RU2596781C1 - Method of decontaminating waste drilling mud and soil contaminated with oil products - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to methods for rehabilitation of lands contaminated by oil products. Waste drilling mud is excavated from earth storages onto a flat surface and dried at the sun. Mixture of phosphogypsum and glauconite is introduced for binding heavy metal salts in hardly soluble forms and thickening the mud and sorption of heavy metal salts. Mass is dried in natural conditions till the moisture content of 8-14 % and reduction of its volume 6-8 times. Mixture is stirred by a bulldozer equipped with a milling-rotary working element, with subsequent placement and sealing in storages, the bottom of which is covered with the glauconite layer of 20-30 cm thick. Then it is covered with a 20-30 cm thick glauconite layer and with a mineral soil layer with a thickness of not less than 0.5-1.0 m. Over it a fertile layer is put with the thickness of 20-40 cm enriched with glauconite. Storages are made on any types of soil with deposition of ground waters of not less than 8-10 m and at the underlayer thickness from 15-20 m and more.

EFFECT: provided is reduced content of heavy metal salts and oil products in waste drilling mud and oil-contaminated soil with simultaneous simplification of decontaminating technology.

1 cl, 1 dwg

Description

The invention relates to the field of the oil industry, and more specifically to methods for improving the ecological condition and returning to the economic turnover of lands contaminated with oil products, in particular spent drill cuttings.

Currently, the problem of disposal of waste drill cuttings is very relevant. Basically, the neutralization of waste drilling fluids and cuttings is carried out by the following methods: thermal, curing, chemical neutralization followed by curing. A disadvantage of the known methods is the high cost and the need for special equipment or reagents. In addition, during the heat treatment of drilling fluids and cuttings, BaSO ₄ becomes aggressive and hazardous to health and the environment.

A known method of cleaning and restoring soils contaminated with oil products (RF Patent No. 2496589, IPC B09C 1/10, A01B 79/02, publ. 10/27/2013, bull. No. 30), which is based on the collection of spilled oil, the mechanical treatment of contaminated plot, bacterial treatment with mineral fertilizers. Mechanical processing is carried out by mixing and moving contaminated soil in one direction at a distance of not less than the width of the trench. The development of the trench is carried out, the bottom and walls of the formed trench are isolated to prevent the spread of pollution. The components for bacterial treatment are laid on contaminated soil, mixed with simultaneous laying in a trench and moistening. Then carry out the planning and restoration of the site.

The disadvantage of this method is the slow degradation of oil-contaminated lands, since the climatic conditions are favorable for the decomposition of oil products. With this method, the process of decomposition of light fractions of petroleum products is carried out, while heavy ones remain in the soil, and their subsequent cleaning requires additional operations, which increases the cost of the technology.

Closest to the claimed invention (prototype) is a method of processing oil sludge, including dehydration in natural conditions, in which the spent drill cuttings are removed by excavator from the barns on a flat surface, dried in the sun, introduced to bind and convert readily soluble salts into sparingly soluble forms and to thicken the cuttings gypsum, then manure or peat activated by mineral fertilizers is added to the dried gypsum mass, the mass is dried under natural conditions until moisture content of 8-14%, which leads to a decrease in its volume by 6-8 times, after which it is cut with a bulldozer and on soils with a heavy mechanical composition, with a thickness of the underlying layer of at least 15-20 meters, they are again placed in barns and compacted, then they fall asleep mineral soil with a layer thickness of 1.5-2.5 m, and on top with a layer of 20-40 cm, a fertile layer is poured, and with soft soils the neutralized and dried drill cuttings are transported to industrial waste landfills for disposal (RF Patent No. 2379137, IPC B09C 01/10, publ. 01/20/2010, bull. No. 2).

The disadvantages of this method are the difficulty of its implementation with large volumes of contaminated soil and the mismatch of some soil conditions when performing the technology proposed in the method. Also, this method does not disinfect heavy metal salts, since manure activated with mineral fertilizer is not a sorbent and a means for disinfecting heavy metals.

An object of the invention is the creation of a simple and economical method of disposal of waste drill cuttings and soils contaminated with oil products.

