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确定合理射孔施工负压差是气井射孔工程优化设计中的重要内容，其中最大无砂负压是气井射孔负压设计中难获得的参数。它不仅直接以射孔的孔眼的稳定性孔隙还与孔眼的负压清洗效果密切相连，直连影响到射孔气井的产能。文章在大量文调研的基础上，建立了求解最大无砂负压差的弹性性力学与渗流力学的耦合模型，从而提出了确定气井射孔完井最大无砂负压差的新方法。该方法同时考虑了气体流劝的非达西效应、岩石力学性质、流体特性、射孔

A RESEARCH ON THE METHOD OF PREDICTING MAXIMUM SANDFREE UNDERBALANCE OF PERFORATION IN GAS WELL

To determine a reasonable underbalance difference of perforating job is an important part in the optimum design of gas well perforation engineering,in which the maximum sandfree underbalance is the parameter being difficult to obtain in underbalance design of perforation in gas well.It is not only directly related to the stability of perforations after perforating but also closely linked up with the underbalance cleaning result of the perforations,by which the productivity of the perforated gas well will be directly affected.On the basis of investigating a large number of literatures,a coupling model of the elastoplasticity and percolation mechanics for solving the maximum sandfree underbalance difference is set up,thus a new method for determining the maximum sandfree underbalance difference of perforation completion of gas well is proposed in the paper.In the method,the influence of the gas flowing's nonDarcy effect,rock mechanics property,fluid characteristic and perforating charge type on calculating the maximum sandfree underbalance is simultaneously considered,thus the factors involved are allsided.The method is generalservice and better than the experiential design method used at present.Through utilizing in practice it is shown that the result calculated by such a method is reliable.