Distribution Rule Of Gas And Water In The Forth Member Of Xujiahe Formation In Chongxi Gasfioled

Chongxi gas reservoir is low-pressure, low permeability, low abundance, large size distribution of lithologic gas reservoir.Reservoir. Exploration and development data indicate that lithology is complex and heterogeneous so accurate identification of gas and water layer, the correct understanding of gas and water distribution are the key technical issues for restricting the development of gas field.On the basis of the previous research results about Chongxi gas reservoir, with the drilling, logging and water quality analysis data of study area, Artificial neural network learning log interpretation and qualitative and quantitative analysis as the theoretical basis, it is comprehensive studied on the reservoir physical property, reservoir characteristic, logging interpretation, reservoir evaluation, gas/water pattern and so on taken the means of multidisciplinary analysis with geological, logging, core analysis tools and other subjects There are following outcomes and understanding:1,Porosity distribution range is mainly 2～15%,average is 7.48%。Permeability distribution range is mainly 0.01¹0×10^-3μm²,Reservoir is low porosity and low permeability. Lithology is thin mudstone main folder mainly, medium-grained lithic sandstone and Feldspathic lithic sandstone. Reservoir type is fractured– porous.2,In the study, based on reservoir characteristics, core analysis data, logging data, Physical parameters of the region for the conventional formula.Basically, the reservoir can accurately predict the physical parameters. At the same time, using the neural network to model, The results show porosity of cored wells, the average absolute forecast error is 0.807%,Relative error is 12.56%.The relative error of permeability is 41.34%, Porosity predicted by the model to explain physical parameters of high precision, the model has a higher reliability.The permeability predicted by the model error of physical parameters of accuracy required. By comparing the properties of conventional log interpretation results and calculated results of artificial neural network settlement, Neural network model has more accurate and High reliability. 3,After analysis of the sand profile, distribution, it is deepen understanding of reservoir. Through natural gamma, porosity, permeability values, it is identified the reservoir, established logging evaluation interpretation and classified the reservoir. Chongxi gas field is the reservoir with low porosity, low permeability and strongly heterogeneity. The reservoir is mainlyⅡ,Ⅲtypes . it is using the contour map of reservoir parameters through logging processing results to understand the reservoir distribution patters on the horizontal and vertical directions. The reservoir physical property of Sub-section of low Xu IV is better than the sub-section of up of it.4,The research used various methods to study fluid log response characteristics of different producing formation and make effective recognition about reservoir fluids of single well from the whole region, and finally selected some better methods to discriminate fluids. It is recommended to use the porosity/resistivity cross plot as the main method, and the formation water porosity, multivariate discriminant analysis and apparent water resiscivity technique as auxiliary method to recognize the fluids from Xu 4 member of western Sichuan gas field. Through the established SPSS discrimination model, it is verified the accuracy is 88.09%, which meets the requirement for modeling.5,Drawing plane distribution of fluid type and longitudinal and transverse profile is to study the plane distribution of gas and water layer. It is considered that the gas and water layer is developed in the middle-low section of Xu IV member of Xujiahe formation, gas and water distribution is controlled by lithology and assisting controlled by structure. After the analysis of gas-water spatial distribution through gas/water profile of the study area, it is fingered t that there is no uniform gas-water contact in this gas reservoir.