Novel Thermal Distillation System for Purifying Produced Water Onsite Using Available Wellsite Gas

G. Katz
Katz Water Technologies,
United States

Keywords: produced water, water purification, waste energy, flare gas, heat exchangers, thermal distillation, oil & gas production, hydrocarbon production, natural gas, electrocoagulation, brine, drilling muds, environment, desalination, regulations


Produced water disposal is increasingly becoming an industry issue because of the well-known economic, environmental and societal issues associated with current disposal options. Recycling produced water for frack water reuse is increasing but can only address a small portion of the total amount of the produced water created. Meanwhile, the world is running out of natural fresh-water resources and most available technologies deployed to purify water to fresh water standards are expensive to build and operate. Reverse osmosis desalination and traditional thermal distillation require expensive equipment and substantial amounts of energy. There is a need to reduce equipment costs and operating costs including energy consumption when purifying produced water for fresh water reuse. A novel apparatus, method and system reduces the equipment and energy costs using thermal distillation. The patented technology performs the entire thermal distillation process including distillation and separation inside a heat exchanger to significantly increase energy efficiency. Standard industrial heat exchangers were internally modified to have a distillation column and alternative flow paths using baffles and tubing to distill and separate the purified water from the contaminates. Existing heat sources or waste energy such as, flare gas can be utilized to operate the modified heat exchangers without the need for additional equipment such as, flash chambers and separation devices. A small human-portable prototype with a maximum throughput of 100 barrels per day was tested on multiple samples including produced water. This standalone piece of equipment was able to remove over 98 percent of the contaminates in a single pass-through of less than 10 seconds. A high TDS sample was tested from Oman and reduced the TDS from over 150,000 TDS to less than 3,000 TDS making the treated produced water suitable for freshwater agricultural reuse. Laboratory testing showed combining this novel equipment with pre-treatment systems such as, electrocoagulation will create pure brine that can concentrated to specific densities including 10-pound (10 lb./gallon) and then be reused as a high-quality drilling mud. Heat energy at the wellsite can be recycled to make the process more efficient. Natural gas, worth billions of dollars, is wasted by being flared annually. This flared gas can be utilized to purify water using thermal distillation, vapor extraction, and condensation. This unique onsite approach solves three pressing problems faced by the oil and gas industry. These problems include gas flaring, produced water disposal and sourcing water for oilfield operations such as, hydraulic fracturing, drilling and water flooding. Multiple technical solutions to purify produced water using flare gas were addressed in designing and testing the equipment and proposed well-site systems. Regulatory constraints regarding flare gas, water usage and water disposal are likely to increase requiring new technology to efficiently solve these issues. This novel technology can address these regulatory concerns, significantly reduce produced water disposal costs and provide a renewable source of clean water from produced water.