Utilization method of low-grade thermal energy during drilling based on insulated Drill pipe

Abstract

Downhole heat damage during drilling seriously restricts the exploration and development of deep oil and gas reservoirs and geothermal resources. The petroleum industry focuses on controlling the downhole heat damage during drilling while utilizing low-grade thermal energy and making it profitable. Therefore, a techno-economic coupling evaluation model is developed for a low-grade thermal energy utilization system developed for use during drilling along with a wellbore heat transfer model. Subsequently, based on the model, the influence of different lengths and installation positions of insulated drill pipe (IDP) on the downhole temperature is studied. Then, on the premise of satisfying the wellbore cooling target, the system is economically evaluated based on factors such as production time, government subsidy, and electricity price, and the corresponding measures are proposed to make the system profitable. Finally, a set of efficient IDP-based low-grade thermal energy utilization methods is developed. The case study presented herein shows that the IDP length that allows the system to reach the maximum profit in the 10th year is 4720 m for a horizontal well with a depth of 6200 m when the government one-off subsidy rate is 30% and electricity price is increased by 30%.