Together at Last: Geomechanics, Hydraulic Fracturing and Flow Simulation in a Fully Integrated Model
Ridgeway Kite has built on its extensive experience in reservoir simulation solver techniques, and coupled this with the latest massively parallel computing systems to develop the 6X simulator.
Simulate multi-well pads and many fracture stages through completion, interference, and depletion in one lifecycle model.
Capture mixed tensile and shear failure, fracture branching, and complexity by evolving both modes within coupled geomechanics and flow—not tensile-only simplifications.
Resolve stress shadowing across wells and stages by coupling geomechanics with the full stress tensor, not mean stress alone.
Evaluate re-fracture and infill programs to improve drainage and mitigate asymmetric fracture growth.
Represent naturally fractured and multi-scale pore systems in unconventional rocks with dual- or N-porosity formulations that resolve matrix–fracture transfer and fluid exchange.
Extend unconventional models into gas-based EOR such as huff-and-puff to forecast incremental recovery.
Apply stress-dependent permeability, net-stress tables, and hysteresis as fractures open, propped, and close.
Track proppant and gel/breaker tracers to capture viscosity, placement, and conductivity in hydraulic fractures.
Build foam models with dynamic scripting and surfactant tracers to limit gas mobility in fractures and improve conformance.
Simulate full huff-and-puff cycles to tune soak times, rates, and gas composition for incremental oil.
Tie unconventional wells and fractures to surface gathering and facilities so forecasts honor routing, pressures, and operational constraints across the system.
Drive uncertainty quantification and development choices with integrated multiple-realization workflows, experimental design, and side-by-side deterministic cases.
Automate pad- and field-scale unconventional studies with scripting scenarios, custom physics hooks, QC, and repeatable reporting.
Manage spacing and timing while limiting fracture driven interactions between infill and parent wells.
Operators are focused on multi-well infill pad development programs to develop drill spacing units (DSUs) using fiscal discipline to generate free cash flow. Infill well design, spacing and timing become critical. Infill wells are impacted by the parent well pressure depletion and the associated change in the stress magnitude in the depleted drainage area.
Infill wells drilled offset to parent wells have experienced slurry loss during treatment due to fracture-to-fracture interactions between the infill and parent well hydraulic fractures. The change in stress magnitude leads to asymmetric fracture growth from the infill well into the depleted region of rock around the parent well.
These effects typically impair the performance of the infill well. Fracture driven interactions (FDIs) that lead to proppant reaching the parent well are detrimental, eroding pad production efficiency and value.
6X has the unique ability to model the changes in saturations, pressure and net mean stress simultaneously in one model. This capability can be used to optimize an infill well pad development program for multiple benches for a DSU. 6X captures the fracture driven interactions as the change in net mean stress is modeled through the infill well treatments and the depletion phase. The model dynamically captures the fracture opening; the propping at the end of the treatment; the compression of the fracture pore volume during depletion; and the loss of fracture conductivity with reservoir depletion. Stochastic multiple realization sensitivities can be performed using a single 6X license to assess the impact of treatment design on FDIs; the infill well count; spacing; the infill well timing; zippering and the impact of different operating strategies to understand and optimize the economic return on investment or net present value.
Use 6X to optimize your infill well completion from stage treatment to multi-well pad optimization.
Manage spacing and timing while limiting fracture driven interactions between infill and parent wells.
Model the effect of well and stage spacing on the induced stress field using the full stress tensor.
Stress shadowing occurs when the induced stress field from the hydraulic fracturing of one stage influences subsequent stages. For this to occur the stages need to be sufficiently close for the induced stress field to propagate to the next stage. The closer the stages the more pronounced the effect is likely to be.
To model stress shadowing the simulator needs to include a geomechanics model. It turns out that this model should solve at least for the normal stress tensor components, rather than just the hydrostatic mean stress. The 6X Simulator has this capability.
The simplest geomechanics model in 6X solves only for the average of the normal stress tensor components (the mean stress). Using this model for a single well study with close stage spacing we see no stress shadowing effect. The figure below shows the dynamic permeability induced by the fracturing of 8 consecutive stages. Clearly, each stage shows the same pattern of SRV generation regardless of the stress field generated by the previous stages.
To understand why this happens we plot the mean stress field along the path of the well just before the start of injection into stage 2.
