What Sets StimPlan apart? The answer is N-Fold.
· Frac Geometry Modeling – the simple answer is sophisticated, 21st Century, numerical modeling technology with gridded fracture models including:
o Planer, Gridded 3D geometry model,
o Finite element technology to allow rigorous simulation of layered modulus cases (an E-StimPlan exclusive),
o Multi-phase flow solution for fluid-flow/proppant-transport (absolutely required for simulating water fracs & acid fracs), and
o 3-D numerical reservoir simulator including non-Darcy flow effects, combined with (suitable for production history matching),
o Seamless integration of all models as discussed below,
o Special (Unique) Simulation Capabilities
▪ Coupled Model – couples a 3D reservoir simulator to the 3D fracture geometry simulator. Used for water injection/water disposal simulations for long term injection simulations (including poro-/thermal- effects from the injection). This is also used to simulate
DFIT behavior for realistic design of these testing programs.
▪ Frac-Pack – couples a wellbore/gravel-pack model to the 3D fracture geometry model. This adds a simulation of the critical “pack” part of a “Frac-Pack”.
▪ “High Angle” Well – allowing simulation of multiple-fractured horizontal wells. This includes frac-to-frac stress shadow effects during a stage as well as stage-to-stage effects.
▪ Acid Fracturing – is the most complete acid fracturing simulator anywhere.
Historical fracture geometry models have been "Pseudo-3D" models, and that includes "StimPlan". However, that is basically 1980's technology. While such models still have a valuable place for scoping studies, on-site data analysis where time is critical, the occasional “simple” 3-Layer geology, etc., the technology for fracture analysis & design has moved on. StimPlan has moved to the new technology with fully 3-D reservoir and fracture geometry models including detailed multi-phase flow simulation for proppant placement in the fracture, non-Darcy flow in the fracture during post-frac production, etc.
StimPlan is the ONLY package combining fast, useful Pseudo-3D geometry solutions for use when applicable, with sophisticated modeling capabilities using the same user friendly I/O for both!
o Integration of Models
Some fracturing projects are relatively simple, and the basic Pseudo-3D models we have used for 25 years still serve admirably. However, many fracturing conditions are, and always have been, too complex for these simple, approximate models, and more sophisticated simulation is required. The StimPlan "package" is the only software integrating a complete range of modeling sophistication from classic P3D to gridded, "Fully" 3D, with all models sharing common I/O.
On the other hand, some functions such as an interactive, automatic treatment schedule design are still forced to rely on P3D models to at least supply a "first pass". Thus, a stand-alone gridded, "Fully 3D" model can become a difficult to use design tool as every treatment becomes a trial & error process. The integration of the StimPlan package avoids this limitation.
o Modeling Sophistication
We have been using the basic P3D models for 25 years, and while these models can be powerful tools for some applications, greater modeling sophistication is required for many situations. A couple of examples include:
▪ Multi-phase flow solution for proppant transport/proppant placement. This is absolutely required for accurate simulation of proppant placement, water frac modeling, and acid frac simulation - and is only done by two models - E-StimPlan and GOHFER.
▪ Non-Darcy flow is a major impact on post-frac productivity for high rate wells, and is rigorously implemented in the finite difference, 3D reservoir model included & integrated with StimPlan.
▪ 3D fracture geometry simulation fully coupled with 3D reservoir model for fluid loss/fluid flow. This is used for rigorous simulation of water injection above fracture pressure (injection wells and water disposal wells) and includes rigorous simulation of poro- and thermal-elastic effects. This can also be used for simulation of propped fracture treatments in extreme environments (common for frac-packs) of super high fluid loss.
▪ Use of Finite Element technology (optional) to allow a rigorous solution for the effect of layered modulus on fracture propagation and fracture width. E-StimPlan is the only model providing a rigorous solution for these cases - and the effects of layered modulus can be very important in some applications.
o Acid Fracturing
Working in conjunction with Dr. Dan Hill of Texas A&M University, E-StimPlan will soon be the first serious attempt to modeling the acid fracturing process. This will consider every major element of the process including use of detail geostatistics for simulation of post-acid fracture conductivity:
▪ Detailed, stage dependent fluid loss and the effect of acid on fluid loss including wormholes and enhanced natural fracture fluid loss
▪ Acid diffusion to the fracture face under both laminar and turbulent flow conditions
· Integrated Petroleum Engineering Functionality/Databasing
StimPlan is much more than a "Fracture Geometry Model"; it includes facilities for inputting, storing, and analyzing ALL data for a single well - in essence, a complete well database. This includes frac data, pre-/post-frac production data, well test data, logs, etc.
