scholarly journals Effect of packer design on hydraulic fracturing of coal seam

2021 ◽  
Vol 330 ◽  
pp. 01002
Author(s):  
Sergei Klishin ◽  
Vladimir Klishin
Keyword(s):  
Finite Element Method ◽  
Hydraulic Fracturing ◽  
Strain Analysis ◽  
Borehole Wall ◽  
The Finite Element Method ◽  
Coal Seams ◽  
Methane Drainage ◽  
Axial Tensile ◽  
Drainage Borehole

The article addresses the issue of in-situ methane drainage from coal seams using multiple hydraulic fracturing. The authors undertake the stress–strain analysis of rock mass in the vicinity of a drainage borehole subjected to loading by sealing packers using the finite element method. The pressures at the packer and borehole wall contacts are calculated. It is shown how the length and spacing of the packers influence the values of the maximum axial tensile stresses on the borehole wall.

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.

Research on Numerical Simulation of Dynamic Pressure for Stress Sensibility Coal Seam

2011 ◽  
Vol 383-390 ◽  
pp. 2293-2299
Author(s):  
Yun Hong Ding ◽  
Bao Hui Wang ◽  
Xiang Zhen Yan
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
History Matching ◽  
Dynamic Pressure ◽  
Ordos Basin ◽  
Coupling Model ◽  
The Finite Element Method ◽  
Coal Seams ◽  
The Face ◽  
Good Agreement

Based on the orthotropic physical properties of coal cleats, the fluid-solid coupling model for stress sensibility coal seams is established. The equations of the coupling model are solved by using the finite element method. The history matching for JS-3 well in Ordos basin is carried on by using the coupling model. The comparison between calculated results based on the coupling model and the measured values indicates their good agreement, which verifies the accuracy and rationality of the model. The effect of the permeability orthotropic coefficient of coal cleats on the pressure distribution in coal seams is analyzed. The results show that the pressure along the butt cleats direction increases with permeability orthotropic coefficient increasing; The pressure along the face cleats decreases with permeability orthotropic coefficient increasing between 0m~30m and 170m~200m, whereas both increases from 30m to 170m.

Evaluation of Hydraulic Fracturing Pressure in a Porous Medium by Using the Finite Element Method

2002 ◽  
Vol 24 (8) ◽  
pp. 715-724 ◽  
Author(s):  
A. Nouri ◽  
A. Komak Panah ◽  
A. Pak ◽  
H. Vaziri ◽  
M. R. Islam
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Porous Medium ◽  
Hydraulic Fracturing ◽  
The Finite Element Method ◽  
Element Method

scholarly journals DETERMINATION OF METHANE DESORPTION ZONE FOR THE DESIGN OF A DRAINAGE BOREHOLE PATTERN (CASE STUDY: E4 PANEL OF THE TABAS MECHANIZED COAL MINE, IRAN)

2021 ◽  
Vol 36 (1) ◽  
pp. 61-75
Author(s):  
Ali Hosseini ◽  
Mehdi Najafi
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Methane Emissions ◽  
Gas Content ◽  
Coal Seams ◽  
Mining Operations ◽  
Methane Drainage ◽  
Tabas Coal Mine ◽  
Drainage Borehole

Underground coal mining is known as one of the major sources of methane emissions which mainly occurs after underground coal extraction. Rock strata in-situ methane can potentially be the most significant hazard in coal mining operations. To prevent or minimize the risks of methane emissions, methane drainage approaches have been adopted by coal mines. Rock mass methane drainage is the most efficient and effective approach toward controlling methane hazards as it prevents and reduces the frequency of methane emissions, outflows into the working area and sudden outbursts of methane and rocks. The method includes drilling boreholes from the tailgate side to the unstressed zone in the roof and floor strata above and below a working coal seam. The coal seam gas content in Tabas Parvadeh I is estimated to be about 16 m3 /t, which is relatively high. Based on exploration data, five distinct coal seams have been identified (B1, B2, C1, C2 and D) at the coal deposit and currently C1 is being worked. Considering the high value of C1 gas content and surrounding rocks, the Methane Drainage System (MDS) has been utilized for gas drainage. This paper tries to determine the desorption area which is essential and helpful for the selection of an effective drilling pattern into the adjacent coal seams. In this study, the methane drainage zone in the E4 panel of the Tabas coal mine was calculated using experimental equations and a drainage borehole pattern was determined.

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