不稳态窜流部分打开压裂井试井分析模型建立及应用

Establishment and application of a well testing analysis model for partially penetrating fractured wells with unsteady interporosity flow

由于火山岩气藏具有产层厚、岩石类型多、岩性和岩相复杂多变、非均质性强、天然裂缝发育等特点,在压裂井开发过程中,存在压裂裂缝难以全部压开储集体的情况,天然裂缝以垂向斜交缝和高角度缝为主,并且大量试井资料显示介质间具有明显的不稳态窜流特征。针对上述特征,考虑压裂裂缝部分打开储集体、将基质简化为柱状基质和天然裂缝呈交替均匀分布特征,建立了不稳态窜流部分打开压裂井试井分析模型,利用点源模型、分离变量法等方法进行求解,并绘制了典型曲线图版,典型曲线分为井储段、过渡段、线性流段、球形流段、不稳态窜流段和边界反映段6个主要的流动段,其中边界包括无限大边界和封闭边界,并对裂缝半长等参数进行敏感性分析。以克拉美丽火山岩气藏的压裂井为例,分析其试井曲线,并进行试井解释,研究结果表明:该压裂井的水平渗透率较小,垂向渗透率特别大,部分打开程度较小,分析结果与气井的静态、动态资料基本一致。

Due to the characteristics of volcanic rocks such as thick productive formations of gas reservoirs,various rock types,complicated and changeable lithologies and lithofacies,strong heterogeneity,and development of natural fractures,it is difficult to open all reservoir body by fracturing fractures during development of fractured wells.Natural fractures are dominated by vertical clinofractures and high-angle fractures,and plenty of well test data show that there are obvious characteristics of unsteady interporosity flow between media.In view of the above characteristics,considering the partially penetrating reservoir body by fracturing fractures,the matrix has been simplified to the columnar matrix evenly and alternatively distributed together with natural fractures;a well testing analysis model is established for the fractured wells partially penetrating using unsteady interporosity flow.Further,this model is solved using the point-source model,and the method of separation of variables;additionally,a chart of typical curves is drawn.The typical curve is divided into six main flow sections:well bore storage section,transition section,linear flow section,spherical flow section,unsteady interporosity flow section and boundary reflection section.The boundaries include infinite boundaries and closed boundaries,and a sensitivity analysis is carried out on the parameters such as fracture half-length.Taking a fractured well in a block of the Kelameili volcanic gas reservoir as an example,this paper analyzes the well test curve and gives well test interpretation.The results show that the horizontal permeability of the fractured well is small,the vertical permeability is particularly large,and the partially penetrating degree is relatively small,basically consistent with static and dynamic data.