A Case Study of Shale Gas Well Casing Deformation in Longwall Chain Pillars Under Deep Cover.
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| Title: | A Case Study of Shale Gas Well Casing Deformation in Longwall Chain Pillars Under Deep Cover. |
|---|---|
| Authors: | Zhang, Peter1 (AUTHOR) nmb2@cdc.gov, Su, Daniel1 (AUTHOR), Van Dyke, Mark1 (AUTHOR), Kim, Bo Hyun2 (AUTHOR) |
| Source: | Rock Mechanics & Rock Engineering. May2026, Vol. 59 Issue 5, p5665-5681. 17p. |
| Subject Terms: | *Longwall mining, *Deformations (Mechanics), *Mine safety, *Computer simulation, *Geological formations, *Metrology, *Shale gas reservoirs |
| Abstract: | Shale gas wells located in longwall chain pillars are subject to longwall-induced subsurface ground movements. Longwall mining on either side of the chain pillars can induce deformations in gas well casings. Excessive casing deformations could diminish casing integrity so that intrusive shale gas might leak into the longwall mine jeopardizing mine safety. This study investigated longwall-induced casing deformations of eight shale gas wells in the chain pillars between two adjacent longwall panels in the Pittsburgh coal seam under a cover depth of 314 m. The casing deformations were measured with a 56-arm caliper after each longwall face passed the gas well pad. Casing deformations were detected at ten locations below the surface after first panel mining, and the maximum casing deformation of 1.27 cm occurred at a 184-m depth. After second panel mining, the caliper survey showed that casing deformation locations remained the same, but generally the deformations increased slightly. The maximum deformation at the 184-m depth increased from 1.27 to 1.5 cm. The eight shale gas wells were also modeled by the FLAC3D modeling technique. The casing deformations predicted by the FLAC3D model were compared with the caliper survey results. The modeling predictions were in a good agreement with the caliper measurements in terms of deformation level and locations. The modeling results suggested that the gas well setback distance to the longwall gob would affect casing deformations, and that casing deformations can be minimized if gas wells are located around the center of the abutment pillar. The study showed that longwall-induced casing deformations occur at the same weak/strong rock interfaces after both first and second panel mining. The study also showed that, under deep cover, casing deformations above the coal seam horizon are smaller than those under shallow cover. Under deep cover, the production casing deformations evaluated in this study were demonstrated to be minimized by locating gas wells at the center of the chain pillars and by leaving the production casing uncemented from the surface to below the coal seam. Highlights: Casing deformations of a shale gas well in longwall chain pillars under deep cover were measured with a multi-finger caliper and predicted by the FLAC3D modeling. The measured casing deformations above the coal seam horizon were less than 1.27 cm after first panel mining and less than 1.50 cm after second panel mining. Longwall-induced casing deformations occur at the same weak/strong rock interfaces after both first and second panel mining. Under deep cover, casing deformations above the coal seam horizon are smaller than those under shallow cover. Under deep cover, production casing deformations can be minimized by locating gas wells at the center of the chain pillars and leaving the production casing uncemented from the surface to below the coal seam. [ABSTRACT FROM AUTHOR] |
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| Header | DbId: enr DbLabel: Energy & Power Source An: 194004659 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: A Case Study of Shale Gas Well Casing Deformation in Longwall Chain Pillars Under Deep Cover. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Zhang%2C+Peter%22">Zhang, Peter</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> nmb2@cdc.gov</i><br /><searchLink fieldCode="AR" term="%22Su%2C+Daniel%22">Su, Daniel</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Van+Dyke%2C+Mark%22">Van Dyke, Mark</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Kim%2C+Bo+Hyun%22">Kim, Bo Hyun</searchLink><relatesTo>2</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Rock+Mechanics+%26+Rock+Engineering%22">Rock Mechanics & Rock Engineering</searchLink>. May2026, Vol. 59 Issue 5, p5665-5681. 