If you want, I can respond to that.
A key driver is the nature of the ore itself, because the ore grade varies tremendously, for example, with respect to the clay content. If you have higher clay ore, which is poorer quality ore, you need more water. Also, the tailings are worse for that ore. You get less water back. One of the main drivers is the ore itself as to why you have such a wide range in water usage. Also, the individual producers have slightly different processes in how they deal with the tailings, such as whether they have thickeners, for example. Again, that will cause variations in the amount of water used or lost per barrel of oil produced.