· StimPlan - The main module is available for Windows and MAC, & consists of:
o QUIK - an integrated analytical set of equations for instantaneous solution of 2-D frac geometries. This is used for fracturing pressure analysis, and for developing initial design schedules that are refined by the simulator. QUIK is also used as a screening tool for reviewing treatment designs and/or for sensitivity studies.
o 3-D SIMULATOR - The main simulator is a "pseudo 3-D" type model, however, it is a true numerical simulation performing implicit finite difference solutions to basic equations of mass balance, elasticity, height growth, and fluid flow. This is the "main model" of StimPlan and is used for finalizing treatment designs and history matching actual net treating pressure data. The model simulates complex geologic environments with frac growth through multiple formations with differing values of stress, strength, modulus, and fluid loss. It also considers the fluid volume changes (for N2, CO2, and binary foams) due to pressure/temperature changes along the fracture length.
o PRODUCTION – Two production models (both including economic analysis):
▪ an analytical fractured well production model for instantaneous solutions for low permeability wells, and
▪ A 3-D finite difference gridded reservoir simulator for more complex cases. Both can be used to optimize treatment designs.
o ECONOMIC OPTIMIZATION – The pseudo-3D geometry model is combined with the 3D numerical Reservoir Simulator to run multiple cases and determine the "optimum" treatment design.
· GRAPHICAL ANALYSIS – This module incorporates a completely integrated package for data handling, data reduction, merging of multiple separate data files, interactive graphical mini-frac analysis, pressure history matching, etc. This includes Nolte-Smith net pressure analysis and allows type curve matches, determination of closure stress, loss coefficient, etc. This also includes “Production Decline Analysis” using production type curves, or production history matching using the 3-D reservoir model. Data handling/analysis capabilities are included for:
o Mini-Frac/Stress-Test Data
o Pre- and Post-Frac Production Data
o Pre- and Post-Frac Well Test (Pressure Build-Up) Data
Basically, this makes StimPlan+Analysis a complete, single well DATABASE with ALL the data for an individual well in one integrated location!
o Merge Data from Separate Sources
StimPlan handles this simple function, in the opinion of many users whom have used other software, far better than any competitive software. This is of major concern for frac-pack operations where memory gauge BHP data is routine and must be merged with the surface pumping data for routine analysis.
o Data Analysis for ALL the Multiple Test Types Associated with Well Stimulation
▪ Stress Tests (Injection/Decline, Pump-In/Flowback, Step-Rate, ….)
▪ Friction Tests (Step-Down tests)
▪ Mini-Frac Analysis (injection & Decline Data Analysis + P-Net History Matching)
□ After-Closure-Analysis from pressure decline (this includes unique “type curve” analysis to allow permeability determination without reaching pseudo-radial flow, a uniquely useful tool for evaluating shale formations).
□ Basic Pressure Build-Up Analysis
□ Production Decline Curve Analysis (including production history matching)
o Log Analysis
▪ Sonic log stress calculations
▪ Statistical functions for building stress’/modulus correlations
· StimPlan Gridded Models - This module represents a new level of technical sophistication for routine, PC based, fracture design models. “Normal” StimPlan is enhanced by including a rigorous, fully numerical solution for two dimensional fluid-flow/proppant-transport calculations. This also includes the use of finite element width calculations giving a rigorous solution for layered modulus formations – an important and unique capability for industry fracture geometry models. The 2-D gridding in E-StimPlan can be critical for: a) layered fluid loss cases, b) proppant settling cases (i.e., water frac design), etc. This module also allows simulation of multiple, separate fractures (i.e., fractures with separate initiation intervals). This also includes additional enhancements to the 3-D reservoir model for multiple layers, horizontal fractured wells, etc. There are two gridded fracture geometry model:
o Pseudo-3D Geometry – allows faster simulations for a very special class of problems, i.e., cases with a simple (fracture initiates from the perforations and grows straight away from the wellbore) fracture geometry with well confined fracture height. This is often seen with water fracs, but the rigorous flow/proppant transport modeling is essential even while the fracture geometry is “simple”.
o Planar 3D – is the “flagship” “Fully 3D” fracture geometry model!
· “FIVE THINGS” – NSI’s idea is that fracturing software should accomplish five tasks – with the “geometry model” (normally seen as the entirety of “fracturing software”) being only one of those tasks. These tools are:
o Geometry model (using the appropriate level of sophistication),
o Fracturing pressure data handling and data analysis,
o Treatment optimization using production prediction and economic analyses,
o Treatment design to automatically generate a pump schedule for the optimized design, and
o Production analysis for post-frac evaluation.
StimPlan™ is developed with the goal of accomplishing these tasks in an integrated, user-friendly environment. Placing powerful simulation tools into the hands of production/completion engineers for whom time is precious.