OilWat®/GasWat® - Material balance analysis
Gain a deeper, more accurate understanding of reservoir performance and potential
Still basing critical decisions on decline curve analysis (DCA) alone? As a reservoir-based, rather than well-based method, material balance (MB) analysis helps you truly understand your assets. Comprehensive and easy-to-use, OilWat/GasWat provides much of the depth of a reservoir simulation, but without the expense and data requirements. With OilWat/GasWat, you can perform quick material balance analyses to gain a deeper, more accurate understanding of reservoir performance and potential while auditing reserves obtained from decline curve analysis.
OGIP Calculation Methods (click image to enlarge)
OilWat/GasWat, originally developed by Texaco, is powerful, yet easy-to-use, reserves analysis software. Using a very comprehensive set of models, it calculates original oil-in-place (OOIP) and original gas-in-place (OGIP) for reservoirs with or without water influx using black oil or compositional fluids. Pressure prediction for multi-compartment gas reservoirs is also allowed.
Complements decline curve analysis and features links to PowerTools® results
Material balance calculations have advantages over DCA, including: (a) MB is much more mechanism-based, (b) MB considers the influence of aquifers, which are very common in both oil and gas reservoirs, and (c) unlike DCA, MB does not depend on constant well configuration or flow rate. With the recent emphasis on better reserve estimations, OilWat/GasWat is an ideal complement to a DCA tool such as IHS's PowerTools. In fact, results from PowerTools can now be imported into OilWat/GasWat. Since PowerTools can import data from both the U.S. PI/Dwights PLUS® and Canadian Accudata databases, this link gives you a streamlined way to use two complementary methods for reserve determination with the fewest possible steps.
Accurate reserve estimates are useful for internal planning, for more accurate filings for governmental agencies and even for property trading. By using both MB and DCA methods, you will have the competitive edge in property transactions if the person across the table is using only one method. Such an advantage could easily be worth millions of dollars.
Multiple models in a single run
ompare multiple reservoir and aquifer models in one run. You can initially select all models, and then narrow the list down to those that match the data - immediately showing you the most effective method. You cut significant time in arriving at answers for OOIP and OGIP.
"Optimizing effort is THE challenge in today's business environment since it's tied directly to the bottom line. We believe that using simple analyses that are associated with the fundamentals is both a starting point for all work and many times is the optimal answer. That's why material balance, and thus OilWat/GasWat, is a staple in our work process. We find that limited data sometimes makes material balance the right tool for the job."
— Tom Harris, Founding Partner
Advanced compositional modeling
OilWat/GasWat features enhanced compositional modeling for retrograde condensate and volatile oil reservoirs. You can easily import advanced PVT calculations directly into OilWat/GasWat, allowing you to calculate accurate OOIP and OGIP values. This capability alone saves significant time and improves the accuracy of your reserves estimates.
OilWat/GasWat offers a number of features that enhance analysis:
Simple, flexible data input
- A simple data input process lets you enter production data for the entire reservoir in two separate tables (pressure-production and time-production) or per well.
- With a flexible units system, you can change any parameter or all parameters simultaneously.
- Import PVT values directly from PVTLIB®, comprehensive PVT software from IHS that contains 140+ correlations from around the world.
- OilWat/GasWat enables you to fine-tune calculated PVT properties manually to match measured data using the Peng-Robinson EOS. Also, you may use packages such as Eclipse® to tune the calculated data and copy it to OilWat/GasWat.
Comprehensive Calculations
- OilWat/GasWat provides the most comprehensive set of methods for hydrocarbon-in-place calculations, including the new "Direct Approach," a method originally developed by Hsieh, et al, and modified by IHS. This method allows you to calculate hydrocarbons-in-place and aquifer constants without prior knowledge of aquifer properties.
- The GasWat simulator provides a way to investigate compartmentalized gas reservoirs to yield faster, more accurate matches to mapped data.
- Aquifer models include small, steady-state, and unsteady-state with different geometry.
- Predict pressures with variable "bubble-point pressure," which supports solid history matching during re-pressurization of depleted reservoirs.
Tehrani's 3-D Method (click image to enlarge)
Compositional Modeling
- The software includes the General Material Balance Equation (GMBE) for compositional modeling, which is fundamental for cases where there is liquid present in the gas phase. This volatile oil-gas ratio substantially improves predictions, especially for gas condensate and volatile oil reservoirs.
- OilWat/GasWat allows for four types of reservoir production: constant composition expansion, differential liberation, constant volume depletion and true reservoir condition. Up to four field separators are allowed to improve fluid property estimates.
- Other powerful features - Correlations for variable rock compressibility, 3-D Tehrani graph, and use of flow tables for wellhead pressure and changes in oil-water and gas-oil contacts on pressure prediction mode.
Support
Free support for the first year included. Continuing support upon contract terms.
Security
Option of hardware or software security schemes for both standalone systems and local area networks.