The suggestion that there is a host of noises in the ground under our feet may seem strange. However, the rock underneath us is not just one solid inactive object. There are various rock types with different physical properties. They have tiny pores that can harbour gas or fluids.
Oil wells are drilled through several layers of different rock types. As a result, the surrounding environment interacts with this newly created channel. Gases and fluids are pushed into this new space due to the high pressures underground. This process must be controlled by intact well structures.
Monitoring the sound in the well can help operators manage well integrity proactively.
Imagine the sound from blowing bubbles through a straw into a glass of juice. (Come on, we’ve all done it.) Now imagine pricking the straw. The air that escapes through the little hole creates a different sound than the main opening at the end of the straw.
Similarly, fractures in the casing of oil wells or broken seals will affect the flow of produced gas and fluids. A gas escape, for example, creates a particular noise pattern that can be detected by Distributed Acoustic Sensing (DAS). An experienced analyst interprets such sounds to draw conclusions about well integrity. The more additional data the analyst has, the more precise will their conclusions be.
That is why we are developing our system, Q-DOS™, to incorporate not only DAS data but also all sorts of other well data such as temperature, pressure or geological information.