| The reservoir of Majiagou Formation in the eastern part of Sulige belongs to the low-pore and low-permeability type,the reservoir heterogeneity is strong,and the distribution law of formation water is complicated.The effluent in the production process of gas well is serious,and the distribution of gas and water becomes the main factor affecting the development of gas reservoirs.Based on the theory of sedimentary petrology,reservoir geology and logging geology,using the core,logging and gas test data to identify the reservoir distribution characteristics,gas and water layers standard,gas-water distribution rule and control factors in the eastern Sulige area have been studied intensively.According to the study on reservoir characteristics of majiagou reservoir,the most serious denudation in the northwest of the study area is in the formation of Ma55and below,while the slight denudation in the central area is mainly in the formation of Ma54,and the formation in the southeast is well preserved,with sporadic distribution of Ma51+2.Through the characteristics of pore permeability and saturation distribution,the porosity of Ma51-5-5 reservoir is 5-8.5%,the permeability range is?0.3-10?×10-3?m2,Ma51+2+2 and Ma541 reservoirs are better than Ma55 reservoirs,the main distribution on theplaneisaffectedbysedimentaryfacies,diagenesisand paleogeomorphology.Ma51+2+2 effective reservoirs are mainly distributed in Yunping,followed by Huiyunping.Ma541 effective reservoir is mainly distributed in gypsum-bearing Yunping.Ma55 effective reservoirs are mainly distributed in granular beach and Baiyunping,followed by Huiyunping.By studying the typical gas and water layer logging response characteristics,combined with a variety of intersection graph method and total hydrocarbon gas curve method to identify the gas and water layers,the accuracy of gas and water layer identification is improved.The upper resistivity limits of water layer in Ma541 layer and Ma55 layer are 90?·m and 85?·m,and the gas-water saturation limits are 60%and 58%.The apparent wave impedance of water layer can be well identified between1.5 and 1.65 in the cross plot of formation impedance and resistivity.The distribution of Ma51+2+2 gas reservoir is controlled by lithology.The horizontal and vertical discontinuity is obvious.Ma541gas reservoir is continuously patched and widely distributed.Ma55 gas reservoir is scattered in the study area as an isolated lens.There are four main controlling factors of gas-water distribution in gas reservoirs:physical characteristics,tectonic evolution,local structure,reservoir heterogeneity and palaeogeomorphology.Through the characteristics of pore permeability and saturation distribution,there are three main gas-water distribution modes in the gas reservoirs in the study area:residual free water mode,gas-water layer mode and lenticular water body mode. |
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