Chengpeng ZhangChongqing University | CQU · Departmnt of Resources and Safety Engineering
Chengpeng Zhang
Doctor of Engineering
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45
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Introduction
Skills and Expertise
Publications
Publications (45)
Micro-proppants with stronger portability have more potential to migrate to the massive micro-sized secondary fractures (SFs) or natural fractures activated by supercritical CO2 (Sc-CO2) fracturing in shale gas reservoirs. However, the transportation behaviour of micro-proppants in massive SFs has been scarcely studied to date. In this study, we re...
Understanding the structure and flow behaviours of methane and water co-existing in shale nanopores is crucial for the optimal exploitation of shale reservoirs after hydro-fracking stimulation. In this study, a number of MD simulations are used to analyse the structure and flow pattern of such a two-phase fluid in quartz and kerogen nanoslits. Our...
Injection of CO2 into coal seams is a critical path to achieve the goals of enhanced coalbed methane recovery and carbon sequestration. Under the in-situ reservoir conditions, CO2 is likely to be stored in the form of supercritical state. Up to date, little understanding is reported regarding the influence of supercritical CO2 (SC-CO2) saturation t...
![Pd\documentclass[12pt]{minimal} \usepackage{amsmath}...](publication/358717235/figure/fig5/AS:1165244084826126@1654827247902/Pddocumentclass12ptminimal-usepackageamsmath-usepackagewasysym_Q320.jpg)
Precise gas permeability measurements of tight rocks are important for the exploration of unconventional reservoirs. Steady-state and varied unsteady-state gas permeability tests were conducted on a heat-treated siltstone. Brace’s approach ignores the sample pore volume resulting in the underestimation of sample permeability, and its discrepancy wi...
CO2 injection into coal seams can not only enhance the recovery of coalbed methane, but also achieve the goal of CO2 geological sequestration, reducing greenhouse gas emissions. CO2 is likely to be stored in the form of supercritical state, when the burial depth of coal seams exceeds 800 m. However, the existing knowledge is still lacking regarding...
To numerically investigate the stress distribution and deformation failure level of gas drainage boreholes in deep soft coal seams, ABAQUS is applied to numerical simulations based on the effective stress principle, under various conditions of compressive strengths, in-situ stresses, borehole diameters, gas pressures, and other factors. Simulation...
For a deeper understanding of the deformation failure behavior of jointed rock, numerical compression simulations are carried out on a rock specimen containing non-persistent joints under confining pressure with the bonded-particle model. The microscopic parameters which can reflect the macroscopic mechanical properties and failure behavior of arti...
Geofluids widely exist in natural rocks, and the fluid overpressure affects the mechanical behavior of rocks, triggering dynamic instability events. To investigate the role of pore fluid in low-permeability coal away from excavation boundary but still influenced by the periodic excavation disturbance, a series of undrained cyclic triaxial compressi...
The permeability of shale reservoir rock and caprock is the key parameters influencing the shale gas production and the storage security of CO2. During the CO2 enhanced shale gas recovery, the issue of how the coupled chemical-mechanical process control the evolution of porosity and permeability in shale remains undetermined. In this study, multipl...
The supercritical CO2 (ScCO2)-water-shale interaction and its influence on adsorption characteristics of shale have significant impact on the estimation of the CO2 storage capacity. In this study, the influence of ScCO2-water exposure pressures and temperatures (P = 0, 10, 15, 20 MPa, T = 308, 323, 338, 353 K) on shale CH4 and CO2 adsorption charac...
The poor proppant-carrying capacity of SC-CO2 fracturing (SCF) negates its potential advantages for the exploitation of deep unconventional gas reservoirs over traditional water-based fracturing (WBF). The low proppant concentration in SCF-created fractures leads to accelerated proppant damage behaviours under high in-situ stress, such as proppant...
Supercritical CO2 (ScCO2) fracturing is a preferred alternative to water-based fracturing for stimulation of the shale gas reservoirs, and also promotes CO2 geological sequestration. The injected ScCO2 will interact with shale minerals and then induce changes in rock matrix micromechanics. In this study, a series of nanoindentation tests was conduc...
The creep phenomenon of rocks is quite complex and the creep mechanisms are far from being well understood. Although laboratory creep tests have been carried out to determine the creep deformation of various rocks, these tests are expensive and time-consuming. Nanoindentation creep tests, as an alternative method, can be performed to investigate th...
