Below are a list of the most frequently asked PC-PUMP questions. If you have any questions, please review the list below. If your question is not listed or you feel the answer is not clear, please contact us by email or through the web form.

Installation

A: There are several possible reasons causing this message.

2) The Hardlock drivers have not been installed properly. These drivers are necessary in order to run PC-PUMP. They are installed differently in Win 95/98/ME and in Win NT/2000/XP/Vista, so if you have recently changed computers or operating systems you cannot simply copy the PC-PUMP directory from your old system to the new system. Note that in Win NT/2000/XP you must be logged on with Administrator privileges to install these drivers. You can ensure these have been loaded correctly by rerunning the hardlock installation program. To do this, open a command line window in the Hardlock subdirectory of your PC-PUMP program directory and type “hldinst -install” at the command prompt. If your operating system is Windows NT, 2000, XP or Vista, ensure you are logged on with administrator privileges, or get your computer support department to do this.

3)If you are using an older version of PC-PUMP with a newer version of windows, you may need to update your Hardlock drivers. (Visit: http://www.aladdin.com/support/hardlock/downloads.asp and download either hardlock_drive r_cmdline.zip, which needs to be run from a command prompt, or hldrv32.zip, which has a graphical interface.) For example, versions of PC-PUMP older than v2.67 may not run properly on Windows XP with SP2, or versions older than v2.68 may not run on Vista, without a newer driver.

4)This, or a similar error can occur if you are using a network Hardlock and there are already the maximum permitted number of users using PC-PUMP. A future version of PC-PUMP may have a more meaningful error message in this case. On a related case, you may encounter this error in trying to run the Swell Model or Sand Settling programs if you have a network key.

5) These last two suggestions have applied in the past to systems with parallel port Hardlocks and older operating systems (before Windows 2000). While we have not seen these problems recently, we still include the solutions:
5 a) Try setting your parallel port to be unidirectional. You can change the driver settings in the control panel—set the parallel port to “SPP” or “Printer Port” (not “ECP” or “EPP”). Ask your computer support department to do this, or contact C-FER for specific instructions.
5 b) Try setting your default printer to an older model of printer. For example, if your default printer is currently a LaserJet 5, try setting it to a LaserJet 2. In some cases, newer printer drivers conflict with the Hardlock.

6) If all these options fail to resolve the problem, contact C-FER technical support.

A: To ensure that only those users who are supporting the PC-PUMP Maintenance Plan have access to the new program upgrades and program databases, C-FER has required users to enter codes (using the included FeatureAdd program) before using some new versions of the software databases. If you are getting this error and your Hardlock should be eligible to run the new version, contact C-FER.

System Configuration

A: The most likely answer is that the data was not typed in correctly. Double-check all your input data. Is your copy clear?—we’ve seen some surveys that have been faxed several times and on these it is quite easy to misread numbers. If the data is all typed in correctly, it is possible that the logging company used a different calculation method. This is more likely if the survey is quite old. Most modern surveys will use the minimum curvature method, which is what PC-PUMP uses, but in older surveys (more than 15 years old) other methods are sometimes seen.

A: C-FER has seen at least three different survey formats that were not traditional, although these are quite rare. If your survey is not of the standard format, and you cannot determine how to translate it, please fax a copy of it to C-FER, or email a scanned image (or the electronic version of the survey if you have it), and we will attempt to tell you how to translate to the format required by PC-PUMP.

A: Yes. Copy the data (just the measured depth, hole angle and azimuth data) in Excel, ensuring that there is a point for zero depth. Go into PC-PUMP, and click on the top left box in the survey spreadsheet. Press Ctrl-V, or use the mouse to select Edit -Paste from the menu. Also, see the PC-PUMP v2.671 User Guide p. 85 for how to import a survey in a text file. The User Guide is installed as a PDF file along with PC-PUMP.

There are many different manufacturers of electric motors, and each manufacturer may make multiple variants (e.g. regular and "high-efficiency"). Each of these motors may have different performance characteristics—the NEMA standard specifies only a minimum efficiency at rated power—it does not specify what the actual efficiency is, nor does it address loading at less than rated power. C-FER does not include motor performance data for surface motors in PC-PUMP. Product literature for the actual motors your company is using should be available from the motor vendors, and you should be able to get efficiency and power factor values for the motors from that literature. Note that both efficiency and power factor will drop at loads less than the motor's rated load, so if the product information only contains efficiency and power factor at rated load, this may not apply if the motor is lightly loaded.

