Imaging Pvc Gas Pipes Using 3-D Gpr

Over the years, many enhancements have been made by the oil and gas industry to improve the quality of seismic<br>images. The GPR project at GTRI borrows heavily from these technologies in order to produce 3-D GPR images of PVC<br>gas pipes. As will be demonstrated, improvements in GPR data acquisition, 3-D processing and visualization schemes yield<br>good images of PVC pipes in the subsurface.<br>Data have been collected in cooperation with the local gas company and at a test facility in Texas. Surveys were<br>conducted over both a metal pipe and PVC pipes of diameters ranging from i/z in. to 4 in. at depths from 1 ft to 3 ft in<br>different soil conditions. The metal pipe produced very good reflections and was used to fine tune and optimize the<br>processing run stream. It was found that the following steps significantly improve the overall image:<br>1) Statics for drift and topography compensation<br>2) Deconvolution<br>3) Filtering and automatic gain control<br>4) Migration for focusing and resolution<br>5) Visualization optimization<br>The processing flow implemented is relatively straightforward, simple to execute and robust under varying<br>conditions. Future work will include testing resolution limits, effects of soil conditions, and leak detection.