Have you quit bashing your wells? That loaded question now features an unqualified “yes” as the answer to a vexing conundrum.

Bashing is the phenomenon in which frac­ture stimulating neighboring wells impacts production from legacy wellbores. The issue is rising in prominence as the industry pur­sues the Holy Grail of proper well spacing in developing an underground cube with mul­tiple laterals to extract the maximum hydro­carbon goody.

Bashing alludes indirectly to a rule of thumb that suggests the first well in a section is the best. Subsequent wells—child wells—seldom reach the parent well’s potential.

Essentially, producing wells create pres­sure sinks. Hydraulically stimulating new wells produce fracture networks that move toward the pressure void, creating inefficien­cies in reservoir development. Worse, fracture stimulating new wells can harm—bash—the subsequent production and reserve profile of the parent well.

Bashing is an unintended consequence of the industry’s tendency to drill a single well to capture acreage before returning two or three years later to drill new wells on the original pad. By then, the reservoir exhibits a substantial depletion zone.

Not all bashing is bad. In over-pressured areas, such as the Bakken or Haynesville, bashing increases production in some cases. However, wells in normally pressured reser­voirs, such as the Woodford or Niobrara, see a negative hit more than half the time. Fur­thermore, as plays mature in the developmen­tal arc, the ratio of new parent wells vs. new child wells erodes with child wells eventually exceeding 50% of reservoir penetration.

In September 2016, Denver independent Highlands Natural Resources Plc field tested a process that creates a temporary pressure blanket in a parent well that allows well stimulation to proceed in neighboring wells without harming production in the original well. The pilot took place in Colorado’s Piceance Basin in concert with Schlum­berger Ltd.

The pilot involved parallel infill comple­tions on a 33-well three-pad configuration using a control group that suffered produc­tion hits from bashing, a second group in which two parent wells used a completion technique, called Highlands’ DT Ultra­vert, pressure blanket to avoid bashing, and a third group in which two child wells applied the pressure blanket to enhance completions.

Wells that were previously bashed by offset fracks were protected by the pressure blanket during Highlands’ experiment, and production returned to the original decline curve without a “step down” from bashing. Additionally, the two new child wells that used a pressure blanket as part of stimula­tion outperformed 85% of peer wells on a 75-day flowback during fourth-quarter 2016.

DT Ultravert uses a non-formation-dam­aging gas to repressurize the parent well’s fracture network before stimulation crews inject the more expensive fracture slurry. The gas occupies smaller fissures and reduces friction, diverting the following slickwater slurry to virgin rock. A series of cyclical repressurizations continues the process along the well bore.

Of note, the combination of nitrogen and water may also inhibit clay swelling associated with water alone. Most diver­sion gas can be reclaimed. The technique works in a range of downhole temperatures and reduces refracture cost by eliminating the need to use the expensive frack slurry to refill existing fractures before diversion takes place.

Highlands has agreements with Schlum­berger and Calfrac Well Services Corp. to jointly market the technology. The Den­ver independent went public on the Lon­don Stock Exchange in early 2015 and acquired a majority stake in U.S-based Diversion Technologies LLC, the “DT” in DT Ultravert and its patent-pending diver­sion concept in May 2015. Highlands is also developing oil and gas properties in the Denver-Julesburg Basin via a Niobrara farm-in with a major international E&P, as well as in Montana.

September’s Piceance pilot has direct application to another oil and gas rule of thumb that says the best place to find new hydrocarbons is where the industry has found old hydrocarbons. Refracturing is a widely-discussed opportunity to do just that in the very best reservoirs by rejuvenating thousands of sub-optimally performing wells that were drilled early in the tight formation cycle using techniques that lack the sophistication of today’s completion recipes at cost reductions up to 80% of new well cost.

Overcoming bashing allows the indus­try to protect the original decline curve, increase repeatability in multi-well pro­grams and thwarts a looming threat to the reserve-based lending model that under­writes industry developmental programs.

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