Research and Application of the Optical Fiber Technology for Real-time Temperature Test of Offshore Thermal Wells

Abstract

Abstract Thermal recovery method with horizontal wells has been conducted in Bohai Oilfield for almost ten years. The horizontal section length of the horizontal well is about 300 m. For thermal wells, monitoring the real-time temperature data downhole is of importance for analyzing the temperature distribution and variation rules along the wellbore, and consequently improving the produced degree of the horizontal wells. Different kinds of high-temperature monitoring technologies are summarized and the high-temperature optical fiber is selected for temperature monitoring of the offshore thermal wells. The steam injection tubing with functions of temperature monitoring is designed by using the optical fiber. In the horizontal section, the optical fiber is installed inside the steam injection tubing, goes outside of the tubing through a Y-joint, and connects to the surface along the annulus. Thus, the optical fiber could monitoring temperature of both the horizontal section and the annulus. Two target well are selected for project design and put into field application during the steam injection process. The monitoring results show that the high-temperature optical fiber works normally for about one month while the steam injection temperature is about 350°C. Besides, with the real-time temperature monitoring, the upward movement of the steam in the annulus is also observed and controlled by adjusting the Nitrogen injection parameters in the annulus. This is the first time that the optical fiber technology is applied in offshore thermal wells, which would be important for verification of wellbore parameter calculation and analysis of the casing variation when heated during the steam injection process. The successful application of the optical fiber in offshore thermal well would provide a guidance for the subsequent offshore thermal exploitation.