Prof Andrew Garnett
Project Director - UQ-SDAAP
Director of UQ Centre for Natural Gas
Researcher biography
Andrew Garnett is Professor and Director of the UQ Centre for Natural Gas (as well as Director of the UQ CCS Program). The Centre for Natural Gas aims to be a leading provider of technical and social science research services in the unconventional gas sector.
A former Shell and Schlumberger executive, Andrew has over 25 years’ world-wide experience with oil majors in conventional and unconventional hydrocarbon exploration, appraisal and development projects.
Prior to joining The University of Queensland, Andrew consulted widely on unconventional developments, most notably those with high greenhouse gas emission footprints and worked on the 500MW, 60 MT ZeroGen IGCC & CCS Project as manager for Carbon Transport and Storage and ultimately as CEO and Project Director.
Further, Andrew was the Project Director of the UQ Surat Deep Aquifer Appraisal Project (UQ-SDAAP), which was completed in 2019. This was a 3-year project related to climate change mitigation. This scientific research project aimed to better inform public debate and policy makers on whether or not large-scale CCS could be a real option in Queensland, and also increased general understanding of Surat Basin groundwater.
| Featured projects | Duration |
|---|---|
| Scoping study for material carbon abatement via carbon capture and storage (CCS) |
Publications
Book Chapters
Garnett, Andrew (2016). Regulating well integrity. Handbook of shale gas law and policy: economics, access, law, and regulations in key jurisdictions. (pp. 213-236) edited by Tina Hunter. Online: Intersentia.
Garnett, Andrew and Greig, Chris (2014). Investing in CCS: Key project gateways. IEA CCS 2014 – What lies in store for CCS?. (pp. 44-51) edited by Juho Lipponen. Online: IEA Publications.
Journal Articles
Byrom, Steph, Bongers, Geoff, Dargusch, Paul and Garnett, Andrew (2023). Integrated policies to reduce Australia’s electricity sector greenhouse gas emissions to net zero by 2050. Energies, 16 (5) 2259, 1-17. doi: 10.3390/en16052259
La Croix, Andrew D., Sobczak, Kasia, Esterle, Joan S., Bianchi, Valeria, Wang, Jiahao, He, Jianhua, Hayes, Phil, Underschultz, Jim R. and Garnett, Andrew (2022). Integrating palynostratigraphy with zircon geochronology in the Lower Jurassic Precipice Sandstone and Evergreen Formation to improve stratigraphic correlation within the Great Artesian Basin, Australia. Marine and Petroleum Geology, 144 105845, 1-13. doi: 10.1016/j.marpetgeo.2022.105845
Lane, Joe, Greig, Chris and Garnett, Andrew (2021). Uncertain storage prospects create a conundrum for carbon capture and storage ambitions. Nature Climate Change, 11 (11), 925-936. doi: 10.1038/s41558-021-01175-7
Sobczak, Kasia, Holl, Heinz-Gerd and Garnett, Andrew (2021). Estimating porosity and permeability in the Springbok Sandstone, Surat Basin (Queensland), using new wireline log-based workflow. The APPEA Journal, 61 (2), 720-725. doi: 10.1071/aj20201
Byrom, S., Boston, A., Bongers, G., Dargusch, P., Garnett, A. and Bongers, N. (2021). Total systems cost: a better metric for valuing electricity in supply network planning and decision-making. Journal of Environmental Informatics Letters. doi: 10.3808/jeil.202100056
Byrom, Stephanie, Bongers, Geoffrey D., Dargusch, Paul, Garnett, Andrew and Boston, Andy (2020). A case study of Australia's emissions reduction policies - an electricity planner's perspective. Journal of Environmental Management, 276 111323, 111323. doi: 10.1016/j.jenvman.2020.111323
He, Jianhua, La Croix, Andrew D., Gonzalez, Sebastian, Pearce, Julie, Ding, Wenlong, Underschultz, Jim R. and Garnett, Andrew (2020). Quantifying and modelling the effects of pre-existing basement faults on folding of overlying strata in the Surat Basin, Australia: Implications for fault seal potential. Journal of Petroleum Science and Engineering, 198 108207, 108207. doi: 10.1016/j.petrol.2020.108207
