Accounting for variability in geology and reservoir parameters is one of the most challenging tasks for operators in the unconventional space. Add in pressure depletion effects from adjacent parent wells and the variability between nearby wells can reach up to 50%. Recent multi-disciplinary industry projects in the Eagle Ford shale and the Midland Basin have shown just how complex the fracture networks are that we create with hydraulic stimulation and how different they are from current fracture mechanics models used in the industry.
Microseismic monitoring has long been a tool to see how individual stages are treating in real-time but rarely ever were changes made on-the-fly. Most applications were limited to avoiding stimulating geo-hazards such as faults or unfavorable fracture sets to avoid fluid loss, casing failure, or communication with water- or H2S-bearing zones. Using MicroSeismic, Inc.’s proprietary Completions Engineering workflows the industry now has access to an effective tool to customize the treatment design for every stage in real-time to achieve optimum stimulation and recovery.
Identical treatment designs for every stage on a wellbore do not account for variability in geology or stress state along the lateral which can either reduce an operator’s capital efficiency due to overstimulation or leave resources behind. In order to make real-time adjustments of treatment parameters such as slurry rate, proppant concentration, or overall slurry volume, MicroSeismic, Inc. now provides drainage forecasts based on source mechanisms and the propped portion of the imaged Discrete Fracture Network (DFN) by utilizing a patent-pending Real-Time Drainage Visualizer.
The new visualizer includes a Production Potential Model (PPM) that provides insights into wellbore interference and identifies by-passed reservoir in real-time to facilitate changes to the treatment resulting in increased production and ultimate recovery. The PPM is a finite element fractal representation of the reservoir where each element inherits the production characteristics of the well that will produce from it. Flow characteristics are based on focal-mechanism-derived fractures in the DFN. Utilizing a fast-marching method to determine optimal flow paths and relative start times for each element, it identifies a pathway back to the wellbore. The PPM is designed to honor the supplied type curves for each well and show how that production is distributed throughout the reservoir volume to identify wellbore interference and by-passed resources.
The PPM has been validated against history-matched reservoir models to ensure accuracy when visualizing drainage volumes used to adjust treatment parameters on-the-fly to ensure the required drainage volume and ultimate recovery are met for a specific wellbore spacing. MicroSeismic, Inc. believes this will be of special importance in multi-target high-wellbore-density areas such as the Permian Basin where suboptimal development can lead to billions of dollars in destroyed resource potential. Image A in Figure 1 shows a case study for a target zone where overstimulation has destroyed NPV due to overstimulation. The propped fracture volumes shown in a gun-barrel view for eight wells severely overlap and will compete over the same volumes in long-term production. They exceed the required drainage volume for the given wellbore spacing and will show significant interference early in the production cycle. Image B shows a custom treatment design enabled by real-time monitoring. The Productive Stimulated Reservoir Volume (P-SRV) that contains the propped DFN is more appropriate for the wellbore spacing and avoids overspending and delays communication between wellbores for improved recovery.
Accounting for reservoir heterogeneity by enabling real-time adjustments to treatment parameters such as injected volume, pump rate, and proppant concentration can help improve capital efficiency especially for high wellbore density developments. Early field testing of the Real-Time Drainage Visualizer and the Production Potential Model show promising results that have been validated by numerical simulation. Customized treatment designs enabled by MicroSeismic, Inc.’s Real-Time Completions Evaluation workflows are the latest step in a fast-paced history of shale development innovations.
Figure 1: Gun-barrel view of Productive SRV for two eight well case studies. Image A shows overstimulation due to identical treatment design and lack of customization to reservoir parameters. Image B shows the result of real-time enabled adjustment of treatment parameters to meet specified drainage requirements for the given wellbore spacing.
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