The Development and Trial Use of Oil Exploration Drill-Cutting Waste as an Aggregate Replacement in Cold-Mix Asphalt

Abstract

The safe disposal and minimisation of offshore drilling waste has been a major environmental concern for the petroleum industry over many years. This paper presents the collaborative work between; oil drill cuttings generator, road authority and asphalt technologists to produce a cold mix asphalt solution to the problem of disposal. The drill cuttings are high in moisture content and contain some hydrocarbon residues, the preliminary design identified that the addition of drill cutting waste into asphalt reduced the stiffness and inherent stability of the mixtures examined. These two problems were overcome by redesigning the binder and by replacing up to 20% of the virgin aggregate with incinerator bottom ash. Use of the ash increased the aggregate pore structure within the mixture and accommodated the relatively high moisture contents whilst the binder modification allowed for the inherent low viscosity oils. The project concluded with a plant/quarry trial of the Laboratory developed mixture to assess suitability for full scale production and any eventual application. This process promises to be an effective method of reducing offshore drilling waste in a cost effective and environmentally sound way. 1. INTRODUCTION One of the primary functions of the drilling fluids (muds) employed in oil and gas Exploration and Production drilling operations is to suspend and transport rock cuttings to the surface where the cuttings are separated from the mud and the fluid returned to the well hole. Oil based muds (OBM) are frequently employed because of the superior drilling performance achieved when compared with water based muds. For offshore operations under the current Oslo and Paris Commissions (OSPAR) legislation, rock cuttings bearing more than 1% oil-on-cuttings by weight cannot be discharged to sea. To date, technology cannot provide cost-effective, large volume cleaning offshore to these levels. Contaminated cuttings are therefore returned to shore uncleaned, for treatment and/or disposal. Operators, and their waste management contractors, are therefore faced with a considerable waste handling and disposal issue. Current estimates suggest of the order of 40,000 tonnes of OBM cuttings are produced in the UKCS annually. OBMs are essential in present practices for drilling certain sections of wells and in certain rock formations. ; therefore it is unlikely that they can be phased out entirely and re-injection of the waste down the well hole is only practical in some 25% of well developments. There are several onshore operations providing a facility for reducing the oil content of OBM cuttings. The most common treatment currently used in the UK is indirect thermal desorption. This process removes oil and water from cuttings and has two objectives; to bring the oil content under the Hazardous classification threshold, and to produce a more easily handled dry product.

Waste Management during the Production Drilling Stage in the Oil and Gas Sector: A Feasibility Study

“…However, several oil and gas companies worldwide opt for alternative technologies that, despite their high costs and the need to use innovations, exhibit a less adverse environmental impact [39][40][41]. In general, drilling-waste management options can be classified into various categories (Figure 4).…”

Towards enhancing sustainable reuse of pre-treated drill cuttings for construction purposes by near-infrared analysis: A review

“…This has prompted the need to look at other potential substitutes for these construction materials that are relatively cheap to obtain. As stated, pre-treated drill cuttings is increasingly becoming recognised as a potential substitute for cement in concrete (Chen, 2007), as aggregate in cold-mix asphalt for road pavement construction (Allen et al, 2007), and as fill material for road construction and fine aggregate in concrete production (IOGP, 2016). Chen et al (2007) used drill cuttings as partial substitute for cement in the manufacture of bricks and concrete for building construction.…”

“…However, the resulting concrete showed variable compressive strength and permeability and was sensitive to the mix design (Chen et al, 2007). Allen et al (2007) reported the use of drill cuttings as aggregate in cold-mix asphalt for road pavement construction. Initial constraints, which according to Allen et al (2007) were later overcome, were the high moisture and hydrocarbon contents of the drill cuttings (Table 1).…”

“…Allen et al (2007) reported the use of drill cuttings as aggregate in cold-mix asphalt for road pavement construction. Initial constraints, which according to Allen et al (2007) were later overcome, were the high moisture and hydrocarbon contents of the drill cuttings (Table 1). It should be pointed out at this point that detailed comparison of the possible management technologies for drill cuttings in terms of portability, relative cost, commercialization, environmental impacts, advantages, and constraints is well documented in the literatures.…”