Drill cuttings

[2] The drill cuttings are commonly examined to make a record (a well log) of the subsurface materials penetrated at various depths.

For water based drilling fluid (WBM) with no particular dangerous additives, the cuttings can be dumped overboard (in offshore scenario).

Pit burial is a low-cost, low-tech method that does not require wastes to be transported away from the well site, and, therefore, is very attractive to many operators.

Inorganic compounds and metals are diluted in the soil, and may also be incorporated into the matrix (through chelation, exchange reactions, covalent bonding, or other processes) or may become less soluble through oxidation, precipitation, and pH effects.

Optimizing Land Farm Operations: The addition of water, nutrients, and other amendments (e.g., manure, straw) can increase the biological activity and aeration of the soil, thereby preventing the development of conditions that might promote leaching and mobilization of inorganic contaminants.

After applying the wastes, hydrocarbon concentrations are monitored to measure progress and determine the need for enhancing the biodegradation processes.

Pretreating the wastes by composting and activating aerobic biodegradation by regular turning (windrows) or by forced ventilation (biopiles) can reduce the amount of acreage required for land farming (Morillon et al. 2002).

Drilling Waste Land Farm Example: In 1995, HS Resources, an oil and gas company operating in Colorado, obtained a permit for a noncommercial land farm to treat and recycle the company's nonhazardous oil field wastes, including drilling muds.

At the land farm, wastes mixed with soil contaminated with hydrocarbons from other facilities are spread in a layer one foot thick or less.

Natural bacterial action is enhanced through occasional addition of commercial fertilizers, monthly tilling (to add oxygen), and watering (to maintain 10–15% moisture content).

At high concentrations, these recalcitrant constituents can increase soil-water repellency, affect plant growth, reduce the ability of the soil to support a diverse community of organisms, and render the land farm no longer usable without treatment or amendment.

[5] Recent studies have supported the idea that field-scale additions of earthworms with selected organic amendments may hasten the long-term recovery of conventionally treated petroleum contaminated soil.

The burrowing and feeding activities of earthworms create space and allow food resources to become available to other soil organisms that would be unable to survive otherwise.

For this reason, alternative mud systems have emerged that use an environmentally preferred beneficial salt, such as calcium nitrate or potassium sulfate, as the emulsified internal water phase.

The objective is to dispose of the waste in a manner that preserves the subsoil's chemical, biological, and physical properties by limiting the accumulation of contaminants and protecting the quality of surface and groundwater.

Optimizing Land Treatment Operations: Addition of water, nutrients, and other amendments (e.g., manure, straw) can increase the biological activity/aeration of the soil and prevent the development of conditions that might promote leaching and mobilization of inorganic contaminants.

After applying the wastes, hydrocarbon concentrations may be monitored to measure progress and determine the need for enhancing the biodegradation processes.

Experiments conducted in France showed that after spreading oil-based mud cuttings on farmland, followed by plowing, tilling, and fertilizing, approximately 10% of the initial quantity of the oil remained in the soil.

Phytotoxic effects on seed germination and sprouting were not observed, but corn and wheat crop yields decreased by 10%.

Land spreading costs are typically $2.50 to $3.00 per barrel of water-based drilling fluids not contaminated with oil, and they could be higher for oily wastes containing salts (Bansal and Sugiarto 1999).

Potential concerns include the need for large land areas; the relatively slow degradation process (the rate of biodegradation is controlled by the inherent biodegradation properties of the waste constituents, soil temperature, soil-water content, and contact between the microorganisms and the wastes); and the need for analyses, tests, and demonstrations.

These include area-wide topographical and geological features; current and likely future activities around the disposal site; hydrogeologic data (location, size, and direction of flow for existing surface water bodies and fresh or usable aquifers); natural or existing drainage patterns; nearby environmentally sensitive features such as wetlands, urban areas, historical or archeological sites, and protected habitats; the presence of endangered species; and potential air quality impacts.

In addition, historical rainfall distribution data should be reviewed to establish moisture requirements for land spreading and predict net evaporation rates.