During the last years, significant progress has been made in the use of fiber-optic technology for well and reservoir surveillance purposes. While most effort in this field appears to be concentrated on the development of fiber-optic based temperature-, pressure- and flow meters, comparably few publications have been made to-date about the use of fiberoptic technology for monitoring deformations of well tubulars and casings.
In this article we report on recent advances in our development of a real-time fiber-optic based casing imager. This device is designed for continuous, high-resolution monitoring of the shape of casings or well tubulars and, therefore, enables the determination of strain imposed on the well. Small-scale and full-casing-size laboratory tests have demonstrated that the latest generation of this system is sufficiently sensitive to detect casing deformations of less than 10 degrees per hundred feet and covers compressive and tensile axial strain ranges from less than 0.1% to 10%. We will discuss the background technology, the measurement sensitivity and strain-response characterization, as well as the scale-up work that has been performed to-date. Our article also includes an overview of field test results and illustrates how real-time deformation monitoring could form a significant component of reservoir surveillance strategies.