What is Depth Conversion?
Depth Conversion is an iterative process which is designed to serve as a rather important one. It is the process of forming an important step in the seismic reflection method, which is generally the act of measuring acoustic wave travel times to the actual depth of a marked asset.
It sounds confusing, and sometimes can be, but essentially, the earth isn’t a flat piece of rock. You may have taken a stroll along the beach and picked up a few rocks and have noticed that some of them have multiple lines on them. These lines indicate the layers that make up the rock and show how they were formed. Imagine this on a much grander scale.
The earth is made of multiple components and multiple layers of different rock forms, which can vary in thickness and form. You may have noticed that some rocks are more porous than others, where others are thick and solid. That is because they are two different types of rock.
There are thousands of different types of rocks within the earth, which means when we dig down, we might not necessarily know what we are up against and consequently can be quite expensive and very dangerous!
How is Depth Conversion Determined?
So, what does any of this have to do with depth conversion? Essentially, the way of which depth is calculated is to use sound. For instance, everyone has tried shouting in a cavern or cave to hear their voice echoing back to them. The deeper the cave, the more you’re going to hear the echo of your voice.
This principle applies to depth conversion (kind of). Geoscientists bounce acoustics off rocks and use the way that the waves come back in order to determine what sort of rock they are dealing with below the earth. Of course, a porous rock will require far different equipment to drill through than a less porous one but all sorts of other factors also apply, meaning depth conversion is not only just about sound waves.
The deeper you’re going to go, the more rock types you’re probably going to see. Imagine a vertical slice of the earth, which you’ve more than likely seen in a diagram once. The diagram would have consisted of layers upon layers of multi coloured lines indicating the varying different types of rock beneath the earth’s surface.
What Does Depth Conversion Software Do?
Using a specialist depth conversion software, which is designed to ascertain factors such as the type of rock and depth from the wavelengths of the acoustics that are bounced back, can gather all types of information about the subsurface.
This information will be interpreted by a geoscientist or a petrophysicist by using depth conversion software such as Petrel or IHS Kingdom in order to create a three-dimensional model, called a velocity model.
The process may not be necessarily exact but there are a number of tools such as Velit, a depth conversion plugin, which is designed to eliminate any errors and can vastly reduce uncertainty.