Advances in Oil Exploration Electronics Soft-Switching Power Supplies:Smoothing Out the Rough Edges in Powering Data Acquisition and Drilling Equipment
Authors: Edmunds Mark 
Published: July 2010

Technology Brief

Over the last two decades, the use of sophisticated electronic equipment to test and measure the size of prospective finds has increased rapidly throughout the global oil industry. Today, "downhole" cables often carry down electricity controlled by programmable DC power supplies to power drilling equipment located 30,000 feet beneath the surface, and then send sensitive telemetry data back up to computers.

In these situations, electrical "noise" can diminish data transmission rates, slowing down acquisition data used by the geologists to map petroleum finds, or even lead to the complete loss of data through power surges that cause computers to reset. In addition, in order to develop 3D maps of a find, drilling companies are now using sensitive electronic data measurement equipment that can be disrupted by power surges. In any case, the cost of reacquiring this lost data can be expensive.

Soft switching in power supplies is an advanced technological solution to the noise and power surge issue involved in the oil drilling industry. Although relatively new, soft switching power conversion has already found widespread acceptance among electronic manufacturers. Yet, as with all new technologies, questions still abound among end users. What are the advantages, and how can soft switching help oil exploration and drilling teams?

First, the origins of soft switching. Soft switching is a superior switch-mode power supply topology (technology) developed by power supply manufacturers that dramatically reduces the electrical noise created by the main power transistors during the switching process, the micro-moment in time when the power supply is switched on and off. (see Figure 1) Its main function is to reduce or eliminate radio frequency interference (RFI) and other problems that have been associated with the switching process since the emergence of high-frequency "hard switching" switch mode power supplies in the 1980s.

Around that time, there was a rapid increase in the use of electronic products in all manner of industrial applications. This, in combination with the phenomena of RFI and other electromagnetic effects, drew the attention of regulatory bodies around the world. In particular, it became apparent that the large amounts of electromagnetic interference conducted and radiated by this type of supply could interfere with radio communication, and have a negative impact on the operation of sensitive electronic and computer circuits in a variety of industries, including the oil industry.

The main benefit derived by the oil exploration and drilling industries from soft switching power supplies is a marked reduction in electrical noise levels. This enables the telemetry coming from below the ground to be detected more easily. Received from deep-land or deep-sea drilling sites, the data usually has a small amplitude by the time it reaches the recording instruments on the surface. It's important the signal-to-noise ratio be sufficient to acquire the signals at these great distances. Since the signal is quite weak, generating less noise is the key.

With the older, traditional "switch-mode" power supply technologies, the problem of noise and power surges is a result of power transistors incorporated to "hard switch" the unregulated input voltage.