Drilling waste and environmental impacts

The pollution caused by drilling waste to the environment is mainly due to the fact that drilling waste contains a large number of water-soluble heavy metal ions and inorganic substances, which will gradually spread and transfer with the passage of time after dissolving in the surface and groundwater, and eventually bring great threats and impacts on the living environment of animals and plants, and even lead to the death of animals and plants.

Therefore, further strengthening the disposal of drilling waste has a very important practical role.

In the drilling waste, the substances produced are mainly drilling wastewater, waste gas and drilling fluid. The main technologies of drilling waste disposal at home and abroad are microbial treatment, backfill, pit seal, remote centralized treatment, injection safety layer and simple treatment and discharge technology.

In addition, the technology of land cultivation and reinjection formation treatment has better environmental benefits, but it has greater limitations in use and can not 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 curing method, due to its relatively large area and high environmental risks, was partially tested in 2004, and the use of curing method was completely banned in 2012.

The drilling waste mud treatment technology without landing while drilling, the use of skid-mounted equipment, can realize the organic combination of physical treatment technology and chemical treatment technology, to ensure the drilling waste mud treatment while drilling, in addition to ensuring that the waste mud can meet the discharge standards, but also reduce the cost of investment, bring less environmental risks, It has strong operability and universality of use.

At present, the waste generated during the drilling process has an environmental impact. Because the water-based drilling fluid contains a large number of chemical agents, such as: alkali, CMC, polymer, lubricant, sulfonated lignite (SMC), sulfonated phenolic resin (SMP), sulfonated asphalt (SAS), inhibitors, sodium silicate, humic acid and plugging agent. Drilling waste fluid not only contains a certain amount of oils, phenols and sulfides, but also small solvent organic molecules and high molecular compounds that need to be biodegraded.

The analysis shows that the drilling waste liquid has the characteristics of high chromaticity (brown-black brown), high suspended solid content (1000-5000 mg/L), high COD content (1000-70000 mg/L) and high pH value.

At present, the environmental pollution caused by drilling waste is becoming more and more prominent. In addition, groundwater and surface rainwater will lead to the precipitation of pollutants. Along with the flow of rainwater, it will carry and transfer, and the impact on the environment will become more and more profound.

Specifically, the environmental impact of drilling waste is manifested in the following aspects:

First, the pH value of drilling waste is too high. Generally, the pH value of drilling waste in oil fields is about 8-10, and the existence of ultra-high pH value and high salt and petroleum substances will lead to soil compaction and soil degradation.

Second, COD is higher and chroma exceeds the standard. In the drilling waste, there are a large number of sulfonated substances and lubricating materials, including some asphalt anti-collapse materials. The application of these oil field additives can optimize the comprehensive efficiency of drilling, but it will also lead to the pollution of surface water because of the high COD.

Third, a small amount of treatment agent may lead to excessive heavy metal ions. Individual treatment agents are difficult to degrade after being discharged into the natural environment, and accumulate in the soil for a long time, which will affect the soil plant system, and then bring poison, leading to the decline of crop product quality, such as monitoring the soil environmental quality and groundwater quality of a certain place, and find that the impact of drilling waste, the pollution indicators seriously exceed the standard.