Here the user can define the parameters of the thermal case.
The user can select one of the following modes:
- Production
- Water-Gas Injection
- Worst Case Discharge
- Circulation
- Transient Shut-In
Each different mode has a different set of inputs.
If the selected mode is Production, the window presents the following inputs:
- Perforation depth: This input defaults to the total well depth MD (in ft. or m) as defined on the Well Definition tab. If no tubing is present, any depth between the top of the innermost string and the total well depth is valid. For wells with tubing strings, the perforation depth cannot be shallower than the packer depth.
- Starting Pressure: This input defaults to the flowing bottom hole pressure from the formation pressure profile in the "Well Characteristics" tab under "The Well". Using the radio button, user can alternatively select to use a calculated flowing wellhead pressure as the target pressure. Its default value is the default pressure at the top of the tubing or innermost string.
- Flowing Bottom Hole Temperature: The default value is the Undisturbed Temperature from the formation definition at the default perforation depth.
- Oil API Gravity: Enter the API Gravity of the production oil.
- Gas Specific Gravity: Specific gravity of Gas in the produced fluid is entered in the next field.
- Oil and Gas Rate: The flow rate of the oil is entered either in terms of units per day according to currently selected units. The gas rate can either be entered as an explicit rate as well, or as a fraction in terms of gas/oil ratio, according to the selection of the radio button.
- Water Cut: Similar to the oil and gas composition definitions, the water composition of the production fluid can be entered either as an explicit rate or as a ratio to oil, in terms of water cut percentage, according to the selection of the radio button.
- Tubing Roughness: The next field allows the user to enter a value for the roughness of the conduit.
- Ocean Current and Wind Speed: In the region of the conduit that passes through water or air, these speeds affect the heat transfer to the surrounding air or water.
- Step size: This denotes the step size used for segmenting the string into calculation units.
- Flow Duration: This parameter is the total flow period of the production operation. It is only meaningful for transient thermal cases so defaults to 2 years for steady state cases.
- Prior Operation: If the current thermal case is a transient case, it is possible to base the calculations on the results from another thermal case by selecting that case here. Only relevant and enabled for transient thermal cases.
- Thermal Mode: This parameter determines whether the current operation will be calculated as a steady state or transient thermal case.
- Notes: Here, the user can enter a description of the case, its assumptions, or any other text information.
- Thermal Mode: This parameter determines whether the current operation will be calculated as a steady state or transient thermal case.
If the selected mode is Injection, the window presents the following inputs:
- Injection Depth: This input defaults to the total well depth MD (in ft. or m) as defined on the Well Definition tab. If no tubing is present, any depth between the top of the innermost string and the total well depth is valid. For wells with tubing strings, the injection depth cannot be shallower than the packer depth.
- Surface Injection Pressure: This input defaults to the pressure at the injection depth from the pore pressure formation pressure profile.
- Surface Injection Temperature: This value defaults to a constant standard temperature, but can be changed.
- Gas Specific Gravity: Specific gravity of Gas in the produced fluid is entered in the next field.
- Gas Rate: The flow rate of the gas in the injection fluid can be entered as an explicit rate, according to the currently selected units.
- Water Rate: The flow rate of the water in the injection fluid can be entered as an explicit rate, according to the currently selected units.
- Injection Fluid Density: The density of the injection fluid in currently selected units.
- Tubing Roughness: The next field allows the user to enter a value for the roughness of the conduit.
- Ocean Current and Wind Speed: In the region of the conduit that passes through water or air, these speeds affect the heat transfer to the surrounding air or water.
- Step Size: This denotes the step size used for segmenting the string into calculation units.
- Flow Duration: This parameter is the total flow period of the production operation. It is only meaningful for transient thermal cases so defaults to 2 years for steady state cases.
- Prior Operation: If the current thermal case is a transient case, it is possible to base the calculations on the results from another thermal case by selecting that case here. Only relevant and enabled for transient thermal cases.
- Thermal Mode: This parameter determines whether the current operation will be calculated as a steady state or transient thermal case.
- Notes: Here, the user can enter a description of the case, its assumptions, or any other text information.
If the selected mode is Worst Case Discharge (WCD), the inputs are nearly identical to those for production, with one exception. The WCD case also allows the user to select the last participating string; this is the last string, counting from outermost inward, that will be considered in the calculations of the thermal case. The flowing fluid is assumed to flow through that string (and any enclosing strings in the case of a liner).
If the selected thermal case mode is Circulating, the inputs are as follows:
- Last Participating String: Similar to the Last Participating String for WCD cases, this is the last string, counting from outermost inward, that will be considered in the calculations of the thermal case. The circulating fluid is assumed to flow down through the inside of the drill string and upward inside the last participating string. In other words, the drill string annulus is the directly inside the last participating string.
- Hole TD: This input defaults to the total well depth, but any valid depth above that can be entered.
- Static Bottom Hole Temperature: This value defaults to the value from the formation profiles for undisturbed temperature at the Hole TD depth, but it can be changed.
- Number of Nozzles and Nozzle Diameter: Here the user can enter some parameters of the drill head: how many nozzles it has and their area in 32nds of an inch. The total nozzle area is calculated and displayed below these fields.
- Drill Bit Type: Whether the bit is a PDC or Roller Cone type has an effect on the pressure drop across the bit.
- Circulating Flow Rate: The flow rate of the circulating fluid.
- Circulating Fluid Temperature: This refers to the temperature of the fluid at the surface, before circulation begins, and defaults to a constant standard temperature.
- Pipe Roughness: The next field allows the user to enter a value for the roughness of the drill pipe.
- Circulating Time: The amount of time the circulating case runs defaults to 3 days, but any value from 1 hour upward can be considered.
- Step Size: This denotes the step size used for segmenting the string into calculation units.
- Drill Pipe OD and ID: These parameters describe the dimensions of the drill pipe. For simplicity, it is assumed to be uniform throughout its length.
- Drill Fluid: From the dropdown, the user can select any of the drill fluids available in the fluid database. The fluid density of the selected fluid is displayed in a read-only field.
A Transient Shut-In case can be defined with the following inputs:
- Static Bottom Hole Temperature and Pressure: These values default to the values from the formation profiles for undisturbed temperature and pore pressure at the perforation depth, but they can be changed.
- Pipe Roughness: The next field allows the user to enter a value for the roughness of the drill pipe.
- Ocean Current and Wind Speed: In the region of the conduit that passes through water or air, these speeds affect the heat transfer to the surrounding air or water.
- Prior Operation: The shut-in case can only be calculated with respect to another transient case. Furthermore, that prior case must have the same step size and starting depth as the current case. Therefore, those fields are read-only in the Shut-In case, and the thermal cases in the drop-down list determine the settings in those fields. If there are no transient cases, the list will be empty and no shut-in case can be created. The Transient / Steady-State selector radio button is visible in a read-only state to serve as a reminder of this constraint.
- Shut-In Duration: This parameter specifies the length of the shut-in operation in the currently selected time unit.