Applying Radial Acoustic Amplitude Signals To Predict Intervals of Sand-Stuck Tubing

Abstract

Summary The reuse of existing well bores is a cost-saving technique used by oil and gas producers in mature fields. This process usually requires the removal of tubing and packers to allow the well to be deepened or sidetracked. The tubing removal process is often made difficult when the tubing is stuck inside the casing because of mechanical binding or binding caused by dehydrated mud or sand in the annulus between the tubing and casing. Conventional direct and indirect methods of finding the stuck point(s) along an interval of tubing, such as free-point indicator tools or acoustic attenuation measurements, have proved themselves useful in finding the point(s) where the tubing is stuck. However, when the sticking is caused by uncompacted sand that has entered the annular space between the tubing and casing, these conventional stuck-pipe indication methods are often inconclusive or misleading. Technological advancements in the design and development of slim, 11116-in. outside diameter (OD), radial cement bond tools allow the application of a new measurement to find sand-stuck tubing intervals. These tools provide up to six independent, closely spaced acoustic attenuation measurements distributed radially around the tool body. When the recording operation is performed inside the tubing, the increased sensitivity of these tools to sound attenuation, as compared with conventional omnidirectional amplitude signals, allows sand intervals along the outside of the tubing to be distinguished from intervals where little or no sand is present. This information is used to select the best depth to sever or back-off the free tubing in order to reduce the interval length and expense associated with the washover process required to remove the remaining tubing from the wellbore. An overview of conventional stuck-pipe recovery techniques is provided here, along with a brief explanation of applicable acoustic technology. A case study of a South Louisiana well is presented to demonstrate the application and illustrate the cost savings which can be gained by use of this very new technology.