Qinghua Lei

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Lei

First Name

Qinghua

ORCID

0000-0002-3990-4707

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Publications 1 - 10 of 120

Modelling the reservoir-to-tubing pressure drop imposed by multiple autonomous inflow control devices installed in a single completion joint in a horizontal well
Lei, Qinghua; Jackson, Matthew D.; Muggeridge, Ann H.; et al. (2020)
Journal of Petroleum Science and Engineering
A fluid-solid coupled approach for numerical modeling of near-wellbore hydraulic fracturing and flow dynamics with adaptive mesh refinement
Obeysekara, Asiri; Lei, Qinghua; Salinas, Pablo; et al. (2016)
50th US Rock Mechanics/Geomechanics Symposium 2016
Mechanisms of Reservoir Impoundment-induced Large Deformation of the Guobu Slope at the Laxiwa Hydropower Station, China: Preliminary Insights from Remote Sensing and Numerical Modelling
Lesche, Moritz; Wang, Liang; Manconi, Andrea; et al. (2024)
Environmental Engineering Science ~ Engineering Geology for a Habitable Earth: IAEG XIV Congress 2023 Proceedings, Chengdu, China. Volume 4: Technological Innovation and Application for Engineering Geology
The construction/operation of ultrahigh arch dams may impose significant perturbations to surrounding mountains, resulting in landslide motions of rock slopes and endangering the safety of hydropower systems and human habitats. For example, the Laxiwa Hydropower Station in China witnessed its nearby Guobu slope displacing significantly after the reservoir impoundment and having so far displaced up to ~40 m. It is of great importance to understand the mechanisms driving this large deformation. Here, we present some preliminary results from a combined remote sensing and numerical modelling investigation of this slope before, during, and after the reservoir impoundment. Analysis based on the differential interferometric synthetic aperture radar (DInSAR) data indicates that the slope had already been actively creeping at a rate of ~10 cm/year (e.g. in years of 2003-2005). We develop a geological model including different rock mass compartments and various discontinuity structures as well as a realistic representation of the suspended ancient landslide. We model the coupled hydro-mechanical and creep behaviour of the slope in response to reservoir impoundment. A good agreement is reached between the simulation results and field measurements of slope displacement time series recorded at different elevations of the slope surface. Our results show that the reservoir impoundment causes notable pressure changes at the toe region of the slope, leading to strong deformations (under coupled poroelastic and primary creep effects) that propagate upslope with the ancient landslide partially reactivated. These deformations tend to decelerate significantly after the impoundment due to the transition to secondary creeps.
A multiphysics platform for modelling coupled deformation, damage, flow and transport in fractured rocks
Lei, Qinghua; Gholizadeh Doonechaly, Nima; Wang, Xiaoguang; et al. (2019)
DECOVALEX 2019 Symposium Abstracts
Combined effects of thermal perturbation and in-situ stress on heat transfer in fractured geothermal reservoirs
Sun, Zhixue; Jiang, Chuanyin; Wang, Xiaoguang; et al. (2021)
Rock Mechanics and Rock Engineering
We develop a new fully coupled thermo-hydro-mechanical (THM) model to investigate the combined effects of thermal perturbation and in-situ stress on heat transfer in two-dimensional fractured rocks. We quantitatively analyze the influence of geomechanical boundary constraints and initial reservoir temperature on the evolutionary behavior of fracture aperture, fluid flow and heat transfer, and further identify the underlying mechanisms dominating the coupled THM processes. The results reveal that, apart from enhancing normal opening of fractures, the transient cooling effect of thermal front may trigger shear dilations under the anisotropic in-situ stress condition. It is found that the applied in-situ stress tends to impose a strong impact on the spatial and temporal variations of fracture apertures and flow rates, and eventually affect heat transfer. The enhancement of reservoir transmissivity during transient cooling tends to be significantly overestimated if the in-situ stress effect is not incorporated, which may lead to unrealistic predictions of heat extraction performance. Our study also provides physical insights into a fundamental thermo-poroelastic behavior of fractured rocks, where fracture aperture evolution during heat extraction tends to be simultaneously governed by two mechanisms: (1) thermal expansion-induced local aperture enlargement and (2) thermal propagation-induced remote aperture variation (can either increase or decrease). The results from our study have important implications for optimizing heat extraction efficiency and managing seismic hazards during fluid injections in geothermal reservoirs.
A novel approach to optimising well trajectory in heterogeneous reservoirs based on the fast-marching method
Lyu, Zehao; Lei, Qinghua; Yang, Liang; et al. (2021)
Journal of Natural Gas Science and Engineering
