Effects of Packer Locations on Downhole Electric Heater Performance: Experimental Test and Economic Analysis

Wei Guo,Xiaoshu Lü,Zhendong Wang,Yuan Wang,Qiang Li,Youhong Sun,Sunhua Deng

doi:10.3390/en13020377

Abstract

A downhole electric heater, which reduces heat loss along a heat insulation pipe, is a key apparatus used to ignite oil shale underground. Downhole heaters working together with packers can improve the heating efficiency of high-temperature gases, while different packer locations will directly affect the external air temperature of the heater shell and, subsequently, the performance and total cost of the downhole heaters. A device was developed to simulate the external conditions of heater shells at different packer locations. Then, the effects of external air temperature on the performance of a downhole heater with pitches of 50, 160, and 210 mm were experimentally studied. In the test, results indicated that the heater with a packer at its outlet had an accelerated heating rate in the initial stage and decreased temperature in the final stage. Additionally, the lowest heating rod surface temperature and highest comprehensive performance were achieved with minimal irreversible loss and lower total cost when using a downhole electric heater with a packer set at its outlet. In addition, the downhole electric heater with a helical pitch of 50 mm and a packer at its outlet was more effective than other schemes in the high Reynolds number region. These findings are beneficial for shortening the oil production time in oil shale in situ pyrolysis and heavy oil thermal recovery.

Highlights

With the continuous exploitation of conventional oil reservoirs, easy-to-exploit light oil is dramatically reduced
It can study the effects of the external air temperature of the heater shell on its performance
The electric heating rod surface temperature is related to the operational stability of the DEHCHB

Summary

Introduction

With the continuous exploitation of conventional oil reservoirs, easy-to-exploit light oil is dramatically reduced. Unconventional oil reservoirs, such as heavy oil and oil shale, are the main driving forces for future oilfield production [1,2,3]. Heavy oil and super-heavy oil can be utilized after reducing their viscosity. Oil shale is an immature source rock that needs to be heat treated to convert kerogen into oil and gas [2,3,4]. Oil shale in situ pyrolysis is the mainstream technology used for oil shale exploitation [5,6,7]. From the perspective of heat transfer, the heat transfer process during heat carrier (superheated steam, nitrogen) injection in steam huff and puff, steam

Methods

Results

Conclusion