A considerable number of studies have been conducted to optimize the perforated completions for horizontal wells, but very few of them took into account the effect of reservoir heterogeneity and coning problems in the completion design. One of the most relevant work directly related to this topic is the one developed by Goode and Wilkinson7. They have presented an analytical solution for the performance of partially completed horizontal well. Their model, however, has two major limitations:
it considers the reservoir as homogeneous and ignores heterogeneity, and
it does not take into account the water and gas coning effects.
In this study, a numerical solution has been developed to optimize the perforated completions for horizontal wells in a heterogeneous reservoir laying between a large gas cap and an active aquifer (double coning problem). Another objective of this study was to examine the performance of various perforation schemes for horizontal wells in Hassi R'mel oil Rim using reservoir simulation. Since the capability of the numerical simulators to model a horizontal well performance is largely controlled by the quality of the geological description of the reservoir, therefore, a reservoir characterization based on geological (sedimentary) units was performed on the A-Sand reservoir of Hassi R'mel oil Rim.
The simulation modeling in this study was undertaken in two large parts. First, a sensitivity analysis was conducted to investigate the effects of the most relevant reservoir parameters on the horizontal well performance for different perforation schemes. This allowed us to examine the effect of the perforation length and its distribution and to find the optimum perforation scheme for horizontal wells in Hassi R'mel oil Rim. Second, the simulation modeling was involved in a real case where the performance of the well HRZ-09 was a concern. The reason for taking this well as a case study is that it was completed non-conventionally using the Inverted High Angle technique. This completion led us to investigate the possibility of perforating the slanted section of the well, in addition to the horizontal section (Double perforation scheme).
As a result of this study, correlation curves have been generated to optimize the perforated completions for horizontal wells in Hassi R'mel oil Rim. It has also been found that the optimum perforation scheme for horizontal wells in Hassi R'mel oil Rim corresponds to the case of 60% uniformly distributed perforation. From the case study, it was found that there is no extra-recovery to be expected from the double perforation of the well HRZ-09. Moreover, such perforation scheme yields much higher gas-oil ratio in comparison to the actual perforation case. This result was confirmed by an economic analysis performed on three proposed perforation schemes.
Horizontal wells are one of the most important strategic tools in petroleum exploitation. As a result of the advances in drilling and completion technologies in the last two decades, the efficiency and economy of horizontal well have significantly increased. Today, horizontal well technology is applied more often and in many different types of formations.