Water-Matching of Fracturing Water Predictably Boosts Early-Time Unconventional Production
Geoffrey Thyne_
Over the past 2 decades, unconventional development has focused on incremental gains largely from well-spacing strategies, completion chemistry, landing-depth selection, and extended laterals. Even so, there remain significant variances in production outcomes, including among wells drilled and completed with near-identical designs in comparable rock qualities.
Less attention has been paid to the influence of the compatibility of fracturing water. However, in recent years, extensive laboratory testing has helped researchers better understand how matching the injected frac water to a formation’s wettability, defined as being preferably oil-wet, water-wet, or neutral, may significantly increase initial production while also reducing produced water volumes.
Adjusting wettability, ideally to neutral, involves matching the formation-water salinity (i.e., total salt content).
This case study presents a procedure in which the operator compared production from wells with adjusted wettability to a control group, finding that the adjustments resulted in significant improvements in production and reductions in produced water.
A Challenge in New Mexico
In 2022, Silverback, a then-active private equity-backed producer in New Mexico’s Yeso formation, had been using fresh water for its hydraulic fracturing fluid. Two factors were prompting the operator to re-evaluate its methods.
One was that new regulations in New Mexico were restricting access to fresh water. The other was that the company’s production from early wells did not meet investor expectations. Additionally, some wells produced only water for up to their first 2 months, meaning their initial production (IP) was limited.
The company sought a way to re-evaluate its frac fluids to boost economics, both by improving initial and ongoing production and by reducing use of fresh water.
Field-Testing Procedure
The producer decided to divide the next round of new wells into two groups. The control group, consisting of 10 wells, would be fractured with fresh water, exactly as before. The test group’s eight wells’ wettability would be tested against a laboratory-researched database to determine if adjusting the frac water to match that wettability would improve initial and ongoing production.
The first round, evaluating the test wells for salinity-altering candidacy, showed that they would indeed be good candidates for adjusting wettability. An internal study based on client results shows this has been effective in about 70% of wells, and this testing has been shown to accurately evaluate which wells are good candidates.
At that point, more detailed tests were run based on oil and water samples collected from nearby wells, along with cuttings from an existing well.
Within weeks, the results came in, showing that produced water salinity and total dissolved solids (TDS) ranged from 100,000 to 120,000 ppm, compared with freshwater levels, which are a small fraction of that. The tests also showed that basing the fracturing fluid on produced water from other wells in the field would be the best first step.