QIU Wenci, SANG Shuxun, GUO Zhijun, et al. Characteristics of stratified coal reservoirs in Liupanshui coalfield of Guizhou Province and exploration and development direction of coalbed methane[J]. Petroleum Reservoir Evaluation and Development, 2024, 14(6): 959-966.
DOI:
QIU Wenci, SANG Shuxun, GUO Zhijun, et al. Characteristics of stratified coal reservoirs in Liupanshui coalfield of Guizhou Province and exploration and development direction of coalbed methane[J]. Petroleum Reservoir Evaluation and Development, 2024, 14(6): 959-966. DOI: 10.13809/j.cnki.cn32-1825/te.2024.06.018.
Characteristics of stratified coal reservoirs in Liupanshui coalfield of Guizhou Province and exploration and development direction of coalbed methane
吸附实验,研究了各分层储层物性特征,讨论了厚煤层构造煤分层形成机制及煤层气富集模式,比较了复杂煤体结构厚煤层煤层气适配性勘探开发技术及其适用性。研究表明:①大河边向斜11号煤层平均厚度为4.48 m,厚煤层的形成是盆地沉降速率和物源沉积补偿平衡的结果,在后期挤压和推覆构造作用下,11号煤层出现挤压、破碎甚至层间滑动,构造煤分层开始发育,中部分层应力集中且煤岩力学性质偏弱;②11号煤层在垂向上发育“三明治”特征,自上而下分别为原生结构煤、糜棱煤和碎裂煤;③中部煤储层的微孔比例最高,吸附能力最强,最大吸附量的兰氏体积呈现出中分层(16.55 cm
Guizhou Province is rich in coalbed methane(CBM) resources; however
the development of tectonic coal constrains the increase of reserves and production. By studying the reservoir characteristics of tectonic coal in Guizhou
adaptable exploration and development technologies are proposed
providing a theoretical basis for the safe and efficient development of tectonic coal reservoirs in the province. Under
the control of the heterogeneous mechanical properties of coal seams and the uneven distribution of tectonic stress fields
the phenomenon of stratification in tectonic coal is more prevalent. Taking the No. 11 coal seam in the Dahebian syncline of the Liupanshui Coalfield as an example
isothermal adsorption
mercury intrusion
low-temperature liquid nitrogen adsorption
and low-temperature CO
2
adsorption experiments were conducted to study the physical properties of each stratified reservoir. The formation mechanism of tectonic coal stratification in thick coal seams and the CBM enrichment pattern were discussed. The adaptability and applicability of exploration and development technologies for CBM in thick coal seams with complex coal structures were compared. The results showed that:1) The average thickness of the No. 11 coal seam in the Dahebian syncline was 4.48 m
and the formation of thick coal seams was the result of a balance between basin subsidence rates and sedimentary supply. Under subsequent compressional and thrust tectonic activities
the No. 11 coal seam underwent compression
fracturing
and even interlayer sliding
leading to the development of stratification in tectonic coal. Stress was concentrated in the middle stratification
where the mechanical properties of the coal were weaker. 2) The No. 11 coal seam exhibited a “sandwich” structure in the vertical direction
consisting of primary structural coal on top
mylonitic coal in the middle
and fragmented coal at the bottom. 3) The middle coal reservoir had the highest proportion of micropores and the strongest adsorption capacity. The Langmuir volume of maximum adsorption followed the trend: middle stratification(16.55 cm³/g) lower stratification(14.69 cm³/g) upper stratification(13.96 cm³/g). 4) The No. 11 coal seam in the study area formed a lithology-fault-hydraulic seal gas reservoir. Based on the stratified characteristics of the coal structure
three different development technology routes were compared
and the most appli
cable direction for CBM development was identified as constructing cavities in the soft stratification of tectonic coal using horizontal wells to achieve pressure relief and CBM extraction.
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