Two polymer pilot tests (PO and PT) have been performed in the Central Area of Daqing Oil Field. The purpose is (1) to study further the economic benefits of polymer flooding in thick heterogeneous reservoirs, (2) to provide some technical and practical experiences for expanding this technique to other areas of Daqing Oil Field. During the polymer pilot tests, a large amount of performance information (such as injection pressure, injection profiles, C/O logging, tracer tests, core data from inspection wells, salinity of effluent fluid as well as the concentration and viscosity of polymer solution in the injected and produced fluids etc.) were collected. In this paper, the results of the polymer flood were evaluated comprehensively by analysing the information. Good results were obtained in the polymer pilot tests. The volumetric sweep efficiency and oil production were all increased. Incremental oil production is more than 200 tons per ton of polymer injected. Oil recovery increased more than 11 % of OOIP. All of these confirm that polymer flooding is very applicable to Daqing Oil Field. In the course of evaluating the results, follow-up matching and result prediction of the polymer flood were performed by numerical simulation. In order to obtain the best economic results, when executing the design or adjusting the project, a new "normalized method" was developed. By applying this method, the results of polymer flooding were evaluated at different stages. This paper demonstrates the effect of Dykstra Parsons permeability coefficient (Vk) on polymer flooding results and presents a optimum range of the Vk value applicable for polymer flooding in Daqing Oil Field. The relationship of the amount of polymer injected versus economic results and the polymer flooding result in multi-layer reservoirs are also discussed and opinions are given. All of these are important to later project design and result evaluation of polymer flooding in Daqing Oil Field.
An enhanced oil recovery (EOR) study by polymer flooding began in 1985 for the Central Area of Daqing Oil Field. With the cooperation of technical people in China and France, a feasibility study for polymer flooding was accomplished in Institut Francais du Petrole (IFP). This study included screening of polymer products, reservoir description as well as design of an optimum displacement project etc.. The relative results have been reported previously. This paper only deals with results of the polymer flooding pilot tests. In these two polymer pilot areas, preflush water Injection began In December 1989. Injection of polymer solution started in August 1990. The pilot tests ended when the water cut reached 98% in the central wells.
The polymer pilot site is located in the West Central area of Daqing Oil Field which is in the center of a water flooding development region and belongs to a larger hydrodynamic system as shown in Fig. 1.