Plugged and Abandoned Well Locating
Using the latest in geophysical and magnetic instruments we are able to precisely map and locate all your abandoned well structures quickly and cost-effectively.
Electromagnetic (EM) Surveys and Tools
An electromagnetic survey is based on the response of the ground to the propagation of electromagnetic fields composed of an alternating electric intensity and magnetizing force. A primary or inducing field is generated by passing an alternating current through a coil (loop of wire called a transmitter coil) placed over the ground. The primary field spreads out in space, both above and below the ground, and can be detected with minor reduction in amplitude by a suitable receiving coil in the case of a homogeneous subsurface.
However, in the presence of a conducting body the magnetic component of an electromagnetic field penetrating the ground induces alternating currents or eddy currents to flow within the conductor. Eddy currents generate their own secondary electromagnetic field distorting the primary field. The receiver will respond to the result of arriving primary and secondary fields so that the response differs in phase, amplitude, and direction. These differences between transmitted and received electromagnetic fields reveal the presence of a conductor and provide information on its geometry and electrical properties.
Unlike conventional resistivity techniques, no ground contact is required. This eliminates direct electrical coupling problems and allows much more rapid data acquisition. For shallow profiling (up to 20 feet), a Geonics, Inc. EM-31 Terrain Conductivity meter is used. One person can collect as many as 10,000 data points per day with this instrument. An EM-34 is used for depths of investigation between 30 and 180 feet. This instrument requires two people to operate, and up to 500 data points per day can be collected under good conditions. These tools are extremely sensitive and accurate, capable of detecting variations in conductivity of as little as 3%. Data are automatically stored in an electronic data logger for later transfer to a computer.
Applications Include
- Locating buried metal objects (drums,UST's, utilities, etc.)
- Delineating contamination plumes
- Defining lateral changes in lithology
- Locating water producing fractures
- Investigating landfills
- Detecting UXO
- Gathering of forensic evidence
