APPLICATION OF DRILLING FLUID AND PRODUCED WATER TO A SOIL SURFACE CAUSING ALTERATION OF SOIL CHEMICAL PROPERTIES

Rotary drilling for oil and natural gas uses drilling fluid for lubrication of the bit, to seal off unstable shale layers, and floating out rock cuttings. Drilling fluid is a water-clay chemical mixture. Land farming of these drilling fluids is a common disposal technique of drilling fluids and produced water. In the land farming process, amendments of fluid are repeatedly applied to the soil surface. Plant yields and soil properties may be adversely affected by amendments of drilling fluids, because of the alkalinity, salinity, trace elements, and petroleum residue contents of these wastes. The objective of this study was determine the influence of land application of drilling fluids on soil chemical properties through soil pH, electrical conductivity (EC), total nitrogen and carbon, and extractable nutrient content. This study will help to give a better understanding of practical ways to landfarm drilling fluid and produced water in a fashion that both minimizes environmental issues and also is economically feasible. Salinity change to soil were expected to be high, because there are excessive amounts of sodium and chloride in spent drilling fluid. The study was a comparison of three plots with similar soil properties and conditions. The three study plots had various levels of drilling fluid application ranging from one previous application (Field 1), a medium application (Field 2), and a high application rate (Field 3). Exact application levels and dates are unknown, as records were not available for all fields. The data show a major difference from field-to-field for EC and salts. The EC and salt levels increased with additional applications of drilling fluid. Field 1 had the lowest levels; Field 3 had the highest. The high values in Field 3 were expected because the data from drilling mud sampled had an EC of 6.42 dS/m. The percent total nitrogen values and soil test P levels were very low in all fields. High EC and salt values, coupled with low N and P levels, are detrimental to plant growth and development.