Simulation and Production Optimization on Enhanced Oil Recovery during the Middle and Late Period for SAGD Development in Ultraheavy Oil Reservoirs with Interlayers
Table 1
Classification and characteristics of the well pair and numerical simulation models.
Classification and characteristics of the well pair
Numerical simulation models
Geological classification
Feature description
Model name
Model scheme
First category (9 well pairs)
Oil recovery ratio is greater than 5%; oil production rate is 30–50 t/d; production degree of horizontal section is greater than or equal to 80%; available degree of reserve control is 100%.
Model A
There is no interlayer in the model.
Second category (13 well pairs)
Oil recovery ratio is 3%–5%; oil production rate is 20–40 t/d; production degree of horizontal section is greater than 70%; available degree of reserve control is less than 90%.
Model B
In the model, an interlayer is located in the middle of the reservoir and above the steam injection well, 15 m away from the bottom of the reservoir. It has a length of 200 m, width of 40 m, thickness of 1 m, and permeability of 10 mD.
Third category (20 well pairs)
Oil recovery ratio is less than 3%; oil production rate is 15–25 t/d; production degree of horizontal section is less than 80%; available degree of reserve control is less than 90%.
Model C
In the model, an interlayer is located at the toe of the SAGD horizontal well pair and between the well pair. It has a length of 130 m, width of 1 m, thickness of 1 m, and permeability of 10 mD.
