A new approach to drilling waste management – prevention!

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Courtesy of SAS Environmental Services Ltd

Grangemouth based Surface Active Solutions (SAS) has developed its microemulsion based technology to aid the prevention and management of drilling waste.

The many activities surrounding the removal of drilling mud in surface and downhole cleaning applications usually generate significant volumes of oil contaminated drilling waste. The drilling mud is typically removed through the use of solvents and emulsion forming cleaning products that do exactly what the name implies; form emulsions. These emulsions are generally referred to as slop waste in the industry. They comprise heavily oil contaminated mixtures of fine solid particulates, water or brine, cleaning chemistries, mud chemicals and oil.

This particular potent combination of ingredients results in a veritable soup that contaminates all equipment and storage tanks it comes into contact with. This results in further cleaning being required at many points downstream, which in turn generates additional volumes of slop waste. The waste is notoriously difficult to treat and especially so on the site of production.

Given the high proportions of emulsified fine solids, water and oil present in the material it can be highly viscous, often causes line and pump blockages, plugs filter media and minimises the amount of oil and clean water that can be recovered. As a result, the large majority of this waste is contained for transport back to shore for treatment and disposal ultimately to landfill.

The logistics required to clean mud pits and to carry out downhole cleaning operations, manage the waste created as a result and transport it back to shore for further treatment are both significant and costly. Through the use of an integrated approach to offshore cleaning and waste prevention, significant cost savings can be realised. The operational risk is said to be reduced through the use of higher efficiency cleaning chemistries which provide the capability of managing the fluids on the site of production.

The Surface Active approach currently being implemented, in partnership with operators and service companies, is to study the entire process from mud pit cleaning to down hole cleaning to drilling waste management and provide the most cost effective technological solution. One product is delivered that is capable of removing built-up mud cake from mud pits and breaking down the mud into an easily pumpable, low viscous fluid. This, the company says, stops blockages of pumps, pipes and other equipment, reducing downtime in mud pit cleaning applications.

By using an automated tank cleaning system, the MicroEmulsion cleaning fluid is delivered to the contaminated surface and the mud cake disperses quickly and with minimal need for men entering and working in confined spaces. The complete removal of mud from a mud pit can become an operation in a matter of minutes, rather than hours or days, significantly reducing rig time.

Because of the rather unique characteristics of this MicroEmulsion system, it becomes very straightforward to remove the solids from the liquid waste stream generated in real time. This results in a clear wash fluid that can be recycled many times over for cleaning the other mud pits on the rig or vessel. When the operation is complete, the solids are retained in skips for disposal and the wash fluid is passed through filtration systems and clean water may be discharged to sea.

The very same product is used to complete the down hole cleaning process. Through the high cleaning efficiency achieved using this chemical system, the well casing and formation is stripped of all mud in a very short space of time and continuous circulation of the well with brine is no longer required in order for the well to come back into specification. All surfaces are rapidly rendered water wet as a result. This is necessary for successful ongoing completion operations to be carried out. The solids are easily removed from the well cleaning fluid at surface by conventional means and the remaining wash fluid is passed through filtration systems and clean brine may be discharged to sea. In many cases, emulsion forming products are still used in these key application areas and the creation of large volumes of liquid slop waste still remains common. In such situations, the SAS microemulsion technology can be applied to the slop waste on the rig site through simple addition of low doses of product.

The mobile slop treatment plant is designed to fit within a standard size container and consists of a chemical injection system and inline mixing method unique to the market. The microemulsion product breaks the slop waste generated through the use of standard cleaning products and is passed through a decanter centrifuge for recovery of the solids phase. The liquid centrate can then be separated under gravity or by conventional hydrocyclone techniques to recover the oil phase for recycling. The water fraction can once again be filtered and may be discharged on site.

This different approach offers the potential to the industry to completely change the way in which drilling waste is considered, handled and disposed of.

Reaching new environmental standards while simultaneously reducing operating expense seems a clear way forward!

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