Studying the effects of heterogeneity on dissolution processes using operator based linearization and high- resolution lidar data

Abstract

Growing demand for cleaner energy sources has led to the comprehensive investigation of high-enthalpy carbonate reservoirs. These reservoirs are often chemically and mechanically altered and hence contain a large uncertainty in the spatial distribution of the reservoir parameters. The resulting discontinuity features commonly include complex fracture networks, large inter-connected cave systems, and other flow barriers/conduits. Several conceptual models exist for simulation of such systems; however, the main driving forces behind the resulting geometry are not fully understood which complicates quantitative predictions. To improve the reservoir characterization of these complex reservoirs, high-resolution LiDAR datasets from several outcrops were acquired. Statistical analysis is performed on the geometry of the resulting cave networks. Several geometrical parameters are deduced from the LiDAR surveys which are then correlated with the possible physical processes involved. The effect of the heterogeneity of the porous media and fracture network is studied extensively using the newly developed reactive transport module in the Delft Advanced Research Terra Simulator (DARTS) framework. DARTS uses the Operator Based Linearization approach which transfers the governing nonlinear Partial Differential Equations into a linearized operator-form where the Jacobian is constructed as a product of a matrix of derivatives with respect to state variables and discretization operators. The state-dependent operators are only evaluated adaptively at vertices of the mesh introduced in the parameter-space. The continuous representation of state-dependent operators as well as their derivatives is achieved by using a multi-linear interpolation in parameter-space which significantly improves simulation performance. We extend the reactive transport module for both kinetic and equilibrium reactions which allows for more complex chemical interactions in the simulation framework. Linking the processes of wormholes creation with the aid of numerical simulations and the measured manifestation of the discontinuity networks will substantially improve the reservoir modeling process and subsequent uncertainty quantification.