Development and application of magnetic positioning system for SAGD pairing horizontal well

Abstract

In the development of heavy oil, SAGD (Steam-Assisted Gravity Drainage) pairing horizontal well refers to two parallel horizontal wells with a fixed interval on the same vertical section. The upper one is a gas injection well, and another is a production well. To ensure the smooth construction of gas injection well, it is required to accurately measure the well spacing and cross-well scanning angle in real time during the drilling process of the gas injection well. Due to the magnetic interference of casings or liners of adjacent wells, conventional measurement-while-drilling tools cannot provide the accurate data of well spacing and cross-well scanning angle, or ensure the interval of pairing horizontal well. A magnetic position system was developed based on the orientation and range finding characteristics of rotating magnetic field. The direct measurement of borehole interval and cross-well scanning angle was completed using amplitude demodulation and angle scanning algorithm, and obtained the measurement range of 3~10 m for borehole interval with measurement accuracy of 0.3 m, measurement range of ±180° for cross-well scanning angle with measurement accuracy of 2°. The accuracy of measuring results was verified by numerical simulation tests and laboratory ground tests, and its feasibility in the directional service of pairing horizontal well was further proved by field tests and application.