Experimental investigation on the influence factors of primary production performance of tight oil.

The effects of permeability, initial fluid pressure, effective stress, gas-oil ratio, pressure depletion rate, and oil viscosity on the primary production oil recovery were investigated in detail. The results show that the permeability of tight core is the most significant influence factor. When the permeability decreases from 3.0 × 10−3 µm2 to 0.0021 × 10−3 µm2, the oil and gas recoveries decrease from 45% and 90% to 10% and 20%. Furthermore, the initial fluid pressure also has great influence and the oil recovery linearly increases with the fluid pressure as well as the decrease of effective stress. When the initial fluid pressure increases from 6 MPa to 15 MPa, the oil and gas recoveries can be enhanced about 10% and 22%. Gas-oil ratio is another important parameter. When the gas-oil ratio is 26 m3⋅m−3, the oil recovery can reach approximately 30% compared to 2.7% at the gas-oil ratio of 0. The pressure depletion rate has a more obvious influence on the ultimate oil recovery for the cores with a low permeability, while with a low depletion rate after bubble point can enhance the oil recovery. The work can provide useful information for the choosing of key parameter and development method in tight oil production. [ABSTRACT FROM AUTHOR]