Flowback Three-Phase Flowmeter Implementation for Post-Fracturing Cleanouts: A Case Study from Argentina

Unconventional horizontal wells completed with plug-and-perf fracturing techniques require coiled tubing (CT) to clean out the well before it is put into production. To remove proppant and plug debris, water is pumped into the wellbore and flowed back to the surface through the annular section between the CT and the production casing. This study describes implementation and impact of a three-phase flowmeter to measure the return rate and detect proppant and gas in real time. During CT post-fracturing cleanouts, fluid return rate is critical to monitor because the annular fluid velocity that carries solids out of the well is proportional to it. In addition, wells in Argentina must be kept in a near-balanced condition to avoid producing gas from the well. Fluid return rates used to be measured with an ultrasonic flowmeter, which experienced signal loss when there was more than 5% sand or gas in the fluid, making it unreliable for this workscope. A three-phase flowmeter was therefore implemented to achieve high-frequency and real-time measurements of water, proppant, and gas at the surface. Implementation of the three-phase flowmeter allowed cleanout optimizations without sacrificing operational safety. Having a precise and continuous measurement permitted the variation of the flowback choke strategy, increasing the return rate to a value closer to the pumping rate by 0.1 bbl/min without affecting the well balance condition. During the execution of the first four-well pad after this new flowmeter was implemented, analysis of the sand flow rate measurement showed that the wells were already clean when the CT had to be pulled out of hole (POOH) after reaching total depth, as only traces of sand were detected during this part of the operation. With this information, the job procedure was optimized by increasing the horizontal section POOH speed from 6 m/min to 12 m/min, if sand was not detected at surface. It also prevented pumping gel pills. This represented a 10% reduction in the total operating time per well and a 25% reduction in xanthan gel consumption in the next completed pad. This is the first time that a three-phase flowmeter has been implemented for post-fracturing cleanouts in Argentina Vaca Muerta operations. The increase in the precision of surface measurements means a more controlled cleanout strategy, during which flowback is evaluated in real time and the operational program can be optimized. Poor flowback control is a known contributing factor to stuck pipe incidents. This technology plays a critical role in addressing one of the major risks during CT operations.