Topaze was first developed in response to Production Analysis (PA) evolving from empirical methods to a methodology more closely aligned to modern transient analysis. The old methods have been largely replaced by advanced methodology such as the Blasingame plot and using true diagnostics developed in Pressure Transient Analysis (PTA). There are now over 1100 commercial licenses of Topaze with clients ranging from the Major IOC’s to NOC’s and smaller independents on all continents.

The merging of the modeling capability of Topaze with the abundance of data from permanent gauges has meant that users are able to obtain answers that were previously only available from transient tests. This information has the advantage that it is available at no extra cost and with no deferred production. As the long-term production is modeled, the evolution in time of the well productivity may also be quantified. Finally, forecasting is based on a real model as opposed to an empirical function.

Complete analyses may be copied from Saphir into Topaze (or vice versa) by simple drag-drop providing a quick start point for production analysis and forecasting. A happy spin-off is that shared development brings cost savings that are passed on to the client. Topaze, when added to Saphir is a marginal cost.

In Topaze NL (NonLinear) the slightly compressible fluid assumption and pseudopressures are replaced by the exact diffusion equations. In particular, Topaze NL can handle water influx, compression effects and 3-phase flow.

v4.12 sees the release of a major re-write of the Topaze Production Analysis (PA) module. The new version now has simultaneous multiwell, decline curve capability allowing full-field forecasting. A field production profile generator has been added. For unconventional gas, desorption based on the Langmuir isotherm is available, which can be combined with a new numerical fractured horizontal well model for shale gas, and with water-gas flow for coalbed methane.

Topaze can load and edit an unlimited number of gauges, rates, pressure and other data in almost any format including ASCII, ExcelTM, PAS, DMP2, Merak and databases of all kinds via OLEDB & ODBC. Data may be input as points or as steps. Topaze has real-time links with various acquisition systems, and data drag-drop from other Ecrin modules or from Diamant Master (DM).

When pressures are acquired at surface, or at any point other than the sandface, the well intake option allows either the loading or generation of a well intake response to simulate sandface pressure. When the user extracts the data for analysis, options include the choice of pressure and rate gauge, time range, time sampling, and whether or not to correct pressures to datum which, in v4.12, may be the wellbore model created and copied seamlessly from the Amethyste (WPA) module.

Topaze is not designed to be a receptacle for the multitude of straight-line methods available. The objective is to use the most up-to-date modeling methods to maximize the use of both rate and pressure data and adapt to the demands of today’s production environment e.g. depleted, multiphase, tight gas and aquifer driven. When classical methods are applicable the interface has been designed to be as simple and flexible as possible. The following is a summary of these methods. Fetkovich type-curves; single pressure and assuming constant producing conditions. Arps plot; multiple empirical plots with log(q) versus time as the default. Nonlinear regression fits the data and displays the decline function leading to an estimate of the ultimate recovery. p-q plot to discriminate between transient and boundary dominated flow; a line can be created in the latter regime to reveal compartments by comparing slopes. Normalized rate cumulative plot; A variation of the Agarwal-Gardner plot that shows (dimensionless) rate versus cumulative production. A straight line at boundary-dominated flow gives an estimate of reserves. Flowing Material Balance (v4.12), resembles a normal P/Z plot provided in terms of reservoir average pressure. A two-step iterative procedure then leads to the reserves estimate.

The three main and complementary diagnostics used in Topaze are the rate and pressure history match, the Blasingame plot and the log-log plot. The Blasingame plot displays instantaneous and average productivity index with respect to material balance time (cumulative production divided by instantaneous rate). It also calculates the derivative, in a display similar to an inverted loglog plot tending to a negative unit slope when pseudo-steady state is reached. A Blasingame type-curve plot can be displayed representing the response of a vertical well in a closed circle, with the data overlaid. This plot is also present for gas where material balance time is replaced by a material balance pseudo time. The loglog plot can be used as a diagnostic tool with exceptionally clean data although even with scattered data, trends may be detected. The simulated model can be compared to the data on both of these plots.

With a wide range of well, reservoir and boundary models shared exactly with Saphir (PTA) (see the technical references page). Topaze offers the unique capacity to simulate pressures from the production history, or simulate rates and cumulative production from the pressure history, or both simultaneously. Nonlinear regression then allows history matching, minimizing the error in terms of pressures, rates, cumulative production or any weighted average.

Since v3.0, numerical models have been used to generate complex geometries with physical parameters beyond the scope of analytical models. This is predominantly 2D but with 3D refinement where needed. The mechanics for building such models are described on the Analysis of Dynamic Data page. In v4.12 the most complex numerical model to date has been added to solve the problem of fractured horizontal wells.

In Topaze NL (NonLinear), nonlinearities are also added to the problem; the slightly compressible fluid assumption and pseudopressures are replaced by the exact diffusion equations solving for real gas diffusion, non-Darcy flow, pressure related physical properties, multiphase flow and water drives. In v4.12 gas desorption based on the Langmuir isotherm, for shale gas (single phase) and coalbed methane (2-phase water-gas) have been added.

The new multiwell mode of Topaze facilitates the analysis of the production of multiple wells. The production data can be loaded simultaneously in formats including DMP2, Merak, or by drag-drop from Diamant. It is then possible to view this data together in a browser, and conduct quick or detailed analysis of all wells or groups of wells. The results are viewed easily as tables or bubble maps as required and then it is a simple step to construct a field profile from any extension of the selected diagnostic, be it a decline curve or a complex model.

The numerical module allows the simulation of multiple well production, where individual wells can be pressure or rate controlled. Topaze permits 2D and 3D visualization of the well drainage areas and their evolution with time. If the simulation deviates from the data and indicates a change in the well productivity index the user may assign individual Skin values to different production periods. Nonlinear regression is then applied on all skins, resulting in a relationship between mechanical Skin and time.

Without data, or after history matching, a production forecast for any model may be run based on the anticipated producing pressure. Sensitivity to improvements or decay of productivity index can be simulated. It is possible to specify a wellhead pressure constraint for the reference well if an intake has been defined.

The former ‘K-Prospect’ is now integrated in Topaze. This tool replaces the non-standard spreadsheets developed by many engineers in the course of their work. It provides a uniform and standardized approach to obtaining quick production estimates for new fields and incremental recovery studies. Valid for oil, gas and condensate the user can model water or gas drive taking into account all producing and/or injecting wells. It allows the input of an unlimited number of various well-type profiles and generates a field production profile consistent with the drilling and workover schedule and facility constraints. Results can be visualized or presented in tabular format. Additionally, the profile generator can use a multiwell field profile as a baseline for an incremental study.

Topaze has an extensive range of comparison, reporting, exporting and printing capabilities. The free and unprotected Topaze Reader allows files to be read, printed and exported without the requirement for an active license. In v4.12 a new ‘slide presentation format’ has been added to use Topaze ‘live’ on a LCD projector or to copy/paste plots into PowerpointTM.