scholarly journals Assessing the impact made by the geological features of a coalfield on producing well’s operation

2020 ◽  
Vol 7 (7) ◽  
pp. 41-48
Author(s):  
Galina I. Matniiazova ◽  
◽  
Mariia P. Khaidina ◽  
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Coal Mining ◽  
Methane Production ◽  
Coalbed Methane ◽  
Gas Production ◽  
Surrounding Rock ◽  
Gas Migration ◽  
Coalbed Methane Production ◽  
The Impact

Introduction. Coalbed methane extraction increases the economic efficiency of coal mining being a main measure mitigating coal mining risks. Research aim was to assess the impact made by host rocks with different reservoir properties on coalbed methane production dynamics before and after hydraulic fracturing. Methodology. A coal seam model has been constructed using software systems; the coal seam has been represented as an integrated deposit of two minerals, coal and gas. Gas production scenarios with and without impact on the seam have been calculated as well. A model of a coal bed with a hydraulic fracture was constructed in application program package Petrel (Shlumberger). Results. The calculation results showed the development of gas migration from the coal matrix to the surrounding rock through the fracture system during gas production. The use of hydraulic fracturing has positive impact on the dynamics of gas production from coal seams. Hydraulic fracturing revealed the growth of desorbed gas migration into the host interlayers. Analysis of coal methane migration to the surrounding rock has shown that the host rock can be considered as a transportation route for coalbed methane production.

scholarly journals Microbial Simulation Experiment on Enhancing Coalbed Methane Production

2019 ◽  
Author(s):  
Chen Hao ◽  
Qin Yong ◽  
Zhou Shangwen ◽  
Wang Hongyan ◽  
Chen Zhenhong ◽  
...  
Keyword(s):  
Methane Production ◽  
Coalbed Methane ◽  
Simulation Experiment ◽  
Bacterial Species ◽  
Gas Production ◽  
Gas Generation ◽  
Exogenous Bacteria ◽  
Different Temperatures ◽  
Cbm Production ◽  
Coalbed Methane Production

Coalbed Methane(CBM) production enhancement for single wells is a big problem to CBM industrialization. Low production is due to insufficient gas generation by thermogenic. Luckily, Biogenic gas was found in many areas and its supply is assumed to improve coalbed methane production. Therefore, microbial simulation experiment will demonstrate the effectiveness of the assumption. From microbial simulation experiment on different coal ranks, it is found that microbes can use coals to produce biogas under laboratory conditions. With different temperatures for different experiments, it turns out that the gas production at 35 ℃ is greater than that at 15℃,indicating that 35℃ is more suitable for microbes to produce gas. According to quantitative experiments, adding exogenous nutrients or exogenous bacteria can improve CBM production. Moreover, the production enhancement ratio can reach up to 115% under the condition of adding exogenous bacterial species, while the ratio for adding nutrients can be up to 144%.

Influence of Coal-Seam Water on Coalbed Methane Production: A Review

2015 ◽  
Vol 51 (2) ◽  
pp. 207-221 ◽  
Author(s):  
Jinxuan Han ◽  
Zhaozhong Yang ◽  
Xiaogang Li ◽  
Jian Zhang
Keyword(s):  
Coal Seam ◽  
Methane Production ◽  
Coalbed Methane ◽  
Coalbed Methane Production

scholarly journals Investigation on the CBM Extraction Techniques in the Broken-Soft and Low-Permeability Coal Seams in Zhaozhuang Coalmine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhaoying Chen ◽  
Xuehai Fu ◽  
Guofu Li ◽  
Jian Shen ◽  
Qingling Tian ◽  
...  
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Coalbed Methane ◽  
Research Result ◽  
Horizontal Stress ◽  
Gas Production ◽  
Vertical Stress ◽  
Low Permeability ◽  
Coal Seams

To enhance the coalbed methane (CBM) extraction in broken-soft coal seams, a method of drilling a horizontal well along the roof to hydraulically fracture the coal seam is studied (i.e., HWR-HFC method). We first tested the physical and mechanical properties of the broken-soft and low-permeability (BSLP) coal resourced from Zhaozhuang coalmine. Afterward, the in situ hydraulic fracturing test was conducted in the No. 3 coal seam of Zhaozhuang coalmine. The results show that (1) the top part of the coal seam is fractured coal, and the bottom is fragmented-mylonitic coal with a firmness coefficient value of less than 1.0. (2) In the hydraulic fracturing test of the layered rock-coal specimens in laboratory, the through-type vertical fractures are usually formed if the applied vertical stress is the maximum principal stress and is greater than 4 MPa compared with the maximum horizontal stress. However, horizontal fractures always developed when horizontal stress is the maximum or it is less than 4 MPa compared with vertical stress. (3) The in situ HWR-HFC hydraulic fracturing tests show that the detected maximum daily gas production is 11,000 m3, and the average gas production is about 7000 m3 per day. This implies that the CBM extraction using this method is increased by 50%~100% compared with traditional hydraulic fracturing in BSLP coal seams. The research result could give an indication of CBM developing in the broken-soft and low-permeability coal seams.

