Control of drilled solids from the mud is one of the major functions of a drilling fluid circulating system. Several types of solids control equipment are used to accomplish this task, including screening equipment（ shale shaker ）, hydrocyclones ( mud cleaner, decanter, desilter ), and decanter centrifuges.
Screening equipment (shale shaker ) performs the bulk of the solids control in most drilling situations. In recent years, the capabilities of screening equipment has greatly improved with the introduction of linear motion, premium performance shale shakers. These shakers typically remove drilled particles from the mud that are half the size of those that were removed economically by previous shaker designs.
Hydrocyclones ( mud cleaner, decanter, desilter ), while not showing the recent improvements of the shakers, are routinely used in low weight muds. Several sizes of hydrocyclones are available to remove sand and silt sized particles from drilling muds. This centrifugal separation equipment is most often used in drilling surface hole with unweighted, low cost muds. In many cases, the use of hydrocyclones are discontinued when the mud density increases because the cost of weight material losses exceed the value of the mud’s liquid phase that would be saved by processing. At this point, centrifuging many times becomes economical.
The decanter centrifuge is a versatile piece of equipment that can be used to process both weighted and unweighted muds. When used on muds, the centrifuge centrifugally separates solids from the mud in a rotating cylinder. With unweighted muds, the solids are discarded and the liquid portion of the mud is retained. In weighted muds, the centrifuge is used to
recover the valuable weighting material solids and to discard the fine solids and the mud’s liquid phase.
Control and evaluation of the above solids removal equipment usually focuses on measuring the individual performance of each piece of equipment. Operating parameters like screen sizes, mud feed rates, etc are adjusted to optimize the performance of each piece of equipment. This process can involve an extensive testing program that is impractical to perform on a regular basis• Experience with each type of equipment can compensate for exacting measurements to a large extent and is the reason regular performance measurements are not required. A simple method for
evaluating the performance of all the removal equipment and the mud system in concert can be used to guide operating practices without extensive mass balance measurements for individual pieces of equipment. The concepts and relationships outlined in this paper allow this to be done.
Main solids control equipment parameters: