A New Modular Approach to Comprehensive Simulation of Horizontal Wells

Abstract

Abstract The development in drilling and completion technology for horizontal wells has created new demands for enhanced comprehensive simulation methods. Wellbores with complex flow geometrics are not easily implemented in commercially available simulation tools. A modular, comprehensive modelling of well and reservoir is proposed in this paper. The model consists of a detailed horizontal well flow simulator coupled to a reservoir simulator. The wellbore simulator is based on a network mode] which is capable of solving a broad range of possible flow configurations in the horizontal part of the well. The modular approach is facilitated by a coupling technique that reduces the requirement for iteration between the modules. The simulator is applied to high flowrate horizontal wells in thin oil zones with high permeability. Due to the flexibility in wellbore configuration, the simulator may be used to optimize well location, well path and completion approach. The coupling provides a detached wellbore simulation module which is reservoir simulator independent. The new simulation approach should be considered for horizontal wells where frictional pressure loss or geological inhomogeneities along the well are of importance to a well's production performance. The simulator will be used to evaluate completions with a complex flow configuration, potential cross-flow and for optimization of production and injection performance of wells in heterogeneous reservoirs. Introduction Optimizing the inflow to long horizontal wells has been recognized as a critical research area with a high potential for increased production rates. New completion designs for horizontal wells have recently been proposed for improved well productivity and reduced production problems. A typical inflow control liner design for use in high permeability, thin oil zones is shown in Figure 1. Efficient use of these completion designs requires that the flow inside the completion can be calculated in a more detailed way than what is possible with available reservoir simulation packages. Thus, a detailed flow simulator for horizontal well completions was developed for modular integration with reservoir simulators. The modular simulator approach is illustrated in Figure 2. The implementation of a detailed near wellbore simulator as indicated in the figure is recognized to be of great importance for prediction of local geology effects on the inflow, but was not within the scope of this study. A modular, comprehensive simulation of the reservoir and the well has shown to be feasible through a coupling project involving a detailed horizontal wellbore simulator (HOSIM) and a 3D, two phase reservoir simulator (FRONTSIM). Based on the experience from this coupling project, a modular. iterative coupling approach was developed between HOSIM and a general black oil reservoir-simulator, which we refer to as RESIM. Enhanced Wellbore Simulation The horizontal wellbore simulator (HOSIM) is based on a general network solver for calculation of steady state flow through wellbore completions. The network solver which was originally developed for use with gas pipeline systems has been modified to perform steady state simulation of horizontal wells. As the network solver also is capable of determining the direction of flow, the simulator can be used for injection wells as well as for indicating cross flow between formations. P. 109^