A: Every progressing cavity pump is different, even if it has the same nominal size and is constructed of the same materials as another. As a result, there is no way to determine the exact volumetric efficiency and friction torque for any given pump under downhole conditions. Moreover, these values can change over the pump’s life. Most notably, these will change over the early period when the pump is first in a well. The stator elastomer will swell (or in some cases shrink) when exposed to well fluid and put under operating pressure. If the stator swells, the friction torque and volumetric efficiency will normally both increase. In addition, changes in viscosity and pump speed will also affect the volumetric efficiency. In determining the friction torque and volumetric efficiency to use, you need to look at the pump’s bench test results and then use field experience—how have the torques and efficiencies of this type of pump in this field under operating conditions been different from their bench test results?

A: In PC-PUMP’s downhole drive mode, the drive equipment must be specified. The drive equipment is important because the produced fluid must flow past it before reaching the pump intake—even if the pump is located below the perforations, in which case the fluid must flow down the annulus and then back up through a shroud. Often, the clearances in the annulus are fairly small. This can cause significant flow losses which cannot be calculated by PC-PUMP if the drive diameter and length are not known. This is why PC-PUMP requires that you enter the downhole drive equipment. There is an option, however, that can be used to avoid this. There is a check box in the Defaults window (Edit-Preferences) which can be used to tell PC-PUMP to calculate flow losses in the tubing in a surface drive case as if the rod string was not present. You can use this option to simulate a downhole drive case. (Note that you must be in surface drive mode and must enter a rod string. A warning message will be issued for every case while this feature is used.)

A: Some rod guides and couplings, most often those of a spin-through type, have fins which are designed to centralize the rod in the tubing. The fins are sized to fit relatively tightly within certain tubing sizes. Starting in PC-PUMP v2.68, the program will issue an output note informing the user if such a guide is selected, but the tubing size is larger than the size it was designed to fit tightly within. This is not a problem; these guides or couplings can still be run—it is just something you should be aware of. NOTE: This feature may display this message incorrectly if you load a file generated with an earlier version of PC-PUMP. If you believe this may be happening, clear and re-enter the rod string. If it still happening when you think it should not be, save your file and send it to C-FER.

A: Some spin-through rod guides or couplings in the database have an outside diameter which is intended to fit relatively tightly within the tubing. These are designed to work in the most common tubing weights for the particular tubing size. If you have selected one of these guides and are using a heavier weight of tubing, the inside diameter of the tubing may be too small for the guides to be run. Use a different guide or select a lighter weight of tubing. If this happens when you are using the lightest weight of tubing for the given tubing size, please email your .pcp file to C-FER with a message describing the problem.

A: Older versions of PC-PUMP assumed that rod guides are placed in such a way as to ensure that the couplings (for any rod which uses guides) are not touching the tubing wall. In other words, the first guide on any rod is located right next to the coupling and has a larger diameter than the coupling. The opposite method, in which the first guide is placed in the middle of the rod, and for which the coupling remains in contact with the tubing wall, is now allowed in PC-PUMP. When selecting rod guides, choose a contact mode of “Guides Only”, which is the assumption in older versions of PC-PUMP, or “Couplings and Guides”. The above error message will only appear if you select “Guides Only”. When specifying guides like the RGI Rod Jake, you should normally select the “Guides and Couplings” contact mode.

A: Yes. The procedure for doing this has changed in v2.65. In v2.65, you must select a brand of rod, for which crossover sizes are available. (“Mod. API” is listed as a brand for generic rods with off size pins.) In the size and grade listing for the selected brand, off-size pins are listed, for example: “1 in. (0.875 in. Pin) Gr. D”. Other cross-over sizes are also available.

A: You should not close the System Configuration or Analysis windows using the X at the top corner. Switch between them using the appropriate buttons. If however, you do close one and end up with no window visible, go to the Window menu in the main PC-PUMP menu bar and select the System Configuration or Analysis window.

