Study On The Calculation Method Of Carbonate Rock Permeability Based On Micropore Structure

Fifty percent of the world's oil and gas resources come from carbonate reservoirs,and the Middle East is rich in oil and gas production,and 80 percent of them come from carbonate reservoirs.At home and abroad,the research on carbonate reservoir is deepening,and the related research is more and more abundant.The study of low porosity and low permeability reservoirs is also becoming more and more in-depth.Among them,carbonate reservoirs are more typical,and carbonate rocks are diverse and complex in structure.The characterization and qualitative evaluation of reservoir pore structure can better study the pore microstructure and provide great help for the follow-up study of this paper.The evaluation of the permeability of carbonate reservoirs has profound significance,which can better predict the reservoir,increase the efficiency of oil and gas recovery,and provide theoretical support and factual basis for subsequent mining.At the same time,it is of great significance for the study of the subsequent carbonate permeability.Taking the carbonate reservoir in block A as an example,this paper conducts an in-depth study on the calculation method and evaluation method of the micro-pore structure permeability of carbonate reservoir,and obtains the following results:(1)based on the collection and arrangement of data of A block,A qualitative and quantitative evaluation method is established for the structure of carbonate reservoirs in this area.Application scale linear and power function scale pseudo capillary pressure builds,think for the experimental data of the capillary pressure curve,using the method of power function scale sectional build pseudo capillary pressure curve is more accurate.But because of the need to build in the whole interval pseudo capillary pressure curve,the calibration method of sectional power function parameters,and then using the error is bigger in the logging curve transformation,so in the whole interval evaluation using the pseudo capillary pressure curve of the linear scale to build a power function calibration method is more accurate.(2)based on the analysis of the experimental data and physical analysis data of mercury injection,the permeability estimation model of carbonate reservoir based on micropore structure was established.This method firstly to pressure mercury pore structure parameters of the experimental data and the permeability is analyzed,that the coefficient of variation and displacement pressure on permeability parameter is most sensitive,therefore with porosity parameters,using the multivariate regression method based on microscopic pore structure of carbonate rock permeability has been establishedto estimate the model.By comparing with the core permeability,the permeability accuracy of the model is high,and the permeability can be calculated accurately.However,due to the complexity of carbonate reservoirs,the accuracy of the pseudo capillary pressure curve based on NMR logging conversion is relatively low,resulting in a large error in the calculation of reservoir permeability and core permeability.(3)the BP neural network was used to calculate the parameters of the parameters,and then the permeability was predicted by means of the method.By analyzing the relationship between Swanson parameters and the parameters and permeability of the in-vitro or the parameters,the comparison is made between the two,and it is concluded that the relationship between the parameters and the core permeability is better.Then the relationship between the parameters and permeability was established by using neural network.The results show that the precision of the pore structure is higher.