In electromagnetic (EM)-friendly areas, EM telemetry is widely used for drilling wells with a high rate-of penetration. However, it is also well known that the EM operating envelope is limited by signal attenuation due to conductive (salty) drilling fluids and various types of formations. In addition, EM telemetry signals are conventionally measured at the surface using long cables between the rig structure and a stake placed on the ground, which picks up high levels of rig-induced electrical noise.
This paper presents an innovative method, which enables using EM telemetry in basins where it was not previously possible. The method consists of deploying a wireline cable in an adjacent cased well and measuring the potential difference between the bottom of the cable (insulated from the top) and the adjacent well's wellhead (Codazzi, 2013; Gao, 2016). This equipment setup, named “deep electrode”, reduces electrical noise from the rig and increases the EM signal amplitude, resulting in an enhanced signal-to-noise ratio (S/N) and bit rate. The method has been validated by several examples presented.
Presentation Date: Monday, September 25, 2017
Start Time: 3:05 PM
Location: 362A
Presentation Type: ORAL
