What Are Solids Control Equipment To Remove Drill Cuttings From Drilling Fluid?

In drilling operations, the recycling and reuse of drilling mud is a key step to reduce pollution and save resources. When drilling mud carries drill cuttings from the downhole back to the wellhead, it contains a large number of solid particles. If directly recycled, it will not only increase the density and viscosity of drilling mud, reduce its working performance, but also may cause downhole accidents. Meanwhile, excessive drill cuttings will aggravate the wear of solids control system equipment and shorten the service life of the equipment. Therefore, the purification treatment of drilling mud is crucial. The solids control system is the core system to achieve drilling mud purification and remove harmful solids such as drill cuttings. Then, what are the special equipment in the solids control system for removing drill cuttings from drilling mud?

The mud solids control system removes solid particles of different particle sizes in graded manner, which is mainly composed of shale shaker, desander, desilter, vacuum degasser, decanter centrifuge and mud tank. As the first-stage defense of solids control equipment, Shale Shaker removes large drill cutting solid particles larger than 74 microns from the drilling mud returned from the bottom of well.  Desander clears 44–74 micron solid particles (sand grains) from the drilling mud after passing through the shale shaker.  Desilter removes small particles of 8–44 microns from the drilling mud treated by the desander.  Decanter centrifuge separates tiny particles of 2–5 microns from the drilling mud processed by the desilter. Vacuum degasser assists in removing gases from drilling mud to ensure drilling safety.

In actual drilling operations, solids control equipment can be flexibly selected and combined according to well conditions and drilling requirements, to ensure that the drilling mud purification effect meets the operation needs.

The shale shaker consists of screen box, screen mesh, shock absorption spring, vibrator and other components. It separates the solids of drilling mud flowing to the screen surface. The liquid and smaller solid particles flow to the next-stage solids control equipment, while the larger solid particles move along the screen surface to the sand trough. According to the motion trajectory of the screen box, the shale shakers of TR Solids Control can be divided into linear motion shale shakers, elliptical motion shale shakers and dual-motion shale shakers. Among them, the linear motion shale shaker is the mainstream model on the market due to its stable separation efficiency and wide adaptability.

Both desilter and desander are hydrocyclones, with basically the same structure and working principle. The desander is composed of 1–3 hydrocyclones with an inner diameter larger than 100 mm, which is used to separate sand grains larger than 44–74 microns. The desilter is made up of more than 4 hydrocyclones with an inner diameter less than or equal to 100 mm, which is designed to separate argillaceous solid particles larger than 8–44 microns.

Decanter centrifuge is deep purification equipment in the solids control system, which is mainly used to separate tiny solid particles that cannot be handled by hydrocyclones (desanders and desilters). It removes solid particles in drilling mud, ensuring and maintaining the stable density and viscosity of drilling mud.

Although the vacuum degasser does not directly remove solid cuttings, as an auxiliary equipment of the solids control system, it is mainly used to remove gases (such as natural gas and air) intruding into the drilling mud. Gas intrusion will damage the performance of drilling mud and may even cause safety accidents such as blowouts. Therefore, the application of vacuum degasser is an important link to ensure the safety of drilling operations.

In the actual drilling process, the selection of solids control equipment needs to be flexibly configured according to specific drilling operation requirements (such as drilling depth and drilling mud type) and well conditions (such as cutting content and formation characteristics). Through graded purification, solids control equipment such as shale shaker, desander, desilter and decanter centrifuge can effectively remove harmful solids such as drill cuttings from drilling mud, improve the utilization efficiency of drilling mud, reduce drilling costs, reduce environmental pollution, and provide strong support for the green and efficient development of drilling operations.