About Sensor

The World's Fastest And Most Robust Full-Physics Reservoir Simulator

Sensor is a generalized 3D numerical model used by engineers to optimize oil and gas recovery processes through simulation of compositional and black oil fluid flow in single porosity, dual porosity, and dual permeability petroleum reservoirs.  Sensor reservoir modeling software provides unparalleled results in terms of speed, accuracy, stability, reliability, and ease of use.  It runs in a fraction of the cpu time required by other reservoir simulators,  for both black oil and compositional fluid pvt descriptions, enabling unprecedented levels of detail and accuracy in your studies, and allowing you to make much better and faster decisions.  The Sensor reservoir simulator has been used in numerous field studies by consultants and by independent, national, and major integrated oil companies.  Sensor is compiled for use on older and on the latest and fastest Windows 32- and 64-bit desktop PCs.  A free evaluation version can be downloaded, along with data sets, mapping and plotting tools, and documentation.  Integrated interfaces and tools for static modeling, data preparation, job submission, pre/post processing and visualization, assisted history matching and optimization, and complete seismic-to-simulation workflows are offered by third parties.

Do you have a reservoir model that won't run, or that runs too slowly?

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Packaged workflows requiring the use of an inadequate component or an inefficient bottleneck have little or no relative value.  Choosing or assembling workflows with links to best-of-breed applications will vastly improve productivity with negligible investment.

What is a real breakthrough?  Demonstrable step change and substantiated claims.

If you are interested in upscaling and in some amazing and previously unpublished Tenth SPE Comparative Solution Project (SPE10) Model 2 results, see our SPE10 page.

Others still claim "unprecedented speed", but offer no evidence.  See our  Benchmarks.  You can download and run them.  They are not even close.  See our Who's Fastest? page for comparisons of published results for the black oil case from the Ninth SPE Comparative Solution Project (SPE9).

If your compositional model isn't running in Sensor, it isn't running, it's just wasting time.

Get over 2 orders of magnitude speedup in compositional first-contact miscible cases.  Usually 5 to 10x in other compositional cases.  See our Miscible page for an example published by a competitor that shows their compositional model (Eclipse 300 AIM) essentially doesn't run, compared to Sensor.

What are the implications of 64 bit technology, advanced workflows, and very fast serial simulation to Reservoir Management?  They are huge.  These tools offer a massively scalable step change in the number of variables that we can consider, and in the speed and reliability of our predictions.  The key to improving applications ranging from reserves estimation to global optimization is serial speed in simultaneous computing.  See our  Parallel? page.

Simulator Development can't be treated as a project, if you want to be successful.

  It's an occupation of continuous and iterative improvement.  It's our business.

Experience has a cumulative and exponential effect on value and capability of developed solution that increases in importance with increasing problem complexity.  Reservoir Simulation is one of the most complex software applications in existence.  Our people have been developing successive generations of commercial reservoir simulators with continuous success and improvement for the last 40 years, since Dr. Keith H. Coats created the commercial reservoir simulation industry when he founded Intercomp Resource Development and Engineering in 1968.  See our Why Sensor? page.

Animation courtesy of JOA Oil & Gas BV, from Jewel Suite^TM

System for Efficient Numerical Simulation of Oil Recovery

Formulations and Solvers

Sensor includes Impes and Implicit formulations.  Its three linear solvers are reduced bandwidth direct (D4), Orthomin preconditioned by Nested Factorization, and Orthomin preconditioned by ILU with red-black and residual constraint options.

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Gridding

Any grid type or combination of grid types may be used with Sensor.  First is the conventional, seven point orthogonal Cartesian xyz grid.  Second is the r-theta-z cylindrical coordinate system.  Third is any grid -e.g. corner-point, refined, unstructured, or hybrid - for which input values of pore volume, transmissibilities, and depth are available from a grid package.  Since the matrix is represented in unstructured form in Sensor's linear solvers, Sensor handles unstructured and other cases with large numbers of non-standard connections much better than some other models with structured matrix representations.  The nine-point option can be used in xy planes with the Cartesian grid to reduce grid orientation effects.  The model handles faults with non-neighbor connections and provides angular closure in the case of cylindrical coordinates when the angular increments sum to 360 degrees.  See our Q&A p. 2 for more discussion of refined, unstructured, and hybrid grids.

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Black Oil PVT

The black oil pvt includes oil in the gas phase (the r_s stb/scf term), and therefore applies to gas condensate and volatile black oil problems. A foamy oil option of black oil treats the first portion of released or injected gas saturation as entrained or emulsified gas which flows with the oleic phase. The black oil pvt table can be re-entered in Recurrent Data at various times to reflect changes in surface processing at the time of the re-entry.  Black oil tables can be internally generated from input compositional descriptions.

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Compositional PVT

Sensor uses the Peng-Robinson and Soave-Redlich-Kwong equations of state (eos), with optional shift factors and any number of components.  Eos parameters may differ for reservoir and surface separation conditions.  A number of options are provided for automatic simplification of compositional eos descriptions that can significantly improve run performance and user productivity.  These options make it easy for the user to determine the required degree of complexity in the fluid characterization.

In cases where only depletion is present, with or without water injection, K-values internally generated from the eos can be used to reduce run cpu times.  In other cases, when using the IMPES formulation, the tracer option can be used in combination with the K-value option in order to revert to the more rigorous eos when injected gas tracer fractions are detected.  Surface separation may be performed using a multi-stage flash or using separator liquid recovery factor tables to simulate both the separator train and a liquids plant.

