A hybrid embedded discrete fracture model for simulating tight porous media with complex fracture systems

Xu, Jianchun; Sun, Baojiang; Chen, Bailian

doi:10.1016/j.petrol.2018.10.094

Cited by 53 publications

(21 citation statements)

References 51 publications

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“…The iteration carries on from inlet to outlet along the well, and by modifying inlet pressure based on the difference between assigned outlet pressure and calculated outlet pressure, the iteration would reach convergence and the flow field in the tubing will finally be obtained. The radial heat transfer between formation rock and flowing nitrogen in the casing can be calculated by Equation (8), and it involves thermal conductivity in the body of steel casing and convection between flowing fluid and casing wall.…”

Section: Solution Proceduresmentioning

confidence: 99%

“…3 However, unconventional gas resources are generally reserved in unfavorable reservoirs with low permeability, 4,5 and stimulations are always necessary to achieve economical production and recovery. [6][7][8] In recent years, the technical development in multistage hydraulic fracture in horizontal well has made it accessible to exploit shale gas commercially, which also facilitates to mitigate the energy crisis and cut its cost. 9 On the other side, water-based fracturing fluid has meet many limitations due to the huge consume of water and potential damages to the environment and underground water.…”

Section: Introductionmentioning

confidence: 99%

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Predicting the radial heat transfer in the wellbore of cryogenic nitrogen fracturing: Insights into stimulating underground reservoir

Song

Shi

Wang

et al. 2020

Energy Science & Engineering

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Cryogenic nitrogen fracturing is an attractive method for stimulating underground reservoir, since it could favorably induce complex fracture due to the huge temperature difference with lower injection pressure and with the replacement of current water‐based fracturing fluid. However, the concern about whether cryogenic nitrogen would be overheated remains unrevealed in the engineering environment with large wellbore length. In addition, reservoir stimulation results are also related with the pressure state at bottom hole. Therefore, in this study, a mathematical model was proposed to predict the radial heat transfer and its influence on vertical pressure transmission in the wellbore with cryogenic nitrogen as fracturing fluid. The model fully couples the heat transfer, hydraulics, and the compressibility of nitrogen, and then, the calculation results were presented and analyzed through a case study. According to the results, the temperature of nitrogen increases too fast under conventional engineering conditions, and it changes into gaseous state at the depth lower than 100 m. Finally, the temperature difference between nitrogen and formation rock becomes too minimal to induce thermal stress at bottom hole. Due to the fast temperature increase, the density of nitrogen decreases too much, and the vertical pressure increasing rate by liquid nitrogen (1.66 MPa/km) is merely 18.2% that in carbon dioxide fracturing (9.13 MPa/km). The results indicate that utilization of special casing with much larger thermal resistance is an indispensable approach to realize the feasibility and advantages of cryogenic nitrogen fracturing.

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Section: Solution Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Predicting the radial heat transfer in the wellbore of cryogenic nitrogen fracturing: Insights into stimulating underground reservoir

Song

Shi

Wang

et al. 2020

Energy Science & Engineering

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“…

Θ_{s}

represents the pseudo‐temperature of sand particles, m 2 s –2 .

J_{s}

stands for the energy lost due to particle collision, kg (m·s) –1 .

η_{Θ}

represents the energy lost due to fluid stickiness, kg (m·s) –1 .…”

Section: Mathematical Modelsmentioning

confidence: 99%

“…k represents the turbulence of the main phase, m 2 s –2 .

G_{k, l}

is the generation item of turbulent kinetic energy, kg (m·s) –1 .

η_{k}

and

η_{ε}

represent the turbulence exchange item of the two phases, kg (m·s) –1 .…”

Section: Mathematical Modelsmentioning

confidence: 99%

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Flow field characters near fracture entrance in supercritical carbon dioxide sand fracturing

et al. 2019

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To investigate the flow field near fracture entrance and promote the development of sand fracturing with carbon dioxide as the working fluid, numerical simulation of multiphase flow was conducted with a 3D geological model considering the compressibility of carbon dioxide. The flow field of carbon dioxide alone was firstly investigated to lay the foundation for the analysis of multiphase flow, and then comparative analysis was conducted on the flow field of both the injecting sand from the pipe and the annulus. The results show that jet fracture with carbon dioxide can achieve a 4.46 MPa pressure boost at the fracture tip compared to the annulus pressure, which theoretically validates the feasibility of the mentioned technology. Sand fracturing can achieve a higher pressure boost in the cavity, while it needs greater pump pressure at the surface. Injecting sand from the annulus could decrease the need for pump pressure by 6.62 MPa at the condition of injecting 25% carbon dioxide from the annulus simultaneously, while the pressure difference between the cavity tip and the annulus decreases as a result. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

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The simulation of transport processes in cementitious materials with embedded healing systems

Freeman

Jefferson

2019

Num Anal Meth Geomechanics

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A new model for simulating the transport of healing agents in self-healing (SH) cementitious materials is presented. The model is applicable to autonomic SH material systems in which embedded channels, or vascular networks, are used to supply healing agents to damaged zones. The essential numerical components of the model are a crack flow model, based on the Navier-Stokes equations, which is coupled to the mass balance equation for simulating unsaturated matrix flow. The driving forces for the crack flow are the capillary meniscus force and the force derived from an external (or internal) pressure applied to the liquid healing agent. The crack flow model component applies to non-uniform cracks and allows for the dynamic variation of the meniscus contact angle, as well as accounting for inertial terms. Particular attention is paid to the effects of curing on the flow characteristics. In this regard, a kinetic reaction model is presented for simulating the curing of the healing agent and a set of relationships established for representing the variation of rheological properties with the degree of cure. Data obtained in a linked experimental programme of work is employed to justif the hoi e a d fo of the o stituti e elatio ships, as ell as to ali ate the odel s evolution functions. Finally, a series of validation examples are presented that include the analysis of a series of concrete beam specimens with an embedded vascular network. These examples demonstrate the ability of the model to capture the transport behaviour of this type of SH cementitious material system.

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A hybrid embedded discrete fracture model for simulating tight porous media with complex fracture systems

Cited by 53 publications

References 51 publications

Predicting the radial heat transfer in the wellbore of cryogenic nitrogen fracturing: Insights into stimulating underground reservoir

Predicting the radial heat transfer in the wellbore of cryogenic nitrogen fracturing: Insights into stimulating underground reservoir

Flow field characters near fracture entrance in supercritical carbon dioxide sand fracturing

The simulation of transport processes in cementitious materials with embedded healing systems

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