Evaluation of Polymer Flooding Potential Based on Orthogonal Design and BP Artificial Neural Network

Abstract

Abstract This paper has proposed a novel approach for evaluation of polymer flooding potential during oil reservoir development, which has integrated orthogonal design and BP artificial network. This paper firstly divides the evaluated polymer flooding reservoir units into four styles using Weighted Euclidean Distance method. On the basic of unit sorting, we have generated predictive samples sets for polymer flooding potential with orthogonal design and reservoir simulation. In order to enhance the reliability and prediction ability of the polymer flooding network models, this paper has created a new orthogonal experiment design table to meet this study. It can cover the evaluated reservoir blocks but improve the extendibility of the network by enhancing training sample numbers. After that, Enhanced Oil Recovery(EOR) and Internal Rate of Return(IRR) predictive models of polymer flooding are constructed using BP artificial neural network method. At last, the paper has introduced two new concepts of applicability degree and risk degree to assess reservoir conditions for polymer flooding and implementation risk. Taking technical, economic and risk factors into account, comprehensive potential evaluation was carried out with the predictive models of polymer flooding potential for part of reservoir blocks in Shengli oilfield in China. The evaluation results have shown that the predictive models are of higher accuracy and better extendibility, which can satisfy the demands of engineering computation application. Introduction Polymer flooding has become one of the main enhanced oil recovery methods for inshore oilfields in China. At present, enhanced oil recovery techniques such as polymer flooding and chemical combination flooding, have been widely implemented in Daqing oilfield and Shengli oilfield in China and obtained great economic and social benefits (Chang et al., 2006; Sun,2006). But as a kind of tertiary recovery method for polymer flooding itself, there must be some certain risk for its field implementation owing to intricate reservoir conditions and high cost of chemical agent. And yet, under the situation of high international oil price, were the polymer flooding applied rationally and appropriately, it would still be able to gain better economic benefits. Therefore, it is very necessary to carry out the evaluation of polymer flooding potential including technical, economic and risk aspects so as to supply guidance for polymer flooding application to reduce investment risk and enhance economic benefits.