低渗储层特殊渗流机理和低渗透气井动态特征探讨

DISCUSSION ON THE SPECIAL PERCOLATION MECHANISM OF LOW PERMEABILITY RES ERVOIR AND THE PERFORMANCE CHARACTERISTICS OF LOW PERMEABILITY GAS WELL

本文针对低渗储层气体低速非达西渗流机理这一前沿课题 ,介绍了开展实际低渗岩样特殊渗流实验的结果和认识 ,探讨了低渗岩石气体低速非达西渗流的物理实质和一般规律 ,认识到了含水状态下岩样渗流偏离达西定律的现象并可以用“启动压差”和“临界压力梯度”两个参数来描述。在实验研究基础上建立了描述气体低速非达西渗流的数学模型 ,采用幂级数解法求得低渗储层气体低速非达西渗流模型繁荣通解。在此基础上通过大量的计算和分析理论曲线 ,提出了低渗气井不稳定试井曲线的后期段连续上翘的原因在于气体低速非达西渗流的新观点。文章最后介绍了上述研究成果在四川低渗气井试井分析中的应用实例 ,对低渗气井的试井分析具有一定指导作用。

In the paper,in order to study such a forward to pic as the low velocity non Darcy flow mechanism of low permeability reservoir, t he result and knowledge of special percolation experiments of low permeability r ock samples are introduced;the physical significance and general rule of the gas low velocity non darcy flow in the low permeability rock samples are discussed ;and it is proposed that the phenomenon of deviating Darcy's law of gas flow pas sing through rock samples under the watered condition may be described by two pa rameters as'starting pressure differential'and'critical pressure gradient' .On the basis of experimental research,a mathematical model of describing gas lo w velocity non Darcy flow in low permeability reservoir was set up and its pros p erous general solution was acquired by use of the solving method of power series .A new viewpoint,that the reason for the successive upwarp of the later section of the transient testing curve of low permeability gas well rested with the gas low velocity non Darcy flow,is put forward through a large number of calculatio n and analysis of the theoretic curve.Some examples of the application of the res earch achievement mentioned above in the testing analysis of low permeability ga s wells in Sichuan Basin are introduced in the paper,which is of a certain guidi ng signification for the testing analysis of low permeability gas well.