Department of Engineering,
Cambridge , Cambs CB2 1PZ
John joined the Geotechnical Research Group in October 2012 to conduct research on deep geomechanics with support from Engineering and Physcial Science Research Council (EPSRC) Industrial CASE Award, Hong Kong Institution of Engineers (HKIE) Young Engineers Arthur & Louise May Memorial Scholarship and Arup. He is a member of Churchill College.
He obtained his Bachelor degree from the University of Hong Kong in 2005. He was awarded Excellent Performance Award in 3rd Inter-University Invitational Civil Engineering Competition, a 7 day competition among 7 top Asian universities. He pursued a part-time Master’s degree from Hong Kong University of Science and Technology in 2007 and was awarded Excellent Student Scholarship.
With 7 years spent in the industry, John is a Chartered Engineer with professional memberships of Institution of Civil Engineers (ICE) and Hong Kong Institution of Engineers (HKIE). After graduation, he joined the Hong Kong Special Administration Region (HKSAR) Government as a Civil Engineering Graduate and was promoted to Assistant Civil Engineer in 2008, with a short period of training in Mainland China at a province-level government institution - Chongqing Municipal Construction Commission.
In 2009, John switched his career to AECOM, a Forbes 500 company and the largest engineering consultancy in Hong Kong. He specialized in the geotechnics, particular in underground construction. Before he started his PhD study in Cambridge, he had been promoted to Project Engineer leading a small team of young engineers. He was awarded Chief Executive Best Win Award in 2009 and John Downer Excellent Awards – Best Large Project.
John has been involved in several mega scale underground railway projects in Hong Kong, including West Island Line, Grangzhou-Shenzhen-Hong Kong Express Rail Link and Shatin to Central Link. He was also involved in MRT Blue Line Extension in Bangkok. He specializes mainly in soil structure interaction problems including deep excavation and soft ground tunneling by TBM or NATM methods in heavily built-up areas. Moreover, he has been involved in some specialized topics such as Artificial Ground Freezing. He has also acquired some structural engineering experience and designed a 117m span cycle track bridge. Furthermore, he has more than 2 years of resident site experience including a mega site at Central Reclamation Phase III (Hong Kong).
Hydraulic Fracturing Simulation using Lattice Element Method
Hydraulic fracturing (HF) is first used in oil/gas industries for enhancing the production of conventional resources. HF simulators were therefore developed for such purposes. The reservoir rock, mainly sandstone, is considered homogeneous and permeable. The following assumptions/simplifications are often made
- Reduce the problem from 3D to 2D (so call pseudo-3D or planar-3D)
- Rock is continuous, homogeneous and isotropic without natural fractures
Now, the heterogeneity nature of reservoir has drawn the attention for extraction of unconventional resources. It is believed that the success of shale gas extraction relies on how well new fractures connecting existing natural fracture network. Also, for the assessment of the environmental concerns associated with HF, namely induced seismicity and contamination, proper modelling of natural fracture is required. From mineback experiments and microseismic monitoring, it is evident that the induced fractures are much complex than an ideal planar bi-wing fractures as predicted by conventional HF simulators. Therefore, there is a pressing need for new simulators that take into account for natural fractures and capable for large scale 3D simulation for complex ground condition on site.
Newly developed HF Simulator based on Lattice Element Method (LEM)
LEM use a lattice network that represent a rock mass. For a 3D problem, the basic unit of LEM is still 1D lattice element. Cambridge University is developing a C++ codes based on LEM. The code can generate a disordered lattice network to represent local heterogeneity of reservoir and support the manual input of larger discontinuities. Fracturing can be simply modelled by removing lattice. The code also includes a fluid module that simulates fracture flow by 1D pipe flow network. The fluid module is fully coupled with LEM such that the fracture permeability varies with fracture aperture. The code also includes highly efficient solver which supports multi-core CPU / GPU for fast computation.
- Full 3D model. Without the need of over-simplification of complex reservoir and large amount of interpretation to translate a 3D problem into a 2D one.
- Straightforward representation of fracture propagation without using advanced mathematical techniques
- Complex fracture (Non-planar, branching, etc) can be simulated with interaction between fractures (natural and induced)
- Fast computation. The basic unit of solid phase and liquid phase are all 1D for 3D problems. Efficient parallelized solver enables 3D HF simulation using desktop computers
1. 3D2 Geotechnical Engineering II
2. 3D3 Construction Material
3. 3D8 Building Physics and Environmental Geotechnics
1. J.K.-W. Wong, K. Soga, X. Xu, J.-Y. Delenne, Modelling fracturing process of geomaterial using Lattice Element Method. Proceedings of International Symposium on Geomechanics from Micro to Macro, Cambridge, United Kingdom, 2014.
2. J.K.-W. Wong, K. Soga, X. Xu, J.-Y. Delenne, Three dimensional hydraulic fracturing simulation using Lattice Element Method. Proceedings of ISRM 13th International Congress on Rock Mechanics, Montreal, Canada, 2015 (Submitted).