| A fully implicit, three-dimensional simulator with local refinement around the wellbore is developed to solve reservoir and horizontal well flow equations simultaneously, for single-phase liquid and gas flow and two-phase liquid-gas flow cases. The model implements the conservation of mass and Darcy's law in the reservoir and conservation of mass and momentum in the wellbore, for isothermal conditions. The coupling requirements are satisfied by establishing the continuity of pressure and preserving mass balance at sandface. The proposed simulator is tested against and verified with the results obtained from a commercial code ECLIPSE-100™, a public-domain simulator and a semi-analytical model.; The model can be used to simulate the transient pressure and flow rate behavior of both the reservoir and the horizontal wellbore. Traditional decoupling of the wellbore transients from the reservoir transients does not capture the horizontal well pressure and flow rate transients at early times since the interaction between the reservoir and wellbore is inherently neglected. Simulation runs with the proposed model reveal the actual characteristics of horizontal wellbore storage and unloading. The effects of permeability, formation thickness, well length, fluid compressibility, reservoir anisotropy, damage around the wellbore, and partial or selective completions are also studied. |
