Shale Shakers - Structure

Structure

Shale shakers consist of the following parts:

• Hopper - The Hopper, commonly called the "base" serves as both a platform for the shaker and collection pan for the fluid processed by the shaker screens, also known as "underflow". The hopper can be ordered according to the needs of the drilling fluid, aka "mud" system. It can come in different depths to accommodate larger quantities of drilling fluid as well as have different ports for returning the underflow to the mud system.

• Feeder- The Feeder is essentially a collection pan for the drilling fluid before it is processed by the shaker, it can come in many different shapes and sizes to accommodate the needs of the mud system. The most commonly used feeder is known as the weir feeder, the drilling fluid enters the feeder usually through a pipe welded to the outside wall near the bottom of the feeder tank, it fills the feeder to a predetermined point and like water flowing over a dam the mud (drilling fluid) spills over the weir and onto the screening area of the shaker. This method of feeding the shaker is most widely used due to its ability to evenly distribute the mud along the entire width of the shaker allowing for maximum use of the shaker's screening deck area.

Some feeders can be equipped with a bypass valve at the bottom of the feeder which allows the drilling fluid to bypass the shaker basket and go directly into the hopper and back into the mud system without being processed by the shaker screens.

• Screen Basket- Also known as the screen "bed" it is the most important part of the machine, it is responsible for transferring the shaking intensity of the machine, measured in "G's", while keeping the "shaking" motion even throughout the entire basket. It must do all that while holding the screens securely in place, eliminating drilled solids bypass to the hopper and allowing for easy operation and maintenance of the machine. Different brands of shakers have different methods of fulfilling these demands by using specialized screen tensioning apparatus, rubber seals around the screens, basket reinforcement to limit flex, rubber Float Mounts rather than springs, rubber Deck seals and selective vibrator placement.

• Basket Angling Mechanism- The shaker basket must be capable of changing its angle to accommodate various flow rates of drilling fluids and to maximize the use of the shaker bed, this is where the angling mechanism plays an important part. The drilling fluid flowing over the shaker bed is designated into two categories:
  • Pool: Which is the area of the screening deck that comprises mostly of drilling fluid with drilled cuttings suspended within it.
  • Beach: Is the area where the fluid has been mostly removed from the cuttings and they begin to look like a pile of solids.

As a rule of thumb the Beach and pool are maintained at a ratio of 80% pool and 20% beach, this of course can change depending on the requirements of cutting dryness and flow rates.

There are various angling mechanisms currently in use which vary from hydraulic to pneumatic and mechanical, they can be controlled from either one side of the shaker or must be adjusted individually per side. Mechanical angling mechanisms can be very dependable often requiring less maintenance but usually take more time to operate than their hydraulic or pneumatic counterparts where as the hydraulic/pneumatic angling mechanisms are much faster to operate and require less a physical means of operation.

• Vibrator- This is the device which applies the vibratory force and motion type to the shaker bed. A vibrator is a specialized motor built for the purpose of vibrating, While containing an electric motor to provide the rotary motion it uses a set of eccentric weights to provide an omnidirectional force. To produce the proper Linear motion a second, counter rotating, vibrator is added in parallel to the first. This is what gives us the linear motion, "high G" shaking of the basket.

Some shakers come with an optional third motor on the shaker bed, this motor is most often used to modify the elliptical motion of the basket making it more circular therefore "soften" the motion, but comes at a cost of decreased G's and slower conveyance of the cuttings. This motion is usually used for sticky solids.