As most of you know, you can enter your own rod string design or you can have RODSTAR design the rod string for you. RODSTAR can automatically design an all-steel rod strings for any rod grade, or a combination of Fiberglass and steel. You can even have RODSTAR design a combination of Ribbon Rod and steel rod string.
Having RODSTAR design a rod string for you is not just faster but better in many ways. RODSTAR uses advanced expert logic in designing a rod string. This logic depends on rod type, pump depth, target production, and many other variables.
When you ask RODSTAR to design a steel rod string for you, you have to specify the rod grade you want, the maximum and minimum diameters to consider, and whether to use sinker bars or not.
From this information, RODSTAR determines the number of tapers needed and the required length of each taper to get equal stress loading at the top of each rod section. This minimizes rod loading and only uses the taper needed to avoid overloading the rods depending on the rod grade you select.
For example, if you select grade D rods, 1 inch maximum and ¾ inch minimum diameters, RODSTAR may come up with all ¾ inch rods for a shallow or lightly loaded system, or a combination of 7/8 and ¾ inch rods for a system with higher loads, or a full taper of 1 to ¾ inch rods for a system with heavier loads.
This saves you a lot of time and results in an ideal design for minimizing rod loading and rod string cost. Otherwise, you would have to decide what taper to use and enter your own rod lengths. This can be done but can take many runs depending on your experience. If you use an API rod string design you will end up with unequal rod loading for each section in most cases.
When you use RODSTAR to design the rod string you get the most accurate results since the program uses the wave equation to calculate rod loading. The API RP 11L does not.
Also, you can change the maximum rod loading the program uses to decide what rod taper you need. By default, RODSTAR uses a maximum rod loading of 95%. In other words, if the rod loading exceeds 95% RODSTAR will add another rod section of larger diameter to reduce the loading below 95%. If rod loading is still over 95%, it will add another larger diameter section (if this does not exceed the maximum rod diameter you specified).
If you prefer to use a different maximum rod loading number, all you have to do is click on the Setup icon on the tool bar and then click on the Defaults/Limits tab. Under Limits you will see the "Maximum desirable steel rod loading" value. You can type the value you want in this field.
For example, if you enter 90% then if the rod loading exceeds 90% RODSTAR will automatically add a larger diameter section in the rod string.
If you want to add sinker bars on the bottom, you must enter the diameter and length of the sinker bar section you want to use. RODSTAR does not automatically recommend sinker bar length since there is no industry accepted standard sinker bar diameter design method. However, RODSTAR will automatically design the rod string above the sinker bars.
The logic required to design a fiberglass and steel rod string is especially complex. However, the end result is a good design that has a long enough stroke at the pump to get the production you want without putting the fiberglass rods in compression, or resulting in excessive undertravel.
You have the option to include sucker rods under the fiberglass and sinker bars on the bottom. Or you can have just Fiberglass and regular steel sucker rods on the bottom, or Fiberglass and sinker bars without any regular rods in between.
The choice of rod string design depends on pump depth, rod string cost, and desired production rate. Regardless of the design option you select, RODSTAR speeds up the rod string design by automatically designing the rod string for you. If you select to have just sinker bars or a single diameter sucker rod under the fiberglass, RODSTAR designs both the fiberglass and steel sections by determining the diameters and section lengths required.
If you want RODSTAR to design a system with regular steel rods under the fiberglass and then sinker bars on the bottom, you must enter the length and diameter of the sinker bar section. RODSTAR will take care of the rest of the rod string design.
After RODSTAR designs a rod string, you can make adjustments to this design without having to re-enter it from scratch. To do this, after RODSTAR designs the rod string for you, go to the rod string entry window and change the rod string entry option to Manual Rod String Entry.
RODSTAR displays the rod string design in memory as if you had entered it yourself. Then, you can adjust it in any way you want. RODSTAR makes it easy to add or remove sections without having to re-enter the data for existing sections.