The objective of multilateral-well technology is to improve well productivity by maximizing reservoir contact, resulting in field development with fewer wells. Long horizontal wells (up to eight km) are drilled, but the greatest opportunity, as well as the greatest technological challenge, lies with MRC wells. A Maximum Reservoir Contact (MRC) well, by definition, is a multilateral horizontal well with more than five km of total contact with the reservoir rock. Planning of these wells requires extensive modeling studies to optimize total length, placement and configuration of branches, and the use of "smart-well" options: selective layer/branch shutoff devices, balanced production to limit flow of fluid through a particular branch, crossflow control, and downhole separators to handle high watercuts. This paper describes how these objectives were met and the well design was optimized.
In this work, a number of sector models were used to evaluate different MRC completions based on their total production, well placement and design, stage of depletion, pressure interference between laterals, and impact of water encroachment by downhole control. Applying this reservoir simulator to the development of the northern area of the Greater Ghawar field, we were able to accomplish the following:
Optimize well placement.
Optimize numbers and lengths of laterals.
Evaluate benefit of "smart" well completions.
Detailed modeling of the proposed MRC wells provided a better understanding of reservoir dynamics that will enable Reservoir Management to make faster and informed decisions. Besides this, the study helped us significantly reduce turnaround time for MRC well evaluation.
The successful implementation of horizontal drilling over the last two decades has led to the development of multilateral-well technology. The number of multilateral-well completions has increased substantially in the last several years due to advances in directional drilling and completion systems. Many field applications have been reported in the literature including compartmentalized reservoirs in UK and Malaysia, stacked dual, triple, and fishbone laterals in Venezuela, and diverse applications in onshore and offshore USA and North Sea, Thailand and Brunei, Canada, Brazil, Italy, Nigeria, and the Middle East.