Subhorizontal geothermal well completion: a promising outlook

Abstract

The paper investigates the performance of sub-horizontal well architectures in upgrading deliverabilities and life cycles of geothermal district heating (GDH) doublets compared to conventional completions. The concept aims at applying horizontal drilling technology, elsewhere routinely practiced by the oil and gas industry, to intersect via long reach drains the entire productive (pay) interval of a multilayered reservoir. Modelling of candidate conventional (vertical, inclined) and alternative (single horizontal drain, several horizontal, multilateral, legs, sub-horizontal, total pay, pathway) well trajectories highlighted the positive impact of multilaterals and sub-horizontal designs in delaying thermal breakthrough times. The foregoing was further validated on actual (Paris Basin) reservoir settings, therefore exemplifying the benefits expected from the sub-horizontal well design from both the productive capacity, heat recovery and thermal life stand points. Implementation of the concept and its economics are discussed in fine.