Estimation of Propped Volume Permeability Using Strain from Geomechanical Modeling of Interacting Hydraulic and Natural Fractures - Application to the Eagle Ford

Abstract

A new workflow that uses the strain derived from geomechanical modeling of hydraulic fractures interacting with natural fractures is applied to an Eagle Ford well. The derived strain map is used to estimate the asymmetric half lengths that are input in any frac design software able to incorporate this new information. The simplistic symmetric and bi-wing design is revised by adjusting the leakoff coefficient, injection rate, and proppant concentration resulting in asymmetric half lengths that do not exceed the lengths of those provided by the strain map. Once the half lengths and orientation from the frac design match those provided by geomechanical simulation, the propped length and other key results provided by the frac design software may be used to optimize the well's completion. This process could be used iteratively to optimize desired metrics and could also be used to improve reservoir simulation. The derived strain map may be propagated in the stimulated geomechanical layer to form a strain volume which may in turn be used to estimate the stimulated permeability. In this paper, we used a radial function to relate the stimulated permeability to the strain within the maximum half lengths provided by the strain map. Two calibration constants are needed in the radial functions and could be estimated by history matching or pressure transient analysis. An adaptive Local Grid Refinement (LGR) and variable stimulated permeability provide a realistic representation of the stimulated reservoir volume (SRV). After history matching, the resulting pressure distribution allows an accurate selection of refrac or new well candidates, for optimizing well spacing, and for estimating an accurate EUR.

Estimation of Optimal Frac Design Parameters for Asymmetric Hydraulic Fractures as a Result of Interacting Hydraulic and Natural Fractures - Application to the Eagle Ford

“…Figure 1C shows strong asymmetricity detected in the microseismic events where better stimulation is observed towards the heel (stages 5-9), less effective stimulation in the middle (stages 3-4) and moderate stimulation towards the toe (stages 1-2). The workflow introduced by Ouenes et al (2015) started by initially reproducing the bi-wing frac design used by Diakhate et al (2015) and then generated asymmetric half lengths constrained by geomechanics using a commercial frac design simulator. They built the bi-wing fracture model using the gamma ray, resistivity, effective porosity and the total organic content (TOC) logs (Diakhate et al 2015).…”

“…Different cut-off values on the conductivity could be used when exporting the SRV and a preview of the expected depletion could be achieved as this stage since the use of a high cut-off value will lead to the best frac stages as seen in Figure 11A. This high cut-off scenario is the most realistic one since it has the same depletion characteristics shown in Ouenes et al (2015) reservoir simulation results where only the stages at the heel appear to have contributed to the depletion. The same observation was made by Diakhate et al (2015) when selecting their refracing candidates.…”

“…The same observation was made by Diakhate et al (2015) when selecting their refracing candidates. Both Ouenes et al (2015) and Diakhate et al (2015) used reservoir simulation to estimate the stages that contributed to depletion. In the workflow described in this paper, a similar conclusion could be reached quicker without the reservoir simulation step as shown in Figure 11A.…”

“…One method to estimate the stimulated permeability in the SRV is to couple geomechanical modeling of the interaction between hydraulic and natural fractures with hydraulic fracture mechanics commonly used to design frac jobs. This paper is an extension of the workflow first presented in Ouenes et al (2015), with the addition of a fast and improved frac design tool using geomechanical constraints and sensitivity analysis in order to optimize frac parameters and overall completion strategies.…”

Coupled Fluid-Solid Geomechanical Modeling of Multiple Hydraulic Fractures Interacting with Natural Fractures and the Resulting Proppant Distribution

“…Given the lack of understanding of the complex distribution of proppant, most of the efforts have been focused on estimating the resulting stimulated propped permeability. In the companion paper, Ouenes et al (2015c) describes one way this stimulated propped permeability is estimated from the geomechanical strain and used in frac design and reservoir simulation software. Yu et al (2015) used a proppant table in a reservoir simulator also to estimate indirectly this proppant distribution.…”