Mainly there are 3 types of drilling fluids, water-based mud, oil based mud & synthetic based mud.
Synthetic-based fluid is a mud where the base fluid is a synthetic oil. This is most often used on offshore rigs because it has the properties of an oil-based mud, but the toxicity of the fluid fumes are much less than an oil-based fluid. This is important when men work with the fluid in an enclosed space such as an offshore drilling rig.
There is a technical limit to what can be achieved with water-based fluids, especially in the short and medium terms. For this reason, I believe advances in the environmental performance of synthetic-based fluids can be expected to occur faster, in combination with improved treatment and new drilling techniques. But synthetic based mud’s cost is much higher than water-based mud.
The mud recycling system for the 3 types of mud is basically similar but has little difference.
Synthetic based mud is mostly used for offshore drilling, people sometimes do not process and recycle the used mud at jobsite, they have the used drilling fluids in mud pits and transport them to a drilling fluids plant or factory for recycling and treatment, then ship back to the rig. In some other situations, they have the solids control system at jobsite, but no drilling waste management equipments at jobsite.
Water based mud is with cheaper cost and also environment friendly, it is mainly used for land drilling, in most oilfield in China or some developing countries, water based mud is widely used, and it works well with solids control system produced in China.