Compositional descriptions can be automatically converted to black oil tables for improved efficiency in cases in which compositional effects prove not to be significant.  The saturation curve can be extended beyond the saturation pressure of the original fluid for improved agreement between compositional and black oil runs.

First contact miscibility options are available for solvent injection into compositional oil reservoirs. An option is provided to automatically pseudoize the oil, along with dispersion control, for maximum accuracy and efficiency.

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Multiple Reservoirs and Multiple PVT

Sensor handles the case of multiple reservoirs, e.g. stacked reservoirs, where no transmissibility connects any pair of reservoirs and no well is completed in more than one reservoir.  This capability can reduce CPU time by a factor of two or more because different reservoirs do not require the same numbers of Newton or linear solver iterations. 

Any number of pvt tables, black oil and/or compositional, may be entered. Each grid block is assigned to one of these tables.  All grid blocks in a given Reservoir must be assigned to compositional pvt tables or to black oil pvt tables.  That is, multiple pvt tables can be used within a Reservoir but each Reservoir must be uniformly black oil or compositional.  There can be any number of Reservoirs in a simulation.  All compositional pvt types must use the same number and names of components.

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Relative Permeability and Capillary Pressure Treatment

Two-phase water-oil and gas-oil relative permeability and capillary pressure tables may be entered for multiple rock types.  These tables are then normalized for use in the model.  Relative permeability endpoints are optionally entered by gridblock for use in denormalization.  Three-phase oil relative permeability is calculated using Stone's first method as extended by Fayers to treat minimum oil saturation as a function of S_g. Optionally, Stone's second method or Baker's Linear Interpolation may be used.  Trapped gas saturation with associated k_rg hysteresis is included.  Analytical forms of the relative permeabilities and capillary pressures are also available.

In default mode, Sensor uses P_cwo and P_cgo from the normalized saturation tables, with appropriate denormalization based on gridblock residual saturations.  In addition, capillary pressures can be scaled using the Leverett J-function.  A vertical equilibrium option can also be applied to the capillary pressure curves.

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Compaction

Compaction with hysteresis is represented using input tables giving rock compressibility as a function of stress and porosity.  Optionally, the effects of water weakening are accounted for by including water saturation parameters in the compaction tables.

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Initialization (Equilibration)

Initial reservoir pressure, saturation, and composition distributions are calculated by capillary-gravitational equilibrium.  Any number of grid initialization regions may be specified with different pressure, fluid contacts, and composition vs depth.

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Dual Porosity Systems for Fractured Reservoirs

Sensor can model dual porosity and dual permeability systems, and also handles mixed unfractured/dual porosity/dual permeability systems.  The number of reservoir layers is doubled, with the first half representing the matrix and the second half representing the fractures.  Matrix-fracture diffusion can be modeled for compositional systems.  Sensor easily handles fractured systems in unstructured grids, through specification of approximately equivalent rectilinear gridblock dimensions and fracture spacings.

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Coal Bed Methane

Sensor can model coal degasification due to depletion in black oil mode.  A trace oil phase represents the coal, and the defined porosity represents the cleats and fractures.  Black oil pvt data represents the gas properties and adsorption isotherm.  Multiple pvt tables and regions allow simulation of depletion in reservoirs with mixed coal and sand layers.  Sensor does not have an enhanced coal bed methane model for processes such as carbon dioxide or nitrogen injection.

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Implicit Well Treatment

The implicit well treatment includes wellbore crossflow, turbulent (non-Darcy) gas flow effects, and tubing head pressure tables with gaslift for multi-phase flow in the tubing.  Special logic is used in compositional cases to achieve specified target rates.  This increases efficiency by avoiding additional Newton iterations to converge on specified rate.  Options are also available for SWAG (simultaneous water and gas) injection, WAG (alternating water and gas) injection cycle control, regional pressure control, drawdown control, planar sources, and management of new well drilling through drilling schedule logic.

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Platforms (Gathering Centers)

Platform or gathering center logic allows assignment of target rates and constraints to groups of wells.  Gas can be reinjected, taking into account available produced gas, gas sales, and fuel loss.  Produced gas from one platform can be transferred for injection on another platform. Allocation of production targets to the wells can be optimized to maximize instantaneous oil recovery based on simple well penalty factors.  On-times can be entered for production, water injection, and gas injection.

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Tracers

Sensor can calculate tracer fractions for any number of traced components in Impes mode.  This feature is useful in equity situations as well as in tracking injected water and gas streams.  Traced components can be any of the fluid components, including water.  Tracer calculations increase run cpu times very little.

A similar feature is the Salinity option, allowing prediction of produced water salinity variation resulting from differing salinities of original and injected water.

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Regions

Initialization regions may be specified for equilibration purposes, and pvt regions may be specified for variation in fluid characterization.  Sensor also provides for specification of output regions for analysis of results and/or for pressure control.  Sensor provides a variety of output for analysis, including recurrent printout, end-of-run summaries, and plot file writes, showing rates and cumulatives of production and injection for different (output) regions of the grid.  Superregions may be used to group given sets of regions for output or for pressure control.

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Stable Step Logic

In default mode, Sensor determines time steps automatically using change-type criteria.  In the Impes case, a stable step option determines time steps using stability theory.  This option ensures smooth results (e.g. gor and watercut) and eliminates the occasional burden of experimenting with change criteria to reduce oscillatory or unstable results.