Dynamic Evolution of the Fluid Effect of Multiple Reservoirs Due to CBM Coproduction: An Experimental Investigation

Li, Qixian; Peng, Shoujian; Yan, Fazhi; Zhou, Bin; Han, Ende; Cheng, Jin

doi:10.1021/acs.energyfuels.0c02270

Cited by 12 publications

(6 citation statements)

References 37 publications

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“…Reservoir pressure is a key force to push CBM moving from wells in the exploitation process, which is an important factor affecting the production of CBM wells. Generally, in order to avoid the influence of in situ stress at different depths, pressure gradient is considered as an important indicator to measure reservoir pressure. , …”

Section: Occurrence Features Of Cbm Resourcesmentioning

confidence: 99%

“…Generally, in order to avoid the influence of in situ stress at different depths, pressure gradient is considered as an important indicator to measure reservoir pressure. 1,72 The investigation by Zhang et al 73 on the pressure gradient in the Ordos, Qinshui, and San Juan basins show that Ordos and Qinshui both have subhydrostatic pressure gradients. Su et al 43 found that only the southern area of Qinshui Basin has high pressure, and the permeability is >1 mD (see Table 4).…”

Section: Occurrence Features Of Cbm Resourcesmentioning

confidence: 99%

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Current Status and Effective Suggestions for Efficient Exploitation of Coalbed Methane in China: A Review

et al. 2021

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The commercial production of coalbed methane (CBM) in China has made significant achievements. To further improve the production of CBM and realize its development, it is necessary to establish a unique, high-efficiency CBM production method that considers the characteristics of coal reservoirs in China. This paper presents the current status of China's CBM exploitation over the past 15 years from three aspects: reservoir characteristics, production mode, and exploitation technology. The achievements, in terms of exploration and development of CBM resources in China, were summarized. The CBM reservoirs in China are characterized by high coal rank, low permeability, high gas content, and low reservoir pressure gradient. Strategic measures for coal and CBM co-mining were proposed creatively as "Huainan", "Jincheng", and "Songzao" modes. CBM production enhancement measures have achieved significant innovations and breakthroughs in drilling and completion technologies and reservoir reconstruction, effectively reducing development costs and increasing single well production. Finally, based on existing basic research, this study proposes efficient CBM exploitation technologies suitable for the characteristics of CBM reservoirs in China. In particular, the uniform permeability enhancement measures of hydraulic grid slotting and fracturing have the advantages of safety, high efficiency, economy, feasibility, and broad application prospects under complex mining conditions. It is of great strategic significance to improve the CBM recovery rate and optimize China's energy structure.

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Section: Occurrence Features Of Cbm Resourcesmentioning

confidence: 99%

Section: Occurrence Features Of Cbm Resourcesmentioning

confidence: 99%

Current Status and Effective Suggestions for Efficient Exploitation of Coalbed Methane in China: A Review

et al. 2021

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“…23,24 Physical simulation experiments of multilayer coproduction were conducted, the influence mechanism of productivity between different production layers was preliminarily revealed, and an evaluation index of interlayer interference was put forward. [25][26][27] The evaluation and prediction of productivity used geochemical information from water produced from CBM wells. 28 To summarize, previous studies have focused on the geological background of multiseam CBM development and the simulation and evaluation of combined production capacity; however, they have not conducted research targeted at the problems that combined-layer drainage wells present, wherein they are generally unable to stabilize production, and the contribution of each production layer and the factors controlling productivity are unclear.…”

Section: Introductionmentioning

confidence: 99%

“…According to the development engineering and productivity characteristics of combined‐layer drainage wells, there is no inevitable relationship between the fracturing effect and the in‐situ permeability of the coal reservoir, and the key lies in the reformability of the reservoir 23,24 . Physical simulation experiments of multilayer coproduction were conducted, the influence mechanism of productivity between different production layers was preliminarily revealed, and an evaluation index of interlayer interference was put forward 25–27 . The evaluation and prediction of productivity used geochemical information from water produced from CBM wells 28 …”