La Croix, Andrew D., Harfoush, Ahmed, Rodger, Iain, Gonzalez, Sebastian, Undershultz, Jim R., Hayes, Phil and Garnett, Andrew (2019). Reservoir modelling notional CO2 injection into the precipice sandstone and evergreen formation in the Surat Basin, Australia. Petroleum Geoscience, 26 (1), petgeo2019-058. doi: 10.1144/petgeo2019-058
Berly, Thomas and Garnett, Andrew (2019). Scaling up CO2 transport and storage infrastructure. SSRN Electronic Journal, 1-7. doi: 10.2139/ssrn.3366352
Hurter, Suzanne, Rodger, Iain and Garnett, Andrew (2019). Comment on “Numerical investigation of the potential contamination of a shallow aquifer in producing coalbed methane” by Xianbo Su, Fengde Zhou, and Stephen Tyson. Energy Exploration and Exploitation, 37 (1), 593-601. doi: 10.1177/0144598718778164
Underschultz, J. R., Vink, S. and Garnett, A. (2018). Coal seam gas associated water production in Queensland: actual vs predicted. Journal of Natural Gas Science and Engineering, 52, 410-422. doi: 10.1016/j.jngse.2018.02.010
Towler, Brian, Firouzi, Mahshid, Underschultz, James, Rifkin, Will, Garnett, Andrew, Schultz, Helen, Esterle, Joan, Tyson, Stephen and Witt, Katherine (2016). An overview of the coal seam gas developments in Queensland. Journal of Natural Gas Science and Engineering, 31, 249-271. doi: 10.1016/j.jngse.2016.02.040
Lane, Joe L, Smart, Simon, Schmeda-Lopez, Diego, Hoegh-Guldberg, Ove, Garnett, Andrew, Greig, Chris and Mcfarland, Eric (2015). Understanding constraints to the transformation rate of global energy infrastructure. Wiley Interdisciplinary Reviews: Energy and Environment, 5 (1), 33-48. doi: 10.1002/wene.177
Conference Papers
Sedaghat, Mohammad, Owen, Des, Hayes, Philip, Hurter, Suzanne and Garnett, Andrew (2021). The Influence of Formation Dip Angle on Buoyancy-Induced Gas Migration During Coal Seam Gas Production. SPE/AAPG/SEG Asia Pacific Unconventional Resources Technology Conference, Online, 16-18 November 2021. Tulsa, OK United States: Unconventional Resources Technology Conference. doi: 10.15530/AP-URTEC-2021-208388
Sedaghat, Mohammad, Hayes, Philip and Garnett, Andrew (2021). Numerical Investigation of Post-Production Gas Flow Mechanisms in Coal Seams. SPE/AAPG/SEG Asia Pacific Unconventional Resources Technology Conference, Online, 16-18 November 2021. Tulsa, OK United States: Unconventional Resources Technology Conference. doi: 10.15530/AP-URTEC-2021-208349
Byrom, Stephanie, Bongers, Geoffrey, Boston, Andy and Garnett, Andrew (2020). Future roles for natural gas in decarbonising the Australian electricity supply within the NEM: Total system costs are key. SPE Asia Pacific Oil & Gas Conference and Exhibition, Online, 17-19 November 2020. Richardson, TX United States: Society of Petroleum Engineers. doi: 10.2118/202210-MS
Honari, Vahab, Wang, Xiangzeng, Underschultz, Jim, Garnett, Andrew, Wang, Xingjin, Johnson, Raymond, Ribeiro, Ayrton, Sedaghat, Mohammad, Gao, Ruimin, Liang, Quansheng and Hurter, Suzanne (2020). Evaluation of CO injectivity for CO-EOR using a two-stage well test approach: case study of a Chinese tight oil reservoir. SPE Asia Pacific Oil & Gas Conference and Exhibition, Virtual, 17-19 November. Richardson, TX, United States: Society of Petroleum Engineers. doi: 10.2118/202374-ms
Witt, Katherine and Garnett, Andrew (2020). Unconventional gas development in Queensland, Australia: How well does it align with the ‘Golden rules’ of gas?. SPE Asia Pacific Oil and Gas Conference and Exhibition 2020, APOG 2020, Online, 17 - 19 November 2020. Richardson, TX United States: Society of Petroleum Engineers. doi: 10.2118/202448-ms
Weatherley, Dion and Garnett, Andrew (2019). Trends in seismicity in the CSG producing region of the Surat Basin in Queensland. SPE/AAPG/SEG Asia Pacific Unconventional Resources Technology Conference, Brisbane, QLD, Australia, 18-19 November 2019. Tulsa, OK, USA: Unconventional Resources Technology Conference (URTEC). doi: 10.15530/AP-URTEC-2019-198329
