|Membrane Technology for Produced Water at Lea County, NM
||Last Reviewed 10/19/2011
The goal of this project is to develop a new micro-filter technology application, based on forward osmosis/bio-desalination, to allow desalinated produced water to offset fresh water consumption by the potash industry and other industries and demonstrate the economic feasibility of this technology in a 1000 gallon/day pilot-scale process. A secondary goal (if total cleanup is not possible) is to determine the level at which produced water cleanup can be realized and at what cost.
Lea County Government, Lovington, NM 88260
New Mexico Institute of Mining & Technology, Socorro, NM 87801
Currently, southeastern New Mexico (SENM) produces in the range of 400 million barrels of produced water/year, with total dissolved solids (TDS) ~ 200,000 ppm, which requires economical and acceptable treatment or disposal. Disposal is most often accomplished by transporting the produced water to disposal ponds at a cost of around $1.2 billion/year with an estimated 0.3 million barrels of transportation fuel used to transport the water. New Mexico ranks first among U.S. states in potash production. More than 85% of all potash produced nationally comes from the Carlsbad potash district in SENM. Potash manufacturing processes use large quantities of brine solution. During manufacturing, a large quantity (50 ton/hr) of water escapes into the environment from the system through evaporation. This loss is replenished with fresh water at a cost of ~ $1.65 million/year.
There is currently an active research program funded by a grant from the Office of Naval Research (ONR) to develop a pilot plant to treat produced water in Lea County. The objective is to find an economical solution to treat large volumes of produced water. Once treated, the water will be used as a part of the replenished component of the make-up water. The proposed 24-month work plan is partly based on discovery driven scientific methodology with very sound economic expectations. Most of the earlier developed treatment technologies were meant for treating water with much less TDS. Seawater, with TDS in the range of 30,000 ppm, is the highest salinity that researchers have dealt with. The current project will adopt a hybrid system that will incorporate a number of pre-treatment units preceding a Forward Osmosis (FO) treatment unit. One group of investigators collected information pertaining to the regulatory requirements for various discharges of produced water; the other group has begun to perform tests leading to the investigation of different treatment processes.
Southeastern New Mexico (SENM) produces around 400 million barrels of produced water per year as a by-product of oil and gas production. Water production volumes have been increasing every year. Ninety percent of this water is injected into deep wells for secondary recovery, pressure maintenance, or disposal purposes. Some of this water is re-injected directly and some is sent via pipeline to tanks or handling facilities. Disposal costs are estimated to be $1.2 billion per year and an estimated 300,000 barrels of fuel is used to transport the produced water to disposal site. All parties involved in the production, transportation, sale, and regulation of oil in SENM were interested in having a better system to provide easy and timely access to produced-water information. NMT is attempting to cost-effectively clean produced water and make it useable for a number of applications.
Because fresh water makes up a large percentage of the water used by the oil and gas industry, the most beneficial outcome would be to treat and make it suitable for addition back to the general fresh water supply as a source of clean water. In addition New Mexico ranks first among US states in potash production, which uses large quantities of water. The need for water has now become even greater in New Mexico as a hugh deposit of potash has been discovered in the extreme southeastern corner of New Mexico, and it is estimated that the potash will be mined for more than 50 years and require 8 million gallons of water per day.
Following successful laboratory tests, the Forward Osmosis (FO) process developed at NMT was implemented in a 1000 gallon/day pilot-scale process to determine its effectiveness. The NMT FO desalination pilot plant (batch mode) was assembled inside a 30 foot long triple-axel trailer. The FO system consists of a feed water unit, membrane modules, a draw solution unit, and a recovery unit. The NMT system was transported to a site near Jal, New Mexico for field demonstrations. The NMT unit was integrated on-site with a pretreatment process provided by Aquastream (AS) to remove the petroleum-based solids and dissolved solids from the produced water before the water enters the cell membrane filtration process.
In September 2010, both the pretreatment and FO processes were proven effective in the field test in Jal, NM. Produced water from two different sites was processed through the integrated system. Chemical analysis was performed on all four water samples prior to their being used in the integrated system. During the testing process, samples were collected at three different stages—before the pretreatment process, after the pretreatment process/ prior to FO treatment, and at the end of treatment—in the process. These samples were tested to determine the effectiveness of both pretreatment and FO processes. Results showed that the FO process removed around two gallons of water from the feed solution in one hour. This is equivalent to a flux of 27.5 liters per meter square of membrane per hour, twice the highest value reported by the membrane manufacturer.
The field demonstration also identified a number of measures for improvement of the NMT pilot process. Laboratory tests on a sample collected from the draw tank after the FO process determined that it had been contaminated by chlorides (57,000 ppm) from the liner of the mixing tank. This was caused by a chemical reaction between either the epoxies or glues binding the membrane to the tank or tank liner materials. To eliminate the reaction, the draw solution tanks and connecting pipes were changed to stainless steel to ensure that there would not be any chloride or other chemical contamination resultant from the system materials. Following the replacement of the draw mixing tank and piping, a test was performed at NMT using another produced water sample which verified that no chlorides or chemicals leached into the water from the new tank materials
The project initially involved the serial enrichment of bacterial cultures to remediate oil. Cultures were assessed based on the qualitative measurement of oil removal. When the cultures were first inoculated they contained a large amount of dark oil and had low turbidity (a measure of bacterial growth in a solution). As the culture degraded the oil, the growth medium became less dark and more turbid. When this change occurred the culture was used as the inoculum for the next culture in the serial enrichment.
Results from the field tests indicate that there is nothing inherent in the design of the newly developed system that precludes scaling to a larger device. In addition, a preliminary economic analysis demonstrated that a well –designed FO process will outperform an RO process for feed solutions having a dissolved contaminant concentration greater than 10,000 ppm.
Due to the importance of finding additional water sources for an ever-expanding population in the southwest U.S., it is felt that a commercial system can be built to clean produced water and offset industrial water use. Lea County plans to continue efforts to obtain funding to build a commercial plant to treat the produced water for use by the potash industry.
Current Status (October 2011)
The project has been completed and the final report is listed below under "Additional Information”.
Project Start: October 1, 2008
Project End: September 30, 2011
DOE Contribution: $1,432,000
Performer Contribution: $358,000
NETL - Gary Covatch (Gary.Covatch@netl.doe.gov or 304-285-4589)
Lea County Government - Cecilia Nelson (firstname.lastname@example.org or 575-396-8609)
New Mexico Institute of Mining & Technology - Ashok Ghosh (email@example.com 575-835-5505)
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Final Project Report [PDF-3.92MB]