Investigation of permeability change in ultradeep coal seams using time-lapse pressure transient analysis: a pilot project in the Cooper Basin, Australia
| dc.contributor.author | Salmachi, A. | |
| dc.contributor.author | Dunlop, E. | |
| dc.contributor.author | Rajabi, M. | |
| dc.contributor.author | Yarmohammadtooski, Z. | |
| dc.contributor.author | Begg, S. | |
| dc.date.issued | 2019 | |
| dc.description.abstract | Very limited literature is available relating to gas production from ultradeep (>9000 ft [>2700 m]) coal seams. This paper investigates permeability enhancement in ultradeep coal seams of the late Carboniferous and early Permian to Late Triassic Cooper Basin in central Australia, using a time-lapse pressure transient analysis (PTA) approach for a pilot well. The gas production history and three extended shut-in periods are used to construct the time-lapse PTA for the study well. A new approach is introduced to construct a permeability ratio function. This function allows the calculation of permeability change resulting from competition between the compaction and coal-matrix shrinkage effects. Pressure transient analysis indicates that gas flow is dominated by a bilinear flow regime in all extended pressure buildup tests. Hence, reservoir depletion is restricted to the stimulated area near the hydraulic fracture. This implies that well-completion practices that create a large contact area with reservoirs, such as multistage hydraulically fractured horizontal wells, may be required for achieving economic success in these extremely low-permeability reservoirs. The permeability ratio is constructed using the slope of the straight lines in bilinear flow analysis. Because of uncertainty in average reservoir pressure, probabilistic analysis is used and a Monte Carlo simulation is performed to generate a set of possible permeability ratio values. The permeability ratio values indicate that coal permeability has increased during the production life of the wellbore because of the coal-matrix shrinkage effect. Permeability enhancement in this ultradeep coal reservoir has offset the effect of permeability reduction caused by compaction, which is beneficial to gas production. | |
| dc.description.statementofresponsibility | Alireza Salmachi, Erik Dunlop, Mojtaba Rajabi, Zahra Yarmohammadtooski, and Steve Begg | |
| dc.identifier.citation | American Association of Petroleum Geologists (AAPG) Bulletin, 2019; 103(1):91-107 | |
| dc.identifier.doi | 10.1306/05111817277 | |
| dc.identifier.issn | 0149-1423 | |
| dc.identifier.issn | 1558-9153 | |
| dc.identifier.orcid | Salmachi, A. [0000-0002-8192-5501] | |
| dc.identifier.orcid | Rajabi, M. [0000-0002-0114-3199] | |
| dc.identifier.orcid | Begg, S. [0000-0003-3329-9064] | |
| dc.identifier.uri | http://hdl.handle.net/2440/127365 | |
| dc.language.iso | en | |
| dc.publisher | American Association of Petroleum Geologists | |
| dc.rights | © 2019. The American Association of Petroleum Geologists. All rights reserved. | |
| dc.source.uri | https://doi.org/10.1306/05111817277 | |
| dc.title | Investigation of permeability change in ultradeep coal seams using time-lapse pressure transient analysis: a pilot project in the Cooper Basin, Australia | |
| dc.type | Journal article | |
| pubs.publication-status | Published |