Han, Ziye (Chinese Academy of Geological Sciences) | Fang, Hui (Chinese Academy of Geological Sciences) | Yang, Zhibin (Chinese Academy of Geological Sciences) | Qin, Aihua (Chinese Academy of Geological Sciences) | Zhang, Fugui (Chinese Academy of Geological Sciences) | Zhou, Yalong (Chinese Academy of Geological Sciences) | Zhang, Shunyao (Chinese Academy of Geological Sciences0)
Abstract Subject to the severe interference of bacterial gas and coal-bed gas of the marsh area, the geochemical exploration over surface hydrate in Muli permafrost of Qilian Mountains takes on widely distributed methane geochemical anomalies. The natural thermoluminescence hydrate prospecting technique was tested in the project. 7 natural thermoluminescence anomalies were detected and circled out. Anomaly I indicates the hydrate reservoir anomaly. In 2013, according to the geophysical and geochemical exploration results (including natural thermoluminescence anomalies), three layers of hydrate were collected from the deployed DK-9 well. Compared with the soil acid extracted hydrocarbon, natural thermoluminescence is not subject to the bacterial gas and coal-bed gas of marsh, so it is considered as a new assistive technology for hydrate prospecting.
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (0.71)
Experimental Study on Methane Hydrate Accumulation from Dissolved Gas in Three-Dimensional Simulation Device
Ma, Qinglan (China University of Petroleum) | Zhong, Xiaoyu (China University of Petroleum) | Li, Nan (China University of Petroleum) | Su, Kehua (China University of Petroleum) | Sun, Changyu (China University of Petroleum) | Chen, Guangjin (China University of Petroleum) | Yang, Lanying (China University of Petroleum) | Liu, Bei (China University of Petroleum)
Abstract In order to obtain the knowledge of hydrate accumulating mechanism in seafloor, and lay the theoretical foundation for gas hydrate exploration and exploitation in the future, in this work, the formation of methane hydrate from dissolved gas was studied using a large three-dimensional accumulation device which was built by our laboratory to simulate the methane hydrate accumulation under the seafloor conditions. First, the real-time detection and analysis were made for the electrical resistivity and acoustic velocity changes at different positions over time during 80 days of methane hydrate formation experiments. The results show that hydrate formation affects the resistivity in different ways. At the beginning of the formation, the resistivity dropped continuously because of the salt-removing effect of hydrate formation which increases the salt concentration in the salt solution. In the late period of hydrate formation, the hydrates cement with particles of sediment making a sharp increase in resistivity. And then, the hydrate saturations in different sediment layers were determined from the experimental data on electrical resistivity using the modified Archie formula. The results demonstrate that the hydrate accumulates mostly in the middle and bottom of the sediment, but less in the upper space. This conclusion has also been confirmed through analyzing the variation of temperature in the sediment.
- North America > United States (0.46)
- Asia (0.46)
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (1.00)