scholarly journals Coalbed Methane Potential Evaluation and Development Sweet Spot Prediction Based on the Analysis of Development Geological Conditions in Yangjiapo Block, Eastern Ordos Basin, China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xinyu Fu ◽  
Yanjun Meng ◽  
Zhongcheng Li ◽  
Peng Kong ◽  
Suoliang Chang ◽  
...  
Keyword(s):  
Water Level ◽  
Coalbed Methane ◽  
Evaluation Method ◽  
Ordos Basin ◽  
Gas Content ◽  
Fuzzy Evaluation ◽  
Sweet Spot ◽  
Southeastern Part ◽  
Geological Conditions ◽  
Reduced Water

The evaluation and prediction of favorable coalbed methane (CBM) sweet spot play an important role in well location deployment and recovery prediction in CBM blocks. This work investigates the CBM geology and accumulation characteristics of No. ( 8 + 9 ) coal in the Carboniferous Taiyuan Formation in Yangjiapo block based on data from 14 CBM wells. The desorption index is proposed to be used to study the CBM desorption potential in Yangjiapo block, and the parameter of reduced water level is adopted to study the CBM hydrodynamics of the block. Furthermore, the analytical hierarchy fuzzy evaluation method is used to evaluate and prediction the CBM development sweet spot in Yangjiapo block. The results show that the buried depth of the No. ( 8 + 9 ) coal seam in Yangjiapo block varies from 693.20 to 1213.20 m, the coal thickness is from 5.40 to 13.10 m, the gas content is from 5.89 to 10.55 m3/t, and the minimum horizontal principal stress is from 9.80 to 20.82 MPa. The desorption potential is better in the southeastern and central-western part of the block. It is found that there is a positive relationship between CBM content and hydrodynamics and indicated that CBM easily concentrates in the lower reduced water level area. The CBM favorable development sweet spot is forecasted to be located in the southeastern part, central-western region, and northeastern part of Yangjiapo block.

scholarly journals Geological conditions of coalbed methane accumulation in the Hancheng area, southeastern Ordos Basin, China: Implications for coalbed methane high-yield potential

2019 ◽  
Vol 37 (3) ◽  
pp. 922-944 ◽  
Author(s):  
Chen Guo ◽  
Yucheng Xia ◽  
Dongmin Ma ◽  
Xueyang Sun ◽  
Gelian Dai ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Hot Spot ◽  
Ordos Basin ◽  
Yield Potential ◽  
High Yield ◽  
Tectonic Deformation ◽  
Critical Depth ◽  
Geological Conditions ◽  
High Yield Potential

The Hancheng area is a hot spot for coalbed methane exploration and exploitation in China. Structure is a key factor affecting coalbed methane accumulation and production in the Hancheng area. For a better understanding of the coalbed methane accumulation conditions and high-yield potential, this study investigates the structural patterns and evolution, the hydrogeological conditions, and the geothermal field in the coal-bearing strata in the Hancheng area. Then, the spatial distribution of the coalbed methane content and the tectonic deformation of the coal seam are evaluated. Finally, the critical depth for coalbed methane enrichment and a high-yield potential are revealed, and the favorable areas for coalbed methane development are predicted. The following conclusions are obtained: (1) Under the Yanshanian SE–NW trending maximum principle stress, the Hancheng overturned anticline was formed and subsequently subjected to uplift and erosion along its axis, which led to the NW limb of the anticline forming the current uniclinal structure of the Hancheng area; (2) Four degrees of tectonic deformation in the coal seam are identified based on structural curvature analysis. The moderately deformed area shallower than 800 m would benefit coalbed methane production with higher permeability. Most of the locations of coal and gas outburst events that occur during coal mining were distributed along the highly and very highly deformed areas; (3) The gas content gradually increases along the NW-trending inclination of the coal seam. 400 m and 800 m are discriminated as the critical depth levels for controlling coalbed methane accumulation and a high yield. Secondary biogenic methane was generated in the shallow formations; and (4) The Hancheng area is divided into four ranks for determining coalbed methane development potential. From high to low, they are ranked A, B-1, B-2, and C. Most of the high-yield wells are located in the areas ranked A and B-1.

