Effective Drilling-Waste Management Reduces Well-Construction Costs

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 96775, "Drilling-Waste Management: Case Histories Demonstrate That Effective Drilling-Waste Management Can Reduce Overall Well-Construction Costs," by K. Browning, SPE, and S. Seaton, SPE, Halliburton Fluid Systems, prepared for the 2005 SPE Annual Technical Conference and Exhibition, Dallas, 9–12 October. The increasing amount of environmental legislation affecting drilling operations has resulted in a rapid increase in drilling-waste-management spending. While traditional perception is that this increased spending adds to well-construction costs, many technologies now available are cost-effective when the entire well-construction cost is evaluated. The full-length paper reviews deployment of both new and traditional drilling-waste-management technologies and demonstrates that correct application of these technologies can result in a reduction in well-construction costs. Introduction Although there are other waste products attributable to drilling operations, most waste-reduction efforts focus on drill cuttings and excess or spent drilling fluids as well as the treatment and/or disposal of these waste products in compliance with governing regulations for the area of operation. All costs associated with treatment and disposal usually are considered part of the overall well-construction costs. Evidence from the case histories presented demonstrates that appropriate waste management and technology applications actually can reduce rather than increase well-construction costs. Time Line Until the 1980s, there was little or no drilling-waste management as we know it today. In offshore operations, cuttings and excess fluid typically were discharged overboard and spread on the lease sites or buried in land operations. There was little, if any, legislation regarding disposal of these materials. Discharge and land spreading were low-cost solutions that allowed the operator to remain in compliance with existing regulations. Consequently, the actual amount of waste generated and subsequently disposed of was of little consequence to the operator or service company. New Regulations. In the 1980s and early 1990s, because of increased global awareness and understanding of environmental issues, the effects of drilling operations and in particular drilling waste became a subject of interest to operators, service companies, and regulators. Early regulations typically restricted what could be disposed of by setting limits on oil or chloride content or the location of disposal sites. The fluid types used also came under closer scrutiny, and fluid and cuttings toxicity was evaluated and regulated. Costs. The new regulations inevitably affected well-construction costs. Fluid selection and cuttings treatment and disposal incurred a cost increase associated with meeting new regulations. The quantity of waste generated received increased attention, and source reduction became one of the pillars of waste management. The initial cost of switching to less-toxic additives, such as switching from diesel to a mineral oil, or reducing oil-on-cuttings by improving solids-control performance or using cuttings fixation or other simple waste-management techniques available at the time, still represented a very small percentage of the total fluids costs and an even smaller percentage of total well-construction costs.