Every construction project produces waste as an unavoidable byproduct. The issue isn’t that waste is generated; it’s how it’s managed.
One challenge for trenchless drilling operations is disposing of all the debris created during the operation without leaving behind any traceable waste outside of property boundaries or within environmentally sensitive areas like streams and ponds where there’s no chance to refill was removed from these places.
Drilling fluid is an important aspect of trenchless technology since it lubricates the pipe and also serves as a carrier for removing drill cuttings from the borehole. Drilling waste must be managed, and the process and rules for waste management differ from project to project.
Every hdd company has adopted the practice of recycling drilling mud since it saves money on mud quantity and disposal.
Companies can use a variety of technologies to execute and manage drilling waste, including onsite disposal, solids control, bioremediation, incineration, thermal desorption, and waste recycling.
What is Solids Control?
Solids control waste management is the separation of solid particles created from rock cuttings during the drilling operation from the drilling mud. Solids control has become more important as the demand for reducing the environmental impact of oil drilling has grown.
The volume of waste generated by the drilling process is greatly reduced by the efficient separation of solids from the drilling mud. Deep well drilling waste can be reduced by 8000 to 10000 barrels with a 10% improvement in drilled solids removal.
Removing particles from the drilling mud also improves its suitability for recirculation. The following items make up solids control equipment:
- Shale shaker to remove big-sized solids.
- Mud tanks for mixing and storage of drilling mud.
- Centrifugal pumps provide feed pressure and volume required to operate the hydrocyclone.
- Cuttings dryer for removing moisture from cuttings below the 5% mark.
- Hydrocyclones to speed up the settling process.
- Desilter to remove small-sized solids.
- Vacuum degasser to remove air from the mud.
- Desander to remove medium-sized solids.
- Decanter centrifuge to recover barite and comply with environmental standards.
- Mud cooler for oil-based drilling muds and those with high-temperature applications.
- Dewatering unit to remove fine solids (<5 microns).
- Cuttings collection and transportation system.
- Conveyance system to transport cuttings.
- Containers for transporting cuttings.
- Mud cleaner.
The Importance of Solids Control
A solids control system extends the fluid’s usable life by twice or three times, making it very attractive to drilling companies. Due to environmental restrictions necessitating stringent regulation of drilling waste disposal, mud dilution and mud dumping have become unacceptable; it is also expensive. Solids control is the most cost-effective solution to run a drilling operation and dispose of spent mud.
The solids content of the mud must be kept below 5% to ensure its quality and suitability for recirculation. The quality of the filter cake degrades as the quantity of particles in the drilling mud increases, increasing the cake thickness and compromising downhole filtration. Increased torque and drag, sloughing, increased surge and swab pressures, and clogged pipe are some of the issues linked with poor filter cake quality.
Excess particles in the drilling mud lower the pace of drill bit penetration, raise the danger of wellbore instability due to extended periods of open borehole, and raise drilling expenses.
How to Achieve Effective Solids Control?
Solids can only be properly removed if the mechanism employed to do so is dependable and efficient. To guarantee that solids of all sizes are correctly removed, every step of the solids control system must be followed.
Since each project is unique and subsurface soil conditions differ, every hdd company‘s solids control system should be tailored to the specific site requirements. This can be accomplished by maintaining a variety of meshes and screen sizes, as well as spare parts, on hand.
The solids control system should be hydraulically balanced, capable of fine-cut and scalp-cut, and have enough mixing and recirculation capacity for drilling fluid.
The initial phase in the solids control system is to remove as many large cuttings as possible without affecting the commercial drilling fluid solids when the drilling fluid is pumped out of the borehole. Only if the solids management equipment is appropriately designed and installed, and sized to process 100% to 125%of the mud circulation rate can this be accomplished.
The removal capacities of the various pieces of equipment in the solids control system differ.
Waste Treatment and Disposal
After the solids control phase, which includes solids collection, the waste drilling fluid must be managed and disposed of. While non-hazardous waste does not require additional treatment, synthetic-based and oil-based muds include toxic substances that must be treated before disposal.
Cutting re-injection (CRI), encapsulation or fixation/stabilization, thermal desorption, and dewatering are some of the available waste treatment and disposal alternatives. Effective solid control has a significant impact on a project’s cost-efficiency. When the particles in the mud are removed, the volume of the mud decreases, lowering transportation expenses.
Maintaining the rheology of the mud also eliminates the requirement for adding mud products to preserve mud quality for drilling operations.