| Steam huff and puff is one of the main methods of heavy oil recovery.However,with the increase of huff and puff rounds,the effect of stimulation becomes worse,which is manifested by the rapid decline of production and the rapid increase of water cut.In order to further develop the reservoir after multiple huff and puff cycles,it is necessary to know the distribution of the remaining oil in the reservoir.Firstly,the characteristics of production wells after multiple huff and puff rounds are analyzed.The curves of displacement and injection-production characteristics of typical units in block Shan56 are obtained by deriving the formulas of the relationship of the accumulative production and injection,and the corresponding amounts of residual oil are calculated respectively as 4.96 × 105 and 5.53 × 105.Secondly,the distribution of remaining oil is studied in terms of vertical and horizontal heterogeneity.The results show that the recovery degree is inversely proportional to the permeability gradient and directly proportional to the permeability.At the same time,through the calculation of comprehensive influence factor and interlayer interference factor,the threshold of the permeability gradient of double-layer simultaneous production reservoir is calculated as 10.The factors that affect the shape of the Hall curve in water injection development are analyzed.The formula of calculating steam channeling volume by Hall curve is deduced.The steam channeling volume of well 13*N11 well is 129.41m3.Finally,the calculation formula of reservoir residual heat is deduced,and the factors that affect residual heat are analyzed,which shows that residual heat is more sensitive to huff and puff cycles than other factors.At the same time,the evaluation method of the validity of residual heat is established.Taking the block of Shan56 as an example,the overall distribution of residual oil of this block is analyzed by using the method of residual heat validity evaluation. |
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