In-situ stress measurements and stress distribution characteristics of coal reservoirs in major coalfields in China: Implication for coalbed methane (CBM) development

Chen, Shida; Tang, Dazhen; Tao, Shu; Xu, Hao; Li, Song; Zhao, Jiaxin; Ren, Pengfei; Fu, Hengzhi

doi:10.1016/j.coal.2017.09.009

Cited by 104 publications

(55 citation statements)

References 63 publications

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“…The reservoir pressure was achieved from the injection/fall-off well test. The detailed test procedure of this method has been discussed by Hopkins et al (1998) and Chen et al (2017).…”

Section: Samples and Methodsmentioning

confidence: 99%

The gas content distribution of coal reservoir at the Changzhi block, south-central Qinshui Basin, North China: Influences of geologic structure and hydrogeology

Xiao-dong

Huang

et al. 2018

Energy Exploration & Exploitation

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Coalbed methane is now large-scalely explorated and exploitated in the world. The Changzhi coalbed methane block, south-central Qinshui Basin, is a new resource target zone for coalbed methane exploration and exploitation in China. However, the gas content distribution of this block and its influential factors have not yet studied. Based on the recent coalbed methane exploration and exploitation activities, the gas content distribution of coal reservoir in this block was studied. The results show that the gas content hold by the coal reservoir is 7.0 − 21.7 m3/t, which was determined by a combining control effect from geologic structure and hydrogeology. The Changzhi coalbed methane block has experienced multiple-stages geologic structure evolution, especially a tectonic-thermal event during the middle Yanshanian Orogeny improved the coal to the current R o,max 1.9 − 2.7% and meanwhile the coalbed methane was greatly generated. Subsequently, the widespreadly developed normal fault structures during the Himalayan Orogeny accelerated the coalbed methane escape through the “gas escape windows”, particularly where the location within the distance of about 1300 m to the “gas escape window” the gas content decreases significantly. Moreover, due to the action of the later Himalayan Orogeny, the slope areas of most Yanshanian fold structures were structurally cross-cut by the Himalayan normal faults, and thus an “open” syncline folds were formed. The coal reservoir was depressurized surrounding this “open” syncline structure and consequently the hydrodynamic losing effect has resulted in a comparatively lower gas content therein. By the control of geologic structure and hydrogeology, this block can be generally, compartmentalized into three hydrodynamic systems including the western groundwater stagnation region, the middle runoff region, and the north-eastern recharge region, where the hydrodynamic sealing effect at the groundwater stagnation region has made a comparatively higher gas content for the coal reservoir, but the hydrodynamic losing effect at the recharge region and runoff region has made a comparatively lower gas content of the coal reservoir.

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“…The reservoir pressure was achieved from the injection/fall-off well test. The detailed test procedure of this method has been discussed by Hopkins et al (1998) and Chen et al (2017).…”

Section: Samples and Methodsmentioning

confidence: 99%

The gas content distribution of coal reservoir at the Changzhi block, south-central Qinshui Basin, North China: Influences of geologic structure and hydrogeology

Xiao-dong

Huang

et al. 2018

Energy Exploration & Exploitation

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“…To make it more clearly, the scatter plot between average depth, CSI, RDR, and DGR of 45 MBHWs is shown in Figure 8. 22 The CSI of MBHW is an important engineering parameter that determines the control area and drainage volume of each well. When the depth >600 m, the average DGR of most wells is <1000 m 3 /d per well.…”

Section: Production Indexes For High Production Wellsmentioning

confidence: 99%

“…This is related to a decrease in permeability, particularly in study area with high in situ stress levels. 22 The CSI of MBHW is an important engineering parameter that determines the control area and drainage volume of each well. Figure 8B indicates that MBHW with a CSI < 3000 m always has a low gas rate.…”

Section: Production Indexes For High Production Wellsmentioning

confidence: 99%

Current status and key factors for coalbed methane development with multibranched horizontal wells in the southern Qinshui basin of China

Chen

Tang

Tao

et al. 2019

Energy Science & Engineering

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The Qinshui basin is the most successful area for coalbed methane (CBM) development in China. Since 2008, 45 multibranched horizontal wells (MBHWs) have been put into production in the Fanzhuang block, of which 10 wells have an average daily gas rate (DGR) of >10 000 m3/d. Well 4‐5 with the total gas production of 1.054 × 108 m3 achieved the China's highest DGR of 63 744 m3/d. Compared with vertical wells, MBHW is an effective way to develop CBM in low permeability reservoirs in China. However, there are still 23 wells have an average DGR of <3000 m3/d, of which 18 wells are below 1000 m3/d. The results show that shallow depth (<600 m), high gas content (>16 m3/t) and saturation (>80%), long coal seam interval (>3000 m), reasonable branch spread, and stable wellbore are the basis for achieving high production. The encountered faults connected to the aquifer will cause a high water production and an extremely low gas rate (<1000 m3/d). In the inclined coal seam, the up‐dip MBHW is more favorable for the formation water drainage and the pressure drop funnel expansion than the down‐dip MBHW, and the horizontal well should be drilled perpendicular to the high‐permeability direction to achieve a higher recovery ratio. MBHW is more sensitivity to drainage rate due to the coal fine migration in the horizontal segments, and the high pressure drop rate will lead to high frequency of stunk pump and eventually affect the gas production. Currently, the biggest challenge for CBM development with MBHW is wellbore stability. 57% of inefficient wells are caused by wellbore collapse during drilling and production processes. Here, a new type of “Roof Drilling‐Tree Shaped” horizontal well structure was presented in this work. The first “Roof Drilling‐Tree Shaped” horizontal well with a total length of 12 288 m and a coal seam interval of 9408 m was successfully applied without drilling accidents.

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“…12 In addition to that, the above phenomenon can also be observed in other coal-bearing basins due to high organic matter and the weak rock mechanical strength of coal petrography. 9,42 As shown in Figure 10, both σ H and σ h of the Jurassic formations decrease with increasing H in the study area, and the relevant relationships are expressed as Equations (11) and (12). In addition, the linear relationship between σ H and H is not obvious, showing a "three-section" change rule ( Figure 10).…”

Section: In Situ Stress Regime Change With the Depthmentioning

confidence: 99%

Characteristics of in situ stress and its influence on coalbed methane development: A case study in the eastern part of the southern Junggar Basin, NW China

Yan

Yang

et al. 2019

Energy Science & Engineering

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Based on 54 sets of well test data of 29 coalbed methane (CBM) wells, the distribution characteristic of in situ stress in the eastern part of the southern Junggar Basin and its control on permeability (K), reservoir pressure (P o ), and gas content (G) were discussed systematically. The results show that three types of in situ stress regime exist and are converted corresponding to a certain depth, (1) <600 m is the strike-slip fault regime (σ H

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In-situ stress measurements and stress distribution characteristics of coal reservoirs in major coalfields in China: Implication for coalbed methane (CBM) development

Cited by 104 publications

References 63 publications

The gas content distribution of coal reservoir at the Changzhi block, south-central Qinshui Basin, North China: Influences of geologic structure and hydrogeology

The gas content distribution of coal reservoir at the Changzhi block, south-central Qinshui Basin, North China: Influences of geologic structure and hydrogeology

Current status and key factors for coalbed methane development with multibranched horizontal wells in the southern Qinshui basin of China

Characteristics of in situ stress and its influence on coalbed methane development: A case study in the eastern part of the southern Junggar Basin, NW China

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