Sedaghat, Mohammad, Owen, Des, Underschultz, James, Hurter, Suzanne, Hayes, Phil and Garnett, Andrew (2019). Water-gas flow in laminated and heterogeneous coal-interburden systems: the effects of gas solubility. SPE/AAPG/SEG Asia Pacific Unconventional Resources Technology Conference, Brisbane, QLD, Australia, 18-19 November 2019. Tulsa, OK, United States: Unconventional Resources Technology Conference. doi: 10.15530/ap-urtec-2019-198320
La Croix, Andrew D., Honari, Vahab, Gonzalez, Sebastian, Underschultz, Jim and Garnett, Andrew (2018). Impact of sequence stratigraphy on static and dynamic reservoir models: examples from the Precipice-Evergreen succession, Surat Basin, Queensland. 1st Australasian Exploration Geoscience Conference – Exploration Innovation Integration, Sydney, NSW Australia, 18-21 February 2018. Clayton South, VIC Australia: CSIRO. doi: 10.1071/aseg2018abm1_3c
Honari, Vahab, Underschultz, Jim, Wang, Xingjin, Garnett, Andrew, Wang, Xiangzeng, Gao, Ruimin and Liang, Quansheng (2018). CO2 sequestration-EOR in Yanchang oilfield, China: Estimation of CO2 storage capacity using a two-stage well test. 2018 Applied Energy Symposium and Forum, Carbon Capture, Utilization and Storage, CCUS 2018, Perth, WA, Australia, 27 - 29 June, 2018. Amsterdam, Netherlands: Elsevier BV. doi: 10.1016/j.egypro.2018.11.003
Dashti, Hossein, Underschultz, Jim, Garnett, Andrew, Honari, Vahab, Sedaghat, Mohammad and Rudolph, Victor (2018). A review of recent advances in cost-effective infrastructure system design of the CO2 distribution to CCS injection wells. SPE Asia Pacific Oil and Gas Conference and Exhibition 2018, APOGCE 2018, Brisbane, QLD Australia, 23 - 25 October 2018. Richardson, TX United States: Society of Petroleum Engineers. doi: 10.2118/192059-MS
Rodger, Iain, Garnett, Andrew and Hurter, Suzanne (2018). Simple numerical simulations to demonstrate key concepts related to Coal Seam Gas well integrity. SPE Asia Pacific Oil and Gas Conference and Exhibition 2018, APOGCE 2018, Brisbane, QLD Australia, 23-25 October 2018. Richardson, TX United States: Society of Petroleum Engineers. doi: 10.2118/192106-MS
Rodger, Iain and Garnett, Andrew (2018). Lost time analysis of Queensland coal seam gas drilling data and where next for improvement?. SPE Asia Pacific Oil and Gas Conference and Exhibition 2018, APOGCE 2018, Brisbane, QLD Australia, 23-25 October 2018. Richardson, TX United States: Society of Petroleum Engineers. doi: 10.2118/192034-MS
Duncan, Ian J., Garnett, Andrew and Underschultz, Jim (2015). The importance of accuracy of facts supporting justice based social license-to-operate arguments for CSG development: information from four decades of CBM production in North America. SEG 2015, International Conference and Exhibition, Melbourne, Australia, 13-16 September 2015. Society of Exploration Geophysicists and American Association of Petroleum Geologists. doi: 10.1190/ice2015-2211473
Hurter, S., Probst, P., Labregere, D., Garnett, A. and Holl, H. (2013). The use of dynamic models to evaluate potential large-scale CO2 storage in the gippsland basin, Victoria, Australia. International Conference on Greenhouse Gas Technologies (GHGT), Kyoto Japan, Nov 18-22, 2012. AMSTERDAM: Elsevier. doi: 10.1016/j.egypro.2013.06.252
Garnett, A., Gonzalez, S., Guiton, S. and Hurter, S. (2013). Preliminary containment evaluation in the Surat Basin, Queensland, Australia. 11th International Conference on Greenhouse Gas Control Technologies (GHGT 2012), Kyoto, Japan, 18-22 November 2012. Amsterdam, The Netherlands: Elsevier. doi: 10.1016/j.egypro.2013.06.402
Hurter, S., Marmin, N., Probst, P. and Garnett, A. (2013). Probabilistic estimates of injectivity and capacity for large scale CO2 storage in the Gippsland basin, Victoria, Australia. 11th International Conference on Greenhouse Gas Control Technologies (GHGT 2012), Kyoto, Japan, 18-22 November 2012. Amsterdam, Netherlands: Elsevier. doi: 10.1016/j.egypro.2013.06.253
