Optimization Study of Conversion Timing for Secondary Development & Tertiary Recovery in the Ultra-High-Water-Cut Oilfield Based on Multi-factor Decision-Making

With the entry of oilfield into the middle and late stages of development, in order to maintain stable production and increase recoverable reserves, the technology of Secondary Development & Tertiary Recovery has come into being. However, its effect greatly affected by the conversion timing of drive medium. This paper analyzes the factors of the conversion time in Oilfield X of Dagang, carries out optimization study from the aspects of technology, economy and well pattern life cycle, constructing an optimization chart of multi-factor decision-making. Under different oil prices and viscosity ratio conditions, by comparing the economic benefits of different conversion timing, the research found that the earlier the conversion to tertiary recovery chemical drive, the greater the increase in recovery rate. Considering the well network lifecycle, it is best to complete the conversion and maintenance of the well network within 5 years to achieve a win-win situation in improving the recovery rate and economic benefits. This optimization method has been successfully applied to Oilfield X, and also provides reference for the research of similar problems in other mature oilfields.