干旱区生态环境知识资源中心

Surface disposal of spent drilling fluids used in petroleum and natural gas exploration causes surface soil contamination that severely inhibits secondary plant succession and artificial revegetation efforts. Selective-placement burial was evaluated at two locations in western Texas for on-site disposal of drilling fluids in arid and semiarid regions. Establishment, yield, and chemical composition of fourwing saltbush [Atriplex canescens (Pursh) Nutt.] and buffalograss [Buchloe dactyloides (Nutt.) Engelm.] transplants on undisturbed soils and on plots with spent drilling fluids and cuttings buried 30, 90 (with and without a 30-cm coarse limestone capillary barrier) and 150 cm were compared. Survival of both species was 97 to 100% 17 months after planting on plots with buried drilling wastes. Canopy cover and aboveground biomass of fourwing saltbush were greater over buried drilling wastes than on untreated plots, whereas canopy cover and aboveground biomass of buffalograss were not affected by the treatments. Significant increases in Na, K, and Mg concentrations in buffalograss after 17 months on plots with drilling fluids buried 30 cm deep at one location indicated plant uptake of some drilling fluid constituents. Elevated Zn concentrations in fourwing saltbush indicated that a portion of the Zn in the drilling fluids was available for plant uptake, while no evidence of plant accumulation of Ba, Cr, Cu, or Ni from drilling fluids was detected. Selective-placement burial of drilling fluids offers an environmentally sound technique that will enhance revegetation efforts.