Analysis Inputs

A: Whenever you have a measurable gas rate in the well. Regardless of the API gravity of the crude oil, its viscosity will decrease due to the gas in solution, and its density will decrease, particularly if some gas comes out of solution in the tubing. Both of these mean that in most cases the pressure losses will decrease in most cases if multiphase flow is used. Note that it is particularly important for oils heavier than 15-20°API to enter the dead oil viscosity in the advanced viscosity window.

A: Every oil field is different. These correlations are based on data from a limited geographical area. The only way to determine which correlation is most accurate would be to compare results from each correlation to actual field data. The User Guide contains references to the sources of these correlations, so you can look up the equations used and determine which ones most accurately match your data. Alternatively, if you have laboratory test data for these fluid properties, and you are currently subscribed to the PC-PUMP Maintenance Plan, send your data to C-FER and we will prepare plots comparing your data to the results from each correlation, to assist you in determining which correlations to use.

A: The best way to determine this is to have the well fluids tested in a lab in the form in which they come from the well. Even small amounts of dissolved gas can make the actual oil viscosity significantly less than the dead oil viscosity. As for the water, if the fluids are emulsified, water can cause the actual viscosity of the mixture to be significantly higher than for pure oil. The advanced viscosity window in PC-PUMP has, for single phase only, options for varying the viscosity with water. This gives you the choice of either specifying that the fluid is an emulsion or that the viscosity is to be calculated as a weighted average of the water and oil viscosities.

A: It is specified relative to vertical depth. Note that this refers to a flowing temperature gradient and not the geothermal gradient. The value for the flowing gradient will always be less than or equal to the geothermal gradient. Newer versions of PC-PUMP allow you the option of entering the flowing wellhead temperature instead of the gradient, if you prefer. In that case, it will display the calculated value for the gradient.

A: This is an option in PC-PUMP, but it uses a correlation which is based on very limited data. We suggest using this option with discretion. Try running it and see if the results make sense. When a pump is pumping a large volume of high viscosity fluid, the viscous torque can easily be 30% or more of the total torque. If the rates and viscosity are both low, the viscous torque should also be low. Due to the extremely limited data available to C-FER for checking the accuracy of this correlation, we recommend that users be careful in evaluating the results of this calculation. The program will always print an output message containing the calculated viscous torque.

If you use this calculation option built into PC-PUMP (in multiphase flow) it will do one of two things. If the pump (or tail joint) intake is located below the perforations, it will assume 100% separation efficiency—all the free gas at the perforations is assumed to go up. If the intake is located above the perforations, it will estimate a separation efficiency. This calculation assumes that the pump intake is centralized and that the well is near vertical where the intake is located—if these conditions are true, the calculation should be reasonably accurate. Times when you might not want to use the calculation option include:
a ) The intake is located below the perforations but there is high velocity and/or high viscosity, which could drag free gas down to the intake. In this case, the separation will be less than 100%.
b) The intake is not centralized. If the intake is pushed against the wall of the tubing, the separation efficiency may be improved.
c ) The intake is not in a vertical portion of the well. If the intake rests on the low side of the well, the efficiency should be improved, but if it is pushed against the high side, it could be worsened. If it is centralized, the efficiency may be increased or decreased, depending on the amount of free gas and the angle of the well.
d) A gas separation device is used. If working properly, a gas separator should increase the separation efficiency, but the amount of increase will depend on several factors.
In any of these cases, you will need to estimate a value for gas separation and enter it manually.

Analysis Outputs

A: Unfortunately, when we developed PC-PUMP, we could not anticipate every possible situation. In the past several years, C-FER has corrected most of the situations which we were aware of which could cause this error. If you get this error, click on the “send” button in the error message and email it to C-FER. It is virtually impossible for us to diagnose your problem with these error messages without having the PC-PUMP data file (.pcp file), but in most cases we can determine the problem and suggest a correction or work-around for you once we see the .pcp file. When these problems are reported to C-FER, we strive to fix them in a new version of PC-PUMP as soon as it is feasible to do so.

