Advanced Modeling of Interwell Fracturing Interference: An Eagle Ford Shale Oil Study - Refracturing

Abstract

This paper continues the investigation of interwell fracturing interference for an infill drilling scenario synthetic case based on Eagle Ford available public data and explores pressure and stress-sink mitigation strategies applied to the simulation cases developed in the previous publication (SPE 174902). Emphasis is given to refracturing scenarios, given the intrinsic restimulation value for depleted parent wells and the strategic importance due to the current low oil prices. The stress and pressure depletion methodology is expanded in this paper, adding a refracturing scenario before the infill child well is stimulated. Changes in stress magnitudes and azimuths caused by new and reactivated fractures are calculated using a finite element model (FEM). After refracturing the parent well, modeling shows that stress deflection and repressurization of the originally depleted production zone will reduce subsequent fracture hits from infill wells. The first mechanism to reduce fracture hits is the stress realignment, which promotes transverse fracture propagation from the infill well away from the parent well. The second fracture-hit-reduction mechanism is repressurization of depleted zones to hinder fracture propagation in lower-pressure zones. Prevention of fracture hits by active deflection results in an increased stimulated reservoir volume (SRV) for both the parent and child wells. Overall pad level and individual wellbore cumulative production experience a significant increase due to increased SRV. With proper reservoir and geomechanical data, this approach can be applied in a predictive manner to decrease fracture-hit risk and improve overall recovery. This workflow represents the first comprehensive multidisciplinary approach to coupling geomechanical, complex hydraulic fracture models, and multiwell production simulation models aimed towards understanding fracture-hit reduction using refracturing. The workflow presented can be applied to study and design an optimum refracturing job to prevent potentially catastrophic fracture hits during refracturing operations.

Parent Well Refracturing: Economic Safety Nets in an Uneconomic Market

“…By creating the pressure barrier around the parent well, the child well's created fracture network is more likely to extend into undepleted reservoir areas with higher remaining oil in place. This occurrence has been modelled and shown by Marongio-Porcu et al (2015) and Morales et al (2016).…”

“…Instead, the current production rates of the well tripled. Morales et al (2016) modeled the interwell fracture interference using a complex fracture modeling workflow for an Eagle Ford study. In this study, Morales et al found that refracturing the parent well before completing the new offset wells can not only increase the production of the existing parent well, but it can also increase the production potential of the new infill wells, as shown in Fig.…”

“…Many papers have been written discussing this occurrence and principles as to how fracture hits may happen (Diakhate et al 2015;Lindsay et al 2016;Malpani et al 2015;Marongio-Porcu et al 2015;Martinez et al 2012;Morales et al 2016;Roussel and Sharma 2010;Roussel and Sharma 2012). The depletion effects during the life of the original parent well create localized pressure sinks.…”

Modeling Interwell Fracture Interference and Huff-N-Puff Pressure Containment in Eagle Ford Using EDFM

“…This interwell communication can be portrayed as "pressure sinks" that interfere with induced fracture effectiveness, and might affect unconventional EOR methods efficacy if they are overridden or not accounted for. For instance, numerous documented studies have demonstrated fracture interference occurrence and assessed this phenomenon in unconventional reservoirs (Ambrose et al, 2011;Manchanda et al, 2013;Portis et al, 2013;Sardinha et al, 2014;Sani et al, 2015;Awada et al, 2016;Morales et al, 2016;Klenner et al, 2018;Seth et al, 2018;Yu and Sepehrnoori, 2018). The current interest is focused on warding off negative impacts caused by fracture hits interwell propagation and affecting further productive wells.…”

Well Performance Simulation and Parametric Study for Different Refracturing Scenarios in Shale Reservoir

“…As shown in Figure 11(b), the cumulative gas production of the well increases from 0.48 × 10 8 m 3 to 0.54 × 10 8 m 3 while the hydraulic fracture half-length increases from 70 m to 110 m. In addition, the reservoir pressure decreases slower with higher hydraulic fracture half-length, which is beneficial for long-time production, as shown in Figures 12 and 13. However, in refracturing, the fracture does not follow the same path of the initial fracture due to the change in stress anisotropy; it is not easy to obtain longer fracture length [14]. Figure 11: Effects of hydraulic fracture half-length on: (a) gas flow rate and (b) gas flow rate of refracturing through new perforation zones.…”