Study on Coalbed Methane well Type Optimization of Badaowan Formation in Junggar Basin

2014 ◽  
Vol 535 ◽  
pp. 622-625
Author(s):  
Cheng Long Liu ◽  
Hui Guo ◽  
Xiang Hao Wang ◽  
Jin Wang
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Evaluation System ◽  
Horizontal Well ◽  
Evaluation Method ◽  
Junggar Basin ◽  
Fuzzy Evaluation ◽  
Ahp Method ◽  
Well Drilling ◽  
Coal Seam Thickness

This paper applies AHP method and fuzzy evaluation method to establish evaluation system of CBM well type in Junggar Basin. Conclusions are drawn as follows: weight of each factor which determines well type optimization is very different, coal seam depth is 0.402, coal seam thickness is 0.295, coal permeability is 0.163, coal seam dip is 0.14. Sikeshu area and center of the basin is not suitable for CBM ground drilling. Changji to Fukang area and Muleihasakexian to Wucaiwan area and East Wuerhe area are favorable for vertical well drilling. Jimusaer area is favorable for horizontal well drilling. Other areas in Junggar Basin need vertical and horizontal well joint drilling.

Structural Features Controls of Coalbed Methane (CBM) Accumulation in the Weibei CBM Field, Southeastern Ordos Basin

2014 ◽  
Vol 962-965 ◽  
pp. 79-82 ◽  
Author(s):  
Ya Dong Bai ◽  
Tao Tao Yan ◽  
Jian Guo Wu ◽  
Yong Luo
Keyword(s):  
Theoretical Analysis ◽  
Seismic Data ◽  
Coalbed Methane ◽  
Ordos Basin ◽  
Structural Features ◽  
Gas Content ◽  
Normal Faults ◽  
Distribution Characteristics ◽  
Structural Interpretation ◽  
High Consistency

Based on the structural interpretation of seismic data, we analyzed the gas controlling effects of folds and faults on CBM accumulation qualitatively. Meanwhile, we discussed the lateral sealing ability of the major overthrust faults quantificationally by bringing in “Shale Gouge Ratio (SGR)”, which is proved to be applicable in analyzing the gas controlling effects of faults. The results of the theoretical analysis show that overthrust faults have better sealing effects than normal faults, and synclines are more conducive to CBM accumulation than anticlines. The SGR computed results show a high consistency with the distribution characteristics of the CBM gas content. In all, the folds have little controlling on CBM accumulation, and the faults play a major role in the gas controlling on CBM accumulation in the Weibei CBM field.

scholarly journals Influence of Overlying Caprock on Coalbed Methane Migration in the Xutuan Coal Mine, Huaibei Coalfield, China: A Conceptional Analysis on Caprock Sealability

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Kaizhong Zhang ◽  
Qingquan Liu ◽  
Kan Jin ◽  
Liang Wang ◽  
Yuanping Cheng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Coalbed Methane ◽  
Evaluation Method ◽  
Gas Content ◽  
Factors Affecting ◽  
Coalbed Gas ◽  
Huaibei Coalfield ◽  
Main Components ◽  
The Impact

In order to determine the controlling factors affecting coalbed gas migration in the Xutuan coal mine, Huaibei Coalfield, China, overlying caprocks with Quaternary and Neogene formation (loose bed), Paleogene formation (Redbed), and coal-bearing strata were investigated via petrography, lithology, and physical properties according to laboratory tests, theoretical analysis, and on-site exploration. Results indicate that the basic properties of coal were not significantly changed whereas the effect of coalbed gas escape was promoted in the presence of Redbed and loose bed. The pore structure analysis shows that Redbed has well-developed pore connectivity than coal-bearing strata (main components are sandstone, siltstone, and mudstone). Also, the diffusion coefficient and permeability of Redbed and loose bed are proved to be a little different than those of sandstone but are much higher than those of mudstone and siltstone. Based on the aforementioned findings, investigation on the sealing mechanism of overlying caprocks on CBM migration was further discussed, interpreting that the thickness, permeation, and diffusion features are crucial factors for sealing capacity of the overlying caprock. Thus, with the simplification on the thickness of overlying strata, a conceptional analysis was carried out to theoretically estimate the sealability of caprocks from surface drilling holes; it appears, though, that the master factor on coalbed methane accumulation is coal-bearing strata instead of Redbed and loose bed with a poor sealability. In this case, the reliability of the evaluation method could be indirectly validated from the on-site gas content data of the actual coal seam to fundamentally reflect the effect of Redbed and loose bed on gas-escaping, and the impact of coal-bearing strata on gas accumulation in the coal seam.

scholarly journals Productivity subarea of CBM field and its key controlling factors: A case study in the Hancheng pilot test area, southeastern Ordos Basin, China

2018 ◽  
Vol 37 (1) ◽  
pp. 102-124 ◽  
Author(s):  
Yanfei Liu ◽  
Dazhen Tang ◽  
Song Li ◽  
Hao Xu ◽  
Shu Tao ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Ordos Basin ◽  
Gas Production ◽  
Test Area ◽  
Gas Content ◽  
Pilot Test ◽  
Coal Seams ◽  
Geological Factors ◽  
Drop Rate

