Once considered a by-product, STW’s water reuse technology is transforming oil field waste water into a sustainable, new water source that can often be used many times over—dramatically reducing the strain on our precious water resources.
Oil & Gas Fields
Hydraulic Fracturing
Click image for larger viewThere are multiple fracture systems in the pressure pumping market. All of the systems utilize fresh water for their make-up and are typically the highest volume fluid. Proppant (Sand) and a polymer system are utilized. The polymer portion of the system is to provide viscosity or thixotropic characteristics (similar to paint) to carry the proppant into the reservoir. These systems are pumped at very high pressure and in some cases very rapid rates. This hydraulic horsepower actually cracks or fractures the gas or oil bearing zone and the fracture fluids enter the zone. The proppant is carried far back into the zone. Once the fracture is completed the pressure drops and the zone settles down on the proppant but does not close. The viscosity or thickness of the fluid dissipates and the water flows back to the surface over time. The proppant left behind provides a fracture or a path with a very low permeability for the gas and oil to flow to the well bore. Carbon dioxide or nitrogen energized fluids are also utilized for wells with low bottom hole pressure to prevent fluid loss.
A new fracture system was developed for the Barnett Shale that is somewhat different than the system discussed above. It is called a “slick water” fracture system and requires much more water. It has proven to be the most cost effective system to date in the Barnett Shale and is being expanded into Haynesville, Marcellus, Woodruff, Pieance, and Fayetteville Shales. Shortages or water has already surfaced in most of the Shale areas. Fresh water is utilized in a low cost but very effective “slick water” package. The system is basically a friction reducer so that high rates of water can be pumped into the well to hydraulically fracture the shale. Proppant or sand is utilized to hold the fracture open after the hydraulic pressure is removed. This allows the gas or oil to flow out of the zone and into the well. Fresh water has proven to be a benefit in the shales due to it dissolving out water soluble salts that were deposited with the shale. Dissolving these salts provides additional paths for the gas to flow through out of the shale or connections of the natural fractures. So massive volumes of fresh water are essential to these shale plays, the slick water fracture provides the most cost effective production over time.
Hydraulic fracturing water issue of using millions of gallon as of fresh water to frac the wells only to have the water returned during the production phase of the well as a highly contaminated un-useable water that needs to be reclaimed or disposed of in disposal wells. By distilling water with TDS (total dissolved solids) of 100,000+ parts per million (ppm) about 70% of the water can be recovered as a fresh water actually superior in quality to the water originally utilized. The water usage for drilling and fracing the active wells in the Barnett Shale area equates to annual average water usage for at least 185,000 households. Utilizing the Brine Concentrator atrates of up to 2,000 gal/min or 68,000 barrels of water per day, the process returns approximately 70% as distilled reuseable water. STW will utilize this technology using the Brine Concentrator/Evaporator with the capacity of 500 gal/min or 17,142 barrels per day. This equipment is modular and can be relocated to other locations. This will help alleviate a large portion of the frac flowback water problem. The disposal of the flowback water is of great concern. The drilling and fracing process pollutes the millions of gallons of water used at each drill site with at least 26 chemicals including carcinogens such as benzene. Currently most of that water is hauled away to be injected into deep disposal wells. There is concern that, if done improperly, this highly polluted water will migrate into existing aquifers, reducing the supply of ground water in Texas.
Gas drilling requires a massive number of trucks to haul equipment and water to and from drilling sites. The oil and gas industry recognizes a need to reclaim the water minimizing the wear and tear on the roads and other impact on the environment. In reclaiming the water a major effect on the environment will be realized through the Oil and Gas Industry proactivity.
By utilizing the GE Brine Concentrator/Evaporator Technology, STW will be a major factor in helping to secure adequate fresh water supplies for the future and helping to reduce the amount of polluting truck traffic on the roads.
STW will utilize the GE technologies to reclaim approximately 70% of the returning water out of these shale wells so that it can re-use in the next well or even returned back to the environment. The volume of water going to disposal will be significantly reduced. Even the disposal volume can be reduced but it is significantly more expensive and a solid salt is generated. This “salt” is a mixture of inorganic salts and requires a use.
For more information, view our GE Technical Presentation
Click image for larger viewProduced Water
More than 250 billion gallons of produced water are taken out of Texas soil every year, 35% of which is unfit for use. (1) Texas is the nation’s largest oil and gas producer with greater than 216,000 active oil and gas wells. The state has more than 50,000 permitted oil and gas injection and disposal wells which service approximately 6 billion barrels of produced water each year. Water placed in disposal wells is lost forever. The same opportunities are available in every gas and oil producing state and country in the world.
The Shale zones are typically dry reservoirs without any formation or connate water, therefore the fracture water is what returns except for having the dissolved salts discussed earlier and contaminated with the gas and hydrocarbons. In most gas and oil production, there is a reservoir or connate water in the zone. The water quality or total dissolved solids varies significantly in different parts of the world. In a large number of the oil fields in the USA, secondary or tertiary such as water floods and steam floods have been initiated. These are operations where water is utilized to maintain reservoir pressure, prevent subsidence, and sweep the zone to remove the oil from the zone. Most of these floods utilized a fresh water source as a supply water so that sufficient volumes are available. As these fields age, less water is required for the flood and so excess contaminated brines require disposal. This water could be reclaimed with the correct technology.
Produced water is mainly salty water trapped in the reservoir rock and brought up along with oil and/or gas during production, and is the most common oil field waste. In the year 2000, over 2 billion barrels of salt water in Texas were carefully disposed according to Texas Railroad Commission regulations. If just 10% of this amount were converted to fresh water, Texas would recover approximately 8.4 billion gallons (25,780 acre feet) of water annually and the potential benefits could be significant, with the treated reclaimed water available for many uses, including many agricultural and environmental applications, as well as re-use in hydraulic fracturing operations.
STW will utilize the GE technologies to reclaim approximately 70% of the returning water out of these shale wells so that it can re-use in the next well or even returned back to the environment. The volume of water going to disposal will be significantly reduced. Even the disposal volume can be reduced but it is significantly more expensive and a solid salt is generated. This “salt” is a mixture of inorganic salts and requires a use.
For more information, view our GE Technical Presentation
Brackish Water / Salt Water
Waste Water Effluent / Grey
By 2050, the population of Texas is predicted to double and the water demand is expected to increase 18% (3 million acre-feet/year increase) according to the Texas Water Development Board. Gulf Coast aquifers (Eocene-aged Wilcox to Pleistocene Chicot Formations) contain a large volume of brackish water (less than 10,000 ppm TDS) that may be feasible for desalinization to help meet the increasing demand. Several factors facilitate (or force) the use of brackish water for water supply, including decreasing supplies of fresh ground water and surface water, improvements in treatment technology, increased competition for surface water resources, and changes in population/demand centers.
STW has access to the technologies & equipment necessary to process these different contaminated waters and they are our target businesses that will be implemented in the future.
Source: Brackish Water Resources of the Gulf Coast Aquifers in Texas
Beach, James A., Kreitler, Charles W., and Klemt, William B.
LBG-Guyton Associates, Austin, TX