Abstract: The micropores of the shale gas reservoir consist of organic pore,clastic pore,clay pore and micro-fracture.After a comprehensive analysis of core properties and the logging response characteristics,several new methods are proposed to evaluate total porosity and porosity of each micropore type of shale gas reservoir quantitatively.1)Based on the volume model,the DEN or DT is used to determine the total porosity of shale gas reservoir.2)Conventional logs and SGR(Natural Gamma Ray Spectroscopy)logs are utilized to determine the volume-percent of organic matter content of shale gas reservoir,a scale parameter is determined by SEM technique,and finally a method for calculating the organic porosity is set up.3)Considering the clay pore is the main storage space for bound water,clay content is obtained from logs and correlated with the adjoining shale to get the evaluation method of clay porosity.4)Based on the response characteristics of dual laterolog for micro-fracture,an evaluation method of micro-fracture porosity is proposed by forward and inverse numerical simulation computations.5)The clastic porosity can be determined by subtracting organic porosity,clay porosity and micro-fracture porosity from the total porosity.A good agreement is found between the core analysis and the micropore porosity computed by using the above methods,which indicates the validity of the methods proposed in this paper.

Key words: ‘four-pore’model, wireline log, quantitative evaluation, shale gas, reservoir evaluation