Modeling Parent/Child Effect Quantifies Infill-Well Effect on Child Performance

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 231225, “Modeling Parent/Child Effect in Vaca Muerta To Quantify the Impact of Infill Timing, Well Spacing, and Completion Design on Child Performance,” by Agustin Garbino, SPE, ResFrac, and Pavel Zuloaga and Gaston Mellado, Pluspetrol, et al. The paper has not been peer-reviewed. _ This work elaborates on recommended practices for calibrating a numerical model to a set of available infill-well field observations. The understanding of parent-/child-well effects plays a key role in defining the development strategy of shale plays. For this purpose, a commercial, fully coupled hydraulic fracturing, reservoir, and geomechanics simulator was used to model the area of interest. Results showed a strong dependence of child-well production losses on infill timing, well spacing, and completion design. Child-well estimated ultimate recovery (EUR) can range from 5 to 50% lower than parent wells within the ranges of well spacing, infill timing, and completion designs tested. Location and Field Diagnostics The area of study is La Calera, an unconventional gas condensate field with an area close to 230 km2. The studied site consists of a pad of three wells drilled and completed in 2020 next to another pad of three infill wells completed in 2022. All wells in each pad navigate different productive targets within the Vaca Muerta. A set of interwell-interference tests was conducted in these wells at different points in time, providing insights on the initial well communication and its development. The initial interference test was conducted in 2020 among the parent-pad wells during their initial flowback period, with Well P3 serving as the observation well with a downhole gauge installed. The test showed clear interference between P3 and its neighbors. Following approximately 2 years of production, the three parent wells were shut in. This shut-in period enabled a second interference test to be performed among the parent wells before childwell stimulation. Well P1 served as the monitoring well in this case, with a downhole gauge installed. The test showed no interference between the wells. Frac-hit events were recorded and quantified through wellhead-pressure measurements on the parent pad during the completion of the offset child wells. The results showed strong fracture-driven interactions (FDIs) between all the wells landed at the same bench, and interbench communication between Wells C2 and P1. After completion of the child-pad stimulation, a third interference test was performed among the parent wells to identify potential changes attributable to the stimulation in the child pad; however, the results of the pressure signature were inconclusive. Lastly, upon initial production startup of the child wells, a fourth interference test was conducted between the parent and child wells. Again, the pressure response in monitoring Well P1 is not overly clear, but a clear response is noted when Well C2 is opened, indicating some level of communication.