The Study On The Reservoir Geological Modeling Of The Quan Ⅲ Member Of Lower Cretaceou Of Shuang Tuozi Gas Field

From the current productivity of Shuang Tuozi gas field, it is can been seen that the pressure dropping quickly in some gas well of gas pool, the gas productivity declining quickly and the water production are directly affected the stable production of the gas pool. The reservoir geological modeling research is the key for the development phase, the necessary parameter for the numerical simulation of reservoir, the directly basis for the development and adjustment program. Establishing the geological modeling correctly reflected geological characteristic of reservoir is the key for the reservoir numerical simulation and dynamic prediction., has important significance for the further understanding the geological characteristic of reservoir and adjusting the development program in order to reach the purpose of improving the recovery ratio. In this paper, it is using the core data, geologic information, logging data to analysis the sedimentary facies of Quan III member of Shuan Tuozi gas field, fine logging interpretation model on reservoir parameters and research on the reservoir characteristic. Finally it is using the above research results to establish the reservoir geological model of Quan III member in Shuang Tuozi gas field.Based on the borehole log, core and log data, it is identified and classified the microfacies of the single well of Quan III member and composed the sedimentation map of III sand set of Quan III member. Then it is summarized the sedimentation model The Quan III member develops snaking stream. The snaking stream is composed of riverbed, marginal bank, crevasse splay, flood plain and so on. The marginal bank is the mostly developed in the Quan III member.The statistics of petrophysical data tested using the core shows that the minimum value of the porosity is 4.4%, the maximum value of the porosity is 27.7% and the average value of the porosity is 19.15% and the minimum value of the permeability is 0.05 10^-3μm², the maximum value of the permeability is 953 10^-3μm², the average value of the permeability is 95.57 10^-3μm². On the basis of the principal of core scale the log, it is established the fine interpretation model of reservoir parameter of single well of Quan III member in the Shuang Tuozi gas field using the non-linear BP artificial neural network. The mean absolute error of the predicted porosity by the neural network is 0.73% and the mean relative error of the predicted permeability by the neural network is 45.89% of the 5 core-well in the studied area. The result shows that the error is minimum.Through the classifying and calculating the reservoir degree of single well of Quan III member, it is obtained that it is mainly developed the I type and II type in the Quan III member. The study demonstrates that it is the medium-large porous- and medium penetrative reservoir in the Quan III member. Through the sand body's thickness map of the mainly productivity IX sand set of Quan III, it is reached that sedimentary facies controls the reservoir's development and reservoir is mainly mainly developed in the marginal bank and natural bank. Along with east-western section, the sand body changed along with the deviating and moving of the river channel. And along with the direction of river channel, the connectivity of the reservoirs is relatively good and the shape is banding.On the basis of comprehensive study of the geologic feature in this area, it is used the Petrel Software to established the structural model, skeleton model and sand set skeleton model of the Quan III member. Using the sequential indication simulated algorithm, it is established the sand-mud lithofacies model of the Quan III member. Based on the data analyses and variation function and under the control of sand-mud lithofacies, it is reached the porosity model after simulation. Using the porosity as the second variable and with the synergistic simulation, it is established the permeability model. By the means of controlling under lithofacies, it is established the saturation model. The model is demonstrated that the characteristic of reservoir is medium-large porosity and medium permeability. And the distribution of the porosity and permeability is under the control of lithofacies. Finally, it is counted that the gas in place is 8.51 billion square of the Quan III member in the Shuang Tuozi gas field in accordance with result of model.