Enhanced Slurrification Method

Abstract

A method of slurrifying oil contaminated materials by introducing a microemulsion or microemulsion-forming surfactant(s) to the material and subjecting the mixture to suitable shear or mixing forces to suitably blend such mixtures. The method may be applied directly to wastes such as waste drill mud cuttings and muds, emulsions, sludges, or soil substrates contaminated with water and / or oil drilling fluids in order to both reduce the viscosity and improve the lubricity, wetting, and flow properties of the substrate.

Description

FIELD OF THE INVENTION[0001]This invention relates to a method for the enhanced slurrification of oily materials. More particularly, the invention relates to the enhanced slurrification of oily materials to allow facilitated transport and / or treatment or subterranean re-injection of e.g. oil contaminated drilling and production wastes produced from oil and gas industry operations or other oil contaminated soil, sludges or emulsion wastes generated by other industrial sectors.BACKGROUND OF THE INVENTION[0002]Within many industries and the oil industry in particular, oily soils, sludges and emulsions may be produced at various times throughout the regular operations or processes employed within the sector. Increasing environmental awareness and more stringent environmental regulation has necessitated the more frequent movement, handling, and treatment of such wastes and more sophisticated and environmentally benign methods of disposal.[0003]Historically, many such wastes were either d...

AI Technical Summary

Benefits of technology

[0030]For example, in the case of invert oil emulsion mud contaminated drill cuttings the mud itself contains a range of surfactants as emulsifiers and oil wetting agents used to ensure that the invert emulsion is stable over the expected range of pressures and temperatures that are to be encountered in the well to be drilled, and that the mud solids in the system, and the additional surfaces generated form the drilled rock, are maintained in an oil wet condition. Drilling fluids are thixotropic fluids having a gel structure to suspend the mud solids and facilitate easy and efficient transport of cuttings within the wellbore. By converting the oil phase adhering to the waste rock from an invert oil emulsion to a microemulsion the viscous forces and gel structures are significantly reduced and the materials become fluid and more mobile without any requirement for dilution materials, though they could also be used if desired. This allows conventional pumps and vacuum suction devices to transport the materials more easily, without significantly increasing the volume of the waste stream. In such a case, it is therefore important that the oil fraction remains present within the waste stream itself.

[0035]The present invention has a number of key advantages over techniques of the prior art in addition to the capability of simply reducing viscosity and aiding flow rates and ease of transport of such materials as described above. Traditional methods in the oil and gas industry for example use large volumes of added oil which increases the volume of waste typically by circa 30%. Alternatively water is often added which can increase the volume of waste to be transported and / or re-injected into the formation by up to an order of magnitude. As previously described, this is particularly the case when clay (shale) based materials are to be slurrified. These materials swell in the presence of water and can become quite sticky in nature potentially hampering the reinjection process.

[0036]The present invention not only reduces the viscosity of oil contaminated drilling and production wastes but does so without any significant increase in waste stream volume and, despite the fact that water is often added, does not result in swelling and hydration of the clay components. As a result the volumes of waste are kept to an absolute minimum which has additional significant time, cost and transportation logistical advantages commercially.

[0037]Furthermore, the use of microemulsions in the method of the invention results in the formation of lubricant within the waste system increasing lubricity of the materials to be transported improving flow rates and preventing blockages which in turn reduces the risks of the operations concerned.

Problems solved by technology

The use of such muds can result in the generation of considerable quantities of oil contaminated drilled material removed from the well (referred to within the industry as waste drill mud cuttings or cuttings).

However, there are problems associated with this method especially concerning the significant logistics involved.

In addition, there are considerable health and safety risks involved when moving large quantities of this kind of equipment under sea faring conditions in relatively short time periods.

The same disadvantages are also encountered at the dockyard for the tasks of unloading to treatment and disposal sites.

Also when at sea such operations are limited by the weather conditions and these operations must be put on hold when weather conditions become more severe.

This may result in significant downtime and lost revenues.

The irregular nature of the drilled rock particles and the in-built viscosity of the drilling fluids poses significant handling problems for all of the above processes and it is common for other fluids such as muds, water and oil to be added to increase the ease of handling.

This can considerably increase the amount of materials that need to be treated or disposed of, increases the volumes that may be required to be transported, and can incur additional costs for the dilution fluid, especially if they are oils or muds.

In addition, the use of hydrocarbon oils complicates the operations in terms of fire / explosion protection and the protection of operators from exposure to vapours that may be carcinogenic or otherwise hazardous to health.

Moreover, in general water added to reduce viscosity can exhibit a hydrating effect in the presence of oil-contaminated shales and the like resulting in an extremely high viscosity or indeed a congealed material.

The viscosity of both the oil spill and production emulsions can be several hundreds of thousands of centipoises, making them virtually impossible to pump other than by very specialist equipment.

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