缝洞型油藏离散介质网络数值试井模型

THE NUMERICAL WELL TEST MODEL OF THE DISCRETE MEDIA NETWORK IN FRACTURED-VUGGY CARBONATE RESERVOIR

针对多重介质试井模型不符合缝洞型油藏网络状分布、非均质性极强的地质特征,建立了新的试井模型,将大尺度溶洞(流体主要的储集空间)视作零维模型,裂缝、孔洞发育的条带状地层(沟通溶洞的渗流通道)作为控制流体流动的一维模型,从而构成离散介质网络(DMN)模型。用有限差分法建立了缝洞型油藏离散介质网络油水两相数值试井模型,对渗流通道的储渗性能、大尺度溶洞的容积和距测试井的距离等因素对测试井压力响应特征的影响进行了研究。结果表明:缝洞型油藏试井压力导数曲线上类似"凹子"的特征是由大尺度溶洞向渗流网络的窜流造成的。实例分析表明,新模型解释结果与缝洞型油藏地质特征一致。

It's very difficult for multi-media well test model to describe the geologic characteristics accurately in fractured-vuggy reservoir due to the high heterogeneity and network-like reservoir space.The big size vugs which are taken as zero-dimensional entities are the main fluid accumulating space,and the strap-shaped formations which are taken as one-dimensional entities are the connection channels,composing the discrete media network(DMN).According to fluid flow in the network,the two-phase mathematical model for the numerical well test of fracturedvuggy reservoirs is established.The effects of flow channels' permeability,big vugs' capacity and distance from well are discussed.Result shows that the 'hollow'feature shown in pressure derivative curves is caused by the cross flow of big size vugs to the percolation Network.Finally,a field data analysis shows that the interpretation results of discrete media network numerical well test model conform to the three-dimensional geological model.