The performance of a shale shaker is influenced by a wide variety of variables and factors. The most important variables affecting the capacity of a shale shaker are the rheological properties of the drilling fluid, the concentration and size distribution of solids, the mesh and area of the screen, the frequency of vibration, the pattern of vibration, the acceleration, and the angle of the deck.
Rheological Characteristics of Drilling Fluid
Shale shaker capacity is maximised by balancing the number of separated cuttings removed from the screen with the amount of filtrated drilling mud that passes through the screen, as shown in the figure.
Tilting the screen up reduces solids velocity while saving more fluid. For example, tilting the screen down increases drilling mudflow and cuttings moisture at the exit. The optimal angle for each shaker varies depending on the manufacturer; nevertheless, tilting the screen up further than that causes particulates to accumulate on the screen and clog the screen pores. However, the fundamental principles that underlie the influence of vibration on the displacement of fluid in porous media are still not fully understood.
It is hypothesised that changes in the pore structure and particle rearrangement are responsible for the increase in flow rate observed. The influence of vibration on the fluid velocity of drilling fluids as a non-wetting phase in a column filled with water and sand was investigated. It was discovered that increasing the amplitude of the vibration enhanced the flow rate of the drilling mud.
Another explanation for the influence of vibration on the flow rate is based on the phenomenon of capillary entrapment (also known as capillary dilation). The process of capillary entrapment seems to be the most promising. The concept for this mechanism was developed based on the interfacial tension, which is believed to be the most critical parameter in multiphase flow in porous media.
Drilling Solids (cuttings) Affect The Performance Of Shale Shaker.
The fluid is trapped in porous media due to changes in pore size, which causes differences in capillary pressures. The flow rate of liquid through the porous medium is altered due to the pressure imbalance. It is clear from experimenting that providing vibration will result in an inertial body force acting on the fluid, which will result in the trapped fluid being pushed back into the stream of flow by the screen vibration. A possible impact of vibration on the increase of flow rate is that it creates internal circulation in the mud and provides the fluid more time to hit the screen. This might be one of the effects that vibrating increases the flow rate.
Both the particle size distribution and the particle concentration impact the solids-liquid separation process. In drilling mud, increasing the solid concentration causes the performance of the drilling operations to be compromised. According to the results of an experimental study, muds comprising more than 10% by mass solids were responsible for the failure of the filtering process. The findings of micro-bit drilling revealed that extremely small particles in a drilling mud had a greater negative impact on the flow rate than bigger particles of the same size.
Shaker Screen Mesh and Screening Surface
It is said that particles less than one micron are much more harmful to the filtering process than particles bigger than one micron. Almost all solids-liquid separation equipment used in the drilling industry is intended to remove particles bigger than 1 micron. The vibration of the shale shaker alters the creation of particle structure in the drilling mud, which results in different drilling results. In the presence of vibration, the shear stress of the drilling fluid is reduced; however, polymeric drilling fluid is not influenced by the presence of vibration.
The viscosity of drilling fluid
According to the results of a study on the effect of plastic viscosity and yield values on the capacity of a shale shaker, the plastic viscosity of drilling mud flowing through the screen and cake has a significant effect on the capacity. In contrast, the yield value has a minor effect on the shaker’s performance. It has also been shown that raising the plastic viscosity and yield value of a drilling fluid increases the screen area needed in a shaker to get the desired results. It is possible to enhance the capacity of a shale shaker by lowering plastic viscosity and increasing the screen area, shaker angle, and acceleration.
Motors for Shale Shakers as well as Deck Factors
Shale shakers are designed with various characteristics in mind, and one of these parameters is the installation placement of the vibrating motors on the shakers. Some manufacturers claim that if a vibrator is precisely mounted on the shaker support, there is no need to incline the shaker downward to achieve the desired mass rate of solids on the screen. However, it is important to note that inclining the screen downward decreases the drilling mud flow rate and increases the moisture content of the particles leaving the channel of the shaker, both of which are undesirable.
Porter’s experimental work on a vibrating electromagnetic screen revealed that raising the frequency increased the capacity while decreasing the amplitude lowered the capacity. Their findings revealed an ideal set of operating circumstances and that after the optimal point is reached the flow rate decreases. The most effective angle was found to be 33 degrees.
It has been shown that frequency is one of the most critical characteristics impacting screen performance, even though other studies have found the opposite. For a feed with particles of sizes near to the opening, the relationship between frequency and particle size reveals that frequency is the most beneficial parameter. According to two experimental studies, screening effectiveness dropped as the frequency of screening increased.
Deck angle increases the effective mesh area and the number of contacts per unit screen length when the deck angle is raised. The flow of particles was made easier by increasing the deck angle. Researchers discovered that angles greater than 15° reduced the method’s efficiency.
G-force
Deck angle increases the effective mesh area and the number of contacts per unit screen length when the deck angle is raised. The flow of particles was made easier by increasing the deck angle. Researchers discovered that angles greater than 15° reduced the method’s efficiency.
According to the shaker results, which operated at 4g of acceleration and two frequencies of 20 and 60 Hz, the frequency had no significant influence on the fluid capacity of the shaker. His research revealed that the flow rate at 60Hz is somewhat lower than at 20Hz. The researchers’ findings on a 100*100 mesh screen with three different kinds of drilling fluids revealed that the acceleration of the shaker greatly influences the capacity of a shale shaker.
A screen with a greater conductivity than the other comparable screens performs better than the other similar screens. The hypothesised method for this improvement is based on considering permeability and screen thickness rather than just the proportion.
The capacity of a shale shaker grows when the g-force of the machine is increased. His research demonstrated that the rate of development in the capacity of the shale shaker was increasing rapidly.
Hit a nadir in terms of productivity. It demonstrates a g-force threshold at which increased acceleration does not influence the functioning of the shaker once the shaker has passed that point.
