Production prediction model of coalbed methane wells in low water production period
Keywords:
cave volume, conservation lawAbstract
The main storage space of fracture-cavity reservoirs is fractures and caves, the phase change of condensate gas is complex. Due to these factors, the interpretation methods of the well testing have not been thoroughly studied in fracture-cavity condensate gas reservoirs. According to the three conservation laws of mechanics, and defined the mass flow rate pseudo pressure of condensate gas, it is proposed that there is not only pipe-seepage coupled flow in the fracture-cavity, but also the formation pressure propagates in the form of waves. The flow equation of wellbore-cave has is established, and the flow pressure is provided between the wellbore and the cave. Using this as the inner boundary condition, the complete set of flow equations are established. On this basis, the well testing interpretation model of the well-cavity-fracture is established in the fracture-cavity reservoir condensate gas reservoirs. Applied to a well in Tarim Basin, The interpretation results: the volume of cave is 75. 66×104 m3, and fracture is 551×104 m3, the dynamic reserves of condensate gas is 21. 5×108 m3, the result of material balance method calculation is 22. 3×108 m3, the difference between they is only 3. 5%. It is the first time to use well testing to interpretation the volume of caves and fractures, which is a beneficial exploration of the flow mode of fractured-cavity condensate gas reservoirs. © 2023 Well Testing. All rights reserved.
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