Method for determining filling property lower limit of tight sandstone gas

Abstract

The invention relates to an oil and gas reservoir assessment method, in particular to a method for determining the filling property lower limit of tight sandstone gas. According to the method for determining the filling property lower limit, a nanoscale water film theory is introduced, on the basis of stress analysis of an adsorbed water film, and key parameters are determined in combination with targeted experiments. The critical filling state of natural gas can be simplified as the fact that when sandstone particles are arranged closely, the water film is in butt joint with blocking throats, and then the pores are effectively prevented from being filled with the natural gas through blocking, wherein at this time, the thickness of the water film equals the critical radius of the throats; if the radius of the throats is smaller than the thickness of the water film, corresponding pore throats and controlled tiny pores are saturated with bound water; only the throats of which the radius is larger than the thickness of the water film are the effective filling channels of the tight sandstone gas. Based on the method for determining the filling property lower limit of the tight sandstone gas, the property lower limit of tight reservoir exploiting can be accurately assessed, the exploration area of the tight sandstone gas can be enlarged, the reserves of the exploitable tight sandstone gas can be increased, and huge economic benefits are brought to oil fields.

Description

technical field [0001] The invention relates to an oil and gas reservoir evaluation method, in particular to a method for determining the lower limit of physical properties of tight sandstone gas charging. Background technique [0002] The lower limit of reservoir physical properties is the basis of reservoir evaluation and resource evaluation, and it is the minimum physical property that a reservoir can become an effective reservoir, usually expressed by porosity or permeability. The methods for determining the lower limit include the occurrence method, empirical statistics, test method, minimum effective pore throat method, etc., but these methods are all aimed at the lower limit of the physical properties of conventional reservoirs for industrial recovery of oil and gas. Tight sandstone reservoirs belong to the field of unconventional oil and gas, and the lower limit of their physical properties is gradually decreasing with the improvement of advanced production technolog...

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Problems solved by technology

The methods for determining the lower limit include the occurrence method, empirical statistics, test method, minimum effective pore throat method, etc., but these methods are all aimed at the lower limit of the physical properties of conventional reservoirs for industrial recovery of oil and gas.

Tight sandstone reservoirs belong to the field of unconventional oil and gas, and the lower limit of their physical properties is gradually decreasing with the improvement of advanced production technologies such as well pattern intensification, large-scale fracturing, and multi-layer well completion. It should tend to be natural gas charging under geological conditions. Obviously, the lower limit of physical properties of conventional gas reservoirs is obtained by using the previous method, which is no longer suitable for obtaining the lower limit of physical properties of tight sandstone reservoirs.

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