The drawing shows a diagram of the layers of materials for the disposal of drill cuttings and soils contaminated with oil products.

The problem is solved in a method for the disposal of waste drill cuttings and soils contaminated with oil products, including dehydration in natural conditions, characterized in that the spent drill cuttings are excavated from earthen barns on a flat surface, dried in the sun, a mixture of phosphogypsum and glauconite is introduced to bind heavy salts metals in sparingly soluble forms and for thickening the sludge and sorbing salts of heavy metals, then dry the mass in vivo to achieve moisture of 8-14% and its reduction in volume by 6-8 times, after which they are mixed and cut with a bulldozer equipped with a milling and mixing working body, and on soils with a groundwater table of at least 8-10 m and with a bed thickness of 15 -20 m or more is again placed in barns, the bottom of which is covered with glauconite with a layer of 20-30 cm, and compacted, then covered with a layer of glauconite with a thickness of 20-30 cm and mineral soil with a layer of a thickness of at least 0.5-1.0 m, and on top 20-40 cm thick pour a fertile layer enriched with glauconite. This technology can be applied to any type of soil.

The proposed method of disposal of waste drill cuttings and soils contaminated with petroleum products is as follows. During the construction of wells, the fertile soil layer is cut and stored in piles. Spent drill cuttings are placed in specially prepared earthen barns. As a result of poor-quality construction of earthen barns or their destruction by flood waters or atmospheric precipitation, waste drill cuttings leak and soil pollution. Since spent drill cuttings contain mobile forms of salts of heavy metals and barium salts, which are environmentally harmful, there is a need to render waste drill cuttings harmless. To do this, an excavated drill cuttings are removed from the barns on a prepared flat site, dried in the sun, and a mixture consisting of phosphogypsum and glauconite is introduced into it to thicken. Moreover, phosphogypsum thickens and forms insoluble salts of heavy metals, which are subsequently sorbed by glauconite. Then the natural mixture is dried, consisting of sludge, phosphogypsum and glauconite, to a moisture content of 8-14%, which leads to a decrease in the volume of the mixture by 6-8 times. After that, using a bulldozer equipped with a milling and rotary working body, the mixture is mixed, followed by its placement and compaction in previously prepared barns. Barns are made on any type of soil with a depth of ground water of at least 8-10 m and with a thickness of the underlying layer of at least 15-20 m. The bottom of the barn is pre-sprinkled with glauconite layer of 20-30 cm. After placement and compaction of the mixture (see drawing), consisting of sludge, phosphogypsum and glauconite, it is covered with glauconite with a layer of 20-30 cm, on top of which mineral soil is poured with a layer of 0.5-1.0 m, and on top of the mineral soil is covered with a fertile layer enriched with glauconite, 20-40 cm thick.

The neutralization of spent drill cuttings from heavy metal salts, barium salts and petroleum products allows them to reduce their content in spent drill cuttings to acceptable values. The proposed method of disposal of waste drill cuttings is easy to use, economical, does not require expensive or scarce materials and equipment, is not time-consuming and can be used everywhere.

Claims (1)

A method of neutralizing waste drill cuttings and soils contaminated with oil products, including dehydration in natural conditions, characterized in that the spent drill cuttings are removed by excavator from earthen barns on a flat surface, dried in the sun, a mixture of phosphogypsum and glauconite is added to bind heavy metal salts to sparingly soluble forms and to thicken the sludge and sorption of salts of heavy metals, then dry the mass in vivo to achieve a moisture content of 8-14% and reduce it in volume 6-8 times, after which they are mixed and cut with a bulldozer equipped with a milling and mixing working body, and on soils with a groundwater table of at least 8-10 m and when the thickness of the underlying layer is 15-20 m or more, they are again placed in barns, the bottom of which is covered with glauconite with a layer of 20-30 cm, and compacted, then they are covered with a layer of glauconite with a thickness of 20-30 cm and mineral soil with a layer of at least 0.5-1.0 m thick, and a fertile layer enriched with 20-40 cm is poured on top glauconite.

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