wellcat载荷介绍,英文版

Custom Load (Tube)

Custom Load has tabs you use to specify density, pressure, and temperature

profiles inside and outside the current string that are not available from any of

the standard load types. Use the String tab to specify profiles inside the string

and the Annulus tab to specify profiles outside.

On the String tab, the Tubing Profile group box, located on the left, is used to

define tubing density or tubing pressure profiles. On the Annulus tab, it is the

Annulus Profile group box, and it is used to define annulus density or annulus

pressure profiles.

The Tubing and Annulus Temperature Profile group boxes are defaulted to

undisturbed temperatures. Enter the temperature profile your want to model as

final temperature for this load. Entries are assumed linear between the entered

depths, and values should be entered at the top and base of the string.

Fracture Screen-Out

This load case models the high injection pressure encountered at the end of a

fracture operation. The prior load case (usually an injection case) is recalled

for temperatures, internal densities, and external conditions (such as casing

pressure).

Fields and Controls

Pump Pressure

Pressure applied at the wellhead.

Operation or Load

This drop- down list box has the names of all loads or operations defined for the

current string that can be linked to other loads. Selecting one of these items

allows the code to use the temperature profile from the item as final

temperature conditions for the current load case.

Overpull (Tube)

This load case models tension in the tubing string due to the air weight of the

tubing (or buoyed weight in mud). An overpull force (usually applied to unseat

a packer) can be specified to model additional surface tension applied to the

tubing (usually to free stuck tubing). The temperatures specified on the

Initial

Conditions dialog

are used as the temperature profile for the load case.

Fields and Controls

Overpull Force

Specify the overpull force.

Running Fluid

Define the fluid inside the well when the current string is run. This drop-down

list box has the names of all fluid types for standard mud, compositional mud,

brine, and air.

Pressure Test (Tube)

This load case models a tubing pressure test with pressure applied at the

surface. An optional plug can be entered, and the axial force due to pressure

acting on the plug will be included. The pressure below the plug is calculated

based on the specified fluid density. The temperatures specified on the

Initial

Conditions dialog

are used as the temperature profile for the load case.

The following calculations are used:

?

From the hanger to the plug depth,

P

internal =

P

test

+ g

?

?

mud

?

TVD

?

From the plug depth to the shoe,

P

internal =

g

?

?

mud

?

TVD

Fields and Controls

Pump Pressure

Pressure applied at the wellhead.

Fluid Inside Tubing

Fluid types available for specifying inside the tubing are

?

?

?

?

Standard muds

Standard hydrocarbons of gas type

Compositional muds

Brines

Plug Present

If this check box is marked, a depth must be specified at which the plug will be

placed. The default depth for the plug is defined as the base of the current

string.

Prod Link

This load case is used to model the current string with the temperature profiles

imported from a Prod operation.

Fields and Controls

Operation

Contains initial conditions and the name of all Prod operations.

Wellhead Pressure

Pressure applied to the top of the fluid column in the current string.

Fill from Annulus Contents Spreadsheet for Next String

If marked, the density for the annulus fluid defined for the next string is used to

define an internal density profile for the current string.

Fluid

If marked, you can specify a different fluid. Fluid types available are

?

?

?

Standard muds

Compositional muds

Brines

Point Axial Load

Marking this check box allows you to optionally apply an axial point load

anywhere along the length of the current string.

Axial Force

Enter the applied load value.

Applied Depth

Specify the depth at which the axial force is applied.

Pump-In to Kill

This load case may result in worst-case burst loads at the surface for low

permeability formations when a pump pressure significantly greater than the

shut-in wellhead pressure is required to begin a bullhead kill operation.

Temperature, internal density, and external conditions are recalled from the

prior case (production or shut-in). It then applies the user-entered surface

pressure.

If you want to model thermal contraction loads during a kill operation, use the

Transient Injection load as the prior operation or load.

Fields and Controls

Pump Pressure

Pressure applied at the wellhead.

Operation or Load

This drop-down list box has the names of all loads or operations defined for the

current string that can be linked to other loads. Selecting one of these items

allows the code to use the temperature profile from the item as final

temperature conditions for the current load case.

Rod Pump

This load calculates tubing loads due to steady-state production in a well using

a rod pump for artificial lift. WELLCAT uses the values you specify to perform a

thermal simulation to calculate tubing temperatures and pressures based on

the specified production conditions. These results are used to determine the

forces acting on the tubing.

The load calculation is based on data you specify to calculate the force acting

on the tubing due to the differential pressure across the pump. This pressure

acts on the cross-sectional area between the tubing ID and the pump bore

diameter.

A stress analysis can be performed for both an upstroke and downstroke. On

an upstroke, the piston force due to the higher pressure above the pump is

carried by the sucker rods and travelling valve, yet the pressure increase can

cause buckling in the tubing. On a down stroke, this pressure force acts

downward on the standing valve, and is carried by the tubing (that is, the valve

is treated as a tubing plug).

Fields and Controls

Wellhead Pressure

Flowing pressure of the produced fluids at the top of the tubing string.

Perforation Depth

This depth defines the location from which hydrocarbons are produced.

Inlet Temperature

Undisturbed temperature at the perforation depth.

Reservoir Pressure

Pressure of the flowing fluid at the perforation depth.

Produced Fluid

Standard hydrocarbon of type oil and gas as defined in the fluids inventory.

Production Rates

Oil

Produced oil flow rate from the well.

Water

Produced water flow rate from the well.

Rod Pump Geometry

Pump Depth

Depth of the standing valve. The default value is the base of the production

tubing.

Pump Bore Diameter

ID of the pump bore.

Sucker Rod Diameter

The diameter of the sucker rod.

Shut-In

This load case models shut-in after production. Temperature, internal density,

and external conditions are usually taken form the production case. Internal

pressures are usually calculated based on the user-entered surface pressure

and the fluid densities.

If this is a long-term shut-in, temperatures are set to undisturbed. If gas is in

the tubing during the shut-in, gas gravity can be entered and this will override