In the event of negligence on your part, you’ll be liable for any property damage or personal injury to a third party caused by your business activities, unless you have an insurance policy. Strictly speaking, drilling contractors insurance isn’t necessary unless you hire staff (in which case you’ll need employer’s liability insurance), but if you want to ensure your business is protected, it should certainly be considered. It’s also worth remembering that you may fail to secure clients if you don’t have adequate insurance in place.