Perm Journal of Petroleum and Mining Engineering (Sep 2019)
Analysing the efficiency of flooding oil reservoirs with water-soluble polyacrylamide and preliminary cross-linked polyacrylamide particles
Abstract
Due to the constant increase in the number of fields entering the final stage of operation, oil-producing companies are raising their demand for integrated technologies that can increase the coverage of the formation by the displacement process and reduce the water cut of well products at the same time. A traditional technology used for this purpose is flooding with viscous solutions of water-soluble polyacrylamide. The paper provides an overview of polymer flooding technologies, identifies the advantages and disadvantages of this approach, in particular, lists the factors that can influence the rheology of a polymer solution. Despite the extensive use of flooding based on polyacrylamide gels, this method has a number of limitations, primarily associated with the rheological characteristics of the polymer. The instability of such rheological characteristics of the polymer is a significant obstacle on the way to achieving the target oil recovery factor. An alternative way of injectivity profile alignment is the flooding technology using polymer gel particles based on a suspension of cross-linked polyacrylamide particles. Such a polymer is synthesized in advance to form a three-dimensional structure (3D polymer). Backed by the literature review, the effectiveness of technologies based on water-soluble polyacrylamide and preliminary cross-linked polyacrylamide particles was compared; as a result, a conclusion was made about the superiority of the latter by a number of significant indicators. Polymers based on polymer gel particles do not change their rheological characteristics during the injection process, while the particles can change their shape and tear, enveloping the obstacles. Besides, the technology injecting the suspension with a smaller volume of reagent, successively selecting the optimal particle size distribution depending on the specific geotechnical conditions of the formation. The flooding based on polymer gel particles has good prospects for implementation in the Russian oilfields.
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