A Shale shaker is industrial equipment that is mainly used to screen solids from the drilling fluid. Mud or drilling fluid plays a vital role in the drilling process. It helps in washing away rock cuttings that are cut by the drill and also helps in reducing the risk of overheating. This industrial equipment is mainly designed to remove the solids and rock cuttings from the drilling mud so that they can be reused again and again. Shale shakers play a vital role in the large mud removal system, which frees the drilling mud from solids, unwanted gases, and other contaminants.
To understand how shale shaker works and how it relates to other drilling processes read on. Drilling fluid comprises oil, water, and chemicals as its main ingredient in the composition, accumulated in the storage pit or the drum present above the level of the ground. Once the drilling process begins, drilling fluid starts flowing through the cables and enters the bore with the help of holes present due to the drill bit mechanism. At this point, it is washed back up the bore side as it carries rock particles and other debris back to the surface. Once this process is done, mud heads back to the storage pit for reuse.
It is vital to have the mud cleaning process in place as this mud will directly flow out of the bore and then into the shale shaker. The Shale shaker comprises a vibrating tray lined with the wire mesh screen. It holds the rock and other solid materials on the top while allowing liquid to pass through it. The vibration action of the screen is designed to support this process.
Therefore the selection of the right shale shaker is important for the successful removal of the solid materials. Besides the size of the holes present on the screen should be the size of the rock that has been extracted from each borehole. It is vital to select corrosion-proof screen material like galvanized steel to hold up in the extreme health care condition on the drilling site. In many projects, multiple shale shakers are involved to ease the drilling of the mud while passing through several layers of refinement and cleaning.
The several benefits of shale shakers for the drilling companies. These solid cleaning systems help in cleaning drilling fluid so that it can be reused again and again. The absence of the solid shaker will allow debris to go along with the mud and it could damage the drill and halt operations. Re-usage of the drilling fluid will help in the conservation of the limited resources and also cut down the cost included in the drilling outfits. A Shale shaker makes it easier to capture the rocks and other solid elements that have been mixed with the oil so that they can dispose of in an environment-friendly manner.
With the help of the shale shaker screen, most formation solids can be removed by mechanical means. It is a well-known fact that small particles are difficult to remove and thus can leave a great impact on the drilling fluid properties in comparison to the larger particles. The particle size of the drilled solids incorporated in the drilling fluid can range somewhere between 1 to 250 microns. Here we are listing 5 important things that you should present in your high-quality shale shaker
1. Mesh Size: – The screen opening size determines the size of the particle that can be removed in the process. In the easier term, mesh size can be explained as it is the number of openings per linear inch as calculated from the center of the wire. For instance, in 70 by 30 oblong shale mesh screen means it has 70 openings in a one-inch line one way by 30 openings along a one-inch line perpendicular to the first.
However, the actual separation size depends on the factors like fluid viscosity, particular shape, particle cohesiveness, and feed rates. In the same case, the drilling fluid forms high surface tension film on the screen’s wires and even clogs the effective opening size of the screen.
It is renowned fact that the size of the opening of the screen is related to the size of the solids that pass through it. But over the years, it has led to a situation of misunderstanding as the developers of the creative screen have manufactured a layered screen or a shale shaker screen with oblong openings. It has made it difficult to choose what is the maximum size of the particle that could pass through it? Manufacturers of shale shaker screens would give 50% cut size or medium size. For determining this 50% cut size, spherical particles would be used.
Although none of the above-mentioned information represents what is the core requirement of the client. Under the API scheme, a manufacturer is liable to test the potential of the screen with the use of Aluminum oxide particles, it represents the great and real shape of the cuttings. The particle size that is mentioned on the screen must be the maximum size of the particle that could pass through the screen. The set of API indicators was developed that is related to the approximate throughput sizes of the earlier used mesh system. The maximum size and API indicators both indicate the maximum size of the particle passing through the screen that is mentioned on the screen label.
2. Design of the screen: – Shale Shaker screens are available in two and three-dimensional designs. The two-dimensional screens can be classified as:-
On the other hand, a three-dimensional screen design comes with a perforated plate screen on the corrugated surface that runs in parallel to allow the flow of the liquid. This configuration allows more screen space in comparison to the two-dimensional screen configurations. Some of the three-dimensional screen designs are:-
3. Screen specification: – API recommends that all screens should be labeled with their respective name and potential for separation. This information should be considered seriously to make a sound decision; a wrong step in this direction can leave a reverse impact on the output.
4. Flow capacity: – It is one of the essential factors that help in the selection of the right shale shaker screen. Two parts are needed to be monitored quite closely to determine the flow capacity. It includes non-blanked and conductance areas.
The conductance of the screen is the amount of fluid that passes through the screen per unit time is a quite important parameter in the selection of the minimum size of the screen that can effectively work under the drilling conditions. The old system manufacturers would share their percentage of the open area and claim the optimum screen life. These two properties will counteract as a large open area can be obtained only through thinner wires. However, in the new API shale shaker screen system, a test is conducted which helps in determining the actual permeability of the screen. It is determined with the help of standard oil and laminar flow patterns. The open area and permeability information must be printed on the screen label for the rightful purchase.
5. Shale shaker screen’s plugging and blinding: – Screen blinding is a common issue that occurs when the grains of the solids are lodged in the screen hole. This occurs when drilling the fine sands. In such a case, it is recommended to choose a coarser or finer screen than the regular one. This strategy will turn out successful if the sand that is being drilled has narrow size distribution. Another alternative is to change the regular screen to a rectangular screen, although the chances of screen blinding are also possible with the multiple sand grains.
The life expectancy of shale shaker screens widely varies from design to design, even under the best condition because of the difference in the operating characteristics. By following the below-listed precautions, the life of shale shakers screen can be increased:-
Final words
The modern shale shakers come with double deck screen arrangements. In this coarse screen run over the fine screen. The selection of the shale shaker screen should be done in such a manner that during the operation 2/3 portion of the screen area will remain wet while 1/3 dry. Although this configuration depends on the mud and type of the shale shaker, make sure that each deck has the same size of the screen on its whole area.
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