Section: Introductionmentioning

confidence: 99%

Impact factors and contributions of commingled production in multiple coal seams

Jin

Fang

et al. 2022

Energy Science & Engineering

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The multilayer development of coalbed methane (CBM) is affected by many factors, and the gas production contribution of each seam is unclear. In this study, 12 geological and 10 engineering parameters were adopted to reveal the key factors affecting the combined-layer drainage productivity of CBM wells before using numerical simulation to clarify the contribution of each coal seam. The results show that the coal reservoir in the Laochang mining area exhibited the advantages of high gas content, intact coal body structure, and large thickness of the combined coal seams, and it was deficient with low saturation and ratio of critical desorption pressure to reservoir pressure. The medium permeability after fracturing and the influence of a small range of fracturing leads to the steep and deep pressure drop funnel of the coal reservoir, and most of the reservoir pressure drop is ineffective; this may be the reason for the unstable production and rapid attenuation of most CBM wells in the study area. The gas production of the Nos. 13 and 18 coal seams is stable and makes a significant contribution, and they can be used as the key objects of follow-up CBM exploration and development in this area. Geological factors, such as coal body structure, ratio of critical desorption pressure to reservoir pressure, thickness of combined coal seams, and gas saturation, as well as engineering factors, such as permeability and half length of fractures after fracturing, are the main factors affecting the productivity of the CBM wells in the Laochang mining area.

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“…Coalbed methane (CBM) has become one of the most important yet unconventional gas resources because it is a clean energy source with a high calorific value. In recent years, the production and utilization of CBM in China have gradually increased. , In 2019, China’s CBM production was 88.8 × 10 8 m 3 . There are still great challenges in single-well production prediction and optimization owing to the lack of accurate understanding of the internal structure of coal reservoirs and gas–water two-phase flow behavior.…”

Section: Introductionmentioning

confidence: 99%

Two-Phase Flow Model of Coalbed Methane Extraction with Different Permeability Evolutions for Hydraulic Fractures and Coal Reservoirs

et al. 2021

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Fluid flow modeling of coalbed methane (CBM) wells is effective in predicting gas production and designing appropriate depressurization schemes. Moreover, hydraulic fracturing is an important measure for improving the permeability of CBM reservoirs. In this work, we assumed the hydraulic fracture area near the main fracture to be rectangular. We developed a gas–water two-phase flow model considering the difference in stress sensitivity between the hydraulic fracturing area and the original coal reservoir. The numerical simulation results indicate that our model can accurately predict the production of CBM wells. In the early stage of CBM extraction, gas production increased with the increase of gas relative permeability. When the water saturation was below 0.7, the relative permeability of the gas phase was difficult to increase. At this time, the absolute permeability of the hydraulic fracturing area continued to decrease, leading to a decrease in gas production. Thus, if the difference of permeability evolution between the two areas is not considered, the production of CBM wells will be overestimated. In the process of CBM extraction, both reservoir pressure and water saturation decreased, but the distribution was inconsistent. The variation in reservoir pressure was mainly affected by absolute permeability and gas desorption, while the variation of water saturation was further affected by the distribution of relative permeability and initial water saturation. Therefore, the evolution of water saturation is generally more complex than that of reservoir pressure. In the hydraulic fracturing area, the effect of fracture compressibility on gas production was greater than the initial permeability. In the original coal reservoir, the larger initial permeability was more beneficial than the fracture compressibility for improving the production of CBM wells.

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Dynamic Evolution of the Fluid Effect of Multiple Reservoirs Due to CBM Coproduction: An Experimental Investigation

Cited by 12 publications

References 37 publications

Current Status and Effective Suggestions for Efficient Exploitation of Coalbed Methane in China: A Review

Current Status and Effective Suggestions for Efficient Exploitation of Coalbed Methane in China: A Review

Impact factors and contributions of commingled production in multiple coal seams

Two-Phase Flow Model of Coalbed Methane Extraction with Different Permeability Evolutions for Hydraulic Fractures and Coal Reservoirs

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