Flowback Processing: Past and Future

In the past, flowback extracted from wells after hydraulic fracturing has typically been stored in either open air pits or temporary storage tanks to await treatment, where it vents a large quantity of natural gas and other VOC's into the atmosphere. This venting often results in the loss of around 10,800 Mcf of natural gas (~$76,000 at $7 per Mcf) into the atmosphere. Previous attempts to capture this methane have been largely fruitless, as the sand present in the flow back would chew through the steel pipes or clog the machine altogether, and the high volume of flowback would not allow time enough for particulates to settle out of the flowback.

However, work-overs and completions of new natural gas wells have recently begun employing the REC (reduced emission completion) technique. This technique employs a series of sand traps, separators, dehydrators, and condensers in order to extract methane and other liquid hydrocarbons from the flowback mixture. The sand trap unsurprisingly removes sand and other particulates from the flow back, and uses water reclaimed from the separator system to flush captured sand into either a storage tank or evaporation pool. From the sand trap, flowback is sent to the separator, which reclaims up to 89% of natural gas and other hydrocarbons from the mixture. From there, gaseous components are sent to a dehydrator and then pumped into the supply line, while liquid hydrocarbons are sent to a condenser and then stored in barrels for shipment to a fuel processing plant.

All in all, the combination of reclaimed gas and liquid fuels may exceed $100,000 in worth depending on current fuel prices and the well, but the initial $500,000 price tag and maintenance costs for the REC machinery are prohibitive to many oil and gas companies.

It is our hope that the development of bacteria with the capability to convert methane to methanol will create a new avenue of REC technology. Given that the VOC's contained in flowback are 95% methane, the conversion of methane to methanol may eliminate the need for the gas extraction component of REC without considerable loss of product. Increases in methanol concentration will increase the yield of condensates in the flowback, and the removal of gas processing components will decrease the capital costs of REC technology, potentially making REC economically viable for thousands of additional gas wells across the US and abroad.