scholarly journals Production analysis for fractured vertical well in rectangular coal reservoirs

2018 ◽  
Vol 73 ◽  
pp. 62
Author(s):  
Chen Li ◽  
Zhenzhen Dong ◽  
Xiang Li
Keyword(s):  
Coal Seam ◽  
Analytical Solutions ◽  
Methane Production ◽  
Coalbed Methane ◽  
Finite Conductivity ◽  
Storage Coefficient ◽  
Vertical Well ◽  
Production Analysis ◽  
Coalbed Methane Production ◽  
And Diffusion

As one kind of unconventional natural gas, coalbed methane is an important energy resource that is subject to active research. Gas exists in coalbed methane reservoirs in two forms: free gas and adsorbed gas. In the course of coalbed methane production, the reservoir experiences pressure decrease, desorption, diffusion, and seepage. Previous models of coalbed methane production were mainly concerned with circular boundaries. However, field tests revealed that some fractured wells possess the characteristics of rectangular boundaries. For fractured rectangular coalbed methane reservoirs, it is necessary to deal with the four boundaries with mirror image theory, which complicates calculations. In addition, the desorption and adsorption process of coalbed methane exerts a strong effect on the seepage process. Furthermore, the complexity of the rectangular coal seam embedded with the finite-conductivity fracture results in a significant computational challenge. For the first time, this paper presented a fast analytical solution for a finite-conductivity fractured vertical well model with either rectangular closed or constant-pressure boundaries in the coal seam. On the basis of the Fick diffusion law and the Darcy seepage law, a mathematical model that considers diffusion in matrix and seepage within natural fractures was established. Then, we integrated the fracture conductivity function method with the hydraulic fracture model to greatly increase computational efficiency. The analytical solutions were validated against a numerical simulation. Parameter sensitivity analysis reveals that interporosity coefficient and storage coefficient, respectively, affect the appearance time and degree of desorption and diffusion. Desorption coefficient mainly describes the capacity of desorption and diffusion. Well storage coefficient, conductivity factor, and skin factor mainly affect the early stage of production. Finally, the proposed solutions were applied to field history match. The model developed is applicable to production analysis and well testing for coalbed methane reservoirs. The new proposed model extended flow mechanism of coalbed methane, and provided a better production and pressure forecast for coalbed methane reservoirs. In addition, the analytical solutions can be used to generate type curves for fractured vertical wells with finite conductivity and in the rectangular boundary, and provide a sound theoretical basis for well tests in the coal seam. The model is also applicable to other types of unconventional gas reservoirs, such as gas shales, in which the same processes are present.

IDENTIFYING THE SOURCE, PATHWAYS, AND RATES OF ENHANCED MICROBIAL COALBED METHANE PRODUCTION

2016 ◽  
Author(s):  
Katherine J. Davis ◽  
◽  
Robin Gerlach ◽  
H.D. Schweitzer ◽  
Al Cunningham ◽  
...  
Keyword(s):  
Methane Production ◽  
Coalbed Methane ◽  
Coalbed Methane Production

scholarly journals Quantify Coal Macrolithotypes of a Whole Coal Seam: A Method Combing Multiple Geophysical Logging and Principal Component Analysis

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 213
Author(s):  
Chao Cui ◽  
Suoliang Chang ◽  
Yanbin Yao ◽  
Lutong Cao
Keyword(s):  
Principal Component Analysis ◽  
Coal Seam ◽  
Coalbed Methane ◽  
Principal Component ◽  
Component Analysis ◽  
Gas Production ◽  
Index Model ◽  
Geophysical Logging ◽  
The Relationship ◽  
Observation Results

Coal macrolithotypes control the reservoir heterogeneity, which plays a significant role in the exploration and development of coalbed methane. Traditional methods for coal macrolithotype evaluation often rely on core observation, but these techniques are non-economical and insufficient. The geophysical logging data are easily available for coalbed methane exploration; thus, it is necessary to find a relationship between core observation results and wireline logging data, and then to provide a new method to quantify coal macrolithotypes of a whole coal seam. In this study, we propose a L-Index model by combing the multiple geophysical logging data with principal component analysis, and we use the L-Index model to quantitatively evaluate the vertical and regional distributions of the macrolithotypes of No. 3 coal seam in Zhengzhuang field, southern Qinshui basin. Moreover, we also proposed a S-Index model to quantitatively evaluate the general brightness of a whole coal seam: the increase of the S-Index from 1 to 3.7, indicates decreasing brightness, i.e., from bright coal to dull coal. Finally, we discussed the relationship between S-Index and the hydro-fracturing effect. It was found that the coal seam with low S-Index values can easily form long extending fractures during hydraulic fracturing. Therefore, the lower S-Index values indicate much more favorable gas production potential in the Zhengzhuang field. This study provides a new methodology to evaluate coal macrolithotypes by using geophysical logging data.

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