Research Of The Log Interpretatina Methods In Low Porous And Permeable Reservoirs In The Eastern South China Sea

Along with the development of exploration activity in the South China Sea, some low porous and permeable oil and gas reservoirs or structures have been found. Since the reservoirs in the Eastern South China Sea have characteristics of low porosity, low permeability, complex pore structure and high capillary bound water saturation, it is difficult, but necessary to establish a log interpretation method suitable for the low porous, low permeable reservoirs in the area. Based on experimental measurement of the porosity and permeability, grain size and capillary pressure of rock samples, the main factors are optimized by analyzing the factors that influence the reservoir parameters, and then multiple regression is used to establish reservoir parameter interpretation models in the paper. By studying the conductivity law in the low porous and permeable reservoirs in the Eastern South China Sea, the variation of m and n with porosity and permeability is found out, and then the method of determination of the m and n is given. On the basis of symmetrical effective medium conductance theory and three kinds of conductive components of free water, capillary bound water and clay, a new water saturation model is established for the complexity of conductive law in low porous and permeable reservoirs. Then, the effects of some factors on the proposed model are analyzed. We employ experimental data of samples to validate the accuracy of water saturation model, and give the method of calculation of percolation exponent and percolation rate in the model. The interpretation software for low porous and permeable reservoirs in the Eastern South China Sea is developed, The log data are processed with the interpretation software, and the validation with experimental measurements of rock samples and testing for oil is done. The result shows that the interpretation method can impove the accuracy of evaluation of oil and gas in low porosity and permeability shaly sand in the Eastern South China Sea and can meet the needs of exploration and development of oil and gas.