Field Experiences With Oilfield Waste Disposal Through Slurry Fracture Injection

Abstract

More than 100 years of extensive oil production in the U.S. and Canada has resulted in the generation of large volumes of oilfield waste, including produced oily sands and tank bottoms, drilling muds and cuttings, and crude contaminated surface soils. Much of this oilfield waste is the result of previous practices in which drilling muds and even produced oil were impounded in unlined storage pits. Many areas have also been contaminated due to spillage around well cellars, tank farms, and pipe yards. The Los Angeles Basin alone contains more than 10 giant oil fields (100MM bbls or larger) which together are estimated to have created more than 2 million cubic meters of crude contaminated soils. In addition to this pre-existing source of oilfield waste, ongoing production operations continue to produce oily sands. A significant portion of the pre-existing and annually generated oilfield waste material is currently being stored on-site until operators are forced to deal with the wastes whether due to regulatory pressure or in order to convert the property to other uses. An economic and environmentally sound technique to dispose of these produced oilfield wastes is to re-inject them back into the subsurface. The Slurry Fracture Injection (SFI) process involves slurrification of oilfield wastes with produced water and re-injection at fracture pressures into appropriate formations at the oil field where the waste was generated. On-site disposal of oilfield wastes provides four major advantages to the oilfield operator. These are:An environmentally attractive permanent disposal solution.Little impairment of surface land use.Reduction of long-term liability to waste generator.Reduction transportation and disposal costs. Terralog Technologies is currently managing slurry fracture injection projects at several sites in the US and Canada, disposing of produced sands, pit sludges, tank bottoms, and crude contaminated surface soils. Typical disposal volumes are on the order of 4,000 to 8000 bbls of slurry waste per day, per well. This paper presents a summary of slurry fracture injection facilities, technical design considerations and monitoring techniques, and regulatory issues in the US and Canada. Two field examples are presented and described in detail. Introduction Permanent, low-risk disposal of Non-hazardous Oilfield Waste (NOW) can be achieved through injection of a slurry comprised of waste material and produced water into deep permeable geologic formations. Waste generated at an oilfield location can often be re-injected at fracture pressure through existing wells into the same subsurface formations from which the wastes originated. The process of Slurry Fracture Injection (SFI) is a means to dispose of accumulated oilfield wastes by deep well injection. This process yields considerable advantages to the operator over conventional disposal methods. SFI provides an environmentally attractive and permanent disposal solution for considerable volumes of NOW waste, and has minimal impact on surface land use. In addition, it affords a significant reduction of long-term liability to the operator while reducing transportation and disposal costs. Traditional alternatives to SFI disposal include road spreading, surface disposal or landfills, incineration, soil washing, and disposal into salt caverns. These methods are generally more costly and leave the operator susceptible to future environmental and other liability concerns.

Deep Underground Injection of Waste from Drilling Activities—An Overview

“…In that sense, the injection of waste from oil and gas explorations and production activities (including waste from drilling activities) into deep subsurface formations as one of the on-site permanent waste disposal methods achieves zero discharge; improves the protection of the groundwater and surface; has a small surface footprint; reduces the need for waste transportation (via pipelines, marine vessels or tankers on-shore) and disposal costs; eliminates risks associated with the surface accumulation of generated waste and is not limited by locations [10,[18][19][20][21][22][23][24]. Besides all that was mentioned above, subsurface injections of drilling waste makes the continuous use of oil-based mud during drilling troubled shale formations in environmentally sensitive areas possible [25].…”

“…Generally, E&P companies independently define processing for drilling waste disposal based on waste composition, best available waste disposal methods, best engineering practices and with respect to regulations. There are also different waste materials that are not suitable for deep underground injections through the slurry fracture injection, such as materials that react with the formation or generate gas under downhole conditions [6,21].…”

“…It is necessary to make a perforation in the steel pipe and set cement into the formation in order to make a pathway for future waste slurry injections (Figure 1 (2. and 3.)). According to Sipple-Srinivasan et al [21] from Terralog Technologies Inc., the maximum length of perforated interval for a slurry fracture injection should be 10 m to keep the desired injection pressure and rate and with a perforation density of 20 shots per meter (phasing between 90 • and 120 • ) to get an as good as possible waste distribution in the radial direction.…”

Multi-criteria evaluation technique for SFI site identification of NORMS and oil industry waste disposal – Possibilities in Kuwait

“…It has been used in the United States, Canada, the North Sea, and Indonesia for disposal of non-hazardous oil field waste as well as naturally occurring radioactive materials -NORMs - (Schuh et al, 1993;Sipple-Srinivasan et al, 1997, 1998Baker et al, 1999;Reed et al, 2001;Arfie et al, 2005, Saif ud din et al, 2009. With SFI, permanent waste disposal is achieved without compromising future land-use, affecting the land-cover or deteriorating groundwater quality.…”

Managing disposal of water produced with petroleum in Kuwait

“…In North America, more than 20 years ago, attention was given to the method of produced water disposal (Baker et al, 1999;Seureau et al, 1994;Srinivasan et al, 1997). A successive excavation method was used to separate water from the produced oil.…”