scholarly journals Numerical Investigation of Non-Darcy Flow Regime Transitions in Shale Gas Production

2019 ◽  
Author(s):  
Dhruvit Satishchandra Berawala ◽  
Pål Østebø Andersen
Keyword(s):  
Numerical Investigation ◽  
Flow Regime ◽  
Shale Gas ◽  
Gas Production ◽  
Darcy Flow ◽  
Regime Transitions

EDFM-based Multi-Continuum Shale Gas Simulation with Low Velocity Non-Darcy Water Flow Effect

2021 ◽  
Author(s):  
Yu Jiang ◽  
John Killough ◽  
Linkai Li ◽  
Xiaona Cui ◽  
Jin Tang
Keyword(s):  
Water Flow ◽  
Shale Gas ◽  
Gas Flow ◽  
Early Stage ◽  
Knudsen Diffusion ◽  
Gas Production ◽  
Darcy Flow ◽  
Low Velocity ◽  
Water Imbibition ◽  
The Impact

Abstract The exploitation of shale gas has attracted extensive attention in industry and academia. Multi-scale gas transportation mechanisms in matrix and fractures have been well studied. However, due to the presence of water originating from both fracking fluids and connate water, shale gas production is also greatly affected by water imbibition and flowback, of which the processes have not been thoroughly analyzed. This paper aims at presenting a comprehensive multi-continuum multi-component model to characterize the complicated shale gas flow behaviors as well as the impact of non-Darcy water flow on shale gas production. A two-phase numerical simulator is built up with multi-continuum settings. Shale matrix is split into organic and inorganic matters while natural and hydraulic fractures are modeled using an embedded discrete fracture model (EDFM). Fracture closure and elongation are modeled using a dynamic gridding approach. Different transportation mechanisms are considered to describe gas flow in shale, including Knudsen diffusion, ab/desorption, and convection. The low-velocity non-Darcy flow of water is used in inorganic pores to analyze the effect of water flow. A pre-stage model based on pumping history is simulated firstly before production starts. This serves as an initialization step to model fracking fluid imbibition and early-stage water flowback. This pre-stage simulation gives out more precise pressure and saturation profiles than the conventional non-equilibrium initialization method, especially in enhanced pore volumes and fractures. Based upon simulation results from the production period, Langmuir isotherm absorption has shown a massive impact on gas flow in shale, and Knudsen diffusion weights highest among transport mechanisms. Water non-Darcy flow better benefits in simulating both early-stage water flowback and production process compared with Darcy flow, which gives us a new explanation on the low flowback efficiency in real shale gas operations. Studies on early-stage water flowback also show that the flowback affects saturation distribution, which has a strong relationship with gas production and shall not be ignored. This work establishes a novel method to simulate and analyze shale gas production. It considers multiple and complex flow mechanisms and gives out better estimates of water flux. It is also used to initialize a model for pumping water imbibition and early-stage flowback, which can be used as technical resources for analyzing and simulating unconventional plays.

scholarly journals Simulation of Gas Transport in Tight/Shale Gas Reservoirs by a Multicomponent Model Based on PEBI Grid

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Longjun Zhang ◽  
Daolun Li ◽  
Lei Wang ◽  
Detang Lu
Keyword(s):  
Shale Gas ◽  
Slip Flow ◽  
Gas Production ◽  
Darcy Flow ◽  
Molecular Flow ◽  
Flow Transition ◽  
Free Molecular Flow ◽  
Transition Flow ◽  
Gas Reservoirs ◽  
Fracture Length

The ultra-low permeability and nanosize pores of tight/shale gas reservoir would lead to non-Darcy flow including slip flow, transition flow, and free molecular flow, which cannot be described by traditional Darcy’s law. The organic content often adsorbs some gas content, while the adsorbed amount for different gas species is different. Based on these facts, we develop a new compositional model based on unstructured PEBI (perpendicular bisection) grid, which is able to characterize non-Darcy flow including slip flow, transition flow, and free molecular flow and the multicomponent adsorption in tight/shale gas reservoirs. With the proposed model, we study the effect of non-Darcy flow, length of the hydraulic fracture, and initial gas composition on gas production. The results show both non-Darcy flow and fracture length have significant influence on gas production. Ignoring non-Darcy flow would underestimate 67% cumulative gas production in lower permeable gas reservoirs. Gas production increases with fracture length. In lower permeable reservoirs, gas production increases almost linearly with the hydraulic fracture length. However, in higher permeable reservoirs, the increment of the former gradually decreases with the increase in the latter. The results also show that the presence of CO2in the formation would lower down gas production.

Numerical Investigation of liquefaction in earth dams: A Comparison of Darcy and Non-Darcy flow models

2019 ◽  
Vol 116 ◽  
pp. 103182 ◽  
Author(s):  
Farideh Hosseinejad ◽  
Farhoud Kalateh ◽  
Alireza Mojtahedi
Keyword(s):  
Numerical Investigation ◽  
Darcy Flow ◽  
Earth Dams ◽  
Flow Models
Sign in / Sign up

Export Citation Format

Share Document