Micro-mechanics of granite is of vital importance because it will contribute to the understanding of the deformation and failure mechanism of granite from a micro-scale perspective. The deformation and fracture properties of rocks are closely related to the mechanical properties of its basic constituents. Nanoindentation tests can be carried out to...
Proppant distribution in rough rock fractures is a key factor in the evaluation of the effectiveness of a hydraulic fracturing operation. This paper focuses on the study of how fracture roughness influences proppant transport and placement based on improved coupled computational fluid dynamics-discrete element method (CFD-DEM). Laboratory-scale syn...
Understanding the mechanical properties of α-quartz is of vital importance to rock engineering because α-quartz is the main component of igneous, metamorphic and sedimentary rocks. Molecular dynamics simulations (MDs) of nanoindentation tests on α-quartz were performed to investigate the effects of indenter tip radius and penetration depth on the m...
To better understand the CO2 sequestration and enhanced shale gas recovery, it is of great significance to study the adsorption characteristics of CO2 and CH4 in different types of shale. In this study, the mineral composition, pore structure and CH4 and CO2 adsorption isothermals of marine and continental shale samples were determined, an adsorpti...
CO2-based fracturing (CBF) has been regarded as the most promising alternative to water-based fracturing (WBF) in water-sensitive unconventional gas reservoirs, and the fracture initiation and propagation at different in-site stresses created by CBF is crucial to the flow conductivity of fracture network. The main aim of this study is to compare th...
The effect of fluid-shale interaction on the mechanical behavior of shale is of great significance for the safety of long-term CO2 sequestration in shale formations. In this paper, uniaxial compression and Brazilian splitting tests were conducted to the examine the mechanical alterations of shale caused by various fluids (brine, subcritical CO2, su...
Liquid carbon dioxide phase change fracturing (LCPCF) technology can effectively increase the coal permeability. In order to evaluate the influence of LCPCF on pore structure and permeability characteristics of coal, mercury intrusion porosimetry (MIP) analyses and permeability tests were used in this study. The experimental results show that LCPCF...
CO2 injections into shale reservoirs can enhance the recovery of oil and gas, while simultaneously sequestrating CO2. However, with the injection of CO2, the microstructure and mechanical properties alteration of shales caused by CO2/CO2-water exposure is should be noticed, which is of great importance to predicting the efficiency of CO2-enhanced s...
Nanoindentation has become an increasingly popular method to determine the mechanical properties of both homogeneous and heterogeneous materials. Rocks are inherently heterogeneous and understanding their mechanical properties is of vital importance for relevant engineering applications. Due to its high precision and resolution in both force and di...
The infilled flaws within rocks significantly influence the mechanical behavior of non-through flawed rocks. To investigate the influence of infilling on strain localization in the pre-cracking, cracking and cracking coalesce stages, experimental and numerical investigations were conducted on sandstone containing two gypsum-infilled parallel flaws,...
In this article, a series of molecular dynamics (MD) simulations were performed to investigate the impacts of indentation size, grain size and temperature on the mechanical properties of polycrystalline α-quartz under quasi-static nanoindentation with conical indenter. Results from MD simulations show that the hardness and Young’s modulus are more...
Fracture surfaces were measured using a 3-D optical topography scanner, and the fracture surfaces caused by CO2 fracturing are much rougher than those caused by water fracturing due to the stronger penetrability of CO2 through tiny pores and channels. The fracture roughness of siltstone with intensive macro-pores is greater than that of shale, beca...
Steady-state and unsteady-state (downstream pressure build-up) gas permeability tests were conducted on low permeability siltstone at a series of upstream pressures during the loading and unloading processes. The characteristics of downstream pressure build-up curves are analysed in detail, and the permeability is calculated based on the data in th...
CO2 fracturing can perform better in enhancing the unconventional gas production than water-based fracturing by avoiding serious reservoir permeability damage. The evolution of the fracture permeability of created and natural fractures during exposure to different fracturing fluids is critical to the effectiveness of CO2 fracturing. Therefore, a co...
