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.