Abstract
Reservoir studies can help determine what parameters or configurations make multilateral wells (MLs) more economical than single-branch horizontal wells (HWs). We simulated 5 years of production from a water-drive reservoir and evaluated the results, using a range of economic criteria. The reservoir simulator uses a multisegment wellbore model to enable better handling of complex well trajectories and detailed description of pressure losses in the horizontal, building angle, and vertical sections of the well. The study compared Levels 3 and 6 ML junction configurations to HWs. We modeled natural flow applications considering normal gravity oil (20 to 29° API) in a homogeneous reservoir with permeability ranging from 10 to 1,250 md. Detailed well-cost estimates for each configuration included taxes, royalties, and water-handling costs. We found that accounting for friction and hydrostatic pressure losses through all the sections of the well created more realistic models. For the cases we studied, a two-branch ML produces 13% more oil than a HW in highpermeability reservoirs and 80% more oil in low-permeability formations with low viscosity oil (1 cp). In addition, the ML well produces 10 to 15% less water than the HW. The extra production of the ML over the HW increases to more than 50% in low-permeability and higher than 90% in lowpermeability. The ML has a higher net present value—20% or greater—than the HW for all permeabilities. Using a profit-toinvestment ratio, the ML is more attractive than the HW in the lower permeability cases. Results using other economic metrics gave similar results.
