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Wei C.,China University of Mining and Technology | Wei C.,Key Laboratory of CBM Resource and Reservoir Formation Process | Zou M.,North China University of Water Conservancy and Electric Power | Sun Y.,China University of Mining and Technology | And 5 more authors.
Journal of Natural Gas Science and Engineering | Year: 2015

This study investigated the behaviors of particle migration within fractures of coalbed methane (CBM) reservoirs using laboratory simulation technology. Two coal samples were collected from Qinshui Basin (Shanxi Province, China) and used in two sets of permeation experiments, which were designed to understand the particle migration process and to determine the critical flux of particle migration. Based on those experimental results, a mathematical model was built to calculate the maximum water production of a CBM well that can be tolerated without damage to the reservoir. Permeation experiments indicate that as upstream pressure increases, the instantaneous permeability of coal samples have different behaviors that represent three distinct stages of non-permeation, particle migration, and stable permeation/particle blockage. In the particle migration stage, particles in the fractures start to migrate and then get deposited in narrower parts of the fractures - this migrating-deposition process repeats a few times. The permeability of the sample also repeatedly increases and then decreases. The migration and deposition of particles will cause a major decline in permeability, and for a working CBM well, this will damage the CBM reservoir. The critical fluxes of the two samples are 0.17 and 0.29mL/min, and their permeability are 0.038 and 0.043mD. When a well near sample QSC2 is chosen as an example, the calculated maximum water production during CBM drainage is 3.98m3/d. This can be a recommended water production value for a real CBM well in the region that can avoid the damage of CBM reservoir. © 2015 Elsevier B.V.


Bao Y.,China University of Mining and Technology | Bao Y.,Key Laboratory of CBM Resource and Reservoir Formation Process | Wei C.,China University of Mining and Technology | Wei C.,Key Laboratory of CBM Resource and Reservoir Formation Process | And 3 more authors.
International Journal of Mining Science and Technology | Year: 2013

The current study tested the gas component and carbon isotopic composition of gas samples from 6 oil-gas fields at the northern margin of Qaidam Basin, and established a chart to quantitatively identify the mixing ratio of source-mixed gas. Besides, this research quantitatively investigated the natural gas generated by different types of organic matter. The results show that different ratios of source-mixed gas exist in the 6 oil-gas fields at the northern margin of Qaidam Basin. Among them, Mabei has the highest mixing ratio of coal-type gas, followed by Nanbaxian, Mahai, Lenghu-4, Lenghu-3 and Lenghu-5, with the ratios of coal-type gas 91%, 87%, 83%, 66%, 55% and 36%, respectively. Lenghu-3 and Lenghu-4 oil-gas fields were mainly filled by coal-type gas earlier. For Lenghu-3, the gas was mainly generated from low matured source rocks in lower Jurassic Series of Lengxi sub-sag. For Lenghu-4, the gas was mainly generated from humus-mature source rocks in lower Jurassic Series of the northern slope of Kunteyi sub-sag. Gas in Lenghu-5 was mainly later filled oil-type gas, which was generated from high matured sapropelics in lower Jurassic Series of Kunteyi sub-sag. Earlier filled coal-type gas was the main part of Mahai, Nanbaxian and Mabei oil-gas fields. Gas source of Mahai was mainly generated from high mature humics in lower Jurassic Series of Yibei sub-sag; for Nanbaxian, the gas was mainly generated from high matured humics in middle-lower Jurassic Series of Saishiteng sub-sag; for Mabei, the gas was mainly generated from humus-mature source rocks in middle Jurassic Series of Yuqia sub-sag. © 2013 Published by Elsevier B.V. on behalf of China University of Mining & Technology.


Bao Y.,Key Laboratory of CBM Resource and Reservoir Formation Process | Bao Y.,China University of Mining and Technology | Bao Y.,University of Chinese Academy of Sciences | Wei C.,Key Laboratory of CBM Resource and Reservoir Formation Process | And 7 more authors.
Geochemical Journal | Year: 2013

Six woody peat samples were heated to 150, 250, 300, 350, 370, and 400°C to determine their geochemical characteristics and identify whether the coal bed methane (CBM) was thermogenic or secondary biogenic. The experiments were conducted in a closed pyrolysis system, from which the generated pyrolysis gas was collected. The composition of the gas and its carbon and hydrogen isotope concentrations were also determined. The results indicate that methane and carbon dioxide were the main hydrocarbon and non-hydrocarbon gases generated from the samples. The carbon isotopic compositions of the generated methane, ethane, and propane became initially lighter and then heavier with increasing experimental temperature: conversely, the hydrogen isotopic composition of the generated methane and the carbon isotopic composition of the generated carbon dioxide became gradually heavier. Therefore, a strong positive correlation exists between the aforementioned parameters. In addition, relationships have been established between carbon and hydrogen isotopic contents and R0 values, and a model for the identification of the maturity and relative content of thermogenic CBM is proposed. Then, the model was applied in a case study to evaluate the gas source of CBM in the Luling CBM field in Anhui Province. China. Copyright © 2013 by The Geochemical Society of Japan.


Sun J.-P.,China University of Petroleum - East China | Chen S.-Y.,China University of Petroleum - East China | Hu Z.-Y.,China University of Petroleum - East China | Liu W.-P.,Petrochina | And 2 more authors.
Natural Gas Geoscience | Year: 2014

Based on previous research, combined with abundant data on outcrops and cores in the study area, we recognized four kinds of mixed sedimentary facies such as mixed tidal flat facies, mixed clastic coast facies, mixed platform facies and mixed continental shelf facies. On the basis of the study of local Paleozoic sedimentary framework, combined with the analysis of sedimentary patterns and their evolution rules in different periods, we summerized two development models of plane sedimentary facies associations, i. e., tidal flat-carbonate platform-under compensated basin assemblage and shoreland-platform-continental shelf assemblage. Rise and fall of the relative sea-level and intensity of the provenance supply ability are the two main factors influencing the development models of sedimentary facies associations. Among them, the tidal flat-carbonate platform-under compensated basin assemblage was mainly developed in the Early Paleozoic, whereas the shoreland-platform-continental shelf assemblage was mainly developed in the Late Paleozoic. ©, 2014, Natural Gas Geoscience. All right reserved.


He J.,China University of Mining and Technology | He J.,Key Laboratory of CBM Resource and Reservoir Formation Process | Zhang X.,China University of Mining and Technology | Zhang X.,Key Laboratory of CBM Resource and Reservoir Formation Process | And 3 more authors.
Open Fuels and Energy Science Journal | Year: 2015

China has considerable coal resources. By benefiting from the widespread distribution of coal measures and the inter-sedimentary development of coal bed, dark shale and fine-grained tight sandstone in coal measures, China has good geological conditions and material basis for co-occurrence of a variety of coal gases. With such huge reservoir of coal gases, the co-occurrence of two or three gases of coal bed methane (CBM), shale gas, tight sandstone gas or natural gas hydrate is very common across the country. The per-well production of individual coal measure gas (e.g. CBM) is generally low when it is exploited separately, therefore it is essential to have more gas explored and produced in one well so as to raise per-well production, lower cost as well as increase economic benefit. Additionally, regarding gas control and treatment, the coal measure gas, including CBM and surrounding rock gas (a major source of CBM) should be preliminarily pumped, so as to significantly cut the coal mine gas accidents and effectively reduce greenhouse gas emission. Contributing to deeper research and further exploration, more and more coal measures holding multiple gases will definitely be explored and the proved resources of coal measure gas will be increased, indicating a prospect for coexploration and joint exploitation of coal bed gas in China. © He et al.; Licensee Bentham Open.

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