Properties Of Produced Water Research Articles

Effect of Clay Mineral Composition on Low-Salinity Water Flooding

Low-salinity water (LSW) flooding technology has obvious operational and economic advantages, so it is applied to practice in many oilfields. However, there are differences in the oil recovery efficiencies in different oilfields, the reasons for which need to be further studied and discussed. This paper studies the effect of different clay mineral compositions on low-salinity water flooding. For this purpose, three groups of core displacement experiments were designed with cores containing different clay mineral compositions for comparison. In the process of formation water and low-salinity water driving, the oil recovery and produced-water properties were measured. By comparing the two types of water flooding, it was found that the cores with the highest montmorillonite content had the best effect (5.7%) on low-salinity water flooding and the cores with the highest kaolinite content had the least effect (1.9%). This phenomenon is closely related to the difference in ion exchange capacity of the clay minerals. Moreover, after switching to low-salinity water flooding, the interfacial tension and wetting angle of the produced-water increased and the value of pH decreased, which are important mechanisms for enhancing oil recovery by low-salinity water flooding. This study reveals the influence of clay mineral composition on low-salinity water flooding and can provide more guidance for conventional and unconventional oilfield application of low-salinity water flooding technology.

Energy consumption in desalinating produced water from shale oil and gas extraction

On-site treatment and reuse is an increasingly preferred option for produced water management in unconventional oil and gas extraction. This paper analyzes and compares the energetics of several desalination technologies at the high salinities and diverse compositions commonly encountered in produced water from shale formations to guide technology selection and to inform further system development. Produced water properties are modeled using Pitzer's equations, and emphasis is placed on how these properties drive differences in system thermodynamics at salinities significantly above the oceanic range. Models of mechanical vapor compression, multi-effect distillation, forward osmosis, humidification–dehumidification, membrane distillation, and a hypothetical high pressure reverse osmosis system show that for a fixed brine salinity, evaporative system energetics tend to be less sensitive to changes in feed salinity. Consequently, second law efficiencies of evaporative systems tend to be higher when treating typical produced waters to near-saturation than when treating seawater. In addition, if realized for high-salinity produced waters, reverse osmosis has the potential to achieve very high efficiencies. The results suggest a different energetic paradigm in comparing membrane and evaporative systems for high salinity wastewater treatment than has been commonly accepted for lower salinity water.

Produced-Water-Volume Estimates and Management Practices

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 125999, ’Produced Water Volume Estimates and Management Practices,’ by J.A. Veil, SPE, and C.E. Clark, Argonne National Laboratory, originally prepared for the 2010 SPE International Conference on Health, Safety, and Environment in Oil and Gas Exploration and Production, Rio de Janeiro, 12-14 April. The paper has not been peer reviewed. Produced water is the largest byproduct associated with oil-and-gas production. Within the USA, nearly one million oil or gas wells are producing hydrocarbons with various volumes of produced water. In the past, several estimates of the annual volume of produced water have been made, but none were highly accurate, nor are they current. The full-length paper describes a study conducted for the US Department of Energy (DOE) to develop accurate estimates of produced-water volumes for 2007. Introduction Produced-water-volume generation and management in the USA are not well characterized at a national level. The DOE asked Argonne National Laboratory to compile data on produced water associated with oil-and-gas production. Produced water is water from underground formations that is brought to the surface during oil-or-gas production. Because the water has been in contact with hydrocarbon-bearing formations, it contains some of the chemicals from the formations and hydrocarbons. It may include water from the reservoir, water previously injected into the formation, and any chemicals added during the production processes. Characteristics of Produced Water The physical and chemical properties of produced water vary considerably, depending on the geographic location of the field, the geologic formation from which the water was produced, and the type of hydrocarbon product being produced. Produced-water properties and volume also vary throughout the lifetime of a reservoir. For those sites where waterflooding is conducted, the properties and volumes of the produced water may vary dramatically because of injection of additional water into the formation to increase hydrocarbon production. The major constituents of concern are salt content, oil and grease (various organic compounds associated with hydrocarbons in the formation), inorganic and organic compounds introduced as chemical additives to improve drilling and production operations, and naturally occurring radioactive material. Produced water from gas production has characteristics that differ from those of produced water from oil production. In addition to formation water, water produced from gas production will contain condensed water, which is water that was in the vapor phase while in the reservoir but condenses into a liquid state in the production/separation system. Produced water from coalbed-methane (CBM) production differs from produced water from both oil and gas production. Oil and grease are less of a concern with CBM water than with other produced waters. To recover the methane in CBM reservoirs, the hydrostatic pressure that caused the adsorption of methane to the coal-bed is reduced through the removal of water from the reservoir through CBM wells. Characteristics of CBM water that may affect reuse are salinity, sodicity, and (to a lesser extent) iron, manganese, and boron.