A method for evaluating the porosity of organic matter in shale

Abstract

The invention relates to a method for evaluating the organic matter porosity of shale, which is characterized in that: 1) the organic carbon content and the total pore volume or Determination of total porosity; 2) establish the relationship between organic carbon content and total pore volume or total porosity; 3) establish a plane coordinate with organic carbon content as the horizontal axis and total pore volume or total porosity as the vertical axis 4) put the data of organic carbon content and total pore volume or total porosity of the shale sample into the plane coordinate system, and fit a straight line, and obtain the slope and longitudinal intercept of the straight line; 5) Obtain the organic matter pore volume or organic matter porosity of the shale samples in the test area, and then evaluate the organic matter porosity of the shale, so as to complete the evaluation of the storage capacity of the shale reservoir in the test area. The method of the invention is easy to operate, practical and low in cost.

Description

technical field [0001] The invention relates to a method for evaluating the porosity of organic matter in mud shale, belonging to the field of geological exploration. Background technique [0002] Shale gas is a natural gas resource that can be exploited in muddy shale formations. Shale gas is a typical unconventional natural gas, which is produced in low porosity and permeability reservoir rock series dominated by organic-rich shale. There are significant differences in the controlling factors for the enrichment and accumulation of shale gas and conventional gas. Shale gas accumulation mainly includes self-generation and self-storage, early accumulation time, no obvious traps, low porosity and low permeability of reservoirs, and various gas occurrence states and shale gas reservoirs are easier to preserve. The researchers found that the organic matter in shale will produce a large number of pores during the thermal evolution process. These pores are important storage spac...

AI Technical Summary

Problems solved by technology

Because the organic matter is difficult to be extracted relatively completely, and the method for directly quantitatively measuring the organic matter pore volume and porosity of mud shale is not yet mature, it is impossible to obtain the organic matter pore volume and porosity of mud shale more accurately.

There are three main methods for evaluating the porosity of organic matter in mud shale: the first is the method of argon ion polishing combined with scanning electron microscopy, which semi-quantitatively analyzes the size and porosity of organic matter in mud shale through human observation. The main disadvantage is human influence. The second method is to calculate the porosity of mud shale by computerized tomography technology, and obtain the volume of organic matter and organic pore volume by tomography to calculate the organic matter porosity and organic matter porosity of mud shale. This method can theoretically accurately measure the organic matter porosity of shale, but the tomographic scanning technology is still immature, it is difficult to identify organic pores and inorganic pores, and the cost of tomographic scanning testing is high. The third is to use scanning electron microscopy or field emission electron gun scanning electron microscopy technology, and use the area counting method to obtain the surface porosity of the total organic pores, and then calculate the organic matter porosity and shale organic matter porosity. When using this method, the computer cannot accurately identify Organic pores and inorganic pores, but the counting of the area of ​​organic pores is greatly affected by human factors, and the calculation is inaccurate and time-consuming.

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