Summary Recently, modern streamline (SL) simulation has been extended to polymer flooding. In this work, we extend the applicability of SL simulation further for efficient management of polymer-injection projects. We first present our method and then demonstrate the applicability of our approach using a Romanian field as an example. Owing to the price of polymers, an optimized injection strategy is crucial to minimize costs, maximize sweep, and thereby ensure profitability of a polymer flood. The biggest advantage of SL simulation in comparison to traditional finite-difference (FD) modeling is that polymer floods can be optimized on an individual-well-pattern basis. By being able to plot cumulative oil produced as a function of polymer injected for an individual well pattern, underperforming patterns—injectors and associated offset producers—can be indentified easily and rates, concentration, and slug size can be modified to improve the local efficiency of the flood. In this paper, we introduced a new metric—the polymer-injection efficiency as a function of time for each pattern—and we show how it is central to containing costs while improving oil recovery. We demonstrate our management method on a Romanian oil field that has been operating since 1961 with 21 injectors and 136 producers. We show that the utility factor (UF) (mass of polymers injected per volume of incremental oil produced) can be reduced while sustaining oil recovery. We conclude with a discussion on SL simulation as an enabling technology for reservoir-management decisions for polymer floods.

Recently, modern streamline simulation has been extended to polymer flooding. In this work, we extended the applicability of streamline simulation further to efficiently manage polymer injection projects. We first present our methodology and then demonstrate the applicability of our approach using a Romanian field as an example. Owing to the price of polymers, an optimised injection strategy is crucial to minimise costs, maximize sweep, and thereby ensure profitability of a polymer flood. The biggest advantage of streamline simulation compared to traditional finite-difference modelling is that polymer floods can be optimised on a well pattern basis. By being able to plot cumulative oil produced as a function of polymer injected for an individual well pattern, underperforming patterns—injectors and associated offset producers—can easily be indentified and rates, concentration, and slug size modified to improve the local efficiency of the flood. In this paper we introduced a new metric: the polymer injection efficiency as a function of time for each pattern and show how it is central to contain costs while improving oil recovery. We demonstrate our management methodology on a Romanian oil field that has been operating since 1961 with 21 injectors and 136 producers. We show that the utility factor (mass of polymers injected per volume of incremental oil produced) can be reduced while sustaining oil recovery. We conclude with a discussion on streamline simulation as an enabling technology for reservoir management decisions for polymer floods and floods in general.

Fractured reservoirs are characterised by a large difference in permeability of the fracture and matrix system. Usually, the matrix contains the bulk of the hydrocarbons while the fractures are the flow paths. These characteristics are challenging for projects aiming at increasing hydrocarbon liquid recovery from gas condensate fields by gas injection. While in fractured oil reservoirs capillary forces (imbibition) or gravity forces can be utilised to improve oil recovery, for gas injection into gas condensate reservoirs, these forces are less important.The recovery mechanisms were investigated using the properties of a rich gas condensate field located in the Middle East. A fine grid sector simulation model was created in which the fractures and matrix were introduced explicitly.Without taking diffusion into account, the injected gas breaks through at the producer very fast. The concentration in the produced gas is closely linked to the effective permeability of the fracture divided by the effective permeability of the matrix.However, taking diffusion into account, the increase in injected gas concentration is much slower. The speed of the increase (for the same pore volume injected) depends on matrix porosity, velocity of the front, fracture spacing and permeability contrast.The molecules of the injected gas are diffusing into the matrix while the components of the reservoir gas are diffusing towards the fracture. The various components have different diffusion coefficients. Dependent on the injection gas, the dew point pressure in the matrix can be reached (despite the reservoir pressure being constant) and condensate drops out. Hence, the condensate recovery depends on the injected gas.The results of the study show that neglecting diffusion in fractured reservoirs can result in errors in the condensate recovery of more than 50 %. In addition, the shape of the condensate recovery curve will be incorrect if diffusion is not accounted for.