API Publ 4758-2006 pdf free download

API Publ 4758-2006 pdf free download.Strategies for Addressing Salt Impacts of Produced Water Releases to Plants, Soil, and Groundwater.
Results of this modeling are combined with other site-specific information to determine the potential effects on groundwater. To use the Planning Model, perform the following steps: Step 1 : Estimate Mass of Chloride using volume and chloride concentration of a produced water release, OR Estimate Mass of Chloride using the area of produced water release (area of affected soil) and the chloride concentration of the soil (page 1 0) Step 2: Estimate Chloride Loading Rate to Groundwater using the Annual Precipitation, (page 1 1 ) Step 3A: Estimate Increase in Chloride Concentration in Groundwater at the Release Point using the width of the release area, (page 1 2) Step 3B: Refine the estimate from Step 3A using site-specific information (either the site location, or more detailed hydrogeologic info), (page 1 3) Step 4: (Optional) Estimate the Increase in Chloride Concentration in Groundwater at a Downgradient Point using the distance from the release area (and other parameters), (page 1 4) Key assumptions and limitations of the Planning Model include: 1 ) salts are mixed evenly throughout the soil; 2) the percentage of the rainfall that infiltrates through the soil to groundwater is proportional to the amount of rainfall; 3) the recharge rate is the 80 th percentile of recharge rates from data compiled from API Publication 4643; 4) almost all the salts in affected soils can be flushed out with 1 2 inches of recharge (from API 4663); 5) no capillary effects, evaporation, or other transport processes except advection, mixing, and dispersion in the saturated zone are present; 6) no density effects are assumed in transport of chloride in groundwater; 7) salt is mixed throughout the water-bearing unit; 8) a 2x safety factor is assumed; and 9) potential impacts only apply to the uppermost water-bearing unit, and NOT to deeper, regional aquifers. WBeneficial Uses of Groundwater If an increase in the chloride concentration in groundwater is known or estimated (i.e., by using the Planning Model, more sophisticated model, or sampling wells), the impact on the beneficial use of the groundwater can be determined. Beneficial uses MAY include: • drinking water supply; • industrial water supply; • irrigation or livestock water; and • discharge to surface water (aquatic life). The applicability of a given groundwater resource for these beneficial uses may depend, in part, on the concentrations of salt- related constituents, such as chloride and/or total dissolved solids (TDS). In the United States, groundwater is often regulated by the state governments on the basis of the use of the groundwater. Examples of beneficial uses are shown below: Industrial water quality requirements vary significantly, depending on the particular industry. For most industries, the acceptable concentrations of chloride and TDS are significantly higher than drinking water standards in most cases.
Produced Water Produced water refers to water from underground geologic formations that is brought to the surface (or “produced”) in the process of oil or natural gas production. This formation water has been in contact with the geologic strata for many thousands of years and, as a result, may contain elevated concentrations of natural minerals that have dissolved from the rock or soil. The resulting chemical composition of the produced water can vary from fresh to very saline, as follows (USGS): • Brine (total dissolved solids (TDS) greater than 35,000 mg/L (ppm)) • Highly saline (TDS between 10,000 and 35,000 mg/L) • Moderately saline (TDS between 3,000 and 10,000 mg/L) • Slightly saline (TDS between 1,000 and 3,000 mg/L) • Freshwater (TDS less than 1,000 mg/L) The E&P industry uses great care during the handling and disposal of produced water. However, unintentional releases do occur. How Does Produced Water Quality Vary Across The U.S.? This map from the U.S. Geological Survey (Breit and Otton, 2002) based on almost 60,000 produced water analyses taken across the country, shows the Total Dissolved Solids (TDS) content to vary significantly among the various oil and gas regions of the U.S. Such variations are explained by the age, geochemistry, and hydrology of the specific formation(s) from which the water comes.