During the drilling operations and the extraction of crude oil, it is necessary to pump large amounts of drilling mud i.e., mixture of clay mixed with oil and water for the sake of lubricating the drilling bit and facilitating in pumping the drill cuttings out of the oil well to transport them to the surface. After the drilling operation is completed, large quantities of this waste mud mixed with drill cuttings will be generated as an industrial byproduct. Generally, disposal sites are needed for the final disposal of this drilling waste that will stay in those disposal sites without any treatment or utilization. These disposal sites should be designed with certain specifications to prevent oil leakage and waste materials from them into the ground.
The dumping of such a huge amount of this solid drilling waste is costly, as it needs a lot of land space and results in a number of serious environmental issues. The waste can easily contaminate soil and groundwater when some of its components leach into the earth. One of the promising strategies to reduce the threat of such wastes and to diminish their accumulations in the disposal sites is by utilizing such wastes in another industry activity. From the viewpoint of recycling, this can be considered sustainable approach to manage this waste and reduce its amount that sent for final disposal to minimum.
Prof. Sabah Ahmed Abdul-Wahab Al-Suleiman from the Department of Mechanical & Industrial Engineering of the College of Engineering at Sultan Qaboos University has received Qatar Sustainability Awards 2018 in the category of Green Research for her research on the use of waste generated from oil drilling operation as alternative raw material in cement industry. According to Prof. Sabah, drilling waste contains significant quantities of calcium oxide (CaO) and silicon dioxide (SiO2).. The presence of these constituents makes drilling waste a suitable material for manufacturing of cement as these oxides are also the basic necessary oxides that are required in the cement industry, where the cement clinker is made from raw materials of limestone (CaCO3) that is rich in calcium oxide (CaO) and the silica ore. Hence, the drilling waste can be used as the alternatives of limestone based materials for clinker production. Being a direct source of calcium oxide (CaO), the drilling waste will assist in the reduction of the emissions of CO2 that is originating from limestone thermal decomposition”, she said.
Prof. Sabah said that there are several advantages of utilizing drilling waste in the cement industry. “The amount of wastes resulting from drilling wells is very large. Hence, utilizing drilling waste in the cement industry is an economic manner for comprehensive utilizing of this waste. The cement industry is one of the huge consumptive industries for raw materials that originate from natural resources. The use of drilling waste in the cement will substitute a part of the raw materials of cement. This will reserve the natural resources used in the manufacturing of cement”, she added.
Prof. Sabah is continuing the research work experimentally with Oman Cement Company by manufacturing cement in the lab. In this lab work with cement manufacturing, drilling waste will be added proportional with the operations and conditions of the cement plant. The influence of drilling waste addition will be investigated to examine its effect on the products and determine the maximum amount that can be added to the raw feed without affecting the quality of the cement. Using drilling waste in cement production provides large-scale recycling, and is environmentally sound and economically sustainable. Prof. Sabah said that through drilling waste use, cement plants would produce sustainable cements consuming less energy and minimizing CO2 discharge. Sustainability in cement production is vital as it is an essential constituent of concrete, a vital resource in the construction industry and in infrastructure development.
“Oil companies need to know how to minimize the problems of disposal and health hazards of their drilling wastes. Currently, the generated drilling wastes are expensive to dispose as they are accumulated in a large quantity. They require a lot of land and cause a number of environmental problems. Thus, utilization of drilling wastes in cement plant will allay concerns about the destructive impacts of drilling wastes on the environment. It will eliminate the cost of their disposals and avoid soil and water contamination. This will allow drilling companies in Oman to run their work, where possible threats to environment will be either eliminated or, at least, reduced to a minimum,” Prof. Sabah concluded.