Distribution Rule Of Gas And Water In Upper Paleozoic In The Fifty-nine Block Of Sulige Gas-area

The Sulige gas reservoir in upper paleozoic of the fifty-nine block is a typicallow porosity and low permeability of tight sandstone lithologic gas reservoir. thereservoir heterogeneity is strong and phase change quickly, which mainly distributedin the "dessert" of the tight sand body with physical properties are relatively well.Along with the further exploration and evaluation, the gas reservoir relationshipbetween water and gas becomes more complex in this region, there is no unifiedgas-water interface, formation water is relatively independent and disconnected.Gas-water distribution of research area is not very clear, the change of sand body isbigger, the cognition about it are not unified to each other. There are urgent problemsneed to solve in the area, figure out distribution of sand body and distribution rule ofgas and water in the study area, looking for development zone of relatively highpermeability and high yield is very indispensable. On the basis of predecessors’research, using the gas test, core, logging, well logging, chip, production dynamicdata and other date in the study area, the distribution of single sand body, microstructure of single sand body, four relationships of reservoir, and identification of gasand water layer, the distribution rule of the gas and water and its control factors arestudied on the work area, the following results having being achieved:(1) The main reservoir box of8and shan1section in the fifty-nine block can besubdivided into seven little layer which include H81、H82、H83、H84、S11、S12、S13layer.The H84layer belongs to the braided river delta plain deposits. sand body has thecharacteristics of large area of distribution and large thickness, It is a result ofmultiphase river’s superposition. The sedimentary facies of other small layers is themeandering river delta plain deposits. Sand body generally develops in the middle ofriver channel, also there are some developed in the crevasse splay outside the riverchannel. The scale of these sand body is not big and the thickness is general.(2) The micro structure of single sand bodies in the research area are mainlyconsists of structural highs, nose-like structure, structural lows and grooves and slope.The positive structure is conducive to the accumulation of oil and gas, the testing data shows that it has the characteristics of natural gas is more procent than water;Structure low easy to enrichment of water bodies; The natural gas gathering ofstructure slope zone between structure highs and lows.(3) Through four relationships of reservoir research on the work area,Established a recognition discriminant criteria of sand and mudstone of shihezi groupand shanxi group, it It can determine sand and mudstone of target layer. Until thephysical property lower limit standard is not set up before that. The reservoir of He8groups may contain oil and gas unless its porosity at above5%and permeability atabove0.08mD. The reservoir of Shan1groups may contain oil and gas unless itsporosity at above4%and permeability at above0.1mD.(4) The gas and water identification of the single well on the work area issuccessed finished by the logging intersection diagram method, apparent formationwater resistivity method and the hydrocarbon gas logging curve method. Which themethod of intersection figure of resistivity and porosity is the most accurate It be ableto effectively identify gas and water layer combined with apparent formation waterresistivity method and the hydrocarbon gas logging curve method in the work area.(5) There have been low resistivity gas reservoirs appear in the research area thatis difficult to identify. Discussed its logging characteristics from different angles andanalysised the three reasons of the formation: The pore structure of reservoir; Highirreducible water saturation; Additional electrical conductivity of clay minerals.(6) On the basis of above work, the gas-water distribution of the fifty-nine blockis discussed from the aspects of plane and profile, and the distribution figure of gasand water is fished in the main reservoir. The reservoir physical property of He8ismore well than Shan1, and each single sand body connectivity is better. But its waterrate is more higher than other layers. Shan1fomation is close to the underlyinghydrocarbon source rocks, it has the characteristics of natural gas is more procentthan water for the high strength of filling of hydrocarbon source rocks. The lateral gasand water is divided into isolated gas or water bodies by mudstone interlayer or denselayer. there is no unified gas-water interface. In the single sand body, gas and waterare clear differential, there is no inversion phenomenon of gas above the water.(7) Gas-water distribution rule in the study area is mainly controlled by themicro structure of the single sand body, lithologic pinchout, the reservoirheterogeneity and other factors comprehensive control. After comprehensiveconsideration the factors of controlling the distribution of the gas-water, theprediction of the distribution gas and water on He8fomation and Shan1fomation is completed, the forecast figure of favorable region is finished of the five purpose layer.