In the process of oil drilling, various kinds of drilling waste often appear. This kind of drilling waste is not only a very big obstacle to oil drilling, but also inestimable to equipment damage and economic damage.
Pollutants and Hazards
Drilling waste is a mixture of drilling sewage, drilling fluid (drilling mud), drilling cuttings and sewage oil. It is a fairly stable colloidal suspension system, containing clay, weighting materials, various chemical treatment agents, sewage and sewage The main chemical components that endanger the environment are hydrocarbons, salts, various polymers, heavy metal ions, impurities in barite, and asphalt and other modified compounds. These pollutants have high chromaticity, high petroleum It is one of the main pollution sources in the process of petroleum exploration and development. Every time a well is drilled in an oil and gas field, an abandoned mud pond is left in place. There are thousands of wells in an oil and gas field, and there are thousands of abandoned mud pools. The drilling waste in each mud pool ranges from a few hundred cubic meters to thousands of cubic meters. These wastes have soluble inorganic salt pollution, heavy metal pollution, and organic hydrocarbon (oil) pollution. If they are stacked or buried at the well site, once they are soaked by rainwater and washed by rivers, they will affect the surrounding soil, water sources and farmland. and air pose serious environmental risks.
(1) After a series of chemical, biological and physical actions, drilling waste will have an impact on the soil, water quality, biology and other environmental ecology.
(2) The main indicators exceeding the standard are chemical oxygen demand (COD), biological oxygen demand (BOD), oil, suspended solids (SS) and metal salts (such as Pb, Cb, Hg, Cr salts, etc.). They mainly come from the addition of various drilling fluid additives in the preparation of the drilling fluid and the carryover of the drilling fluid during the drilling process. The value of chemical oxygen demand (COD) is often as high as several thousand or even tens of thousands of milligrams per liter.
(3) Calculated as 300m3 of waste drilling fluid in each well, the total amount of metal pollutants reaches 13.2kg, and the amount of heavy metal leaching reaches 4.3kg, indicating that the heavy metals in the waste drilling fluid are potential pollution sources.
(4) Through the simulated rainwater leaching analysis of the waste drilling fluid, the leaching rate of oil in the waste drilling fluid is up to 90%, followed by total chromium, with a leaching rate of 50%. The elution sequence is: Oil>TCr>CODCr>As>Pb>F-1>Hg. For heavy metals, although most of the leaching solutions meet the standard except for total chromium, the leaching rate is relatively large. The main pollutants in the leachate were CODCr, total chromium and oil. This further shows that the waste drilling fluid cannot be directly discharged. ?
(5) The environmental biodegradability of drilling waste is poor, and it is not suitable for biochemical treatment.
(6) Toxic and harmful substances in drilling waste will overflow or infiltrate into the ground through natural rainfall leaching, which will affect surface water, groundwater and soil. And it may be enriched in the soil, which will not only adversely affect a large number of microorganisms in the soil, but also alkalize or poison the soil. If absorbed by vegetation, it will have a toxic effect on it, and even harm humans and animals.
(7) The waste drilling fluid itself is a very complex dispersion system. It is based on clay and water, so that the clay is dispersed in water to form a relatively stable dispersion system. The particle size is generally between 10-2~2μm. It has the properties of colloid and suspension, so it has considerable stability.
(8) Due to its special components, it has considerable stability. This stability enables the waste drilling fluid to maintain a stable state for a long time, and the zeta potential value is very high. Therefore, in order to destroy its stability, a large amount of treatment agent must be added to destabilize it, which is one of the reasons why the treatment of waste drilling fluid is difficult and expensive.
The generation of drilling waste will undoubtedly bring great harm to environmental protection. In the face of this different waste, KOSUN has developed and produced different waste treatment machines according to different drilling wastes. In application, it not only reduces the burden of waste disposal for operators, but also brings great convenience to drilling operations. These machines are divided into: vertical cuttings dryer, drying screen, screw pump, screw conveyor. These mechanical applications have achieved significant success throughout the drilling operation.