Garnett, A., Hurter, S., Marmin, N., Probst, P., Gonzalez, S. and Guiton, S. (2013). Injectivity in the Surat basin, Queensland, Australia: likelihood and uncertainty evaluation. 11th International Conference on Greenhouse Gas Control Technologies (GHGT 2012), Kyoto, Japan, 18-22 November 2012. Amsterdam, The Netherlands: Elsevier. doi: 10.1016/j.egypro.2013.06.270
Gendrin, Aline, Fiah, Norzita Mat, Poupeau, Francois, Pekot, Lawrence J. and Garnett, Andrew (2013). Rewards and challenges of seismic monitoring for CO2 storage: a fluid substitution study in the Gippsland basin, Victoria, Australia. 11th International Conference on Greenhouse Gas Control Technologies (GHGT 2012), Kyoto, Japan, 18-22 November 2012. Amsterdam, The Netherlands: Elsevier. doi: 10.1016/j.egypro.2013.06.316
Hurter, S., Garnett, A., Probst, P., Pamukcu, Y., Gonzalez, S. and Guiton, S. (2013). Dynamic models of CO2 injection in the Surat and Bowen basins, Queensland, Australia. 11th International Conference on Greenhouse Gas Control Technologies (GHGT 2012), Kyoto, Japan, 18-22 November 2012. Amsterdam, The Netherlands: Elsevier. doi: 10.1016/j.egypro.2013.06.271
Hodkinson, J., Fiah, N. M., Poupeau, F., Pekot, L. J., Garnett, A. and Gonzalez, S. (2012). Building confidence in containment security and reservoir performance for CO2 geostorage at the regional scale.. Eastern Australasian Basins Symposium 2012, Brisbane / Brisbane Convention Centre, 11-14 September 2012.
Dalhius, Leon, Garnett, Andrew, Whitcombe, Jason, Galybin, Konstantin and Shafiq, Muhammad (2012). Onshore time-lapse borehole seismic project for CO2 injection monitoring. 22nd International Geophysical Conference and Exhibition, Brisbane, Australia, 26-29 February 2012. Collingwood, VIC, Australia: CSIRO. doi: 10.1071/ASEG2012ab262
Kvien, Knut, Garnett, Andrew, Carpenter, Michael E. and Arnesa, Jorg (2011). Application of the CO2QUALSTORE guideline for developing a risk-based investment schedule for an integrated CCS project. 10th International Conference on Greenhouse Gas Control Technologies, Amsterdam, The Netherlands, 19 - 23 September 2010. Amsterdam, The Netherlands: Elsevier BV. doi: 10.1016/j.egypro.2011.02.592
Garnett, Andrew, Greig, Chris and Wheeler, Chris (2011). The ZeroGen project — Managing risk and uncertainty. 10th International Conference on Greenhouse Gas Control Technologies, Amersterdam, The Netherlands, 19 - 23 September 2010. Amsterdam, The Netherlands: Elsevier. doi: 10.1016/j.egypro.2011.02.554
Kumar, Viren, Garnett, Andrew, Kumar, Giridhar Chinagandham, James, Simon David, Trivedi, Bhaskar, Salunke, Sarita and Rao, Narsimha (2010). Design operations and interpretation of CO2 and water injection tests of low permeability saline aquifer. SPE International Conference on CO2 Capture, Storage, and Utilization, New Orleans, United States, 10-12 November 2010. Richardson, TX, United States: Society of Petroleum Engineers. doi: 10.2118/139562-MS
James, Simon David, Garnett, Andrew J., Kumar, Giridhar, Kumar, Viren, Venkata, Kosuri, Rao, Narasimha, Salunke, Sarita, Trivedi, Bhaskar, Gupta, Arjit, Sarkar, Subhendu, Srinivasan, Ashwin, Meena, Prakash, Doran, Seán, Hall, Nick J. and Barlas, Peter (2010). What does it take to evaluate a potential CO2 storage site ? The ZeroGen example. 14th Abu Dhabi International Petroleum Exhibition and Conference 2010 (ADIPEC 2010), Abu Dhabi, United Arab Emirates, 1-4 November 2010. Richardson, TX, United States: Society of Petroleum Engineers. doi: 10.2118/137447-MS
Hurter, Suzanne, Garnett, Andrew Alf, Bielinski, Andreas and Kopp, Andreas (2007). Thermal Signature of Free-Phase CO2 in Porous Rocks: Detectability of CO2 by Temperature Logging. Offshore Europe, Scotland, U.K, 4 – 7 September 2007. Aberdeen, Scotland: Society of Petroleum Engineers. doi: 10.2118/109007-MS
Working Papers
Garnett, Andrew (2020). The development of US unconventional gas: 30 years of policy & technology support. UQ Centre for Natural Gas, The University of Queensland.
