Environment

Integrated Solution Handles Drilling Waste in Environmentally Sensitive Area

This paper presents the challenges and results of performing offshore drilling-waste management in a highly environmentally sensitive marine environment and UNESCO World Biosphere Reserve offshore Abu Dhabi. The solution required both thermal-treatment technology and cuttings-reinjection technology and became the world’s first single-source operation for this equipment.

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As the focus on the environmental impact of drilling waste increases, the challenges related to this create a requirement for continuous improvement and innovation. The disposal of oil-based and water-based drilling fluids not only requires a solution for the end disposal but also carries a high carbon footprint within the logistics required to contain and transport the drilling waste to the processing and disposal sites.

For many years in offshore drilling, solutions for disposal of oil-based mud to below 4% oil on cuttings followed by discharge to sea, or transportation to an onshore thermal processing facility followed by landfill disposal, have been the common industry solutions. All drilling and offshore environments have their own limitations in terms of rig space or regulatory requirements for disposal, which is major factor in determining the disposal options for the operator.

When faced with drilling in an environmentally sensitive protected marine area, the treatment and disposal solutions require the utmost focus on regulatory compliance and minimal environmental impact.

The solutions detailed in this paper were implemented for such an environment on an artificial offshore island. The drilling field was within a World Biosphere Reserve under the United Nations Educational, Scientific, and Cultural Organization Man and Biosphere Program, which imposed a complete zero-discharge policy for all drilling activities on the island.

The most common solution in this environment is traditional skip-and-ship processes whereby the drilling waste is contained in skips and transported onshore with supply vessels for onshore treatment (for removal of oil content to below a certain percentage) before final disposal of the recovered solids at a landfill site.

In order to provide a more environmentally efficient solution, a system incorporating a high-temperature thermal desorption unit and a cuttings-reinjection system was proposed to provide the capability to treat the drilling waste at site and dispose through a dedicated disposal well on the artificial island, thus reducing the requirement for any transportation to shore or disposal to landfill.

This paper presents the challenges, solutions, and results of performing the offshore drilling-waste management.

The solution was to treat all drilling waste at source. This required both thermal-treatment technology and cuttings-reinjection technology and became the world’s first single-source operation for this equipment. The equipment was shipped to the island, installed, and operated in parallel with the operator’s drilling program. The drilling waste (oil-based mud) was handled and stored then processed through a thermal treatment unit, which generated three separate treated waste streams—oil, water, and solids. The recovered oil and water were reused on-site, while the treated solids were slurrified and fed to the cuttings reinjection system, which injected the solids into a disposal well.

Download the complete paper from SPE’s Health, Safety, Environment, and Sustainability Technical Discipline page for free until 29 December.

Find paper SPE 203274 on OnePetro here.