Abstract: This paper introduced the properties and characteristics of solid waste from drilling old wells in oil and gas exploration and technical principles and treatment process of biodegradation. It focused on analyzing the restoration effects of biodegradation technology on two old wells of the Southwest Oil & Gasfield Company. The results showed that the index of harmful heavy metallic elements in the soil treated and restored by biodegradation technology did not exceed the index in the Soil environmental quality Risk control standard for soil contamination of agricultural land (GB 15618-2018) (other, pH > 7.5, risk screening value); the pollutant index of soil leachate can meet category class 5 water quality requirements in Environment quality standard for surface water (GB3838- 2002). The solid waste from drilling after biodegradation treatment can be used as afforestation and planting soil. After treatment, the soil is relatively poor in nutrients and can be supplemented with targeted organic, phosphate and nitrogen fertilizers to replenish nutrients for further use. It is feasible to adopt biodegradation technology to treat and utilize the residual solid waste from drilling old wells in oil and gas exploration and turn them into general plantable soil, which can not only eliminate the environmental hazards of old wells, but also turn the land occupied by the solid waste into arable land, thus realizing ecological restoration and sustainable development. 

Key words: oil-gas exploration, old wells, solid waste from drilling, biodegradation, treatment and utilization