Abstract: Based on the basic solutions of the pressure response of point source in infinite space, pressure responses at any point in a horizontally infinite reservoir are studied. Furthermore, methods of welltest interpretation are researched in aspects of observation points, equivalent pressure point and treatment for multisolutions of pressure response. An example of horizontal multilateral well with 4 branches is given as Well SZ361CF1 in Bohai Oilfield, the authors systematically study the efficient algorithm about transient pressure response in heterogeneous reservoirs with dual porosity, the calculation of equivalent pressure points in a well hole with infinite conductivity, the welltest interpretation method with serious solvability, etc. The achievement is of great importance to EOR and stimulation measures.
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Key words: horizontal multilateral well, transient pressure, equivalent pressure point, conductivity model, well test