DE-10ER85357

Goal
The project goal is to further develop a proprietary, high-temperature nanofiltration (NF) technology (Duraflux^TM) to remove salt and other dissolved solids from produced water originating from domestic oil and gas production. Treated water can be re-used in the extraction process without cooling/re-heating costs or can be recycled as an acceptable supply of source water. Project objectives are to (1) scale-up the fabrication process to create full-length tubular membranes; (2) perform long-term tests on processed water samples to demonstrate salt rejection, stability after multiple cleaning cycles, and stability under harsh temperature/dissolved solid exposure; and (3) develop a membrane filter plant reference design model and cost structure.

Performers
Eltron Research and Development Inc., Boulder, CO

Background
Methods of produced water treatment vary by location in chemical makeup, volume, regulatory requirements, soil characteristics, and access to off-site disposal or deep well injection. Treatment costs are a combined sum of costs broken down into primary treatment, secondary treatment, pre- and post-treatment requirements, operating costs, and byproduct disposal (oil and grease, brine, solids). Primary treatment of produced water from traditional oil and gas production typically uses a variety of physical separation methods to strip gas, volatiles, suspended oil, grease, and solids from the water. Secondary treatment often requires pretreatment steps to protect secondary treatment systems, such as reducing water temperature; removing dissolved organics, fine particulate and precipitated iron oxides; adding antiscalants or water softeners; and adjusting pH and calcium.

Impact
The recovery of oil and natural gas in the United States, especially from unconventional sources, is often limited by economic and environmental impacts of water co-produced during the extraction process. Innovative and cost-effective produced water treatment methods are needed to improve the economic viability of unconventional reserves, particularly for removing salts and organic contaminants to meet regulatory quality standards for surface discharge.

The fastest growing source of produced water originates from capture of hydrocarbons from coalbed methane and shale gas reserves. Economic and environmentally responsible treatment methods will increase gas yields and provide freshwater resources for beneficial uses in arid regions while reducing environmental impacts in others. Cost-effective recycling of boiler feed water used for steam injection will reduce freshwater consumption and disposal costs. Duraflux™ technology also provides the ability to treat the produced water at high temperature, which will reduce the energy required to re-heat the water.

Accomplishments
Membranes were delivered to AQWATEC for high temperature and pressure testing. The membranes were tested with a 2000 ppm MgSO₄ feed solution at three different temperatures and pressures. Two membranes showed higher MgSO₄ rejection and less change in performance after high temperature exposure. Membranes were prepared on the ceramic substrate and MgSO₄ rejection ranged from 14% to 64%.

Membranes were deposited using the polymer formulation from Phase I studies, and MgSO₄ rejection averaged 20%. Optimizing the polymer deposition conditions resulted in membranes with MgSO₄ rejection of up to 60%. Membrane creation will continue in order to confirm reproducibility, and synthesis parameters will be adjusted to improve salt rejection results.

Eight polymer coated tubes were tested for permeation flux and salt rejection. Salt rejection for these membranes ranged from 3% to 5% whereas Phase I membranes achieved 30% rejection. Flat membranes were tested with SEM and FTIR and results show that the plates may not be sufficiently coated.

Current Status (May 2012)
Phase II membranes have reached >60 percent MgSO₄ rejection in reproducible trials. The membranes are now being optimized for NaCl rejection. Scale-up to full membranes will begin once MgSO₄ rejection is >80 percent and NaCl rejection is near 50 percent.

Eltron has requested a 12-month no-cost extension in order to improve the performance of the ceramic tubular substrates.

Project Start: August 15, 2010
Project End: August 14, 2012

DOE Contribution: $1,000,000
Performer Contribution: $0

Contact Information:
NETL - Sandra McSurdy (sandra.mcsurdy@netl.doe.gov or 412-386-4533)
Eltron Research & Development Inc.- David Peterson (dpeterson@eltronresearch.com or 303-440-8008)