A generalized semi-analytical productivity model, accounting for any well and reservoir configuration has been constructed and presented recently. The model allows for the production or injection prediction of any well (vertical, horizontal, deviated) and reservoir configurations in both isotropic and anisotropic media. Partially completed wells can also be simulated.
A concern in modern reservoir management is the potential desirability of multiple horizontal laterals, frequently emanating from the same vertical well. Once pseudosteady state is reached, the productivity index differences among various well configurations are diminished. Thus, multiple laterals in higher-permeability formations, draining an assigned "box," may not offer incremental benefits. However, at early time and under transient conditions in low-to-medium- permeability reservoirs, the relative productivity improvements provided by multiple laterals may result in sufficient incremental benefits to warrant their drilling. This paper presents a series of parametric studies for a range of reservoir permeabilities and permeability anisotropies for various multiple well configurations. The desirability or lack thereof for these configurations is demonstrated.
A comprehensive multi- and single-well productivity or injectivity prediction model was introduced recently that allows arbitrary positioning of the well(s) in anisotropic formations.
Such a flexible and generalized model can be used to study several plausible scenarios, especially the economic attractiveness of drilling multiple horizontal wells-which in some cases may be multiple laterals configured from the same wellbore.
Clearly, multiple wells (vertical or horizontal) in the same drainage area will interfere with each other. This interference will be felt earlier in higher permeability formations, and the relative economic attractiveness of the multi-well configurations may begin to diminish early. The lower the reservoir permeability, the later the interference will be felt.