A: PC-PUMP checks the input in the wellbore survey to ensure it meets certain criteria (for example each survey point must be at a deeper measured depth than the previous one). PC-PUMP, however, does not check everything. This error is most likely caused by an incorrect value in the survey. You can probably find the problem by scanning your inputs for a number that looks out of place. If not, save the file and email it to C-FER for diagnosis.

A: There can be several reasons for this. First of all, any time you are having problems either in multiphase mode or if you are using an IPR (or both), try using flow rate as an input. This removes some problems associated with iterating to a solution. (If you are in multiphase and using an IPR, look at the next two questions below as well.) You must also remain within the limits of your IPR. The following error indicates that you are trying to draw the well down below the maximum flow rate permitted using the IPR:

In this case, the IPR reached a producing pressure of 0 at a flow rate of 148 m³/d, and the user tried to obtain a flow rate of 200 m³/d. When an IPR is selected, the flow rate can never be higher than the flow rate calculated by the IPR at a producing pressure of 0. If you are getting this message when you are specifying pump speed instead of flow rate, it is because PC-PUMP is having difficulty accounting for the gas going through the pump—try specifying flow rate instead.

In this case, PC-PUMP has not been able to locate the fluid level—it’s trying to put it below the pump, which is not allowed (unless there is a tail joint, in which case the fluid level may not go below the bottom of the tail joint). If you’ve specified a flow rate, PC-PUMP calculates a producing pressure from the IPR. It will then calculate where the fluid level should be. If the casing head pressure is greater than the producing pressure, it will fail with the above error message. Try a lower flow rate to increase the producing pressure, or determine if you can use a lower casing head pressure.

This message also indicates that the program cannot calculate a valid fluid level. It is often caused by large amounts of gas flowing up the annulus. This gas decreases the effective density of the fluid, meaning it needs more height to reach the required pressure at the perforations. In some cases, the fluid column may go all the way to surface, at which time this error message will be reached. Such a well will actually produce some liquid (along with a lot of gas) up the annulus, and PC-PUMP does not allow this.

This message is similar to the previous two. If you get this error, you need to check the same things. Your flow rate could be too high or too low for the circumstances, or you may need to adjust your casing head or tubing head pressure.

In general, if you are having problems of this nature, a good idea would be to run a batch comparison with flow rate as the batch parameter. Enter flow rates from just over zero to just under the maximum value from the IPR (i.e. the flow rate at zero producing pressure). See what range the calculation will allow and try to stay in that range.

A: When you specify a higher flow rate and you have an IPR active, PC-PUMP uses a lower pressure at the perforations (as defined by your IPR). At lower pressure, more gas comes out of solution before entering the pump. The free gas reduces the amount of volume within the pump occupied by liquid. PC-PUMP calculates pump speed based on the efficiency you’ve specified, the liquid flow rate you’ve specified, the proportion of the volume filled by liquid, and the pump displacement. As the amount of gas increases, the pump must run at a higher speed to achieve the liquid flow rate you’ve specified. This is indicative of a problem you would encounter in trying to pump off a gassy well by increasing the pump speed—you may find that above a certain speed you get very little incremental liquid flow rate.

A: This can happen in some cases with very gassy wells. As the pressure at the perforations decreases (as happens when the flow rate is increased with an IPR) more gas comes out of this solution. Some or all of this gas goes up the casing annulus (depending on the free gas separation value, and on whether the pump intake is above or below the perforations). This gas serves to decrease the overall density of the fluid in the casing. The fluid level is determined by calculating what depth of fluid is necessary for there to be the required pressure at the perforations. The pressure at the perforations is determined from the IPR, but is also the sum of the casing head pressure, the hydrostatic pressure due to the gas column (normally very small) and the hydrostatic pressure due to the liquid column. The hydrostatic pressure due to the liquid column depends on the fluid level and the fluid density. In some cases, as the density decreases, the fluid level must be higher in the well (i.e. at a lower mKB or ftKB value) to achieve the required pressure at the perforations. In some extreme cases, it will not be possible to calculate a fluid level. In these cases, you will either get Error 813 or Error 8002 (both these error messages are shown above). Interestingly, in many of these cases, you will see that at higher flow rates a valid result can once again be obtained.