The permeability variation of shale due to the CO2 saturation induced deformation has significant influence on the overall CO2 injection capacity and shale gas production. In this study, the effect of subcritical (SubCO2) and supercritical CO2 (ScCO2) saturation and its action time on the permeability evolution of fractured shale sample was examine...
As an alternative to water-based fracturing (WBF), CO2-based fracturing (CBF) with many unique advantages has been successfully used to enhance unconventional gas production. However, the study on the great difference of fracturing behaviours between WBF and CBF for different gas reservoirs is still scarce. The intention of this study is to investi...
The use of foam-based fracturing fluids for hydraulic fracturing has been identified as a promising technique to extract unconventional natural gases. However, lack of knowledge of foam properties and the two-phase flow behaviour of foam under high pressure makes it challenging to use in field conditions. Therefore, this comprehensive study was con...
With its low viscosity properties, CO2 has much greater penetration capacity into micro-fractures, and therefore has more potential to create expanded and effective fractures in shales during the hydraulic fracturing process. However, the feasibility of this technique is dependent on the accurate prediction of formation flow characteristics, given...
Hydraulic fracturing is essential for commercial-scale gas production from many unconventional gas reservoirs. While the effectiveness of the fractures created is associated with the stress created during the fracturing process, the use of water in the hydraulic fracturing process has been found to significantly reduce fracturing efficiency. In par...
![Figure 1. Mineral composition of shale samples [29].](publication/353430739/figure/fig1/AS:1049071280193536@1627129492504/Mineral-composition-of-shale-samples-29_Q320.jpg)
Because the limitations of water-based fracturing fluids restrict their fracturing efficiency and scope of application, liquid CO2 is regarded as a promising substitute, owing to its unique characteristics, including its greater environmental friendliness, shorter clean-up time, greater adsorption capacity than CH4 and less formation damage. Conver...
Fluid flow in a rock fracture bounded by two rock surfaces with surface asperities is a complex phenomenon to study. However, precise knowledge of the flow characteristics through a real rock fracture is essential in order to design and estimate the efficiency and production of unconventional oil and gas exploration and geothermal energy extraction...
Hydraulic fracturing is a promising technique to enhance gas production from deep geological formations by enhancing reservoir rock permeability. However, permeability enhancement may vary with reservoir conditions and fracturing fluid. The main objective of this study is to investigate the effect of fracturing fluid on the fracture pattern and per...
![Figure 3. Relationship between swelling effect and clay content [60,61].](publication/321119792/figure/fig3/AS:561491615993867@1510881441780/Relationship-between-swelling-effect-and-clay-content-60-61_Q320.jpg)
![Figure 4. The D-spacing of clay minerals in solutions [24,63,64].](publication/321119792/figure/fig4/AS:561491617083394@1510881441811/The-D-spacing-of-clay-minerals-in-solutions-24-63-64_Q320.jpg)
![Figure 5. Pore size distribution of reservoir rock [14,40].](publication/321119792/figure/fig5/AS:561491617083395@1510881441851/Pore-size-distribution-of-reservoir-rock-14-40_Q320.jpg)
Clay-abundant shale formations are quite common worldwide shale plays. This particular type of shale play has unique physico-chemical characteristics and therefore responds uniquely to the gas storage and production process. Clay minerals have huge surface areas due to prevailing laminated structures, and the deficiency in positive charges in the c...
The influence of water on the mechanical properties of rocks has been observed by many researchers in rock engineering and laboratory tests, especially for sedimentary rocks. In order to investigate the effect of water saturation on the mechanical properties of low-permeability rocks, uniaxial compression tests were conducted on siltstone with diff...
Since the secure storage of CO2 in any geological sink is largely dependent on its caprock and reservoir rock flow properties, it is necessary to check the permeability of both in assessing geological reservoirs for CO2 storage. Siltstone is a common rock type in both. On the other hand, the highly complicated thermodynamic properties of CO2 cause...
Projects
Project (1)
Nanoindentation tests and simulations will be carried out to investigate the mechanical properties of rock minerals. Inverse analysis methods will be adopted to obtain the constitutive model of these minerals of polycrystalline rocks. In addition, multi-scale analysis and asymptotic expansion homogenization (AEH) will be carried out to obtain the macro-scale properties of polycrystalline rocks using the nanoindentation results as well as the results from XRD qualification, EBSD and thin-section tests.
