The goal of the project was to develop improved reverse osmosis (RO) membrane filtration technology for treating wastewater produced during oil and gas operations. Objectives included evaluation of a new pretreatment technology using combinations of liquid-liquid centrifuges, organoclay absorbents, and microfiltration and the evaluation and modification of different oil-resistant trans-membrane pressure and recycling ratios to permit optimization of a process design.

Texas Engineering Experiment Station, Texas A&M University, College Station, TX 
GeoPure Water Technologies, LLC, College Station, TX

Results 
The research program for this project has been completed. The goals of the project have been met. The technology transfer portion of the project will be satisfied through a commercialization partnership with a new oilfield service company. The desalination technology developed through the project has been licensed to GeoPure Water Technologies, LLC. GeoPure has commissioned a larger-scale mobile unit designed for delivery of 20 gallons per minute (gpm), or 18,800 gallons per day, to be used in field operations. A photograph of the unit is shown in Figure 1.

The unit has been on site in Johnson County, TX, for the past 2 months and has achieved satisfactory results in desalinating fracturing fluid flow-back brine recovered from Barnett Shale well completions.

The new system is capable of treating wastewater at the rate of 20 gpm and incorporates cartridge filters, microfiltration membranes, a dedicated hydrocarbon removal system, and reverse osmosis membranes. It is now being used to demonstrate the capabilities of the technology by processing sample batches of water for clients at the GeoPure test laboratory and by purifying produced water at clients’ field sites. In conjunction with the construction of a demonstration system, GeoPure also began a marketing program targeted to the Texas oil and gas industry, as well as groundwater users in west Texas. The marketing program includes papers given in industry conferences, such as the International Petroleum Environmental Conference and International Association of Drilling Contractors; a marketing booth; published articles; and company-dedicated marketing presentations.

As a result of this marketing effort, GeoPure is now working with over 30 clients in various stages of feasibility studies. GeoPure has also completed its first commercial oilfield wastewater treatment system in Texas. The system was installed at a location in Benbrook, TX, and is now processing over 200 gpm of feed water, consisting of a combination of fracturing fluid and mud pit slurry. GeoPure designed, constructed, and sold the treatment system to handle feed water where suspended solids have already been removed. The GeoPure system consists of a mechanical filtration step, microfiltration membranes, Mycelex hydrocarbon removal system, and RO membranes. It is equipped with monitoring and automatic shutoff controls for maximum performance and safety. While the 200 gpm system was being constructed, GeoPure deployed its 20 gpm demonstration system to serve as an interim fluid handling solution. A Texas A&M microfiltration system was added to increase the interim treatment capacity. The table below shows analysis of brine water treated in the field with the 20 gpm unit.

Starting in February 2007, GeoPure will begin a series of field tests for clients in Canada, Oregon, Wyoming, and Oklahoma to prove the capability of the treatment technology. The 20 gpm demonstration unit has been mounted in a travel-friendly container that can be shipped to locations without damaging components. The clients range from service companies to oil and gas operators, including a coalbed methane producer.

Benefits
The benefits of desalination of oilfield brine coming from well completions in the Barnet Shale are significant. Currently the Barnett Shale play is the most active drilling and production area in the Nation. More than 2,000 wells are planned for the 2007 year period, with the majority of the wells being drilled in populated areas. Massive hydraulic fracturing is used to stimulate horizontal wells, where many of the fracs are multi-stage and require as much as 5,000,000 gallons of fresh water. Competition for scarce fresh water has caused conflict among local citizenry, and anger is building toward operators.

Operating companies can utilize the Texas A&M technology offered by GeoPure Water Technologies to re-use frac brines and eliminate many of the environmental objections to drilling in populated areas.

Texas citizens need large volumes of water for agriculture and human use, and the diminishing water supply from the major aquifers supplying water has resulted in a search for additional water resources. Oil and gas development brings significant volumes of water to the surface. In Texas there are currently over 300,000 operating wells producing over 500 million gallons of water a day.

However, the produced water contains salts and minerals of sufficiently high content to require disposal or reinjection. In addition, before oilfield brine can be used for any beneficial purpose, it must be processed to remover residual petroleum material. The potential for reclaiming water from oil and gas produced waste streams for beneficial use in agriculture and commercial industry prompted research at Texas A&M University.

Summary
Experiments were done for the pretreatment of produced water using a new liquid-liquid centrifuge, organoclay, and microfiltration and ultrafiltration membranes for the removal of hydrocarbons from produced water. The results of these experiments show that hydrocarbons from produced water can be reduced from 200 ppm to below 29 ppm level. Experiments were also done to remove the dissolved solids (salts) from the pretreated produced water using desalination membranes. Produced water with up to 45,000 ppm total dissolved solids (TDS) can be treated to agricultural water quality standards having less than 500 ppm TDS.

Finally, an economic analysis, including capital and operational costs, was done to predict the water treatment costs. The cost of treating produced water containing 15,000 ppm TDS and 200 ppm hydrocarbons to obtain agricultural water quality with less than 200 ppm TDS and 2 ppm hydrocarbons is $0.50-1.50/bbl.

The contribution of fresh water resource from produced water will contribute enormously to the sustainable development of the communities where oil and gas is produced and fresh water is a scarce resource. This water can be used for many beneficial purposes, such as agriculture, horticulture, rangeland, and ecological restorations and other environmental and industrial applications.

The research effort represented by this project has been completed. All project tasks and activities have completed. A final report has been written, submitted and has been approved.. The program is described in two reports. Section 1 describes work to evaluate the technical and economical feasibility of treating produced water with a combination of different separation processes to obtain water of agricultural water quality standards.

Section 2 provides a comprehensive description of what is involved in the desalination of oilfield produced brine and the technical developments and regulatory changes needed to make the concept a commercial reality. It contains three sections related to “conventional” produced-water treatment: 1) the basics of produced-water management, 2) the potential for desalination of produced brine in order to make the resource more useful and available in areas of limited fresh water availability, and 3) the potential beneficial uses of produced water for other than oil production operations.

Funding
This project was selected under the Broad-Based Announcement Round 2, solicitation DE-PS26-02NT41613, in 2003.

$350,000 

$109,000 (24% of total)

NETL - Jesse Garcia (jesse.garcia@netl.doe.gov or 918-699-2036)
TEES - David Burnett (burnett@spindletop.tamu.edu or 979-845-2274)

Publications 
Barrufet, M., Burnett, D., and Mareth, B., Modeling and Operating of Oil Removal and Deslating Oilfield Brines and Modular Units, SPE 95647, SPE Annual Technical Conference and Exhibition, Dallas, TX, October 9-12, 2005.