The Research On Permeability Evaluation Method Of Carbonate Reservoir In M Block Of Middle East

Different from the fracture-vug carbonate reservoirs such as the Tarim Basin in China,carbonate reservoirs in the M block of the Middle East are pore-type carbonate reservoirs.Although there is no fractures or vugs,owing to its complex lithology and various pore types,the pore structure in research area is more complex,making it difficult to accurately predict reservoir permeability.Aiming at this problem,this paper takes the Cenozoic Asmari reservoir in M block of Middle East as the main research object.,based on the core physical property data,mercury injection experimental data,casting thin sections,logging data and so on,reservoir characteristics and main influencing factors of permeability in the research area are emphatically analyzed,preliminary determining porosity and pore structure is the main controlling factor of permeability,and based on actual logging data,the relationship between permeability and porosity in the research area is analyzed.it is found that the permeability model based on porosity is not effective in the research area,whether it is based on integer,lithology or flow units.At the same time,the relationship between permeability and pore structure is analyzed,six common permeability models based on pore structure parameters are applied in the research area,these six types of models have lower calculation accuracy in the research area,and it is also found that the correlation between core permeability and pore structure parameters such as displacement pressure,average pore throat radius,sorting coefficient and so on is poor,which further proves that the pore structure of the research area is very complex,the existing pore structure parameters can not accurately characterize the reservoir seepage mechanism and pore throat distribution characteristics.The applicability of the classical NMR permeability evaluation model in the research area is analyzed.In order to accurately characterize reservoir seepage mechanism and pore throat distribution characteristics,this paper starts from the pore structure,combines mercury injection experimental data and nuclear magnetic resonance logging data,and divides the pore throat system into four categories in the research area,the pore-throat radius distribution interval and the transverse relaxation time interval of NMR for each type of pore-throat system are determined,the NMR interval porosity corresponding to each pore throat system is calculated by NMR logging data,at the same time,a new pore structure parameter which can be calculated directly from the NMR data is proposed,through analysis,it is found that the new pore structure parameter and the NMR interval porosity corresponding to the fourth pore throat system are well correlated with permeability,combining the two,a new model for permeability evaluation is established.The new model has a better application effect and significantly improves the the accuracy of permeability prediction in the research area,is beneficial to the development and production of reservoirs in the research area.