_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper URTeC 4034948, “Effective Fracture-Geometry Analysis Based on Data of Well Production, Pressure Gauge, and Strain Change of HFTS-1, Phase III, in Eagle Ford Shale, ” by Fatima Almarzoog and Kan Wu, Texas A&M University, and Ge Jin, Colorado School of Mines. The paper has not been peer reviewed. _ The objective of the complete paper is to apply a developed workflow to determine the propped hydraulic fracture geometry in a horizontal multistage fractured well, incorporating production, pressure, and strain data. The essential feature of the workflow is the integration of offset monitoring well data. The model is validated with data from the US Department of Energy (DOE) Hydraulic Fracture Test Site-I, Phase III (HFTS-I, Phase-III), in the Eagle Ford shale. Introduction The objective of Phase III is to improve the recovery of the Zgabay-A field through liner refracturing of two producing wells (3H and 5H) and drilling of three infill wells (11H, 12H, and 13H). The test site included drilling of a monitoring well, 14H, that acquired extensive diagnostic data sets during preload, refracturing, infill-well stimulation, and production interference. Because of limited surface spacing, the infill wells and monitoring well were drilled from south to north, opposite to the direction of the parent wells. Pressure depletion and in-situ stress changes found near the parent-well fracture network system will result in newly stimulated hydraulic fractures of refrac and infill wells preferentially propagating toward these areas of lower pressure, causing fracture hits. Repressurization, also referred to as preloading, involves temporarily increasing the reservoir pressure close to the parent-well fractures. This increase in pressure induces a poroelastic stress increase in the reservoir rock near the parent-well fractures. This stress increase creates a high-stress barrier that helps prevent child-well fractures from hitting the parent-well fractures. Well Data This paper models and analyzes data collected from Well 4H, where water was injected during 1 day. The well is positioned 400 ft away from refracturing Wells 3H and 5H. Because the wells were drilled in opposite directions, the toe of Well 14H aligns with the heel of Well 4H. The distance between Wells 4H and 14H is 235 ft. The monitoring well is equipped with nine downhole external (reservoir) pressure gauges. Approximately 10, 000 bbl of water was injected into Well 4H while pressure was monitored in Well 14H. The preload started on 5 January 2022 and continued until the next day. Initially, a gradual increase in the injection rate was noted before the well was shut in, followed by minor fluctuations until the rate stabilized at an average of 6 bbl/min. Seventy percent of the water volume injected into Well 4H was below the estimated fracture gradient. At the low injection rate of 6 bbl/min, offset-pressure measurements from the six valid gauges remained moderately stable and unchanged. After approximately 19 hours, the water-injection rate was increased to 16 bbl/min for approximately 3 hours. Initial observations showed that, at higher injection rates, a pressure-peak response was observed at Gauges 1, 2, and 4, primarily located at the toe of Well 14H, which aligns with the heel of Well 4H. These responses were interpreted as fracture dilation. Pressure falloff occurred immediately after injections stopped.
Chris Carpenter (Sat,) studied this question.