Matrix permeability calculation method and system

Abstract

The invention discloses a matrix permeability calculation method and system. The method comprises the following steps of establishing natural gamma neutron logging cross plots of sandstones with different granularities, and determining constraint boundaries of the sandstones with different granularities; obtaining a rock granularity profile according to the natural gamma neutron logging cross plot; determining granularity median ranges corresponding to different granularities according to the rock granularity profile; establishing a cross plot according to the known particle size median, the constraint boundary and the natural gamma, and calculating the initial particle size median of the unknown sandstone; determining the particle size median of the unknown sandstone according to the particle size median range corresponding to the unknown sandstone and the initial particle size median; and calculating permeability of the matrix according to the particle size median. According to the method, evaluation of the matrix permeability is realized by establishing the granularity profile calculation chart and calculating the granularity median, the influence of granularity on the matrix permeability is reflected, and permeability of the double-hole medium reservoir can be accurately determined by combining the fracture permeability.

Description

technical field [0001] The invention relates to the field of petroleum exploration and development, and more specifically, to a method and system for calculating matrix permeability. Background technique [0002] Permeability is an important parameter to measure the permeability of reservoirs, and plays a very important role in the exploration and development of oil and gas fields. To evaluate permeability by logging, the indirect evaluation of permeability is mostly achieved by establishing its relationship with other petrophysical parameters. For single-porous media, the pore space is mainly primary intergranular pores, and the homogeneity is good. The earliest research on single-porosity sandstone found that the logarithm of permeability has a linear relationship with porosity. However, this method does not consider the influence of pore structure changes, and cannot meet the accuracy requirements of complex reservoir permeability evaluation. Subsequently, the relationsh...

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Problems solved by technology

In short, the predecessors have carried out in-depth research on the theoretical model of permeability, and established a series of single-porous media and double-porous media models, trying to establish the relationship between permeability and other petrophysical parameters to achieve permeability evaluation. However, through logging The lithological grain size profile is obtained through evaluation, and then the profile is used as a constraint to restrict the median grain size result calculated by natural gamma ray logging, and finally, there are few studies on using the calculated median grain size and porosity to jointly calculate permeability

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