Free water is defined as water not required for cement hydration. Free water in a drilling fluid is able to react with other substances. This can be problematic when reacting with swellable formations leading to borehole instabilities and a thickening of the mud. High free water content is often a sign of an unstable slurry which may lead to fluid separation at the top of long columns or in pockets to be filled. The required sealing effect cannot be achieved. The amount of free water can be classified by the filtration characteristics (fluid loss) of a slurry. The mud filtration ring is used to determine the free water content, filtration characteristics and fluid loss of drilling fluids and cement slurries and thus can make the use of an API filter press unnecessary in many cases.
The mud filtration ring consists of a stepped, polished base plate and a funnel, which is positioned in the middle of the base plate by means of two positioning stoppers. A filter paper is placed between the base plate and the funnel. The funnel is filled with slurry up to the top edge, and at the same time a stopwatch is started. Time is taken until the filter paper is completely wetted with the water from the slurry tested. In contradiction to the API filter press water binding capacity of the mud is tested rather than water loss. The longer it takes until the filter paper is completely wetted, the better the water binding capacity.
Compared to previous models with an embedded and breakable glass plate, the MUDTEST mud filtration ring is made entirely of stainless steel. It is robust and suitable for field operation. A shock proof aluminum box is part of the product and protects the precision instrument during transport.
The mud filtration ring is mentioned in the German regulations of DVGW W 116.
|Mud filtration ring||7300.11.00000|