For several years the chemical industry has used diatomaceous earth systems as a standard in effluent dewatering. Recognizing the similarities in clarity requirements between effluent dewatering and brine completion-fluid filtering, a new diatomaceous earth filtration system has been designed, tested, and is successfully being used in Gulf Coast operations.* The system consistently shows a one-pass solids removal efficiency of greater than 98%, at varying flow rates. Resulting solid concentrations average 74 parts per million (ppm, 0.007% by volume) and have been recorded as low as 10 ppm. This is a 40% improvement in removal efficiency and a filtrate that is 17 times cleaner, after one pass filtration, than the average of several existing cartridge units.
The efficiency of filtering high density brines is dependent upon several factors including the effectiveness of the filtration system, the physical characteristics of the brine and suspended solids, and operator experience.
Filtration removal efficiency and Industry standards for brine cleanliness can be modified to become more realistic and field-oriented. In future filter unit evaluations or comparisons, an absolute term of removal efficiency, which is defined by multivariable correlations through time, should be utilized. And rather than a maximum particle size standard, the Industry standards for brine cleanliness should be field-oriented and can be based on a concept of clarity and degree of contamination.