17p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Longwall+mining%22">Longwall mining</searchLink><br />*<searchLink fieldCode="DE" term="%22Deformations+%28Mechanics%29%22">Deformations (Mechanics)</searchLink><br />*<searchLink fieldCode="DE" term="%22Mine+safety%22">Mine safety</searchLink><br />*<searchLink fieldCode="DE" term="%22Computer+simulation%22">Computer simulation</searchLink><br />*<searchLink fieldCode="DE" term="%22Geological+formations%22">Geological formations</searchLink><br />*<searchLink fieldCode="DE" term="%22Metrology%22">Metrology</searchLink><br />*<searchLink fieldCode="DE" term="%22Shale+gas+reservoirs%22">Shale gas reservoirs</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Shale gas wells located in longwall chain pillars are subject to longwall-induced subsurface ground movements. Longwall mining on either side of the chain pillars can induce deformations in gas well casings. Excessive casing deformations could diminish casing integrity so that intrusive shale gas might leak into the longwall mine jeopardizing mine safety. This study investigated longwall-induced casing deformations of eight shale gas wells in the chain pillars between two adjacent longwall panels in the Pittsburgh coal seam under a cover depth of 314 m. The casing deformations were measured with a 56-arm caliper after each longwall face passed the gas well pad. Casing deformations were detected at ten locations below the surface after first panel mining, and the maximum casing deformation of 1.27 cm occurred at a 184-m depth. After second panel mining, the caliper survey showed that casing deformation locations remained the same, but generally the deformations increased slightly. The maximum deformation at the 184-m depth increased from 1.27 to 1.5 cm. The eight shale gas wells were also modeled by the FLAC3D modeling technique. The casing deformations predicted by the FLAC3D model were compared with the caliper survey results. The modeling predictions were in a good agreement with the caliper measurements in terms of deformation level and locations. The modeling results suggested that the gas well setback distance to the longwall gob would affect casing deformations, and that casing deformations can be minimized if gas wells are located around the center of the abutment pillar. The study showed that longwall-induced casing deformations occur at the same weak/strong rock interfaces after both first and second panel mining. The study also showed that, under deep cover, casing deformations above the coal seam horizon are smaller than those under shallow cover. Under deep cover, the production casing deformations evaluated in this study were demonstrated to be minimized by locating gas wells at the center of the chain pillars and by leaving the production casing uncemented from the surface to below the coal seam. Highlights: Casing deformations of a shale gas well in longwall chain pillars under deep cover were measured with a multi-finger caliper and predicted by the FLAC3D modeling. The measured casing deformations above the coal seam horizon were less than 1.27 cm after first panel mining and less than 1.50 cm after second panel mining. Longwall-induced casing deformations occur at the same weak/strong rock interfaces after both first and second panel mining. Under deep cover, casing deformations above the coal seam horizon are smaller than those under shallow cover. Under deep cover, production casing deformations can be minimized by locating gas wells at the center of the chain pillars and leaving the production casing uncemented from the surface to below the coal seam. [ABSTRACT FROM AUTHOR] |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1007/s00603-024-04084-1 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 17 StartPage: 5665 Subjects: – SubjectFull: Longwall mining Type: general – SubjectFull: Deformations (Mechanics) Type: general – SubjectFull: Mine safety Type: general – SubjectFull: Computer simulation Type: general – SubjectFull: Geological formations Type: general – SubjectFull: Metrology Type: general – SubjectFull: Shale gas reservoirs Type: general Titles: – TitleFull: A Case Study of Shale Gas Well Casing Deformation in Longwall Chain Pillars Under Deep Cover. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Zhang, Peter – PersonEntity: Name: NameFull: Su, Daniel – PersonEntity: Name: NameFull: Van Dyke, Mark – PersonEntity: Name: NameFull: Kim, Bo Hyun IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 05 Text: May2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 07232632 Numbering: – Type: volume Value: 59 – Type: issue Value: 5 Titles: – TitleFull: Rock Mechanics & Rock Engineering Type: main |
| ResultId | 1 |
