The pollution caused by drilling waste to the environment is mainly due to the presence of a large amount of water-soluble heavy metal ions and inorganic substances in drilling waste. After these substances are dissolved in surface and groundwater, they will gradually spread and transfer over time, and eventually bring great threats and impacts to the living environment of animals and plants, and even cause the death of animals and plants.
Therefore, further strengthening the treatment of drilling waste has a very important practical role.
Among drilling waste, the substances produced are mainly drilling wastewater, waste gas, and drilling fluid. The drilling waste treatment technologies at home and abroad are mainly based on microbial treatment, backfilling, pit sealing, off-site centralized treatment, injection safety layer and simple treatment and discharge technology.
In addition, land cultivation and reinjection formation treatment technology have good environmental benefits, but have great limitations in use and cannot be popularized and promoted in the region. At the same time, these treatment technologies have certain requirements for mud and are not suitable for use in all drilling waste mud systems. The solidification method, due to its relatively large footprint and high environmental risks, was partially tested in 2004, and was completely banned in 2012.
The drilling waste mud treatment technology that does not fall to the ground uses skid-mounted equipment, which can achieve an organic combination of physical treatment technology and chemical treatment technology, ensuring the treatment of waste mud during drilling. In addition to ensuring that the waste mud meets the emission standards, it can also reduce cost investment, bring less environmental risks, and has strong operability and universal applicability.
At present, the waste generated during the drilling process has an impact on the environment. This is because the water-based drilling fluid contains a large amount of chemical agents, such as alkali, CMC, polymers, lubricants, sulfonated lignite (SMC), sulfonated phenolic resin (SMP), sulfonated asphalt (SAS), inhibitors, sodium silicate, humic acid and plugging agents. Drilling waste fluid not only contains a certain amount of oil substances, phenolic substances and sulfides, but also soluble organic small molecules and polymer compounds that need to be biologically reduced.
Analysis shows that drilling waste fluid has the characteristics of high chroma (brown-dark brown), high suspended solids content (1000-5000 mg/L), high COD content (1000-70000 mg/L), and high pH value.
At present, the pollution problem caused by drilling waste to the environment has become more and more prominent. In addition, groundwater and surface rainwater will cause pollutants to precipitate. With the flow of rainwater, they will be carried and transferred, and the impact on the environment has become more and more profound.
Specifically, the impact of drilling waste on the environment is manifested in the following aspects: First, the pH value of drilling waste is too high. Under normal circumstances, the pH value of drilling waste in oil fields is about 8-10. The ultra-high pH value and the presence of high salt and petroleum substances will cause soil compaction and soil degradation;
Second, the COD is high and the chroma exceeds the standard. There are a lot of sulfonated substances and lubricating materials in drilling waste, including certain asphalt anti-collapse materials. The use of these oil field additives can optimize the overall efficiency of drilling, but because of the high COD, it will cause surface water pollution;
Third, a small amount of treatment agents may cause heavy metal ions to exceed the standard. Some treatment agents are difficult to degrade after being discharged into the natural environment. If they accumulate in the soil for a long time, they will affect the soil plant system and cause poisoning, resulting in a decline in the quality of agricultural products. For example, when monitoring the soil environment quality and groundwater quality in a certain place, it was found that various pollution indicators were seriously exceeded due to the influence of drilling waste.