The plot shows that the mean stress (red) is simply a multiple of the fracture pressure (blue) and matrix pressure (green). Since neither of these properties have significant values at the location of the second stage (dotted blue) there will be no stress shadowing effect modeled.
6X also has a more advanced geomechanics model, which can solve for each individual component of the stress tensor and use these values to predict the rock breakage in more detail. Using this model and plotting the normal stress tensor components along the well trajectory before the start of stage 2 we see an interesting effect.
The individual normal stress components are non-zero at the location of the next stage, despite the fact that they sum to zero, giving zero mean stress. Consequently we can expect stress shadowing effects when taking account of these components. The plot below shows the dynamic permeability, which clearly shows the influence of the stress field on subsequent stages.
Optimize Re-fracture Design to Maximize Drainage and Avoid Asymmetric Fractures.
Re-fracturing a well has two primary benefits: (i) Providing incremental production from a well with an early generation completion by re-fracturing with tighter cluster spacing; (ii) Elevating stress and pressure prior to fracturing an adjacent infill well to prevent EUR loss due to asymmetric fracture growth.
6X uniquely incorporates the stress change from fracture creation and reservoir depletion in one model. The simulator models the stress increase and decrease of the initial completion execution and subsequent depletion; Also, the stress increase of the re-fracture and infill well completions followed by the stress decrease as the wells deplete.
With the Implicit Stress Solution, the above model shows virgin pressure between the original clusters. [The rock must be hydraulically re-fractured to produce.]
Assess and optimize your refracture design to improve well performance, model stress changes and design adjacent infill wells to avoid asymmetrical fractures and maximize reservoir drainage. Validate historical stress and well performance to assess new re-fracture opportunities using cemented or an expandable liner combined with extreme limited entry. Evaluate improved cluster efficiency to increase well EUR and maximize drainage.
In a recently published field test by an operator, 6X confirmed that incremental oil production increased by 32% over a 6-month forecast after re-fracturing a well.
6X models the unique physics of unconventional reservoirs including multi-porosity systems and vapor-liquid equilibrium.
Multi Porosity 6X has multi-porosity capabilities, in which different porosity systems (e.g. fractures, kerogen, sandstone) can be arbitrarily connected in a hierarchical model. They can be connected directly, in serial, or more generally as seen in the image above.
The presence of high capillary forces in very small pores in unconventional reservoirs results in suppression of the bubble point pressure. To correctly model this, 6X solves the vapor-liquid equilibrium problem consistent with capillary pressures to make this correction.
Optimizing EOR Through Cyclic Gas Injection in Unconventional Reservoirs.
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Advanced fracture mechanics modeling including stress-dependent permeabilities, gels and proppants, and rock compaction.
Fracturing events are captured in 6X using regional tables of permeability modifiers versus net stress, which are applied dynamically to modify the reservoir flows. The table modifiers are either applied directly, or conditionally using a Mohr-Coulomb model and an input stress field. Several hysteresis models are also available to model the closing of fractures.
In addition, special consideration is given to the effects on well PIs and flows between different porosity systems, and provision is made to model background effects in nearby zones with transmissibility compressibilities.
The 6X simulator has a tracer capability in which extra fluid components are carried around with the reservoir fluids, but which do not on their own affect the flow solution. They can be used as markers, to trace the flow of injected or initially in-place fluids through the reservoir throughout a simulation run.
6X uses the tracer facility in unconventionals for modeling the effects on flow of gels and proppants. Gels and gel breaker properties can be specified and their combined effect on fluid viscosity modulated. Proppant density can also be accounted for, with special consideration given to the prevention of ingress into non-fracture matrix, and to the differential flow of proppant in a fluid due to the effects of gravity.
Rock compaction models include a standard rock compressibility input, or tables of compressibility versus net stress, including hysteresis effects.
Sizing Your Treatment To Maximize Well Economics.
Proppant selection, proppant concentration and the pump schedule are key design parameters for well hydraulic fracture treatments.
In recent years, in attempting to increase production, operators have increased the proppant concentration and the fluid volume pumped. Fracturing fluids have evolved from gel-fracs to slickwater fracs, recently with high-viscosity friction reducers (HVFR) and operators are pumping cheaper regional sand in order to reduce costs.
