Improved Calculation of Wellblock Pressures for Numerical Simulation of Non-Newtonian Polymer Injection

Summary The viability of any enhanced-oil-recovery project depends on the ability to inject the displacing fluid at an economic rate. This is typically evaluated using finite-volume numerical simulation. These simulators calculate injectivity using the Peaceman method (Peaceman 1978), which assumes that flow is Newtonian. Most polymer solutions exhibit some degree of non-Newtonian behavior resulting in a changing polymer viscosity with distance from the injection well. For shear-thinning polymer solutions, conventional simulations can overpredict injection-well bottomhole pressure (BHP) by several hundred psi, unless a computationally costly local grid refinement is used in the near-wellboreregion. We show theoretically and numerically that the Peaceman pressure-equivalent radius, based on Darcy flow, is not correct when fluids are shear thinning, and derive an analytical expression for calculating the correct radius. The expression does not depend on any particular functional relationship between polymer-solution viscosity and velocity. We test it using the relationship described by the Meter equation (Meter and Bird 1964) and the Cannella et al. (1988) correlation. Numerical tests indicate that the solution provides a significant improvement in the accuracy of BHP calculations for conventional numerical simulation, reducing or removing the need for expensive local grid refinement around the well when simulating the injection of fluids with shear-thinningnon-Newtonianrheology.

Evaluation of pond/aquifer flow exchanges using local discretization and contrasting different boundary condition in MODFLOW. Case of Santa Olalla pond (SW Spain)

<p>Almonte-Marismas is a coastal aquifer situated in Doñana Natural Park (Southwestern of Spain, Huelva). It supports one of the most important wetland areas in Europe due to its biodiversity, size and strategic location. Nowadays, the aquifer suffers serious threats due to the large amount of water extraction that takes place in the area due to the high demand for water that exists for the supply of tourism and irrigation.</p><p>There is a flow model of the regional aquifer which is used to support the water management Administration. However, this model does not take into account groundwater interactions with local ponds. Santa Olalla pond is a hypogenic wetland that, on a regional scale, it receives the discharge of the Almonte-Marismas aquifer. This fact allows it to maintain a permanent water regime without suffering a reduction in its volume of water. Despite of that, the intense pumping in the zone could affect it and be a risk in the future.</p><p>The objective of this study is the identification of an appropriate model structure to characterize and implement the Santa Olalla Pond in the current steady-state model of the regional aquifer of Doñana employing ModelMuse interface. For this purpose, different boundary conditions (LAKE and DRAIN packages) were contrasted to represent the pond, combined with different local grid refinement (LGR2 package). The contrast criteria to assess the goodness of the numerical representation have been the piezometric heads in the wells situated in the surroundings of the pond and the stage levels and water balance of the pond.</p>

Mountain-wave Induced Polar Stratospheric Clouds with ICON-ART: An Example at the Antarctic Peninsula

<p>Polar Stratospheric Clouds (PSCs) play a key role in explaining ozone depletion on large<br>scales as well as on regional scales. Mountain waves can be formed in the lee of a mountain<br>in a stably stratified atmosphere. They can propagate upwards into the stratosphere and<br>induce temperature changes in the order of 10 to 15 K. Thus, large PSCs localised around the<br>mountain ridge can be formed, leading to increased chlorine activation and subsequently to<br>a larger ozone depletion. It was estimated that 30 % of the southern hemispheric PSCs can<br>be explained by mountain waves. However, for the direct simulation of mountain-wave<br>induced PSCs, the mountains have to be represented adequately in global chemistry climate<br>models which was a challenge in the past due to too low horizontal resolution.</p><p><br>The ICOsahedral Nonhydrostatic (ICON) modelling framework with its extension for Aerosols<br>and Reactive Trace gases (ART) includes a PSC scheme coupled to the atmospheric chemistry<br>in the model. The PSC scheme calculates the formation of all three PSC types independently<br>resulting in the calculation of the heterogeneous reaction rates of chlorine and bromine<br>species on the surface of PSCs. ICON-ART provides the possibility of local grid refinement<br>with two-way interaction. With this, the grid around a mountain can be refined so that<br>mountain waves can be directly simulated in this region with a feedback to the coarser<br>global resolution.</p><p><br>In this study, we show the formation of mountain-wave induced PSCs with ICON-ART for the<br>example of a mountain wave event in July 2008 around the Antarctic Peninsula. It is<br>evaluated with satellite measurements of AIRS and CALIOP and its impact on chlorine and<br>bromine activation as well as on the ozone depletion in the southern hemisphere are<br>analysed. We demonstrate that the effect of mountain-wave induced PSCs can be<br>represented in the coarser global grid by using local grid refinement with two-way<br>interaction. Thus, this study bridges the gap between directly simulated mountain-wave<br>induced PSCs and their representation in a global simulation.</p>

Tropical cyclone induced gravity wave perturbations in the upper atmosphere: GITM-R simulations

<p>The tropical cyclone induced concentric gravity waves (CGWs) are capable of propagating upward from convective sources in the troposphere to the upper atmosphere and creating concentric traveling ionosphere disturbances (CTIDs). To examine the CGWs propagation, we implement tropical cyclone induced CGWs into the lower boundary of Global Ionosphere–Thermosphere Model with local-grid refinement (GITM-R). GITM-R is a three-dimensional non-hydrostatic general circulation model for the upper atmosphere with the local-grid refinement module to enhance the resolution at the location of interest. In this study, we simulate CGWs induced by typhoon Meranti in 2016. Information of the TC shape and moving trails is obtained from the TC best-track dataset and the gravity wave patterns are specified at the lower boundary of GITM-R (100 km altitude). The horizontal wavelength and phase speed of wave perturbation at the lower boundary are specified to be consistent with the TEC observations. The simulation results reveal a clear evolution of CTIDs, which shows reasonable agreement with the GPS-TEC observations. To further examine the dependence of the CTIDs on the wavelength and frequency of the gravity wave perturbation at the lower boundary, different waveforms have been tested as well. The magnitude of CTIDs has a negative correlation with the period, but a positive correlation with the wavelength when the horizontal phase velocities are sufficiently fast against the critical- level absorption.</p>

Numerical Modelling of Round Impinging Jet Heat Transfer Using Scale-Resolving-Simulation Methods: Influence of Local Grid Refinement

An accurate prediction of heat transfer is crucial in many engineering applications and a typical representative is heat transfer of impinging jets. The present study addresses numerical simulations using three Scale-Resolving-Simulation methods, namely the Detached Eddy Simulation, Large Eddy Simulation and the Partially Averaged Navier-Stokes. The study focus on the influence of a local grid refinement on predicted heat transfer. The closest match with experimental data was achieved with DES and PANS (fk = 0.5) models for all computational grids. The grid refinement led to an improvement of predicted results for LES and PANS with a high physical resolution (fk = 0.25).