Holistic Drilling-Fluid and Waste Management in the Fayetteville Shale

Abstract

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 144036, ’Holistic Drilling-Fluid and Waste Management in the Fayetteville Shale,’ by Mark Mabile, SPE, and David Richardson, Southwestern Energy, and Steven Garner, Barry Broussard, and Richard Smith, SPE, Performance Fluid Management, prepared for the 2011 SPE North American Unconventional Gas Conference and Exhibition, The Woodlands, Texas, 14-16 June. The paper has not been peer reviewed. Successful application of a holistic-fluid-management (HFM) program from January 2009 through December 2010 improved drilling-fluid performance and reduced waste and costs in Southwestern Energy’s Fayetteville shale-gas project in Arkansas. The HFM program lowered drilling-waste volumes by approximately 45%, while reducing drilling-fluid and -waste costs by 36%. The reduction in combined costs (i.e., fluid systems, solids-control equipment, and waste disposal) totaled USD 69 million while drilling more than 4,200,000 ft in 705 wells with oil-based mud (OBM) during the 24-month study period. Introduction Like most shale-gas projects, the Fayetteville shale requires specific well-construction techniques. Most of the wells drilled during the project period were horizontal, with total measured depths of 8,000 to 9,000 ft with lateral sections approximately 4,500 ft long. On average, 15 rigs were active during 2010, each unit completing approximately 35 wells/yr. During this 24-month study, 1,000 wells were drilled for a total footage of more than 5,700,000 ft. Of these, 720 wells were drilled with oil-based mud (OBM) with a total footage of more than 4,200,000 ft. Fifteen anomalous wells that exhibited severe lost circulation or other problems were excluded from the study. The remaining 705 wells drilled with OBM are the subject of this paper. Various studies have shown the economic and environmental benefits gained by use of drilling-fluid-management programs for conventional oil and gas plays. Typically, before management programs were applied, procurement of drilling fluids and associated services accounted for 20 to 30% of the combined costs for overall fluid management, solids control, and waste disposal. Reductions in the quantities of chemicals and base fluids used and in waste generated at drilling sites can result in significant cost savings and a reduction in environmental effects. Drilling-Fluid-Management Considerations The solid- and liquid-waste streams produced in typical well construction can be grouped into five general categories—cuttings; drilling fluid on cuttings; drilling-fluid dilution, dumping, and tank bottoms; water; and other waste fluids. The aggregate volume of the generated waste typically is 10 to 15 times the overall volume of the hole drilled. The cuttings volume cannot be reduced, but all other waste streams can be reduced.