Search for a command to run...
Almost a quarter century into the modern era of horizontal wells and multistage hydraulic fracturing, many questions remain about what actually happens in the deep subsurface when water and sand meet tight rock. Two of the biggest questions can be boiled down to this: What do hydraulic fractures really look like, and how are they really created? These mysteries were the focus of two technical papers presented at the recent SPE Hydraulic Fracturing Technology Conference (HFTC) in The Woodlands, Texas. One of them, SPE 230601, comes from a team of 10 researchers from academia, the private sector, and US government laboratories and presents what is believed to be the first documented field evidence of large-scale bedding-plane slippage induced by hydraulic fracturing operations in the US. SM Energy, which merged with Civitas Resources in 2025, hosted the study site in southwest Texas near the US-Mexico border. The $20-million project involved a highly instrumented pair of three-well pads that were part of the Austin Chalk/Eagle Ford Field Laboratory, which was partially funded by the US Department of Energy and led by researchers from Texas A&M University. The latest study on the data obtained from the test site is focused on a treatment-monitor well pair within one of the three-well pads that were stimulated between late 2021 and early 2022. The paper about what happened there stands out because it argues that a substantial fracture area was created through bedding-plane slippage of a soft layer of clay that is known to be present within the formation. This is well outside what most completions engineers plan for, because it is not only difficult to predict but can also lead to casing deformation or induced seismicity. But in this case, the outcome was oil and gas production from both wells that beat the operator’s typical type curves. The paper did not share production figures, leaving conference attendees without a clear sense of how strongly the wells ultimately performed. What the industry is told in the paper is that the above-average result “suggests that bedding planes and preexisting vertical fractures effectively connected wells to complex natural fracture networks, significantly increasing effective fracture surface area.” The authors continued, writing, “The shear motion of bedding plane shear and vertical natural fracture reactivation may preserve conductivity in the long term, which would significantly increase reservoir productivity.” Ge Jin, a geophysicist and associate professor at the Colorado School of Mines, is the lead author and presented the paper at HFTC in February. He said the case study represents an underdiscussed opportunity for operators to look for geological clues, such as large vertical natural fractures in seismic data, and optimize completions accordingly. He added that “this is not just one single case in that corner of the Eagle Ford; this could be a global problem, and when we start to deplete Tier 1 [reservoirs] and tap into more geologically complex Tier 2 assets, we may encounter more and more areas like this.”