Soil and water body oil pollution treatment status and prevention countermeasures

5.3.1 The current status of governance in the oil sector

According to statistics from the establishment of the oilfield in 1964 to the end of 1998, the total cumulative investment in environmental protection in the oilfield was 963 million yuan, of which 963.49 million yuan in environmental protection facilities in fixed assets, and the environmental protection investment in 1998 was 110.95 million yuan.In the environmental protection investment in 1998, 87.47 million yuan was used for wastewater treatment , 11.82 million yuan for waste gas treatment, 860,000 yuan for solid waste treatment, 200,000 yuan for noise treatment, and other 10.6 million yuan.

1. Treatment of industrial wastewater in oilfields

The current treatment of industrial wastewater mainly focuses on several measures such as improving the discharge rate to meet the standards, reducing the content of petroleum in wastewater pollutants and improving the reinjection rate of extracted water from oilfields. According to the latest information:

In 1998, the oilfield discharged 27.5332 million tons of industrial wastewater, and the amount of discharge to meet the standard was 20.793 million tons, and the rate of discharge to meet the standard was 75.22%; In 1999, the oilfield discharged 27.2704 million tons of industrial wastewater, and the amount of discharge to meet the standard was 20.3037 million tons, and the rate of discharge to meet the standard was 74.45%.

In 1998, the discharge of industrial wastewater pollutants in the petroleum category is 414.52t; oilfield 1999 discharge of industrial wastewater pollutants in the petroleum category is 288.36t; expected to be discharged in 2000 in the industrial wastewater pollutants in the petroleum category for 162t, petroleum category can be compared with the 1998 abatement of 2,525,200t. oilfield wastewater petroleum category in the production of about 5.4 million t/a, the recovery rate of about 70% (recovery of about 3.78 million t/a).

Because the oilfield wastewater pollution is mainly caused by the discharge of the oilfield water, the current main drainage water is injected back into the ground. 1998 oilfield water amounted to 260 million tons, more than 92% of the injection, and there are six oil extraction plants with a 100% injection rate.

2. Recovery of fallen crude oil

Shengli oilfield oil extraction well field and other work sites have fallen crude oil pollution problems, every year into the environment of the fallen crude oil is a huge number of fallen crude oil, the amount of fallen crude oil production is about 61,200t/a.

Because of the process and technical reasons, can not be completely eliminated fallen crude oil, in order to avoid waste and pollution, the main use of the current Wellhead set up a fixed or movable storage pool regular recovery to solve the problem, each oil extraction plant specifically set up landing crude oil contaminated oil recovery team is responsible for the recovery, the recovery rate of about 98% (recovery of about 60,000t / a), but there is still a part of the residual surface, each year, there are still 0.12 million tons of landing crude oil can not be recovered and left in the environment.

5.3.2 Soil and water body pollution prevention and control countermeasures

1. Water pollution prevention and control countermeasures

From the survey of oilfield pollution sources, volatile phenol is the number one pollutant in industrial wastewater according to the ratio of equal pollution load, followed by petroleum type and chemical oxygen demand. From the ground water actual monitoring, according to the equivalent standard pollution load ratio, chemical oxygen demand is the first pollutant, petroleum is the second pollutant. In the study of total water pollution control, petroleum and chemical oxygen demand are listed as the main control pollutants, in order to ensure that the receiving sewage river pollutants in the national permissible range, to improve the following pollutant prevention and control countermeasures:

(1) there are 19 major outfalls in the oilfield, the pollution of surface water pollution is serious pollution source is mainly oil recovery sewage, so we must strengthen the management of oil recovery sewage treatment, in strict accordance with the Sewage treatment design process, operation process specification, it is strictly prohibited to privately simplify the treatment process, violation of the operation, to strengthen the supervision and inspection, the discharge of sewage must meet the standards.

(2) new and reconstructed sewage treatment stations, must choose the treatment process advanced treatment efficiency of sewage treatment equipment.

