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The SNAP tutorial gives step-by-step instructions for creating a SNAP project. The tour uses the SNAP Default Dataset.SNP file, which is included with your SNAP application. Working through the SNAP tutorial is an excellent way to become proficient with SNAP.

 

Beginning the Snap Tutorial

 

We will begin by starting SNAP. If you have not yet installed SNAP, please take the time to do so.

 

 

General Project Definition

In SNAP, you begin defining the well system in the General Project Definition dialog box. Gain access to this dialog box by clicking the General button on the schematic

or by selecting General from the toolbar using this button ->

 

You will see this screen:

 

 

In this dialog box, you can name your dataset, indicate whether the primary phase is oil or gas, and select an IPR type to define system temperatures and pressures, as well as other system conditions.

 

Well Type

SNAP performs calculations on the following well types:

 

Completion Type

The Completion Type is dependent upon the IPR chosen for evaluation.

Completion Type options are:

 

IPR Type

Online Help explains each IPR Type in the Inflow Reservoir and Well Data sections. The IPR equations in SNAP include:

 

General Project Definition Exercise

The following steps will demonstrate how the selections you make in the General Project Definition dialog box affect the end results.

 

 

Note: Making changes early on may activate or remove certain input panels. It is a good idea to make sure you have data in the correct locations and are not left with empty dialogs that were not previously available.

 

and click OK.

 

 

PVT Properties

The PVT Properties dialog box enables you to enter basic reservoir pressure, volume, and temperature data  (hence the name "PVT") to describe a reservoir's fluid. PVT parameters are pressure dependent and therefore change with time.

 

This dialog box changes slightly depending on whether you select an oil well or a gas well. For an oil well, specific correlations are available for determining the gas/oil ratio (GOR), formation volume factor (Bo), and oil viscosity. The differences in the oil correlations represent the variances in the type of reservoir fluid or oil properties. Help>>Input Panels>>PVT Properties gives information about which correlation is appropriate to use under specific circumstances.

 

If you select a gas well, there are no correlations available and SNAP deactivates the Oil API Gravity and Water Specific Gravity fields.

 

PVT Exercise

 

Inflow Properties

The Inflow dialog box is specific to the type of IPR you select in the General Projection Definition dialog box. The IPR type selected for the tour is Vogel's Method with Fluid Data, therefore choosing the Inflow command displays the corresponding dialog box. Use this dialog box to enter data for the various single- and multi-point correlations that SNAP uses in pressure drop calculations.

This page can be accessed through the Inflow button on the toolbar, by clicking the Inflow button on the schematic, or choosing Inputs>> Inflow to open the Constant PI from Fluid Levels dialog box.

 

Inflow Properties Exercise

 

 

Completion Data

The Completion Data dialog box is not active because the IPR equation selected for this tutorial does not require Completion Type user input to perform necessary calculations. When the dialog box is active, you can fine tune the completion algorithms for the corresponding equations. You can model up to five commingled zones when using Darcy's Law or Vogel's Method with reservoir data.

 

Flowline Geometry

The total length of the flowline is described using pipe diameter changes, non-linear temperature profiles, and segments that describe the flowline profile. You begin describing the geometry at the separator and work towards the wellhead. Because the flowline components' elevations affect performance relationships, SNAP offers three methods for calculating flowline geometry.  These methods are ML (Measured Length) versus Angle, ML versus Elevation, and Elevation versus Angle or click the Flowline button on the toolbar.

 

You can choose from the following five hydraulic correlations:

 

Flowline Geometry Exercise

 

 

 

Wellbore Geometry

Wellbore Geometry can be a single tubing string or multiple strings depicted as individual segments that describe the wellbore. You begin at the wellhead and end at the bottom of the hole. You can also model either annular or tubular flow. Hydraulic correlations include: Hagedorn and Brown, Orkiszewski, Duns and Ros, Aziz, Beggs and Brill, Gray, Mona, Modified Gray, Dus-Ros-Gray, Mechanistic, and Cullender-Smith. Click Hydraulics Correlation to open the Correlation advisor.

Wellbore Geometry Exercise

Gas Lift

If your well uses gas lift, you need to provide SNAP with gas lift characteristics to obtain an accurate analysis. SNAP only enables the Gas Lift item if you select the Include Gas Lift check box in the General Project Definition dialog box.

Note: For this tour, Gas Lift is not being considered, and therefore, the option was not activated in the General Project Definition dialog box.

 

Sensitivities for Calculations

 

 

Calculating the Nodal System

 

 

Plots

After entering and editing data in the options dialog boxes, you can generate, manipulate, and print IPR, hydraulics, and system plots. You can also elect to generate a gradient plot of the baseline and optional hydraulic flowrates. See “Calculate Menu” on page 71 for further information on this topic.

 

When you generate a plot using Calculate, it is displayed in a Plot Viewer window. As a Result, tree new menu items appear on the menu bar, the new menu items are:

SNAP can generate any of the following five types of plots:

Plots Exercise

To view the generated plots:

 

Report Format

Although you can display and print results graphically in SNAP, you may also find it necessary to obtain results in report format. SNAP automatically generates reports after you have performed a calculation on the system.

 

Report Exercise

To Exit SNAP

 To exit SNAP choose File>> Exit.