Garnett, Andrew (2020). Critical success factors for onshore unconventional gas: USA vs Australia. UQ Centre for Natural Gas, The University of Queensland.
Garnett, Andrew (2019). Literature review on capacity methods, storage efficiency, factors affecting injection rate decline and underlying mathematics. Scoping study for material carbon abatement via carbon capture and storage. UQ Centre for Natural Gas, Centre for Natural Gas.
Research Reports
Honari, Vahab, Gonzalez, Sebastian and Garnett, Andrew (2019). Site appraisal plan. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Honari, Vahab, Garnett, Andrew and Underschultz, Jim (2019). Risk register report. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Rodger, Iain, Garnett, Andrew and Underschultz, Jim (2019). Notional injection well design. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Wolhuter, Alexandra, Garnett, Andrew and Underschultz, Jim (2019). Notional pipeline route analysis. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Wolhuter, Alexandra, Garnett, Andrew and Underschultz, Jim (2019). Notional injection site identification report. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Honari, Vahab, Underschultz, Jim and Garnett, Andrew (2019). Appraisal well test design. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Bongers, Geoff, Byrom, Steph and Garnett, Andrew (2019). Hub development: Industrial scale deployment via retrofitting sequencing and pipeline development. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Gonzalez, Sebastian, He, Jianhua, Underschultz, Jim and Garnett, Andrew (2019). Seismic interpretation – geophysics. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Honari, Vahab, Gonzalez, Sebastian, Underschultz, Jim and Garnett, Andrew (2019). Moonie oil field history match and re-evaluation. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Rodger, Iain, Altaf, Ifti, Underschultz, Jim and Garnett, Andrew (2019). Pressure constraints on injection. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Rodger, Iain, La Croix, Andrew, Underschultz, Jim and Garnett, Andrew (2019). Transition zone behaviour test models. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Ribeiro, Ayrton Soares, Rodger, Iain, Underschultz, Jim and Garnett, Andrew (2019). Notional injection sites – injection scenarios. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Gonzalez, Sebastian, Harfoush, Ahmed, La Croix, Andrew, Underschultz, Jim and Garnett, Andrew (2019). Regional static model. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
La Croix, Andrew, Wang, Jiahao, Gonzalez, Sebastian, He, Jianhua, Underschultz, Jim and Garnett, Andrew (2019). Sequence stratigraphy of the Precipice Sandstone and Evergreen Formation in the Surat Basin. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Garnett, Andrew (2019). Experiences in adapting legacy oil and gas wells for CCS-related well testing. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Garnett, Andrew (2019). Estimates of unit costs and discussion of the value of investment in appraisal. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Garnett, Andrew and Underschultz, Jim (2019). Methodology for assessment of dynamic capacity. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Robertson, Jacqueline and Garnett, Andrew (2019). Discussion document - A regulatory review of greenhouse gas storage - governance of pressure impacts in the GAB, Queensland. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Ampofo, Kwasi and Garnett, Andrew (2019). Reviews of previous work on costs in Australian CCS. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Garnett, Andrew, Underschultz, Jim and Ashworth, Peta (2019). Scoping study for material carbon abatement via carbon capture and storage: Executive summary. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Garnett, Andrew, Underschultz, Jim and Ashworth, Peta (2019). Scoping study for material carbon abatement via carbon capture and storage: Extended socio-economic-technical summary. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Garnett, Andrew, Underschultz, Jim and Ashworth, Peta (2019). Scoping study for material carbon abatement via carbon capture and storage: Project report. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Garnett, Andrew, Underschultz, Jim, Ashworth, Peta, Honari, Vahab and Johnson, Ray (2019). Scoping study for material carbon abatement via carbon capture and storage: China engagement: Special edition. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Garnett, Andrew (2019). Literature review on capacity methods, storage efficiency, factors affecting injection rate decline and underlying mathematics. The University of Queensland Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Brisbane, Australia: The University of Queensland.
Garnett, A. and Greig, C. (2014). What lies in store for CCS?.
Zakkour, Paul, Cook, Greg, Solsberry, Lee, Heidug, Wolfgang, Garnett, Andrew and Marsh, Peter (2007). ERM - Carbon capture and stoarge in the Clena Development Machanism. 2007/TR2, April 2007 London, United Kingdom: ERM.