Mud Tank Cleaning Using Microemulsions

We are all aware of the traditional method of manual mud tank cleaning, where teams of trained personnel enter contaminated mud tanks, often erecting scaffolding in order to gain access to the higher parts of the wall and the roof of the tank. However, we don't think this is the most efficient or effective way to get the cleaning done...

Manually cleaning mud tanks is time intensive, costly, and overall a very dirty, tiring job. When you take all these factors into consideration, it is definitely time to find a new way to approach this old issue. We believe the answer lies within the development of microemulsion delivery systems for the cleaning of drilling rig mud pits and platform supply vessels. 

Microemulsion chemical technology, when paired with an innovative mechanical delivery system, really reaches a new, optimised level of tank cleaning with fewer health and safety issues compared to the traditional method of operation. Cleaning operations can also be greatly enhanced through the use of 'cleaning in place systems' or 'CIP'. These systems consist of designed skids containing filtration and pumping equipment capable of delivering sufficient pressure and flow to deliver a microemulsion solution to as many as four mud tanks at a time!

By using geared cleaning nozzles, the entire inside of a mud tank can be covered with a microemulsion cleaning solution within a matter of minutes. This minimises man entry into the mud tank, resulting in a fraction of the time being required. Once these nozzles are in place and connected to the CIP system, the microemulsion cleaning solution is pumped through the system and breaks up the drilling mud on the tank walls and the mud cake on the tank floor. The resulting liquid waste can be easily removed using standard pumping equipment.

The microemulsion technology breaks down the mud, creating low viscous slurry. This waste stream is then placed either in a weir tank where solids can settle, and the liquid is reused for further cleaning operations, or the waste is treated using hydro cyclones and/or filtration equipment. The use of microemulsion chemistry allows for a continuous mud tank cleaning process, either onshore for the processing of supply vessels or offshore on the rig.

More information on microemulsions is available on our website!

The Green Tank Clean Solution

More specialised and effective cleaning products and processes are needed now more than ever due to increasingly stringent health, safety and environmental regulations. Using products and processes like this could reduce the volume of waste produced from tank cleaning and dramatically cut project completion times. So, where can we find them?

A way to achieve a more effective process is by using more environmentally sound biobased chemistry, instead of partly biobased or petroleum-based. Unlike in the past, there is now a range of fully biobased products available primarily from suppliers in North America, Europe and China. However, the definition of what is actually a "fully" biobased product is not entirely certain. This definition is important to get right in order to establish the true environmental credentials of the chemicals industry in this field, effectively countering any accusations of greenwash.

The development and use of biosurfactants and biochemicals is aiding the implementation of fully biobased chemicals that can be used in developing new cleaning products. These surfactants are manufactured by bacteria and are subsequently harvested and purified. There are some biosurfactants on the market however, their high cost inhibits the uptake of this technology on a wider scale. Their performance is also not yet comparable to other components to be used in microemulsion formulations.

Here at SAS-ES we want to improve this, which is why we have an active research programme in the development and commercialisation of new biosurfactants with higher effectiveness. This process is called microemulsification and it has proven particularly effective in hard surface cleaning applications in the oil and gas industry. 

A microemulsion forming surfactant system can absorb oil from a bulk oil phase, forming a microemulsion. The same solution absorbs oil from an oil coated surface or fine solid particulates with the same result without forming stable emulsion waste as a result. In the microemulsion environment, any oil is effectively encapsulated within the surfactant monolayer and is therefore no longer in direct contact with the original surface or solid. Oil contaminated surfaces may therefore be rendered completely oil free as a result of the microemulsification process.

The mode of action of these cleaning systems is threefold:

1. The penetration of the contaminating oil layer through the solvent/microemulsion mechanism

2. The microemulsification of the oil components into the water phase

3. The water-wetting of the underlying solid surfaces through the surfactant action

Case Study: Offshore Mud Pit Cleaning - Brazil

For a period of 4 years SAS Environmental Services supplied its SAS Semi-Automated Tank Cleaning System and microemulsion SAS PitClean 102C products from Houston, Texas to Brazil.

The SAS Solution:

The fixed installed tank cleaning system, using Scanjet tank cleaning machines worked with the SAS PitClean 102C to quickly clean out the mud pits, fluidise all of the caked mud, flush the lines and reduce men entry into the pits. 

The SAS PitClean 102C was used to create a wash pill in a pit of 40bbl (3% SAS PitClean 102C). This wash pill was used to clean out all 14 mud pits and flush the lines.

After each pit the dirty wash pill was placed in pit 1 for settling out. The solids would settle out and the wash pill was re-used to clean out the next mud pit.

This was repeated until all 14 mud pits were clean to brine standard.

To Sum Up...

The total waste volume was approximately 80bbl. This would separate out under gravity into water for polishing and disposal and solids for transport back to shore.

Time reduction was 50% - 70% compared to standard cleaning approach using men entry and regular detergents.

Find out more about this case study here: