The disposal of exploration and production wastes through deep well injection has increased dramatically during the last seven years. Prior to that time, most injection wells were used almost exclusively for produced water and brine disposal. During this period, the injection of waste solids in slurried form has been accomplished through low, sub-fracture pressure injection, slurry fracture injection, annular injection and injection into salt caverns. All of these types of disposal have been permitted by the governing regulatory bodies and have operated with varying degrees of success, problems and environmental impact. The injection of E & P solid waste has been, and continues to be, driven by the changing regulatory climate and by the sociopolitical perception of the industry, its' past and present methods of waste management and projections of future impacts and regulations. As the search for hydrocarbons has shifted to the offshore, the regulations governing handling and disposal of all wastes has become more rigorous. Of particular impact to E & P waste handling is past and projected modifications to permits tied to the National Pollutant Discharge Elimination System (NPDES). The key word in the title is "elimination" and the industry looks to injection to handle the elimination of the discharge of generated wastes into surface waters. Each different injection technology has its' own set of issues relative to its' applicability to a particular situation. These include regulatory controls and limitations, engineering parameters and guidelines, disposal capacities available, potential environmental and safety issues and liabilities and the public and regulatory community perception of all of the above. The continually changing regulatory framework and its' interpretation within a given region or state affects the implementation of the different injection technologies, as well as their commercialization. Introduction During the last two decades, various forms of injection have been used in the oil and gas industries to achieve permanent disposal of exploration and production wastes. For the purpose of this paper, we will focus on the recent methods used to dispose of solid wastes generated during operations. The disposal by injection of "clean liquids" such as produced waters filtered to various standards, has been part of the industry for several decades. Injection of these solid wastes usually entails the slurrification of the solids following some degree of particle sizing tailored to the limitations of the targeted receiving formation and the process employed. Disposal operations target structures ranging from salt caverns to highly consolidated formations that are fractured to achieve transport, containment and isolation of the injected slurried wastes. Certainly the bulk of the solid wastes disposed of by injection have utilized slurry fracture injection (SFI) or sub-fracture pressure injection methods. All of the methods available have the same goal; the safe and permanent disposal of solid wastes such that they are placed below the surface and isolated from any environmentally sensitive receptor in order to eliminate or minimize long term liabilities associated with the waste.
Disposal of non-hazardous oilfield waste (NOW) containing naturally occurring radioactive material (NORM) is a critical cost consideration within industry. Depending on activity levels, onsite disposal of NORM waste may be possible through onsite land spreading, injection and/or encapsulation during P & A work or, rarely, injection into permitted Class II wells. Some companies have investigated the processing and injection of slurried solid waste for disposal into depleted production boreholes. In most cases, this would require controlled fracturing, classic, dissolution or both, in order to provide disposal pathways and storage volume. Most state regulatory agencies will not consider such action due to federal regulations and the perceived potential for "uncontrolled" fractures allowing direct or indirect contamination of USDW aquifers. Present permitted offsite disposal alternatives include surface disposal facilities; landfilling at sites in Washington and Utah or land treating to below 5 pCi/g in Louisiana, or subsurface injection into Class II wells. Injection takes place after chelating and solubilizing or slurrying NORM solids. Injection as a slurried solid waste at a licensed commercial facility in Texas has become the dominant disposal method for oilfield waste containing NORM. Upfront processing and disposal costs and potential for future liability with each method of disposal is presented as related to both the NORM waste itself and to associated processed oil and gas wastes. For (relatively) high activity NORM from the oilfield >6,000 pCi/g 226Ra activity and/or 30,000 pCi/g total specific activity), near surface storage/disposal is the only present option. For lower activity levels, the choice is between near surface and underground disposal. Potential liability appears to be limited with injection of non-solubilized slurried waste. Real onsite disposal cost evaluations must consider well modifications, processing and closure charges. Processing and transport costs define the upfront costs for offsite disposal and are competitive across the board. An assessment of future liability costs related to NORM and associated oilfield wastes is necessary to determine the best disposal method. Introduction Since the discovery of scales containing Naturally Occurring Radioactive Materials (NORM) in oil and gas industry production and processing equipment, the industry has been faced with two major concerns. The first has been to determine the best way to handle and/or dispose of NORM waste, that is, how to manage the physical problem. And the second has been to prepare and speculate on the response of regulatory bodies in dealing with the problem and its real and perceived risk to workers and the public in general. As we know, these two items are intricately, and some might say intimately, connected. The American Petroleum Institute (API) began to look at the problem of NORM by commissioning a survey that has become known as the "Otto Report", which evaluated the presence and activity of NORM in oil and gas production facilities. The API followed that report three years later with a bulletin on managing NORM in the oilfield that addressed the methods then available and what appeared to be in the near future. As it turns out, the physical focus needs to be on addressing perceived safety and health concerns related to the presence, handling and disposal of the NORM, while the regulatory focus must involve proactive regulatory involvement, waste management and bottom line costs. These are increasingly related to the risks and liability that might be associated with past and future NORM contamination and how it has and will be managed. Liability and waste management issues have come to focus on the method of disposal. Norm Waste Disposal Methods There are a number of different methods to be considered in the disposal of NORM. Some methods are more applicable with a given set of criteria than others and some are the only solution available for a particular waste volume or material.
An Evaluation of the Radiation Health Physics Data Collected at a Commercial NORM Oilfield Waste Disposal Facility With Application to Field Production Facilities F.L. Lyon, SPE, M.B. Hebert, and S.A. Marinello, SPE, Newpark Resources, Inc. Abstract Regulations pertaining to naturally occurring radioactive materials (NORM) in oilfield wastes have now been promulgated in many of the major oil & gas producing states (AR, AL, LA, MS, NM, TX, etc.). This paper will evaluate the radiation exposure of workers and members of the general public to these wastes by looking at the radiation health physics data compiled at the largest NORM oilfield waste disposal facility in the country. This facility, owned by Newpark Environmental Services, has been in operation since October, 1994. In this paper, we will assume that the facility (operating under a typical worker protection plan) represents a worst case scenario for exposure to radiation when compared to oil & gas production facilities containing diffuse NORM. Monitoring methods used to determine both external and internal exposure will be described for both occupational doses (not to exceed 5000, millirem (mrem) per year) and doses to individual members of the public (not to exceed 100 mrem per year). Occupational monitoring included measurements of external dose using individual thermoluminescent dosimeters (TLDs), breathing zone air samples (BZA) to determine the potential intake to workers in conjunction with derived air concentration (DAC) limits, and urine bioassay samples to determine actual individual intakes in conjunction with annual limits of intake (ALI). Public monitoring included continuous external gamma monitoring using environmental TLDs at multiple locations around the facility, downwind boundary effluent air monitoring and passive radon monitoring. From these measurements, a total effective dose equivalent (TEDE) can be calculated and compared to the limits for occupational and public exposure. Though the data were analyzed over time in the paper they can be summarized, since the opening of the facility through September 30, 1996 (24 months), as follows:–The average annual TEDE for occupational dose is <5 mrem/year.–The same calculation for public exposure is <25 mrem/year. The public dose is higher because 100% occupancy must be assumed, whereas workers exposure is based on actual time on the job. Through the end of 1996 (27 months), 129,999 barrels of NORM oilfield wastes were received with an average specific activity of 131 picoCuries per gram (pCi/g) for 226Ra and 708 pCi/g total activity (the range was 3-5,865 pCi/g 226Ra and 15-28,509 pCi/g total activity). Introduction NORM has been associated with oilfield wastes since the early 1900s. Following a national survey sponsored by the American Petroleum Institute (API), several of the major oil and gas producing states began to consider regulating NORM wastes. This led to many investigations to better understand why NORM occurs. Several states, beginning with Louisiana, developed NORM regulations. As legislation has been enacted, a need developed for the disposal of NORM wastes. Many disposal options have been examined. Newpark's technology involves surface processing for particle size reduction and viscosification, followed by downhole injection into subpressured geological structures at non-fracturing pressures (typically less than 150 psi). Data presented in this paper was collected at two different facilities. Both facilities operated under similar worker protection plans. The initial facility opened in October, 1994. Operations were moved to the present facility in June, 1996. Oilfield wastes containing NORM not exceeding 6,000 pCi/g of 226Ra and 30,000 pCi/g total activity could be received at either facility. P. 93^
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