Applications of near-surface geophysics to detect a buried gas pipe | |
| Author | Pollathorn Chariprasit |
| Call Number | AIT Thesis no.GE-13-06 |
| Subject(s) | Geophysics--Methodology Gas pipelines--Thailand |
| Note | A thesis submitted in partial fulfillment of the requirements for thedegree of Master of Science inGeotechnical and Earth Resources Engineeringwith area of specialization in Geosystem Exploration and Petroleum Geoengineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-13-06 |
| Abstract | The goal of this research is to find out an optimal methodology of near-surface geophysics to detect a gas pipe buriedin a deltaic subsoil. The main difficultgeophysical exploration work is the diameter of the buried pipe is small comparing to the installation depth. The gas pipe diameter is commonly in the range of 30 to 40 inches (0.85 to 1.00m), while the burieddepth can reach 50m. In this study, two geophysical methods were applied, i.e., seismic and resistivity. The former was not effective, while the latter proved to be successful for the pipewhichis not too deep located. A combination of soil sampling, soil sample resistivity measurement in the laboratory, simulation of resistivity on the tank models and by forward modeling, were conducted to fine out the most suitable array and electrode spacing for the field survey. Soil sample resistivity measurement wasdone using Wenner-4 electrode method, and the Moris’s correction was applied for the boundary correction. The forward modeling was done for the suitable electrode array selection, which will be used in the tank model test and the field works. The tank model test was performed to simulate the buried pipe in the homogenous sand. Electrical imaging (EI) was applied on the model test using Wenner array which was selected based on the forward modeling, and electrode spacing was 0.02m. High resistivity (PVC) andlow resistivity (metal) pipes were used, and the filled fluids were water and air. As a result, electrical imaging (EI) can reveal the buried pipe as 2-D pseudo section. The electrical imaging (EI) using Wenner array and 0.40m electrode spacing was used in the field survey for the buried concrete pipe. Three line directions, parallel, perpendicular, and inclined, were applied for this field. As a results, electrical imaging (EI) was successful, and inclinedline is suitable when the pipe diameter is small.For the buried gas pipe detection, three line electrical imaging (EI) was applied. There were two line directions. Two lines were inclined, and the other was perpendicular line. Wenner array was used, and the electrode spacing were 1.00m for perpendicularline and 2.00m for inclined lines.Finally, the buried gas pipe can be detected using electrical imaging (EI). The buried depth is around 3m, and the pipe location can be seen by 2-D pseudo section. |
| Year | 2014 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-13-06 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Pham Huy Giao; |
| Examination Committee(s) | Noppadol Phien-wej;Adichat Surinkam; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2013 |