1ères JOURNEES NATIONALES SUR LE FORAGE ET LA MAINTENANCE PUITS

DRILLING WASTE MANAGEMENT Auteur : MECHERI Fethi, HS&E Supervisor, ENAFOR Hassi Messaoud Principles of drilling waste disposal: This communication provides a comprehension overview of on-and off-site disposal methods, our commitment in managing wastes especially those of drilling is to promote the following principles: • Protect the environment and return the disposal site and any affected areas to an equivalent land capability. We must therefore aware of site-specific reclamation and certification requirements. • Minimize the overall extent of land surface disturbance. • Plan for waste management that assists in timely and environmentally safe handling and disposal. • Achieve the handling of drilling wastes in cost effective manner. • Practice wastes volume minimization and re-use where possible. • Promote the use of mud additives which allow for proper and easy disposal of the drilling waste. Disposal methods One of the earliest decisions you will need to make as you develop a well drilling program is how to dispose of drilling wastes. This communication is designed to help us in making the decision-making process by providing an overview description of accepted methods. Overview of disposal method: The figure below identifies drilling waste disposal methods: • On-site, which includes Mix-Bury-Cover (M-B-C) and landspreading. • Off-site, which includes Pump-off, Landspraying, and Landspraying While drilling (LWD). • Land treatment, is intended for hydrocarbon or salt based mud systems. • Alternative Disposal Methods, used for new disposal technology or new mud formulations.

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1ères JOURNEES NATIONALES SUR LE FORAGE ET LA MAINTENANCE PUITS

DRILLING WASTE DISPOSAL METHODS

ON-SITE DISPOSAL

LAND TREATMENT DISPOSAL

OFF-SITE DISPOSAL

ALTERNATIVE DISPOSAL

PUMP OFF MIX-BURY-COVER

LANDSPREADING

LANDSPRAYING

LANDSPRAYING WHILE

On-site disposal is conducted on area of land where the subsoil is used for the disposal of drilling waste. This normally includes stripped wellsites and remote sump locations. Off-site disposal is conducted on area of land where the topsoil is used for the disposal of drilling waste. This normally includes cultivated land, vegetated land, but can also include non-stripped portions of a wellsite or drilling waste storage area. Landowner approval is required for all off-site disposal operations, outside of the surface lease boundaries. A combination of any of the disposal methods may occur at any one drilling location. The Land Treatment disposal method is intended for hydrocarbon based drilling wastes and/or wastes with a high salt content, and can take place either on-site or offsite. Alternative Disposal Methods are intended for disposal utilising new or innovative technology, or when new mud formulations or additives are used. Disposal of specific drilling wastes such as cement returns and drill cuttings may need to be addressed as a separate disposal. Cement returns that have been isolated from the drilling waste must be buried on-site under one metre of clean fill. Drill cuttings that have been separated from the slide phase of the drilling waste must be disposed by one of the on-site disposal options, or as apart of Land Treatment disposal plan. Alternative Disposal Methods requiring regulatory approval could also be considered for the disposal of cement returns and drill cuttings. These waste disposal methods and analytical requirements are based on the premise that drilling waste loading limits represent lifetime limits for any combination of waste disposal methods. This means that wastes are usually disposed of only once on a specific site. When additional land, the well owner and the appropriate regulatory agency must agree on an acceptable disposal plan for the site.

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1ères JOURNEES NATIONALES SUR LE FORAGE ET LA MAINTENANCE PUITS

Each disposal method includes calculations which specify the minimum area required for disposal. Operators are encouraged to utilise more than the minimum area to lower overall affect on soil at disposal site. ON-SITE DISPOSAL OPTIONS : Mix-Bury-Cover disposal method : Mix-Bury-Cover (M-B-C) disposal method occurs when drilling waste solids (and sometimes fluids or total waste) are stabilised by mixing with subsoil. The goal of Mix-Bury-Cover is to incorporate waste into the subsoil below the major rooting zone and above the water table in a manner that preserves soil chemical properties and protects groundwater quality. Mix-Bury-Cover is not intended for wastes resulting from the use of hydrocarbon based mud systems. The ratio of subsoil to waste is THREE PARTS SUBSOIL TO ONE PART WASTE by volume. The base of the final subsoil and waste mixture must be at least one metre above the water table and layer of permeable material, and is covered with at least one metre of clean subsoil. The topsoil is then replaced. Typical Mix-Bury-Cover methods are : • Mixing waste and subsoil on the surface, putting mixture back in the sump and covering. • Mixing the waste and subsoil, putting the mixture into a new pit and covering. • Bailing the waste and subsoil, mixing with the subsoil, and burying when filling a cut. • Spreading the wastes on surface, allowing them to dry, putting the wastes back into the sump, mixing and covering. Land spreading Disposal Method : Landspreading is a disposal method whereby the drilling waste is spread on-site and incorporated into the subsoil. The landspreading area is based on calculated loading rate. The goal of Landspreading is to dispose of the waste in a manner that preserves the subsoil’s chemical, biological and physical properties by limiting the accumulation of salts, and protects the quality of surface water and groundwater. Landspreading is not intended for wastes resulting from the use of hydrocarbon based mud systems. Typical methods for Landspreading are : • Ripping subsoil and spreading and incorporating the waste on-site. • Spreading (squeezing) the waste on-site, drying and incorporating. OFF-SITE DISPOSAL OPTIONS : Landspraying Disposal Method : Landspraying disposal method occurs when the waste is sprayed off-site on to topsoil and may or may not be incorporated. The Landspraying area is determined based on a calculated loading rate or a maximum application rate.

