Permeability Characteristics and Influencing Factors of Fracturing Fluid in Glutenite Reservoir Based on NMR

摘要

The low permeability conglomerate reservoir in Mahu sag has huge resource potential. However, due to the large distribution of fine throats and complex pore seepage system, Mahu tight glutenite reservoir is characterized by large production difference of single well, high oil and gas decline rate and low recovery factor. In this paper, the microstructure and composition characteristics of Mahu conglomerate are studied by means of NMR, Water sensitive injury experiment was carried out. The results show that the strong heterogeneity of the reservoir in Mahu Baikouquan formation seriously affects the physical property characteristics and pore throat development characteristics. The strong heterogeneity leads to the uneven advance of water drive front, and the highest recovery factor is 30. With the increase of the number of soak back flow, the fracture closed unevenly, resulting in the low flowback rate of soaking well after fracturing. The higher the proppant concentration is, the stronger the conductivity is. Compared with carbon dioxide, natural gas and deoxidized air, the oil displacement efficiency of carbon dioxide is the highest (70–85), followed by natural gas (55). In the aspect of research on the law of cross permeability between fractures and matrix, the natural energy release and exploitation of conglomerate reservoir is carried out. The recovery factor is relatively low, but after natural gas flooding, the core matrix will supply oil to the fractures in the process of backflow, which eventually makes the oil saturation in the matrix decrease significantly, and the degree of crude oil production increases. The matrix in the middle of the fracture is the main residual oil enrichment area. It is of great significance to improve the recovery rate of conglomerate.