Study On High-Capacity Channel Evaluation And Remaining Oil Distribution Of Heavy Oil Reservoir With Edge And Bottom Water

During the development of water flooding in medium-high permeability reservoir,due to the long-term erosion effect of water flow,the high-capacity channel is relatively developed and the injection water has a serious invalid circulation,which affects the development efficiency of the reservoir.The thesis takes G block high permeability heavy oil reservoir as the research object,due to the long-term erosion of the edge and bottom water of G block,the reservoirs have strong time-variation properties,the remaining oil production becomes more difficult,and the reservoir recovery ratio decreases.To solve this problem,a set of quantitative high-capacity channel identification methods was established to provide a basis for the accurate description of remaining oil.On the basis of preliminary geological understanding,the selection of 10dynamic and static parameters and by using the sand production of wells to determine the intersubjective effect of each evaluation index and the importance of each evaluation index.The Analytic Hierarchy Process（AHP）was used to construct a judgment matrix to determine the index weights of oil and water wells.Considering the influence of 22 production systems on the evaluation of high-capacity channel,a mathematical model of high-capacity channel evaluation was established by using VBA programming.The identification model of high-capacity channel is verified by using the data of profile-log of water injection and oil wells and the distribution map of high-capacity channel with time is given.On the basis of high-capacity channel evaluation,combined with the development history of the block,the effects of liquid production,profile control,polymer flooding,CO₂ huff and puff on the development of high-capacity channel are analyzed.The thesis is based on relevant laboratory data,and considering a number of measures such as profile control,polymer flooding and CO₂ huff and puff,combined with the results of quantitative identification of high-capacity channel,CMG numerical simulation software was used in this paper to complete the numerical simulation history fitting of Ng12+Ng13 small layer in G block.The cumulative oil production error of the G block is-1.5%,159 single wells were successfully fitted,and the single well fitting rate was 86.8%,meeting the accuracy requirements.On the basis of numerical simulation history fitting,the distribution law of remaining oil is analyzed in detail.The genetic types of remaining oil on the plane mainly include the bottom water（secondary）retention type,the edge of the low potential zone,the high structure（local）,the flow zone around the flooded path and the barrier layer shielding type.Longitudinally,the remaining oil is mainly distributed at the top of the oil layer and at the bottom of the barrier layer.At present,the comprehensive recovery degree of the G block is 26.51%,the recovery degree of recoverable reserves is 74.24%,and the recoverable reserves of remaining oil are 93.59×10⁴t.According to the recovery degree of recoverable reserves of each small layer,the whole block is longitudinally a connected flow unit,and interlayer channeling exists in the production.The research results of this thesis have important guiding significance for understanding the spatio-temporal evolution law of high-capacity channel in medium-high permeability heavy oil reservoir and for potential tapping of remaining oil in G reservoir.