The Hancheng block in the southeastern Ordos Basin is one of the earliest and the most important areas for coalbed methane exploration and development in China. However, there are significant production variations in different wells or even some adjacent wells in the Hancheng block. To reveal the reasons of production differences in such a small scale, further detailed studies of coalbed methane productivity in the Hancheng pilot test area, a precursor trial area in Hancheng block with mature, well-characterized coalbed methane reservoirs and long-term production database, were conducted. The influence of nine factors (including engineering and geological factors) on gas production was analyzed. By introducing the rough set theory, which is applicable to the vague, imprecise, and incomplete information system, this paper presents a method for quantitative evaluation of the influencing factors on gas production. The results indicate that there are certain distribution characteristics of productivity in Hancheng pilot test area, which can be partitioned into four zones. The degressive order of the influencing degree of these nine factors is (i) the distance between the well and the fault, (ii) the structure curvature of the coal seams, (iii) the gas content, (iv) the critical reservoir ratio, (v) the volume of the fracturing liquids per meter, (vi) the volume of the fracturing sand per meter, (vii) the dynamic liquid level drop rate, (viii) the depth, and (ix) the thickness. Geological factors, especially the influence of fault, structural curvature of the coal seams and gas content, play a major role in controlling long-term gas production. Engineering factors (effect of fracturing and dynamic liquid level drop rate) have always been integral parts of coalbed methane development.

Evaluation of the Gas Content of Coal Reservoirs with Geophysical Logging in Weibei Coalbed Methane Field, Southeastern Ordos Basin, China

2013 ◽  
Vol 734-737 ◽  
pp. 331-334
Author(s):  
Tao Tao Yan ◽  
Zhi Qiang Liu ◽  
Li Ren Xing ◽  
Yong Luo ◽  
Ya Dong Bai ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Gamma Ray ◽  
Ordos Basin ◽  
Measured Data ◽  
Gas Content ◽  
Burial Depth ◽  
Geophysical Logging ◽  
Natural Gamma ◽  
Geophysical Logs ◽  
Movement Intensity

Gas content is one of the most important factors in the process of exploration and development of coalbed methane (CBM). The relationships between gas content and characteristics of geophysical logs have been evaluated for the No. 5 coal seam in Weibei CBM field. It is found that the main well loggings that have good responses for gas contents are the compensating density, natural gamma-ray, compensating neutron, natural spontaneous potential and acoustic. A theoretical model was proposed to calculate the gas content by using these well logging data and as well as the burial depth. The calculated gas contents fits well with the measured data with a small relative-error of 0.38-5.05%. In the model, both tectonic movement intensity and the gas accumulation were taken into consideration. Key words: Coalbed methane, Weibei coalfield, Ordos Basin, Gas content, Geophysical logging

Comprehensive Analysis of Factors Affecting Coalbed Methane Productivity: A Case Study of Southern Qinshui Basin

2014 ◽  
Vol 962-965 ◽  
pp. 21-28
Author(s):  
Bei Liu ◽  
Wei Hua Ao ◽  
Wen Hui Huang ◽  
Qi Lu Xu ◽  
Juan Teng
Keyword(s):  
Coalbed Methane ◽  
Gas Production ◽  
Gas Content ◽  
Burial Depth ◽  
Reservoir Pressure ◽  
Factors Affecting ◽  
Qinshui Basin ◽  
Geological Conditions ◽  
Geological Factors ◽  
Southern Qinshui Basin

Coalbed methane (CBM) productivity is influenced by various factors. Based on field production data and test data of southern Qinshui Basin, factors including geological factors, engineering factors and drainage factors that affect CBM productivity are analyzed. Analytic hierarchy process (AHP) is introduced to calculate the contribution of each parameter to CBM productivity. A three-level model for evaluating CBM productivity based on AHP is established. The results show that average daily gas production of single well in southern Qinshui Basin increases with gas content, coal seam thickness, permeability, porosity, gas saturation, critical desorption pressure. Filling minerals in pores and fractures of coal can decrease gas content, porosity and permeability of coal reservoir. When burial depth is deeper than 500m or reservoir pressure is greater than 2MPa and burial depth is shallower than 1000m or reservoir pressure is less than 10MPa, CBM productivity is relatively high. According to the calculation, the weight of geological factors, engineering factors and drainage factors are 50%, 25% and 25%, respectively. Reservoir physical properties, geological conditions, fracturing technology and drainage process have the most impact, the weight of which are 33.33%, 16.67%, 11.79%, and 15.00%, respectively.

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