6X uniquely incorporates fracture creation and reservoir depletion in one model. It can model production forecast sensitivities over a range of proppant concentrations for economic evaluation and design optimization.
Proppant selection, proppant concentration and the pump schedule are key design parameters for well hydraulic fracture treatments.
In recent years, in attempting to increase production, operators have increased the proppant concentration and the fluid volume pumped. Fracturing fluids have evolved from gel-fracs to slickwater fracs, recently with high-viscosity friction reducers (HVFR) and operators are pumping cheaper regional sand in order to reduce costs.
6X uniquely incorporates fracture creation and reservoir depletion in one model. It can model production forecast sensitivities over a range of proppant concentrations for economic evaluation and design optimization.
Control gas mobility and conformance in fractured rock with surfactant foam and custom kinetic models.
In EOR foam can be particularly useful in highly fractured reservoirs such as in unconventional and tight oil fields. Here the primary challenge is to maintain gas within the target formation and prevent it from escaping into adjacent wells.
Without conformance improvement techniques, the gas might simply rush through the high conductivity fractures, channels, or weakness planes in the reservoir.
Foam is created by injecting a mix of water and surfactant into the reservoir. Surfactants decrease surface tension, enabling gas to be encapsulated in water-based films, thus generating foam. The foam then decreases the mobility of the gas by increasing its viscosity.
Traditional simulator foam models use empirical methods to represent surfactant-induced foam generation, selecting certain variables while leaving others out.
6X enables dynamic scripting, which allows for the creation of custom foam models that incorporate userderived data and insights.
6X employs tracers to simulate the transport of surfactants, carried by the aqueous or liquid phases.
Custom foam models in 6X can be used in simulating the entire life-span of foam in a reservoir, including its
generation, stability, and collapse.
Variables such as surfactant concentration, foam quality, velocities, pressure, saturation of phases, and temperature effects are all taken into account.
The models also simulate the time decay of foam effectiveness and collapse, and the adsorption of surfactant into the rock as a function of surface area.
For this type of foam modeling it is essential to utilize multi-well models to account for connectivity among the wells. 6X is fully equipped to integrate these models into its simulations.
The following figures display gas saturation within the fractures, filtered to highlight only the middle part of the reservoir. Gas is injected from the right side of the wells and subsequently migrates to the left side. In the second figure, the introduction of a surfactant has effectively limited the spread of gas.
Model cyclic gas injection with soak and production periods to optimize cycle design in unconventionals.
The hydraulic fracturing of wells in unconventional reservoirs has resulted in high initial oil production. However the decline rates are very high with low recovery factors. Recently, Enhanced Oil Recovery (EOR) through cyclic gas injection (huff & puff) has increased recovery factors in the Eagle Ford and is being investigated for use in other shale basins.
When planning an EOR campaign, or when analysing the early results from a well/pilot, a reservoir simulator (together with a model of the subsurface) is the only tool available to predict the production and the economics of the project.
6X has been successfully used in many EOR projects, for example see the 2021 URTeC paper: 5649 A Simulation Study to Evaluate Operational Parameter Ranges for a Successful Cyclic Gas Injection in Different Areas of Eagle Ford by M. Gaddipati, B. Basbug, T. Firincioglu of NITEC LLC.
Tie unconventional forecasts to surface gathering and facility constraints using integrated network modeling.
Fully integrated Multiple Realizations capability - integral to every decision.
Quantification of uncertainty can be difficult and time consuming. Subsurface uncertainty exists from intrinsic geological complexity. A desire to quantify development options drives the successful application of Multiple Realizations; a pragmatic approach to optimize performance and maximize recovery from oil and gas reservoirs. It has successfully been applied from development appraisal stage projects to mature field projects and has increased project net present value.
6X provides integrated functionality to create automated workflows performing hundreds of runs to quantify uncertainty in the following:
Many decisions are required to optimize recovery and economics from an unconventional well program. How many stages, how many clusters per stage, how much fluid and proppant to pump; how to determine the optimal well spacing and how many wells are required to develop a multi-bench drill spacing unit (DSU). A 6X Multiple Realization modeling workflow generates a range of outcomes to understand the hydraulic fracture growth and depletion to optimize EUR against net present value for a DSU.1
The MR functionality exploits modern massively parallel architecture of 6X and runs on multi-CPU and multi-GPU systems. With the breakthrough and general availability of Cloud systems, clients can access 6X on Amazon AWS, Microsoft Azure and Google GCP.
