Identification method for unconventional superpressured tight gas effective reservoir

Abstract

The invention provides an identification method for an unconventional superpressured tight gas effective reservoir. The identification method comprises the steps of acquiring the porosity, permeability, pore throat radius distribution characteristics and high-pressure mercury injection data of a rock core of a gas-producing layer section of a production well of a superpressured tight gas reservoir; by utilizing a linear regression equation, establishing relational expressions between a throat radius representation value and the porosity and between the throat radius representation value and the permeability, and establishing a projection chart of the porosity, the permeability and the throat radius representation value; by utilizing data of the production well, projecting porosity values and permeability values of the gas layer and a dry layer to the projection chart; selecting the throat radius representation value, which optimally separates the dry layer from the gas layer, as a throat threshold value for identifying the unconventional superpressured tight gas effective reservoir; and projecting to-be-identified reservoir porosity and permeability data to the projection chart, and judging reservoir effectiveness according to the positions of a projection point and a curve of the throat radius representation value. The method is simple, quick, convenient and accurate.

Description

technical field [0001] The invention relates to a method for identifying effective reservoirs, in particular to a method for identifying effective reservoirs of unconventional overpressure tight gas, and belongs to the technical field of oil and gas reservoir exploitation. Background technique [0002] At present, the identification of the effectiveness of gas reservoirs is mainly focused on conventional carbonate reservoirs and low-porosity and low-permeability sandstone reservoirs. In the field of unconventional tight gas, the effectiveness identification methods of reservoirs are rarely reported. [0003] The key parameter of reservoir effectiveness is the gas saturation of the reservoir. The prediction and evaluation methods for the gas saturation of the reservoir are mainly realized by using seismic and logging data combined with the analysis data of actual samples. [0004] For example, Zhu Honglin published in "Journal of Rock Mechanics and Engineering" (Journal of Ro...

AI Technical Summary

Problems solved by technology

From the scatter diagram of porosity and permeability of effective reservoirs and dry layers in the eastern part of Kuqa, Tarim Basin, it can be found that it is very difficult to identify effective reservoirs simply by using the parameters of porosity and permeability. Poor and the physical properties of the dry layer may also be better

Applying such parameters to identify may identify invalid dry layers as gas-bearing layers, resulting in an increase in exploration and development costs, and may also identify gas-bearing layers as dry layers, resulting in loss of potential gas layers

[0007] The patent application with the publication number CN104504182A discloses a method for rapid identification of unconventional gas reservoirs. However, this method still uses logging curves combined with geological engineering parameters and geological parameters to carry out analysis, and professional technicians are required to master it. A large number of parameters mentioned in this method are less operable for ordinary geologists, and this method is only to identify the quality of the reservoir, not the ultimate identification of the effectiveness of the reservoir

[0008] In short, the existing reservoir effectiveness identification methods all have unfavorable factors such as difficult operation, high cost, and long cycle, which seriously affect the efficiency of exploration, especially the efficiency and success rate of reservoir gas testing.

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