| Accurate calculation of horizontal and vertical wells' productivity indices is not possible if their respective drainage areas are not estimated accurately. Determination of their respective drainage areas is of great importance in field development when utilizing both horizontal and vertical well drilling. This research has, for the first time in petroleum engineering discipline, suggested the use of a mathematical model describing the interference testing of an active horizontal well in the presence of another vertical well in order to estimate the drainage areas of both wells. This study has, also for the first time in reservoir engineering discipline, introduced two criteria, based on production rate and bottomhole flowing pressure in order to accurately compare horizontal well and vertical well performances. The highest A{dollar}sb{lcub}rm hw{rcub}{dollar}/A{dollar}sb{lcub}rm vw{rcub}{dollar} and q{dollar}sb{lcub}rm h{rcub}{dollar}/q{dollar}sb{lcub}rm v{rcub}{dollar} ratios correspond to long horizontal wells drilled in thin isotropic reservoirs developed in a manner that yields high value of drainage area length compared to drainage area width. It was observed that the advantage of horizontal wells over vertical wells increases when well spacing in a reservoir developed by both horizontal and vertical wells is chosen, by necessity, to be small, such as the one chosen in developed reservoirs and reservoirs undergoing enhanced oil recovery operations. It is also observed that flow rate ratio, q{dollar}sb{lcub}rm h{rcub}{dollar}/q{dollar}sb{lcub}rm v{rcub},{dollar} is always higher than drainage area ratio, A{dollar}sb{lcub}rm hw{rcub}{dollar}/A{dollar}sb{lcub}rm vw{rcub}.{dollar} This research presented some results which show that the new concept yield drastically different results than the one obtained by Joshi. It is important to note that Joshi's results are based solely on assumptions regarding the geometry while the concept introduced in this research is based on the fundamentals of flow through porous media. |
