ESTIMATION OF DRILLING WASTES – AN ENVIRONMENTAL CONCERN WHILE DRILL…
Despite its numerous benefits the search and production of crude oil poses a lot of dangers to the environment. Among these include land, water and air pollution. Prominent among the major sources of E&P waste is drilling operations which form the second largest source of waste after production activities. The major drilling wastes are drill cuttings, drilling mud and obnoxious gas emissions. These wastes are introduced into the environment through intentional as well as accidental discharges and this expulsion into the environment has direct and indirect effects on aquatic life, personnel working on the rig, plants, flying birds, as well as the soil. This research work purposes to identify the various forms of drilling waste, their effect on the environment and to develop strategies in managing these waste effectively. The ability to effectively identify, quantify, classify and adopt strategies to eliminate or reduce the impact of drilling waste on the environment defines an effective waste management practice. In all situations source reduction of waste is the most favorable and economically feasible drilling waste management option and should in all cases be a priority over the other methods of waste management. However, this task of adopting an effective waste management tactics is not as simple as it looks. In its quest to developing effective strategies for managing drilling waste, it is identified that the quantity of waste generated plays an important role in drilling waste management. It dictates the type of waste management method to adopt, the design of waste boxes, waste disposal cost among others. A simple user-friendly spreadsheet is therefore developed for waste volume estimation. Again, a ten steps effective waste management procedure is developed to serve as guidelines for drawing waste management plans. Waste management plans should be updated regularly to capture changes in regulations, new technologies and new operations. In conclusion it is shown that the choice of the ideal drilling waste management is usually dependent on the local regulations in place, technical efficiencies, cost and the quantity of waste. The selection should always be therefore subjected to effective environmental, economic and technical analysis. As a result, a waste selection criterion has been developed which will help eliminate some of the options that are not favorable.
FORMULATION OF PROBLEM
1.1 Problem Definition
Petroleum is among the world’s most important natural resources. It is the most significant and highly traded primary commodity in the international market (Illedare, et al., 1999) and has remained the world’s primary source of energy for both industrial and domestic applications since replacing coal early in this century. However, the finding and production of petroleum involves the generation of drilling waste which forms a major source of pollution in oil producing environment. Almost every process in the finding and production of petroleum generates wastes which impacts the environment negatively. Until 1980’s, little or no thought was given to the generation and disposal of cuttings and excess drilling fluids. Typically, these materials were discharged overboard in offshore operations or buried when drilling in land-based locations. The global environmental awareness in the late 1980s to early 1990s made the oil and gas industry and its regulators to understand and appreciate the potential environmental impact of drilling waste (Geehan, et al, 2000).
In an effort to manage and reduce the impact of drilling waste on the environment, a number of technologies and publications have been written. Technologies such as directional drilling, slim-hole drilling, coil-tubing drilling and pneumatic drilling are few of the drilling practices that generates less amount of drilling waste. A number of drilling waste management plans and programs have also been designed by different companies and researchers. Drilling waste management refers to ways by which drilling and associated wastes could be handled effectively in order to minimize their effect on the environment. Wastes that are usually associated with drilling operations are: – drill cuttings, contaminated drilling fluids and additives, gaseous contaminants from internal combustion engines, produced water as well as heavy metals. The principal aim of waste management is to ensure that waste does not contaminate the environment at such a rate or in such a form or quantity as to overload natural assimilative processes. Eliminating or minimizing waste generation is crucial, not only to reduce environmental liabilities but also operational cost (Richards, 2007). The waste hierarchy is a common waste management technique that has been reported in a number of literatures. This refers to the “3 Rs” Reduce, Reuse and Recycle, which classify waste management strategies according to their desirability in terms of waste minimization (Anon [a] , 2011). However, this technique is not extensive enough. Before the waste hierarchy is effectively applied, it is desirable to identify, classify and estimate the quantity or the volume of waste to be generated. An effective waste management technique must incorporate all these factors.
The volume of drilling waste generated when drilling a well is also an important and costly factor, especially when the waste must be transported, treated, or disposed off-site(Fleming, et al., 2010). It is an important planning tool which is usually not mentioned in the drilling waste management process. Drilling waste could be better managed if the anticipated amount or volume is appropriately quantified. Unfortunately, very few publications have reported on drilling waste volume quantification and estimation methods. This study seeks to identify the various types of drilling wastes that pollutes the environment and how to minimize it. It presents an effective method to quantify the volume of drilling waste generated for an efficient waste management plan.
1.2 Literature Review
Environmental pollution and waste management is a broad and extensive study area with lots of publications. There is a tremendous amount of valuable information available on the environmental impact of petroleum operations and on ways to minimize that impact: however, this information are scattered among thousands of books, reports and papers making it difficult for industrial personnel to obtain specific information on controlling the environmental effects of particular operations (Reis, 1996). Again, very little of these materials focuses on waste volume quantification.