Lyle D. Burns
Salt contamination of soil is a serious environmental issue facing the oil and gas industry today according to many Stripper Well Operators and Regulators. Salts, particularly sodium chloride, from produced water spills and leaks can completely devastate surrounding vegetation. Remediating sodium-affected soils is a time consuming, frequently ineffective and an expensive process. Dig and haul as a means of disposal is an expensive operation and carries with it a Superfund risk potential. Today, there is much more emphasis on operating in an environmentally conscious manner. The problem lacks a suitable solution with the benefits of being rapid, simple, economical, and dependable.
The sodium ion is detrimental due to its toxic effect on plants and devastation to soil. The chemical change brought about is an ion exchange reaction where the calcium and magnesium in clays are exchanged for sodium. This reaction causes the clay particles to swell, reduces the soil pore space and the water permeability of the soil making it difficult to purge or flush the sodium from the plant root area. In effect, the soil becomes dense and highly erodible. The traditional gypsum fix is usually insufficient to promote grass growth in soils that have been badly damaged by produced water spills. Gypsum solves only part of the problem and because of its low water solubility, a lengthy time is required to exchange the calcium for sodium on the clay particles.
The proposed “Soil Amendment Product For Oil Field Brine Contaminated Soil” (2008 Stripper Well Consortium (SWC)) technology was demonstrated in the laboratory and two field tests in 2008-2010 to remediate salt damaged soils. The soil amendment product has a multi-basic component that would assist the calcium amendment by 1) Tying up excess sodium in the clays from the root area, 2) Providing organic material to the soil, 3) Assist in rejuvenation of the bacterial population, and 4) Participate in nutrient transport into the plant. This component was used with a highly soluble calcium amendment rather than gypsum, allowing for rapid remediation of the soil. The product also binds heavy metal contamination and absorbs low levels of light hydrocarbon contamination. The technology requires tilling the soil, adding the amendment components with fertilizer, followed by re-tilling and water or rainfall to complete the remediation procedure. Usually within about four weeks, the grass seed may be planted with additional water/rainfall and grass germination will occur.
The first successful SWC project addressed a suitable solution with the benefits of being rapid and economical. This proposed project addresses the benefits of simple and dependable. Additional field tests will be performed for verification (dependable) and the necessary activities required to simplify (simple) the soil amendment product(s) for successful commercialization will be performed. No two salt contamination areas are likely to be exactly the same. But there are certain generalizations that may be made to simplify the remediation recommendation for application by the customer or service provider such that a “rocket scientist” is not needed for guidance. To perform the remediation correctly requires the customer or service provider to obtain minimal laboratory analysis for the sodium, potassium, calcium, magnesium concentrations and a soil pH measurement. In this proposal, 1) Correlations with the laboratory analysis and the soil treatment equations will be made, 2) The number of products must be minimized, and 3) Treatment application rates will be derived that include most of the saline and/or sodic contaminated soils encountered. These three issues will be summarized succinctly for the customer to understand how to have the best chance of a successful remediation by following simple instructions.