Abstract:

The existing faults affects the propagation of pressure waves in the composite reservoirs, meanwhile, the location of faults affects the curves of the bottom hole pressure. Based on the principle of seepage mechanics and point source function, the fractured-well line source solution of fault composite reservoirs in Laplace domain was obtained by image principle, pressure drop superposition principle and Laplace integral transformation. The bottom hole pressure solution of finite-conductivity fractured wells was obtained by coupling fracture of fractured-well and reservoir model. The typical characteristic curves of dimensionless bottom hole pressure and pressure derivative were drawn by Stehfest numerical inversion in the real space. The results showed that the characteristic curve was divided into seven flow stages generally. In the early stage, the position of dimensionless bottom hole pressure and pressure derivative curves decreased with the increase of the fracture conductivity. When the mirror well was located in the inner region, the pressure derivative curves of radial flow and subsequent bottom hole pressure showed horizontal lines of 0.5, 1 and fluidity ratio M₁₂ in inner part and outer part, and the larger the inner radius was, the longer the radial flow in the inner zone would be. When the mirror well was located in the outer region, the pressure-derivative curve of radial flow and subsequent bottom hole pressure showed horizontal lines with the value of 0.5, 0.5M₁₂ and fluidity ratio of M₁₂ in inner and outer zones.

Key words: composite reservoir, point source function, finite-conductivity, closed fault, fractured well