Simulation of Field Roll-Out of Polymer Injection and Pattern Optimization
Research output: Research › Master's Thesis
The growing global energy demand is one of the key drivers for the development of enhanced depletion methods in order to optimize the recovery efficiency of existing hydrocarbon reservoirs. Polymer-flooding is a sophisticated tertiary recovery method, which addresses the improvement of the macroscopic sweep efficiency in terms of an efficient mobility control. The technology has been successfully applied by OMV E&P GmbH as part of an unconfined pilot-test in the 8 TH reservoir of the Matzen-field. However, in order to implement polymer injection on a larger scale, it is necessary to transfer the test results to full-field conditions. These conditions are significantly different from pilot tests as inter-pattern crossflow of the injected polymer-solution is influencing the production behavior of neighboring patterns. The main goal of this thesis is to investigate the performance of polymer-flooding within confined production patterns, which are representative for a sector and full field roll-out. Based on numerical reservoir simulation, a number of different pattern configurations under various confinement scenarios are modeled in order to evaluate the influence of inter-pattern crossflow for tertiary displacement processes. The dynamic reservoir model is used to improve a fundamental understanding about subsurface flow-dynamics during polymer-flooding on field-scale. It is shown that incremental oil increases within confined production patterns, but the increment can be attributed to pattern-external areas. On the other hand, the study demonstrates the impact of productivity problems for polymer-flooding using vertical wellbores in low permeability reservoirs. The advantages of horizontal wells are revealed based on an improved productivity index, which decreases the susceptibility to production related issues. Eventually, this thesis addresses the question of an optimal pattern design for polymer-flooding as part of a field roll-out. A set of different pattern configurations are investigated and evaluated based on various key performance indicators, which can be seen as a general benchmark for tertiary recovery projects. The study highlights that for horizontal wellbores the cumulative oil production improves with increasing well spacing. However, a large injector-producer spacing shows a deferment of the arrival of the displacement front, which affects the economic profile of polymer-flooding ventures.