Research on the Mechanism of Expansion and Energy Increase of Steam Flooding for Chang7 Tight Oil in Ordos Basin

Abstract

AbstractThe tight oil reserves of Chang7 in Ordos Basin are rich. After years of technical research, the economic and effective development of tight oil has been realized. However, the rapid drop and low recovery of the oil production were challenges for the tight oil development, which were mainly due to the inefficient supplement of formation energy. The supplement inefficiency restricted the efficient development of tight oil reservoirs. Based on the analysis of the mechanism of steam flooding, this paper systematically combs the advantages of chang7 tight oil steam flooding crude oil expansion and energy increase, and makes clear that tight oil crude oil has high content of light components, good physical properties, high oil saturation, which is good material basis for expansion and energy increase. At the same time, according to the expansion coefficient and compression coefficient of crude oil, the theoretical calculation formula between formation pressure change and temperature change is established. The mechanism of increasing energy of crude oil by steam expansion is clarified. Taking the typical block A83 of Ordos tight oil as an example, the variation of crude oil compression coefficient and expansion coefficient and formation pressure under different reservoir steam temperature is calculated by using fluid phase simulator. The results show that the formation pressure can be increased by 29.3 MPa when the reservoir temperature is increased from 70 ℃ to 200 ℃ by steam driving, which proves that the expansion energy increase of Chang7 tight oil in Ordos Basin is feasible.KeywordsTight oilSteam floodingExpansion and energy increaseMechanism