A: PC-PUMP calculates power requirements based on straight-forward energy calculation. PC-PUMP converts these power requirements into a cost per day by multiplying the power requirement (in kW) by 24 hours to get a total energy per day (in kWh/d), and then multiplying this by the Power Cost value (in $/kWh, or, in newer versions of the program, other currency units per kWh, depending on your International settings in Windows) stored in the program to get a total cost per day. You can set the Power Cost value in the Prime Mover tab of the Surface Equipment Selection window. The default value that is used comes from the Defaults tab of the Edit-Preferences window. PC-PUMP uses $0.05/kWh unless you have changed it, or unless the currency setting is not dollars (in which case a default value would have been entered when the program was installed or first run on your computer). The values you have entered for electric motor efficiency and power factor will have an effect on the results. Note that some power companies will charge other fees beyond the energy costs, such as demand charges and power factor charges. These are not included in the result provided by PC-PUMP.

A: In reality, negative pressures are not physically possible. In single phase mode, PC-PUMP will give an error in this case even though it will complete the calculation and show a result—if this was a multiphase case, the program would not complete the calculation. What is causing this is excessive flow losses between the perforations and the pump intake. If you are in surface drive, this is most likely to occur if you have a tail joint, and is more likely to occur if the tail joint is very long or of a small tubing size. If you are in downhole drive mode, you probably have a very small clearance between the motor and casing (or a shroud that is causing there to be a small clearance either between the casing and the shroud OD or between the shroud OD and the motor, or both). In either surface or downhole drive, high flow rates or very viscous fluids will exacerbate the problem.

A: This occurs only in multiphase flow. Many of the correlations that are used to determine fluid properties (such as dead and live oil viscosity, solution gas ratio, bubble point, etc.) were not designed to work in heavy oil. Those correlations which were intended for use in heavy oil may only be applicable to oils from certain regions. With heavy oil, there is much more regional variation in properties (for oils with the same API gravity) than there is with medium or light oil. PC-PUMP will allow to continue your calculation—this is just a warning message and not an error. We do recommend, however, that you enter your oil’s actual dead oil viscosity at several temperatures in the Advanced Viscosity window. This will remove one correlation and should significantly improve the accuracy of the results.

A: This is in relation to the single-phase, specify fluid composition option. PC-PUMP makes several assumptions about the way the sand affects the density. If these assumptions are correct, the density calculation will be accurate at any sand cut, but if they are not correct, the accuracy will decrease as the sand cut increases; 10% was chosen as the limit at which to issue a warning. The four assumptions used are: 1) The sand cut is based on the level of the sand in a test tube after being spun in a centrifuge. 2) The water cut is based on the difference in the levels of the sand and the oil/water interface in the test tube. 3) The sand has a porosity of 40%. 4) The porosity of the sand is filled entirely with water (even if the water cut is specified as 0%).

Auxiliary Calculations

A: If no wellbore survey is entered, no wear will be calculated. (Note that you may still have wear in wells that are considered vertical, as some supposedly vertical wells are drilled very poorly. Without a survey, however, PC-PUMP cannot calculate any wear.) You must also click on the Calculate button in the Wear window before results will be displayed. Lastly, if every rod in the deviated section has spin-through guides (and couplings if the Couplings and Guides contact mode is selected), then the wear rate will be reported as zero—see below for more information.

A: If a spin-through centralizer or rod guide is working as designed, there is no sliding contact against the tubing wall, and therefore no wear on the tubing wall. PC-PUMP does not consider wear on or in the guide/coupling.

Demo Version

This problem is usually due to a communication issue between your computer and the internet based hardlock. Please check the following:

If your computer is located behind a firewall, can you verify that the network supports NAT (network address translation) for the computers inside and that they can communicate on port UDP 3047. If there is a firewall in between and it is blocking this communication then you will not be able to see our hardlock server. If the computer is directly connected to the internet then it could be a firewall package on your computer that is blocking the communication.

Can you open the control panel for your computer and do the following:

1. Open the System object by double-clicking on it.
2. Select the Advanced tab
3. Click on the "Environment Variables.." button
4. Look for the following environment variables in either the user or system variables
a. HL_SEARCH=IP
b. HLS_IPADDR=hardlockdemo.cfertech.com
c. HLS_WAIT=5000