Comparing Productivity from Post-frac Vertical and Horizontal Wells
Mohamad Johan, Josey Areza
Engineering Honours Degree, 2006
University of Adelaide
In this report, a comparative study between productivity of horizontal wells and fractured vertical well is presented. Both methods are used widely around the world to improve productivity for old and new reservoirs. The study is done based on specific sample cases using existing statistical analytical method. The affect of reservoir parameters on the productivity was tested and
Parameters that were changed are horizontal and vertical permeability, reservoir heights and reservoir drainage area. Based on these changes, the effect on productivity for the specific cases was recorded and presented. The productivity of both horizontal well and fractured vertical is compared in order to determine which method is better than the other.
The changes in parameters give different values of productivity. Some affect the productivity more than the others. For example, for a fractured vertical well, a change in horizontal permeability will affect more to the productivity compared to change in vertical permeability.
All the results show that the length also influences which method is better. For most of the case, fractured vertical well will gives higher productivity with shorter lengths. As we increase the lengths, horizontal well become the preferred choice. Apart from that, we can also predict at which value of reservoir parameters that will result in only one method giving a higher productivity for every length. For example, for a horizontal permeability value of 188 mD and above, fractured vertical well will always yield a higher productivity than the horizontal well.
Results and discussions presented in this paper are only true for this particular reservoir. It cannot be generalize as a universal answer.