Extend 6X with scripting for bespoke physics, batch runs, and automated reporting.
Discover how 6X transforms unconventional reservoir challenges into opportunities. These real-world applications demonstrate how integrated geomechanics and flow simulation enable smarter development decisions from initial drilling through enhanced recovery.
Determine optimal lateral spacing and cluster placement to maximize reservoir contact while minimizing fracture-driven interactions. 6X models the full stress field changes during multi-well development, helping you balance capital efficiency with EUR optimization across your DSU.
Calibrate models through parent well history matching, then optimize child well completion designs for maximum ROI. Test stage spacing, perforation cluster designs, proppant concentrations, and fluid volumes to find the economic sweet spot for your asset.
Model the pressure depletion and stress changes from parent wells to design infill programs that avoid asymmetric fracture growth and EUR degradation. Optimize the sequencing and timing of infill wells to maximize value while managing fracture-driven interactions.
Evaluate re-fracture opportunities to restore production or prepare wells for adjacent infill development. 6X's integrated geomechanical modeling captures how depletion and stress changes affect re-fracture geometry, enabling you to design treatments that maximize incremental recovery.
Plan the complete development sequence across multiple benches within your drilling spacing unit. Model the interaction between benches, optimize stacking order, and determine the timing that delivers the best economic outcome while managing subsurface complexity.
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Assess enhanced oil recovery opportunities through gas injection processes. Model the complete cycle from injection through soaking to production, accounting for compositional effects and pressure changes unique to unconventional reservoirs.
Design complete pad development programs from first spud to final completion. Optimize the drilling and completion sequence, manage stress shadowing across the pad, and forecast production under various development scenarios to maximize NPV.
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Leverage integrated multiple realizations to quantify subsurface uncertainty and generate probabilistic forecasts. Run hundreds of sensitivities across geological parameters, completion designs, and operational variables to support confident decision-making.
Conventional and Unconventional Simulator with Fully Integrated Geomechanics
Conventional and Unconventional reservoirs — from structurally simple to geologically complex — can be modeled with 6X in Black Oil or Compositional mode.
For Unconventional reservoirs, 6X models the life cycle of multi-well DSU; from the fracturing of the first well through to the end of production of the last well. The model accounts for fracture generation, closure and well interference.
6X is a single model used for both the hydraulic fracturing and depletion periods. Incorporating the physics for the dynamic geomechanical stress change, the model captures the impact of infill wells on parent wells enabling the user to match observed data and evaluate different development scenarios including:
The modern design of 6X delivers consistent results across all platforms whether running on multi-CPU, multi-GPU or Cloud systems.
Unlike traditional workflows that require multiple software packages, 6X integrates geomechanics, hydraulic fracturing, and flow simulation in a single model.
Built on massively parallel architecture, 6X delivers simulation speeds that enable multiple realizations and comprehensive sensitivity analysis.
6X captures stress-dependent permeabilities, proppant transport and settling, and the interaction between propped and unpropped fracture networks.
6X helps you deploy capital where it generates the highest returns while avoiding value-destroying well interactions.
Operators have achieved 32% production increases through optimized re-fracture designs, improved EUR through better infill well spacing, and reduced completion costs through stage count optimization.
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6X's extensible architecture supports CPUs, GPUs, and cloud deployment, scaling seamlessly from single-well analysis to full-field development planning .
Built on decades of reservoir simulation expertise and validated through real-world field applications, 6X delivers results you can trust. The integrated approach has been proven across major unconventional plays.
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The fully integrated Multiple Realizations module (included with every license) enables automated workflows for assisted history matching, experimental design, and probabilistic forecasting.
See how 6X can help optimize your unconventional reservoir development workflows
Stay updated with Ridgeway Kite’s latest technology bulletins, case studies, and event highlights featuring the 6X simulator.
Geomechanics in 6X: why mean-stress-only models miss stress shadowing between stages, and how the full stress tensor captures stage-to-stage effects on SRV.
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Enhanced geothermal systems (EGS) in 6X: HDR, fracture mechanics, implicit energy equation, and workflow. From EGSModeling.pdf.
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URTEC 2023 triple porosity modelling with 6X. DOI and full paper access via Datapages, SEG, or OnePetro.
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