NSI Software

At the SPE’s Hydraulic Fracturing Plenary Session (2000 Annual Meeting), one presentation pre­sented a list of “5 Critical Functions” that fracturing software should perform. These were:

• Data Handling/Data Analysis – This should be for pre-treatment fracturing pressure testing and real time analysis, post-treatment analysis and history matching of measured data from the propped fracture treatment, and post-frac production data.
• Fracture Geometry Model – This is the classical definition of fracturing software. Current software needs to provide this of course, in addition to the other critical capabilities. In addition, the geometry modeling should allow the use of solution sophistication required by the current in situ geologic conditions being attacked.
• Automatic Economics – Fracturing is an economic problem, and the geometry model should be coupled with a reservoir model to allow automatic comparison of treatment designs.
• Generate Pump Schedule – No one has time to trial & error their way to the final product of fracture modeling – a treatment pump schedule. Thus, the software should generate this!
• Post-Frac Production Analysis – The most common information available after a propped fracture treatment for assessing results is production. Therefore, proper analysis tools for this data are critical.

NSI's STIMPLAN is a state-of-the-art PC software package that integrates ALL these functions! It is the only commercial package providing this complete fracture analysis/design tool kit in a single software. This includes complete data handling & analysis (both “real time” and post-job), multiple fracture geo­metry models, 3-D numeric reservoir simulation, and economics. The package generates fracture optimization, design, and stimulation post appraisal reports. The interface is modularized for user-friendly data input, and includes a wide range of output handling features.

The Fracture Geometry/Design Module includes four fracture simulators.

• STIMPLAN is a pseudo 3-D, true numerical model performing implicit finite difference solutions to basic equations of mass balance, elasticity, height growth, and fluid flow. This can be used for fracture design and analysis in complex situations involving fracture height growth, proppant settling, foam fluids, and tip screenout.
• E-STIMPLAN is an enhanced version, with rigorous, fully numerical solution for two-dimen­sion­al fluid flow and proppant transport. This also includes the only commercial geometry model to correctly handle layered modulus cases using finite element technology.
• N-FRACS uses the E-StimPlan technology to consider multiple fractures initiation from sepa­rate perforated intervals. This incorporates the wellbore into the solution, and simultaneously solves for fracture growth, fracture geometry, etc. for all “N” fractures simultaneously. This also includes rigorous calculations for effects of these fractures joining, or interfering.
• E-StimPlan 3D is a full, planar 3-D geometry model for analyzing the effects of complex geologic environments on fracture propagation and final geometry. This tool is particularly valuable for cuttings injection and disposal type analysis where large volumes can create dangerous height growth, and where effects such as filter cake buildup, normally ignorable for propped fracture treatment modeling, can become important.

Thus, the proper solution sophistication for the problem at hand is available in one integrated pack­age with uniform I/O for all geometry models.

Reservoir Simulation is a critical part for any fracturing software, though only indirectly referred to in the “5 Critical Functions” of the SPE presentation. StimPlan includes a 3-D reservoir simulator for predicting (or history matching) production data from fractured (and un-fractured) wells. This in­cludes the ability to simulate such effects as limiting perforated interval length (possibly to allow more favorable fracture geometry growth), non-Darcy flow, etc.

The Fracture Optimization Module integrates fracture geometry simulations with the numerical 3-D reservoir model and an economics package to provide detailed production and economic optimi­zation. This allows you to maximize both well performance and profitability from a planned fracture treatment.

StimPlan’s Analysis Module allows fracture pressure and production post appraisal. The pressure decline analysis function allows the user to interpret mini-frac pressure decline data using cutting edge fracture diagnostics to determine fluid efficiency and leak-off coefficient. It also supports pro­duction history matching with a 3-D numerical reservoir simulator to appraise effects of stimulation.