The displacement target of the ASP flooding in Daqing Oilfield has gradually shifted to class II reservoirs, which are characterized by multiple layers and great difference in permeabilities. The percentage of 3-5 layer injection wells has reached more than 50%. Currently, there are two main problems existing with the separate injection technology. First, due to the different microscopic molecular structure of the ASP solution, the viscosity loss of the ASP solution is more than 1 times higher than that of the polymer under the same injection conditions, which affects the displacement effect of ASP flooding. Second, the ASP system of a single molecular weight cannot meet the displacement requirements of all oil layers. To solve the two problems, a separate molecular weight and pressure injection technology is developed for ASP flooding. Based on the microscopic mechanism and simulation study, the separate molecular weight and pressure injection technology for ASP flooding is developed in this paper. The injection string can inject different ASP solutions of different molecular weights into different layers at different injection rates as required to match different oil layer permeabilities. Thus, the control of molecular weight and injection rate for separate layers in ASP flooding can be achieved. At the flow rate of 50m3/d, the adjustment range of molecular weight is 20-50%, the maximum throttling pressure difference can reach 1.5MPa or more, and the maximum loss of viscosity is less than 7.8%. Up to now, this technology has been applied to the field tests of more than 800 wells. Since the application of this technology, the injection profile has been effectively improved, and the pay-gross thickness ratio has been increased by 8%. With this technology, the separate injection for 3-5 layers and control of molecular weight as well as injection rate for separate layers to match the different oil layer permeabilities in ASP flooding can be achieved. This technology will play an important role in the development of major oil fields in the future.
At present, the technology of ASP flooding in Daqing Oilfield has entered the stage of industrialization and popularization. The total number of injection wells of ASP flooding has reached more than 4000. At present, the main problem of ASP flooding layered injection wells is that after injection of ASP compound solution for a certain period of time, the displacement effect is poor due to the sticking of scale and micelle in the partial hole and throttling element of injector A series of influences, such as the increase of the workload and the shortening of the period of measurement and adjustment, etc. However, the existing anti scaling technology mainly deals with the parts that are easy to scale, which has the advantages of high lubrication, low friction and non viscosity. However, due to the variety and different performance, it is necessary to compare and evaluate the anti scaling performance. However, the conventional coating evaluation method mainly judges the advantages and disadvantages of the coating technology through the conventional inspection indexes such as appearance size, roughness and smoothness There is no practical significance for the evaluation of the anti scaling performance of the special environment of ternary injection. Based on the field test, this paper forms a set of evaluation method for the scale prevention performance of ASP flooding, realizes the evaluation and optimization of the scale prevention performance of ASP flooding, and effectively prolongs the testing and adjusting period
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