To achieve efficient recovery of subsurface energy resources, a suitable trajectory needs to be identified for the production well. In this study, a new approach is presented for automated identification of optimum well trajectories in heterogeneous oil/gas reservoirs. The optimisation procedures are as follows. First, a productivity potential map is generated based on the site characterisation data of a reservoir (when available). Second, based on the fast-marching method, well paths are generated from a number of entrance positions to a number of exit points at opposite sides of the reservoir. The well trajectory is also locally constrained by a prescribed maximum curvature to ensure that the well trajectory is drillable. Finally, the optimum well trajectory is selected from all the candidate paths based on the calculation of a benefit-to-cost ratio. If required, a straight directional well path, may also be derived through a linear approximation to the optimised non-linear trajectory by least squares analysis. Model performance has been demonstrated in both 2D and 3D. In the 2D example, the benefit-to-cost ratio of the optimised well is much higher than that of a straight well; in the 3D example, laterals of various curvatures are generated. The applicability of the method is tested by exploring different reservoir heterogeneities and curvature constraints. This approach can be applied to determine the entrance/exit positions and the well path for subsurface energy system development, which is useful for field applications.
Modelling stress-dependent single and multi-phase flows in fractured porous media based on an immersed-body method with mesh adaptivity
Obeysekara, Asiri; Lei, Qinghua; Salinas, Pablo; et al. (2018)
Computers and Geotechnics
This paper presents a novel approach for hydromechanical modelling of fractured rocks by linking a finite-discrete element solid model with a control volume-finite element fluid model based on an immersed-body approach. The adaptive meshing capability permits flow within/near fractures to be accurately captured by locally-refined mesh. The model is validated against analytical solutions for single-phase flow through a smooth/rough fracture and reported numerical solutions for multi-phase flow through intersecting fractures. Examples of modelling single- and multi-phase flows through fracture networks under in situ stresses are further presented, illustrating the important geomechanical effects on the hydrological behaviour of fractured porous media.
Polyaxial stress-induced variable aperture model for persistent 3D fracture networks
Lei, Qinghua; Latham, John-Paul; Xiang, Jiansheng; et al. (2015)
Geomechanics for Energy and the Environment
Fluid injection-induced off-fault deformation and seismicity in shallow crustal faults: Preliminary results from fully-coupled hydro-mechanical simulations
Lei, Qinghua; Brixel, Bernard (2021)
Abstract Volume 19th Swiss Geoscience Meeting
Interactive roles of geometrical distribution and geomechanical deformation of fracture networks in fluid flow through fractured geological media
Lei, Qinghua; Wang, Xiaoguang; Min, Ki‐Bok; et al. (2020)
Journal of Rock Mechanics and Geotechnical Engineering
In this study, the combined effects of geometrical distribution and geomechanical deformation of fracture networks on fluid flow through fractured geological media are investigated numerically. We consider a finite-sized model domain in which the geometry of fracture systems follows a power-law length scaling. The geomechanical response of the fractured rock is simulated using a hybrid finite-discrete element model, which can capture the deformation of intact rocks, the interaction of matrix blocks, the displacement of discrete fractures and the propagation of new cracks. Under far-field stress loading, the locally variable stress distribution in the fractured rock leads to a stress-dependent variable aperture field controlled by compression-induced closure and shear-induced dilatancy of rough fractures. The equivalent permeability of the deformed fractured rock is calculated by solving for the fracture-matrix flow considering the cubic relationship between fracture aperture and flow rate at each local fracture segment. We report that the geometrical connectivity of fracture networks plays a critical role in the hydromechanical processes in fractured rocks. A well-connected fracture system under a high stress ratio condition exhibits intense frictional sliding and large fracture dilation/opening, leading to greater rock mass permeability. However, a disconnected fracture network accommodates much less fracture shearing and opening, and has much lower bulk permeability. We further propose an analytical solution for the relationship between the equivalent permeability of fractured rocks and the connectivity metric (i.e. percolation parameter) of fracture networks, which yields an excellent match to the numerical results. We infer that fluid flow through a well-connected system is governed by traversing channels (forming an “in parallel” architecture) and thus equivalent permeability is sensitive to stress loading (due to stress-dependent fracture permeability), whilst fluid flow through a disconnected system is more ruled by matrix (linking isolated clusters “in series”) and has much less stress dependency.

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Qinghua Lei

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