POTASSIUM SILICATE DRILLING FLUID AS A LAND RECLAMATION AMENDMENT

Abstract

Drilling fluid, also referred to as drilling mud, is used to lubricate and cool the drilling apparatus, transport drill cuttings to the surface and seal off porous geologic formations. Disposal of drilling fluid is a growing concern to the global oil and gas industry as it can require extensive waste management and result in significant land disturbance. The oil and gas industry has developed potassium silicate drilling fluids (PSDF), a relatively new advanced chemical gel drilling fluid system, to reduce sodium concentrations, which are considered to have a detrimental environmental impact. Hypothetically, high concentrations of potassium in PSDF could serve as a nutrient amendment for land reclamation, thus not only would land disposal be practical, but also provide benefits for reclamation. Environmental impacts associated with PSDF disposal are unclear. Before guidelines can be developed and modified, it is necessary to assess the intensity of disturbance on soil-plant-water systems by disposal of PSDF from land based operations. In this study, responses of soils of three textures, two plant species and leachate were studied when raw, spent once and spent twice PSDF were incorporated or sprayed at six rates with and without fertilizer. Raw and spent PSDF had no detrimental effects on soil, vegetation and water at rates ≤ 60 m3 ha-1. Addition of PSDF to soil generally resulted in positive changes to soil physical, chemical and microbiological properties and enhanced plant establishment, development and yield. Slightly acidic and medium textured soils with inorganic fertilizer benefitted most by addition of PSDF. Both an agricultural crop, barley (Hordeum vulgare L.), and a native grass, slender wheat grass (Agropyron trachycaulum (Link) Malte ex H.F. Lewis) survived and developed through physiological growth stages. Constituents in PSDF significantly increased soil potassium concentrations, reduced hydraulic conductivity, stimulated populations of the microbial community and increased their diversity. Incorporating PSDF into soil provided greater benefits for vegetation than spraying it, increasing soil water content and macronutrients. Effects of PSDF recycling times on vegetation varied.