The Effect of Amendment Addition Drill Cuttings On Heavy Metals Accumulation In Soils And Plants: Experimental Study And Artificial Network Simulation

A greenhouse experiment was carried out to evaluate the influence of drill cuttings addition on the accumulation of heavy metals in soil, in plant biomass (Trifolium pretense L.) cultivated on soils with the addition of this type of waste. The transfer and transformation of heavy metals in the soil with drill cuttings– Trifolium pretense L were discussed.Drilling waste in the amount of 2.5%, 5%, 10% and 15% of dry weight were added to acidic soil. The concentrations of heavy metals in the soil and plant materials were determined by an inductively coupled plasma mass spectrometry method. Results indicated that drilling wastes addition had a positive influence on the growth of Trifolium pretense L. However, the concentrations of heavy metals increased in the prepared mixtures along with the dose of drilling wastes. The drilling wastes addition also changed the metal accumulation capacity in plant parts. Nevertheless, the concentrations of heavy metals in soils and above-ground parts of plants did not exceed the permissible values in respective legal standards. The values of the heavy metals bioconcentration coefficient in Trifolium pretense L at the highest dose of drill cuttings were as follows: in the above-ground parts Cd>Cu>Ni>Cr>Pb>Zn, in roots Cd>Ni>Cr>Zn>Pb>Cu.An artificial neural network model was developed in order to predict the concentration of heavy metals in the plants cultivated on the soils polluted with drill cuttings. The input (drill cuttings dose, pH, organic matter content) and the output data (concentration of heavy metals in the shoot cover) were simulated using an artificial neural network program. The results of this study indicate that an artificial neural network trained for experimental measurements can be successfully employed to rapidly predict the heavy metal content in clover. The artificial neural network achieved coefficients of correlation over 90%.

PROBLEMS OF STORAGE, REFINERY AND DISPOSING OF DRILLING WASTE OF THE EXPLORATION AND PRODUCTION SECTOR OF KAZAKHSTAN. ARRANGEMENT AND OPERATION FEATURES OF SLUDGE COLLECTORS AND OIL STORAGE PITS

A lot of drilling wastes with various content of oil products is formed annually during production of hydrocarbons in the result of accidents at the facilities of transportation and oil production, soil is polluted. So, main contaminants of the environment are drilling wastes such as drilling, drilling waste water, waste drilling fluid and places of their disposition - sludge pits. Total amount of the oil slurry annually formed at enterprises of the oil sector of Kazakhstan is about 100 thousand ton, and resources of these wastes are estimated in more than 40 mln. ton. The wastes are placed in special sludge pits equipped with watertight screen. However, in spite of the available modern technologies for arrangement of waterproof finish of the drilling waste disposal facilities, high level of soil pollution is still observed. As a rule, pollutions are related to violation of the requirements of the standards during construction and operation of sludge pits, products pipelines, tailing dumps, sludge collectors and temporary storages. Therefore it is necessary to build reliable storages for temporary placement of the formed wastes until their delivery for recovery or disposing, during operation of which there will be no migration of pollutants to the environment. It is suggested to use bentonitic mats as waterproof finish of such facilities - this is innovative by properties, multifunctional composite material, which is combination of textile materials with the layer of the natural self- recovering mineral component - bentonite.

AN OVERVIEW OF OIL BASED DRILL CUTTINGS WASTE ENVIRONMENTAL EFFECT AND DISPOSAL TREATMENTS

The drilling fluid is essential for drilling operations in the oil and gas industry. It is a complex mixture of organic and inorganic materials blended together to achieve desired multi-functions. There are several types of drilling fluid commonly in use, oil-based drilling fluid considered the most hazardous and harmful for the surrounding environment because of contaminated waste produced, normally consisting of diesel, oil, asphalt, polymers, crude oil and surfactants. Produced drill cuttings are contaminated by hydrocarbons, and other chemical additives. The produced drill cuttings are hazardous for environment as they contain polycyclic aromatic hydrocarbons and undesirable heavy metals. Presently, various oil and gas operator companies in Yemen and other parts of the world dispose the drilling wastes in excavated pits or landfill sites. It is not acceptable to deal with such hazardous substances in this manner. Other operator companies use thermal desorption technique as a separation method. This method still has many disadvantages. Therefore, it is vital to search for sufficient and efficient technologies and processes to treat oil-based drilling wastes as the existing methods in use cannot be considered as a viable solution to eliminate the environmental damaged caused by contaminated drill cuttings. This paper review three existing experimental methods of extraction that have significant total organic carbon removal efficiency and highlighted factors that effect on the extraction efficiency. They are; supercritical water oxidation, superheated steam extraction, and supercritical carbon dioxide extraction. The stated experimental studies -have shown promising results and efficiency in extraction of carbon content and are considered environmentally friendly.

Effect of Drilling Wastes on Urease Activities and Substrate Induced Respiration (SIR) in Wetland Soil of Delta and Bayelsa States, South-South, Nigeria

The effect of drilling waste on urease activities and substrate-induced respiration in wetland soil of Niger Delta of Nigeria was investigated, using Fadama, mangrove and meander soils respectively. Urease activity and substrate-induced respiration (SIR) were measured after 1, 7, 14, 28, 42, 56, 70, 105 and 140 days of incubation to evaluate the effects of drilling waste on soil biochemical perimeters. Results obtained indicated that Fadama soil urease activities varied from 13.5 to 2.10 mg NH4 – Hg-1 dry soil in drilling waste. Mangrove soil varied from 13.5 to 2.22 mg NH4 – Ng-1 dry soil in drilling waste. Meander soil activities varied from 14.7 to 3.10 mg NH4 – Ng-1 dry soil in drilling waste. Also, the substrate-induced respiration in Fadama and mangrove soil range from 2.05 to 0.05 ml CO2 kg-1 24 h-1 in drilling waste respectively. Analysis of enzyme activities indicated positive relationship between urease activities and SIR (r = 0.78, p < 0.05 Fadama (r = 1, P < 0.05 Mangrove) and (r = 0.83, P < 0.05 Meander). There was also a positive relationship between 5%, 10% and 15% treatment levels in Fadama, meander and mangrove soils.

Documentation of Acidic Mining Exploration Drill Cuttings at the Pebble Copper–Gold Mineral Prospect, Southwest Alaska

During exploration drilling of the Pebble copper–gold–molybdenum (Cu–Au–Mo) deposit, drilling wastes were disposed of directly on the landscape or passed through unlined sumps prior to disposal. The ore and host rock are rich in sulfides, which weather to sulfuric acid with consequent metal leaching. Oxidized cuttings were visually evident, and confirmed with laboratory and field testing to have a pH of 2.7–4.3. At these sites, Cu and Mo exceeded or were at the high end of the natural background. With one exception, Cu was in the range of 545 mg/kg to 4865 mg/kg. Dead vegetation was observed at all sites with drill cuttings on the surface. Dead vegetation was also observed on sump soil covers, unrelated to drilling waste. Sites where vegetation had not re-established were from four to thirteen years old. The potential impact to surface and groundwater was not determined. Understanding the source and extent of damage from cuttings could lead to better site management.