TY - JOUR
T1 - Dynamic impacts on the survivability of shale gas wells piercing longwall panels
AU - Liang, Shun
AU - Elsworth, Derek
AU - Li, Xuehua
AU - Fu, Xuehai
AU - Yang, Dong
AU - Yao, Qiangling
AU - Wang, Yi
N1 - Funding Information:
Financial support for this work, provided by the National Natural Science Foundation of China (Nos. 51474208 and 51304208 ), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) , the Program for Postgraduate Research Innovation in Universities of Jiangsu Province (No. CXZZ12_0951 ) and the China Scholarship Council ( 201206420029 ), is gratefully acknowledged.
Publisher Copyright:
© 2015 Elsevier B.V..
PY - 2015/9/1
Y1 - 2015/9/1
N2 - Gas wells traversing active longwall panels are susceptible to failure on account of various strata movements induced by mining activities. To reveal the dynamic impacts of longwall mining on the survivability of these shale gas wells, particularly during the mining cycle as the twin flanking panels successively approach and then pass beyond the wells, a three dimensional finite element model is applied to explore the evolution of potential distress to the wells by defining the magnitudes of various well deformations. The results demonstrate that, wellbores undergo accelerated or significant deformation (increase or decrease) when each advancing panel approaches within tens of meters and the deformation stabilizes as the panel passes the well by tens (deep mining, ~300 m) or up to one hundred plus (shallow mining, ~100 m) meters. Wells are more susceptible to instability when each panel, especially the second panel, advances past the well by approximately 50 m in the case of deep mining and more than one hundred meters for shallow mining with the accumulative deformation reaching the maximum. For mining at shallow depths (~100 m), wells deform by axial compaction, longitudinal distortion, lateral compression and tension in the vicinity of the seam, and by shear in layers close to the surface. Conversely, for deep mining (~300 m) the most severe deformations are mainly restricted to the seam and its shallow roof and floor. Locating the well slightly closer to the rib of the second advancing panel (e.g., 7.5 m out from the pillar-center for a 50 m wide three-entry longwall pillar) achieves improved well integrity.
AB - Gas wells traversing active longwall panels are susceptible to failure on account of various strata movements induced by mining activities. To reveal the dynamic impacts of longwall mining on the survivability of these shale gas wells, particularly during the mining cycle as the twin flanking panels successively approach and then pass beyond the wells, a three dimensional finite element model is applied to explore the evolution of potential distress to the wells by defining the magnitudes of various well deformations. The results demonstrate that, wellbores undergo accelerated or significant deformation (increase or decrease) when each advancing panel approaches within tens of meters and the deformation stabilizes as the panel passes the well by tens (deep mining, ~300 m) or up to one hundred plus (shallow mining, ~100 m) meters. Wells are more susceptible to instability when each panel, especially the second panel, advances past the well by approximately 50 m in the case of deep mining and more than one hundred meters for shallow mining with the accumulative deformation reaching the maximum. For mining at shallow depths (~100 m), wells deform by axial compaction, longitudinal distortion, lateral compression and tension in the vicinity of the seam, and by shear in layers close to the surface. Conversely, for deep mining (~300 m) the most severe deformations are mainly restricted to the seam and its shallow roof and floor. Locating the well slightly closer to the rib of the second advancing panel (e.g., 7.5 m out from the pillar-center for a 50 m wide three-entry longwall pillar) achieves improved well integrity.
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U2 - 10.1016/j.jngse.2015.08.008
DO - 10.1016/j.jngse.2015.08.008
M3 - Article
AN - SCOPUS:84940195012
SN - 1875-5100
VL - 26
SP - 1130
EP - 1147
JO - Journal of Natural Gas Science and Engineering
JF - Journal of Natural Gas Science and Engineering
ER -