Study of a quantitative characterization parameter “oil and gas producing efficiency” of the producing degree of reserves in the developed area

Abstract

Implementing the producing degree of reserves in the developed area is of great significance for timely understanding of oil and gas development trends in the developed area, and then taking targeted adjustment measures to improve oil and gas producing efficiency. On the basis of the analysis of different scale pore percolation capacity of reservoir and the study of four kinds of porosity (connected porosity, effective porosity, flowing porosity, filling porosity) and their corresponding calculation models of oil saturation, a quantitative characterization parameter - “oil and gas producing efficiency” of the producing degree of reserves in the developed area is proposed, and its theoretical discussion and case analysis are carried out. Research shows: 1) Oil and gas producing efficiency is the ratio of the reserves involved in percolation to geological reserves in the developed area of the oilfield, which is finally expressed as the ratio of the product of the flowing porosity and the original oil saturation of the flowing pores to the product of the connected porosity and the original oil saturation of the connected pores. 2) Reservoir flowing porosity and the original oil saturation of flowing pores are a function of displacement power, while the original oil saturation of connected pores is a function of reservoir forming power. Therefore, the oil and gas producing efficiency is essentially a coupling function of displacement power and reservoir forming power. 3) When the displacement power is greater than the reservoir forming power, the oil and gas will be fully developed, and the oil and gas producing efficiency will be 1; when the displacement power is less than the reservoir forming power, the oil and gas will be partially developed, and the oil and gas producing efficiency will be less than 1. 4) The calculation examples of X oilfield in Ordos Basin show that the connected porosity is 11.2%, the original oil saturation of the connected pores is 57.1%, the flowing porosity is 5.32%, the oil and gas producing efficiency is 0.832, and the oil and gas are partially developed. If the oil and gas are to be fully developed, the production pressure difference can be increased from 4.1MPa to 6.2MPa. 5) The study of oil and gas producing efficiency deepens the understanding of reserves producing status in the developed area of the oilfield, and has guiding significance for the targeted production adjustment and production pressure difference optimization of the oilfield.