Advanced separation technologies encourage on-site conversion of produced water into dischargeable or fresh water via distributed water processing and recycling (DWPR) system which involves oil removal and total solids (TS) removal units. Several combinations of such units can be designed according to the quality of the produced water and the desired results. In this work the results of oil removal and Total Dissolved Solid (TDS) removal parts of DWPR system are discussed in detail. Several laboratory tests were performed to evaluate a recently developed oil adsorbing product (Organoclay - PS12385). The results show appreciable removal of emulsified and soluble oil. Fast kinetics and high adsorption capacities were observed. Reverse Osmosis experiments were performed to determine the processing parameters for TDS removal. The results of combining oil adsorption and reverse osmosis process shows cost reduction in produced water handling and proves the DWPR system very effective in produced water management. The DWPR system can be advanced to develop applications such as; habitat and rangeland restoration, reservoir recharge, aquifer recharge and agriculture use. From oil and gas producer's point of view DWPR is able to convert produced water as a revenue generating source.
The composition of produced water is strongly fielddependent and includes a variety of inorganic and organic compounds. The produced water contains small amounts of emulsified oil, organic compounds including dissolved hydrocarbons, organic acids, phenols and traces of chemicals added in the during production, inorganic compounds, suspended solids, dissolved solids and natural low-radioactive elements.
The most popular option to handle the produced water is to re-inject it back into the formation. Produced water re-injection (PWRI) requires minimal or modified treatment before injection to obtain better results, but the injectivity decreases with time. Transportation of produced water from production to injection sites increases re-injection costs. Alternate option of disposal of produced water is costly (as high as $4/bbl) because of its makeup and because of the transport of large volumes, which must be handled and also have to face stringent environmental regulations1.
Oil field produced water has been an issue of concern for oil and gas producers. Approximately four million barrels of produced water is produced along with oil and gas per year in the state of Texas. In West Texas Coal Bed Methane (CBM) producing regions the fresh water is a scarcity and produced water is in excessive amount. If properly treated produced water can be a source of fresh water and can prove beneficiary to the society particularly in arid areas. Many efforts are being made to convert CBM produced water into usable water by EPA, DOE and other institutions.
Evans et al. 2 have discussed several produced water handling options and associated dangers. Disposal, re-injection and treatment of produced water are the available options. Produced water disposal requires meeting stringent environmental regulations and so requires proper treatment before the disposal. Mackay et al. 3 described risk involved in re-injection. Produced water re-injection requires skillful planning and treatment to meet the quality of re-injection water to avoid formation damage.