(3) actively promote the experience of not discharging sewage oil extraction plant, the sewage will be qualified, all injected back into the ground, the oilfield internal implementation of sewage treatment incentives and penalties, and a limited time to realize the oil extraction plant sewage is not discharged.

(4) each sewage treatment station should be established impermeable, overflow-proof sewage temporary storage pool, once an accident occurs after the sewage treatment is unqualified, the sewage can be temporarily stored in the pool, and then after the treatment of qualified back into the injection or external discharge.

(5) Strengthen the management of drilling waste mud and wastewater, so that the drilling mud and wastewater reuse and recycling. After the completion of drilling, the mud and other pollutants in the well site are all cleared to the mud pool to prevent spillage, and trees are planted on top of it and around it after the mud dries and solidifies.

(6) Strengthen the management of operational wastewater treatment and improve the rate of pollution-free operation. During the operation of oil and water wells, the wastewater will be pressed into the trunk line, and after the completion of the operation, the dirty oil, sewage and other pollutants at the operation site will be cleaned up into the mud to reduce the pollutants that fall to the ground during the operation.

(7) As chemical oxygen demand is another major pollutant in the river in addition to petroleum-based, and the pollutant, in addition to the contribution of oilfield industrial effluent, the main source of its local enterprises, especially paper mills, petrochemical industry. Another major source of COD is domestic sewage from urban residents. To completely improve the water environment, but also must be treated and controlled sewage from these sectors.

2. Soil pollution prevention countermeasures

(1) the implementation of mud recycling: in order to make the mud with the drilling process required by a variety of properties, the need to add a large number of inorganic and organic treatment agents, once the drilling is completed, these chemicals treatment agents will be discarded with the mud in the well site, which not only creates a great waste, but also these chemicals are bound to be associated with surface water movement, migration and diffusion to the surrounding areas, polluting the water environment. This not only causes a great waste, but also these chemicals are bound to move with the surface water movement, migration and diffusion to the surrounding areas, polluting the local environment, if these mud collection, to be reused, not only can save a lot of money for the country, but also greatly reduce the pollution.

(2) the utilization of non-toxic new mud, is also an effective measure to reduce pollution. At present, the mud is often added to the soda ash and caustic soda, so that the pH value of the mud up to 10 ~ 11, these highly alkaline chemicals into the farmland can change the soil composition, so that the soil alkaline increase sloughing and hardening; in the drilling of deep wells when a large number of iron-chromium salts, so that the chromium-containing elements of the toxic substances, the digestive tract of the human body, the skin has a strong stimulating and corrosive effect on the respiratory tract has also caused a lot of damage, often cause dermatitis , skin ulcers, loss of sense of smell, and even carcinogenic. From the 1993 statistics, the current oilfield drilling production in the use of iron and chromium salts is still very large, which is bound to cause great harm to the region's population, so the use of new non-toxic mud has been a major trend.

(3) study the causes of crude oil landing, reduce the amount of crude oil landing in crude oil production, in the drilling, oil and gas gathering and transportation, storage and transportation process, all kinds of accidental leakage, equipment, pipeline running leakage of dirty oil, and well site site of the landing of the crude oil also has a large number of accumulation, they are discharged into the environment, on the soil, plants and humans caused harm. Therefore, exploring the causes to reduce the quantity of crude oil on the ground and studying its recovery to reduce waste are the ways to solve the environmental pollution of crude oil on the ground.

(4) Control of unorganized diffusion of external sewage water: unorganized discharge of sewage water is mainly generated in the drilling process, including diesel engine cooling water, drilling wastewater and well-washing water, and its control can limit the scope of pollutant diffusion in order to weaken its pollution.

(5) Early biological treatment of fallen crude oil, according to research, many bacteria can effectively decompose fallen crude oil, which can not only eliminate its pollution, but also increase soil fertility.