NMR Analysis Method of Gas Flow Pattern in the Process of Shale Gas Depletion Development

Shale gas reservoirs have pores of various sizes, in which gas flows in different patterns. The coexistence of multiple gas flow patterns is common. In order to quantitatively characterize the flow pattern in the process of shale gas depletion development, a physical simulation experiment of shale gas depletion development was designed, and a high-pressure on-line NMR analysis method of gas flow pattern in this process was proposed. The signal amplitudes of methane in pores of various sizes at different pressure levels were calculated according to the conversion relationship between the NMR T 2 relaxation time and pore radius, and then, the flow patterns of methane in pores of various sizes under different pore pressure conditions were analyzed as per the flow pattern determination criteria. It is found that there are three flow patterns in the process of shale gas depletion development, i.e., continuous medium flow, slip flow, and transitional flow, which account for 73.5%, 25.8%, and 0.7% of total gas flow, respectively. When the pore pressure is high, the continuous medium flow is dominant. With the gas production in shale reservoir, the pore pressure decreases, the Knudsen number increases, and the pore size range of slip flow zone and transitional flow zone expands. When the reservoir pressure is higher than the critical desorption pressure, the adsorbed gas is not desorbed intensively, and the produced gas is mainly free gas. When the reservoir pressure is lower than the critical desorption pressure, the adsorbed gas is gradually desorbed, and the proportion of desorbed gas in the produced gas gradually increases.

Evaluation of Nusselt Number for a Flow in a Parallel Plates Using MHD Second Order Slip Model

In this study, two separate boundary condition models, as proposed by Beskok and Karniadakis [1] and Deissler [2], widely preferred for the second order boundary condition, were used. These two proposed boundary condition models were solved in the presence of a magnetic field moving normal to the plate surface in magneto-hydrodynamic (MHD) flow between micro-parallel plates with constant wall heat flux. The energy equation for the second-order temperature jump boundary condition, taking into account the momentum and viscous dissipation, as well as the corresponding Nusselt value were solved analytically in slip flow regime.The flow of an incompressible viscous flow between fixed micro-parallel plates with electrical conductivity is assumed to be constant, laminar, hydrodynamically and thermally developed. The closed form solutions for the temperature field and the fully developed Nusselt number are derived as a function of the Magnetic parameter (MHD), Knudsen number and Brinkman number and shown graphically and in a tabular form. The second order boundary condition model proposed by Deissler [2] predicts the Nusselt number to be at lower values when compared to the first order boundary condition model, and the second order boundary condition model proposed by Beskok and Karniadakis [1] predicts the Nusselt number to be at higher values than that of the first order boundary condition model. Moreover, increasing the magnetic field parameter M, led to higher Nusselt values in the slip flow model proposed by both Deissler [2] and Beskok and Karniadakis [1] compared to that when M = 0.

Analysis of hydromagnetically modulated multiple slips motion of hybrid-nanofluid through a converging/diverging moving channel

The utility of convergent/divergent channel driven flow to improve the effectiveness of heat transport rate in industrial and engineering systems is diverse. This motivates us to disclose hybrid nanofluid flow features through non-parallel walls under hydro-magnetic aspect. The modified Darcian (Darcy–Forchheimer) expression is utilized for formulation. Reflection of improved Darcian form modifies the expression of velocity via square of velocity term. The effects of temperature jump and viscous dissipation are implemented in energy expression. Additionally, the slip flow phenomenon under the stretching/shrinking characteristics is studied. The analysis is carried out under the theory of boundary layer. Significant variables are implemented to acquire the dimensionless mathematical expressions. Dimensionless problem is tackled through a well-known homotopy technique. To observe the upshots of numerous pertinent parameters upon non-dimensional profiles of velocity and temperature, the graphs are plotted for both convergent/divergent channels. The heat transfer rate as well as drag force is also analyzed. In this study, it is concluded that temperature field rises in both divergent/convergent channels for dominant thermal slip parameter. Moreover, inertia parameter effects are seen weaker in converging channel for the velocity profile, while opposite trend is observed for diverging channel.