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 ?ρmud? TVD ?From the plug depth to the shoe, P internal = g ?ρmud? 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 the internal densities from the production case. Note that if gas gravity is not used, the calculated internal pressures may be slightly inaccurate for compressible fluids because the internal density is based on production temperatures and pressures. Fields and Controls Pressure The pressure at the defined location. Location The location of either the wellhead or perforation. It defines the pressure location. Perforation Depth The depth of the perforation. The default is the tubing base. 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. Tubing Density From Operation of Load Marking this option button imports the density from the Operation or Load field and uses it to calculate the densities inside the tubing. This option button is marked as the default setting inside this group box. Fluid Inside Tubing Marking this option button allows you to specify a standard hydrocarbon or standard mud inside the tubing. Fluid Gradient Inside Tubing Marking this option button allows you to specify a gradient inside the tubing rather than a density. Long Term Shut-In (Undisturbed Temperatures) Marking this check box sets the final temperatures to undisturbed. Steady-State Injection This load case models the injection of a water-base fluid into the tubing beginning with an undisturbed temperature profile. Injecting cool fluid will normally increase the tension in the tubing due to ballooning and thermal contraction. However, if there is a floating seal assembly at the packer, this load case can result in a reduction in tension due to the piston force acting on the seal assembly. Friction pressure drops are calculated using a power law rheological model. The rheological parameters (n prime and K prime) are determined by the program for user-entered fluid density. A temperature and pressure-dependent rheological fluid model is used, so the calculated pressure drop will not exactly equal the entered pressure drop for the entire tubing flow patch even with a single section tubing string. Fields and Controls Pump Pressure Defines the injection pressure at the top of the tubing string. Inlet Temperature Defines the temperature of the fluid as it is injected into the tubing. Injected Fluid Defines the fluid being injected. The fluid type can be standard hydrocarbon, standard mud, or brine. Injection Rate Defines the pump rate during the injection simulation. The depth at which injected fluids enter the formation. Steady-State Production This load case models steady-state production of gas/oil/water fluids. Production usually results in a considerable amount of heat transfer to the tubing from the hotter produced fluid. This can result in a reduction in tension causing buckling due to thermal growth. The program uses a hybrid black oil model for the oil and dissolved gas, and a compositional model for the free gas. A composition using C1 – C4 is determined based on the gas gravity. The Beggs and Brill model is used for two-phase flow pressure drops. The gas rate can be zero for water/oil production, and the liquid rates can be zero for gas production. Fields and Controls Pressure Defines the pressure of the flowing fluid at the specified location. Location Location of either the wellhead or perforations. Perforation Depth Defines the depth at which produced fluids enter the wellbore. Inlet Temperature Defines the temperature at the perforation depth. Produced Fluid Defines the fluid being produced up the well. It can be a standard hydrocarbon as defined in the fluids inventory. Input This drop down list box provides different criteria for entering production rate data. The options available are ?oil, gas, water ?oil, water, GOR ?gas, water, GOR The input option selected determines which three of the four input fields in the production rates group box are enabled. Oil Defines the rate of oil production from the well. Gas Defines the rate of gas production from the well. Water Defines the rate of water production from the well. GOR Defines the rate of GOR (gas-to-oil ratio) production from the well. Transient Injection This load case models steady state injection of natural gas. A compositional model for free gas is used. A composition using C1 – C4 is determined based on the gas gravity. Gas pressures are based on the gas dynamic theories of Zucrow and Hoffman. Fields and Controls Pump Pressure Defines the injection pressure at the top of the tubing string. Inlet Temperature Define the temperature of the fluid as it is injected into the tubing. Injected Fluid Defines the fluid injected into the well, and can be of type standard hydrocarbon or of type gas. Injection Rate Defines the pump rate during the injection simulation. Perforation Depth The depth at which injected fluids enter the formation. Tubing Evacuation This load simulates air in the tubing with a zero surface pressure. Temperatures are assumed to be undisturbed unless a prior case is specified. The Operation or Load 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. Tubing Leak (Tube) This load case recalls all of the load conditions from the prior case (usually a production case), and applies the tubing pressure on the annulus at the surface, that can result in high-collapse loads near the packer (particularly if a kill weight packer fluid is used). The Operation or Load 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 density and pressure profiles from the item as final conditions for the current load case.