Initially, it was believed that a horizontal well should be drilled with as much length as possible. However, field experience and flowmeter surveys in long horizontal drainholes revealed that the frictional pressure loss in the wellbore is an important factor hindering the full use of the entire length of the horizontal well. This paper presents a new approach to maximize the use of the full length of long horizontal drainholes.
Horizontal-well drilling allowed the drilling of different well architectures and made it possible to offset well costs and productivity limitations. Intuitively, drilling longer wells will maximize exposure to the producing formation and yield higher flow capacity. Paradoxically, however, some wells were drilled longer than the optimal horizontal-section length and the extra length did not yield additional flow. Therefore, it is important to determine the optimal horizontal-section length that would achieve flow contribution along the whole section.
Experience has revealed that long horizontal wells suffer from frictional pressure losses. This fact is exacerbated in the presence of highly productive formations; these would require low pressure drawdowns that may well be similar to the frictional pressure losses, which would therefore hinder wellbore flow ingress. Thus, some horizontal wells are equipped with downhole flow-choke systems to optimize well productivity....
A New Approach for Optimization of Long-Horizontal-Well Performance
20 October 2016