Aqueous Cleaning of Drill Cuttings Produced Using Oil-Based Muds/Fluids

Drill cuttings arise from drilling exploration wells, new production wells and work-overs on producing wells. They contain agglomerates of rock fragments, oils, hydrocarbons, salts, drilling muds and other chemicals, some of which are hazardous and toxic. The chemistry of many modern oil-based drilling muds is formulated to remain stable under the high temperature and pressure conditions present during drilling.

Current techniques used to clean and decontaminate drill cuttings prior to disposal are energy intensive and costly: e.g. by thermal desorption using hammer mills or drying at temperatures of 350°C or higher. High pressure washing systems and various surfactant formulations have been tested for cleaning drill cuttings. However these tests failed, because they were either unable to separate the agglomerates and release crude oil particulates or they created large volumes of difficult to manage secondary waste.

Global Advantech combines proven physical and electrochemical technology with innovative chemistry to build systems, which efficiently clean and remediate drill cuttings from wells drilled using both oil-based muds/fluids (OBM) and water-based muds/fluids (WBM). These systems utilise:

• Cavitation scrubbing (see page 4) to separate adhering and adsorbed oil and hydrocarbons from drill cutting particulates
• Electrocoagulation cells to remove hydrocarbons, suspended particulates, most organic compounds, heavy metals, etc., from the process solution, enabling it to be recycled many times through the cleaning process
• Chemistry to increase the rate of release of adsorbed oils and hydrocarbons from the cutting particulates

The features and benefits of Global Advantech’s aqueous systems for cleaning and decontamination of drill cuttings include:

• Mobile and static plant configurations available
• Throughput capacities: 1 tonne per hour to 20+ tonnes per hour
• Oil/hydrocarbon reduction to <1/0% and two cleaning passes to 0.2%-0.5%, depending upon porosity of rock fragments
• Non-thermal processing – ambient temperature operation, therefore substantially lower energy consumption (<20%) compared to thermal desorption plant with similar processing capacity
• Low environmental impact, with minimal emissions
• Use available water supplies for operation - fresh, brackish or seawater
• 75% lower capital costs and 80% lower operating costs compared to thermal desorption plant with similar processing capacity
• All process water recycled - treated to remove dissolved/emulsified oils, suspended ultra-fines, heavy metals, etc.

	Global Advantech’s Cavitation Scrubbing System (5 tonne/hour)	Thermal Desorption Hammer Mill (3 tonne/hour max.)
Energy requirement	150KW (peak electricity demand)	1,000KW (750KW diesel engine + electricity demand)
Hydrocarbon recovery	Most, no degradation	Most, with thermal degradation
Gaseous emissions control for combustion products + plant exhaust	N/A	Required
Carbon footprint	Low	Very high
Environmental impact	Minimal	Very high
Freshwater requirement	None, process works with seawater	Cooling, emissions abatement
Water treatment system	Integral Oil, BOD+COD removal	Additional Oil, BOD+COD removal required
ATEX Zone 2 configuration available	Yes	No
Building requirements	Mobile configurations: self‑contained in ISO containers, with integral bunds	Building with concrete floor and steel support structure for plant required
System maintenance costs	Low	High
System capital cost	USD 1.1million	USD 4.5million -3 tonne/hour 0% moisture content -1 tonne/hour 15% moisture content