Selecting the most appropriate E O R: A case study of block Shen84-An12, Liaohe oilfield, north-east China

Abstract

Given the high water cut (over 79%) situation in Shen84-An12 oil reservoirs, it has become more difficult to achieve further recoveries even with the most advanced technologies like polymer flooding. We would like to advocate for the use of steam flooding because of its track records with recovery schemes generally and heavy oil reservoirs in particular. Our approach is to study the circumstances that had led to the problems, prominent among them is the multi-layer nature of the reservoirs (at least 94 layers), heterogeneity, as well as their low depths. It was discovered, based on previous research, that reservoir formation damage has occurred as a result of excessive use of cold water and this combined with heavy nature of the oil lead to wax precipitation and the eventual of blocking of reservoir pore throat. Horizontal wells have the advantages of selectively targeting a desired zone so steam could be directed at certain targets such was the case of Du84 and other oil blocks in Liaohe oilfield. Another approach is to evacuate the water that has taken over most part of the reservoirs as a result of previous cold water flooding, based on sublimation principles. Applying both treatments intermittently by first eliminating water followed by the use of horizontal wells to target specific layers of interest, can enhance even better recovery but considering cost, either of the methods may be sufficient to salvage the situation. Although, we cannot guarantee the viability of the second method, instead, it is a mere suggestion based on scientific principle and the authors believe it should be experimented.