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1ères JOURNEES NATIONALES SUR LE FORAGE ET LA MAINTENANCE PUITS

The goal of Landspraying is to dispose of the waste in a manner that preserves the topsoil’s chemical, biological and physical properties by limiting the accumulation of salts, and protects the quality of surface water and groundwater. Landspraying is not intended for wastes resulting from the use of hydrocarbon based mud systems. The Landspraying and Landspraying While Drilling (LWD) disposal criteria appear similar. However, since LWD is limited to three approved mud systems (fresh water gel, gypsum water, or nitrate gypsum water), many of the testing requirements for Landspraying have been waved for LWD.. Typical methods for Landspraying are : • Applying the waste on cultivated land (off-site) and incorporating by cultivation. • Applying the waste on vegetated land and the waste is not incorporated. PUMP-OFF DISPOSAL METHOD (clear liquids only) : Pump-off disposal method occurs when drilling waste Clear liquids are applied off-site, normally on to vegetated land, following the calculated loading criteria. Clear liquids are not normally incorporated into topsoil. The goal of pump-off method is to dispose of the clear liquids in a manner that preserves the soil’s chemical, biological, and physical properties, does not harm the vegetation, and protects the quality of surface water and groundwater. Pump-off allows access to a larger spread area as it is conducted off-site normally on vegetated land The typical pump-off method is to pump drilling waste through hoses or irrigation equipment such as a big gun, sprinklers, gated pipe, perforated hoses. Landspraying While Drilling disposal method : Landspraying While Drilling (LWD) is a Landspraying disposal method and occurs when drilling wastes from approved mud systems are sprayed off-site onto topsoil at low application rates. The application is conducted during the drilling operation. Drilling wastes are sprayed on land at application rates less than 40m³ per hectare. Spraying techniques may include the use of vacuum trucks or similar equipment. The goal of this disposal method is to dispose of drilling waste in a manner that preserves soil chemical, biological, and physical properties, does not harm vegetation, and protects the quality of surface water and groundwater. Mud systems presently approved for LWD are limited to : • Fresh water gel • Gypsum water • Nitrate gypsum water. The Landspraying and LWD disposal criteria appear similar. However, since LWD is limited to three approved mud systems, many of the testing requirements for Landspraying have been waived. The loading requirements for trace elements remain even though the testing requirements have been waived.

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1ères JOURNEES NATIONALES SUR LE FORAGE ET LA MAINTENANCE PUITS

These systems have been shown to be non-toxic. However, if there is any uncertainty about the drilling wastes passing the toxicity assessment, chloride or metal limits due to changes in drilling program, the drilling wastes must be disposed of by another method. Drilling wastes which have visible hydrocarbons must not be disposed by LWD. Cement returns must be isolated from the drilling wastes and may be buried under one metre of clean fill. Drill stem fluids must be isolated and disposed of by the other disposal methods. If sections of mud system become contaminated with hydrocarbons, those sections must be handled by either Mix-Bury-Cover, Landspreading or another disposal method. LAND TREATMENT DISPOSAL OPTION : Land treatment disposal method : Land treatment is a waste treatment and disposal method whereby applications from one waste site are made on dedicated parcel of land. The land is managed in a manner which allows the soil system to degrade, transform and assimilate the waste constituents. The Land Treatment site can be used only once. The goal of Land Treatment is to biodegrade the organic constituents in the waste using natural soil processes in a manner that protects soil and ground water quality. The Land Treatment disposal method, or an Alternative Disposal Method must be used when hydrocarbon based mud systems have been employed. Elevated hydrocarbon content levels may also occur when drilling conditions result in the unforeseen production of hydrocarbons, such as drill stem testing or when drilling in underbalanced condition, Land Treatment should be considered in these cases. Wastes that require Land Treatment may have high salt content, thus management practices must deal with both the salt and hydrocarbon. Land Treatment may be conducted on-site or off-site, either the topsoil or subsoil. Land Treatment is an active practice that requires frequent tillage and application of nutrients break down the hydrocarbon in the waste. Organic amendment (e.g. :manure, straw) are added to increase biological activity and aeration of the soil. Sampling and analysis are necessary to monitor the progress of the remediation. Remediation may take place over several years to achieve closure. When considering the Land Treatment disposal method, we should also be familiar with other guidelines that address the storage, transportation, and bioremediation of hydrocarbon wastes. ALTERNATIVE DISPOSAL OPTION : Alternative disposal method : Alternative or innovative disposal methods are primarily used for drilling wastes that cannot be disposed of using the methods described before.

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1ères JOURNEES NATIONALES SUR LE FORAGE ET LA MAINTENANCE PUITS

If a new or innovative disposal method is being considered, the appropriate regulatory office must be advised as soon as possible to have the approval prior to waste disposal. New mud formulation or additives may also require consideration by the approving agency. Early notification to the appropriate regulatory office will help avoid delays and potential adverse environment impact. As part of this notification, the proponent must indicate why an alternative method is required, the technical requirements, and potential stakeholder concerns. Information of the regulatory office of the plans is recommended as soon as possible. CONCLUSION: Managing our wastes means preserving a safe environment for us and for the future humanity especially our children. Because we create illness we are obliged to find Remediation and avoid its escalation.

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