STUDY ON INTERPRETATION METHOD OF GAS SATURATION IN COMPLEX PORE STRUCTURE,TAKING NANBAXIAN OIL AND GAS FIELD AS AN EXAMPLE

摘要

In this paper,Nanbaxian oil and gas field,China,was taking as an example to investigate the interpretation method of gas saturation in complex pore structure.The "Four properties" relationship of formation reservoirin Nanbaxian oil and gas field was studied in depthaccording to the conventional logging data and core analysis data.The neural network algorithm was used to reconstruct the resistivity curve of water layer to eliminate the influence of lithology,shale content and pore structure on the resistivity.The difference between the reconstructed curve and the measured resistivity curve was used to identify the gas and water,and the ratio of the two was used to calculate the gas saturation,and good results was achieved.It was found that the sedimentary types of Nanbaxian oil and gas fieldcause the reservoir to be thin,numerous and dispersed,the lateral correlation is difficult.In addition,the structural features lead to the reservoir types being various in the vertical direction,which makes the identification of reservoir fluid more difficult.The results revealed that the rock compaction,poor physical properties,complex pore structure,high resistivity of surrounding rocks,and low formation water salinity make the water layer with high resistivity and difficult to identify gas and water.