Evaluation of Coal Body Structures and Their Distributions by Geophysical Logging Methods: Case Study in the Laochang Block, Eastern Yunnan, China

Qin, Yong; Wang, Geoff; Sun, Haixin; You, Zhenjiang; Jin, Jun; Yang, Zhaobiao

doi:10.1007/s11053-021-09834-4

Cited by 42 publications

(23 citation statements)

References 24 publications

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“…15 coal seam mainly developed along the NNE direction of fault DF 4 , which is subjected to weak tectonic stress. Most faults only developed in the coal seam, and the coal structure did not suffer severe damage (Cao et al, 2021;Zhang et al, 2021bZhang et al, , 2021c) (Figure 8).…”

Section: Evaluating the Index Of Conditions Of Preservationmentioning

confidence: 99%

Evaluation of coalbed methane resources in Xinjing Baoan block based on PCA, TOPSIS, & MLFM

Chen¹,

Jiang²,

Wu³

et al. 2022

Energy Exploration & Exploitation

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Coalbed methane (CBM) resources are abundant in the Baoan blocks of the Xinjing coalfield, China; their exploration and development remain in infancy. Suitable development blocks can be selected by evaluating their development potential; that of the No. 8 and 15 CBM systems in the Baoan blocks was evaluated using three quantitative evaluation methods via existing geological data: multi-level fuzzy mathematics (MLFM), technique for order preference by similarity to ideal solution (TOPSIS), and principal component analysis (PCA). The results demonstrated that the CBM development potential in the central part of the Baoan blocks is low and unbecoming. The favorable areas of the No. 8 coal seam are distributed in the northeast and northwest, and that of No. 15 in the northwest and southwest Differences exist in quantitative selection; with limited data, the evaluation of the TOPSIS method is considerably different from actuality, and is unbecoming for evaluating the development potential.

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Section: Evaluating the Index Of Conditions Of Preservationmentioning

confidence: 99%

Evaluation of coalbed methane resources in Xinjing Baoan block based on PCA, TOPSIS, & MLFM

Chen¹,

Jiang²,

Wu³

et al. 2022

Energy Exploration & Exploitation

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“…[13][14][15] Coal structure is affected by coal thickness, in situ stress, geological structure, and coal mine goaf; furthermore, the homogeneity of primary structural coal is better than tectonic coal. 16,17 The development degree of coal-seam fractures has significant anisotropy in both horizontal and vertical directions, which is related to the complex tectonic stress in this area. 18 The coal seam is dominated by micropores, which provide considerable storage space for adsorbed gas, and the adsorption and expansion of the coal matrix are not conducive to CBM migration.…”

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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“…In this kind of complex fracture, T-shaped and I-shaped fracture are special shapes [7,8]. The mutual influence of many factors leads to this phenomenon, such as the existence of the coalbed cleats at the interface of coalbed and cover/bottom layer [9], the large differences in the mechanical properties between coalbed and cover/bottom layer, tectonic stress of coal seams, coal blockage, interface effects of different lithologies [10,11], etc. The T-shaped and I-shaped fracture have been found in some realistic areas, and they were directly observed after HF [12].…”

Section: Introductionmentioning

confidence: 99%

3D Fracture Propagation Simulation and Pressure Decline Analysis Research for I-Shaped Fracture of Coalbed

Wang¹,

Guo

Zhang

et al. 2022

Energies

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After hydraulic fracturing, some treatments intended for production enhancement fail to yield predetermined effects. The main reason is the insufficient research about the fracture propagation mechanism. There is compelling evidence that I-shaped fracture, two horizontal fractures at the junction of coalbed and cover/bottom layer, and one vertical fracture in the coalbed have formed in part of the coalbed after hydraulic fracturing. Therefore, this paper aims at I-shaped fracture propagation simulation. A novel propagation model is derived on the basis of a three-dimensional (3D) model, and the coupling conditions of vertical fracture and horizontal fractures are established based on the flow rate distribution and the bottom-hole pressure equality, respectively. Moreover, an associated PDA (pressure decline analysis of post-fracturing) model is established. Both models complement with each other and work together to guide fracturing treatment. Finally, a field case is studied to show that the proposed models can effectively investigate and simulate fracture initiation/propagation and pressure decline.

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Evaluation of Coal Body Structures and Their Distributions by Geophysical Logging Methods: Case Study in the Laochang Block, Eastern Yunnan, China

Cited by 42 publications

References 24 publications

Evaluation of coalbed methane resources in Xinjing Baoan block based on PCA, TOPSIS, & MLFM

Evaluation of coalbed methane resources in Xinjing Baoan block based on PCA, TOPSIS, & MLFM

Impact factors and contributions of commingled production in multiple coal seams

3D Fracture Propagation Simulation and Pressure Decline Analysis Research for I-Shaped Fracture of Coalbed

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