Innovative Solution to Environmental Challenges in Oil Fields: 'Oil Extraction from Mud' through Oxygen-Free Pyrolysis

From May 18th to 19th, 2023, the Oil and Gas Development and Refining Industry Wastewater and Sludge Treatment and Oilfield Water Injection Technology Promotion and Exchange Conference, jointly organized by the China Petroleum Enterprise Association and relevant institutions and departments, took place in Xi'an. Over 300 representatives from national oil and gas field exploration, refining enterprises such as China National Petroleum, Sinopec, CNOOC, Yanchang Petroleum Group, research institutes, higher education institutions, and oilfield service companies gathered to discuss innovative technologies, application demonstrations, and solutions for the treatment of industry wastewater and sludge and oilfield water injection. Hunan Vary Technology Co., Ltd., as a service provider for oil sludge pyrolysis equipment systems, was invited to attend, and the Director of the Research and Design Institute, Zuo Zhiyue, delivered a keynote speech on 'Oil Sludge Pyrolysis Resource Utilization Technology and Equipment.'

In 2022, China's crude oil production reached 204 million tons, natural gas production reached 220 billion cubic meters, and crude oil processing amounted to 710 million tons. Various types of oil-containing sludge generated during exploration, development, and processing processes totaled up to 12 million tons. According to petroleum production data since 1965, the stock of oil-containing sludge has reached 159 million tons, making the oil sludge disposal market worth over a trillion yuan. How to achieve large-capacity, continuous treatment of various types of oil sludge, improve oil recovery rates, ensure the safe and stable operation of the system, and ultimately meet environmental standards has become a major concern for petroleum exploration and refining enterprises.

Oil sludge contains a significant amount of petroleum hydrocarbons, with a high oil content. Through pyrolysis technology and equipment, it can be converted into pyrolysis gas, charcoal, and oil. The excess pyrolysis gas can be reused in the system, and the pyrolysis oil can be used as raw material oil in refineries or directly as fuel oil. The stabilization of heavy metals in oil sludge during pyrolysis prevents the generation of dioxins, while enabling oil and gas recovery and carbon residue regeneration. All products are fully utilized, demonstrating the effectiveness of 'oil extraction from mud.'

Zuo Zhiyue from Vary Technology, in light of practical issues encountered in oil sludge projects, provided targeted insights into the core technologies of the company's pyrolysis technology equipment for oil sludge treatment: 1) Oil and gas purification technology, using multi-stage dust removal and condensation to achieve gas purification, increase oil recovery from sludge, and ensure the cleanliness of non-condensable gases; 2) Automatic coke removal device, capable of continuous and fully automatic coke removal, effectively improving the heat transfer efficiency of pyrolysis equipment, avoiding coking and blockages, increasing continuous operation time, and extending the service life compared to other similar equipment; 3) Unique flue gas and oil and gas dynamic sealing technology, self-compensating flexible packing seal technology, minimizing the entry of external cold air into the flue gas interlayer, reducing additional heat loss, and improving heat efficiency; combination flexible sealing, accommodating a certain degree of radial and axial movement within the inner cylinder during the large rotary kiln drive process, isolating the material pyrolysis environment from the external environment; 4) For high-viscosity, high-glue content refinery sludge, and tank-cleaning sludge prone to clogging the feeding and slagging device, a combination of material sealing, mechanical sealing, and inert gas-assisted sealing is used to ensure stable and uniform feeding into the pyrolysis furnace; 5) Heat transfer technology, increasing the residence time of flue gas in the heating flue, improving heat transfer efficiency; hot air recycling technology, reducing combustible gas consumption, decreasing exhaust gas volume, reducing energy consumption, and lowering operational costs and investments in the exhaust gas treatment system; 6) Simple equipment structure, easy maintenance, and automatic continuous production, convenient operation. With nearly a decade of technological accumulation, Vary Technology has developed over 50 sets of pyrolysis equipment technologies, overcoming the environmental challenges in oilfields. The utilization of oil sludge pyrolysis resources has been successfully applied in various domestic projects in Jiangsu, Shaanxi, Shandong, Hunan, Hebei, Guangdong, Xinjiang, among others.

With the intensification of policies such as the 'Catalog of Major Environmental Protection Technology and Equipment Encouraged by the State' and the dual-carbon goals, coupled with the considerable economic, safety, and environmental benefits of pyrolysis, oil sludge pyrolysis may become the mainstream trend for future oil sludge disposal. Vary Technology will continue to focus on refining its technology, working with petroleum and petrochemical enterprises to innovate, promote the green transformation and upgrading of the oil sludge industry, and achieve high-quality development.