Rod Pump Performance in Heavy Oil Applications

[REP45]

Can anyone help me find information on problems that arise and changes that need to be made in rod pumping system designs for heavy oil (high viscosity) applications?

 

[KernOily]

I am not a downhole guy but I've been exposed a little. Most of the downhole guys around here (San Joaquin valley) depend on the rod pump vendors (Herco, etc.) to bail them out. They seem to have a lot of knowledge on what works and what doesn't in regard to design of the overall system. Besides that, isn't it just the usual adjustments for viscosity etc. for flow up the tubing? Thanks!
Pete

 

[yimc]

One of the things that is affected is the fall rate of the rods. Usually sinker bar is the recommended solution to the problem, and this is not (in my experience anyways) normally run in high water cut or maturing fields. This will affect rod loading.

Also, ensuring adequate fillage of the pump is very important, as the inflow rate is normally not as great as lower vis. fluids. Therefore, a slower stroke rate is recommended.

There can also be significantly greater sand production in heavy oil applications as well, and the resulting abrasion can be challenging. This depends on volume of sand, "angularity" of the sand grains and grain composition.

 

[dadfap]

REP45

For heavier crudes Progressive Cavity Pumps may be a better bet if you are at the front end of the develpoment or are experiencing repetative failures / problems with the rod pumps.

all the best

dadfap

 

[yimc]

dadfap is absolutely right on the mark when he says PC Pumps may be better. Just to add a couple points, PC Pumps (for tubing) normally start at about 4 m3/day (/100 rpm) which is about 25 bbl /day. If you have a very small rod pump in the well, you may need to look at something like an insertable tubing PC Pump which can go down to about 6-7 bbl. They are quite a bit more expensive that regular PC Pumps.

There are a number of other factors to consider as well; water cut, oil composition, GOR, fluid level, et. al.

PC pumps will be harder on your tubing, as the rods tend to spin in one spot. This may be an issue if you have a badly deviated well.

 

[dadfap]

yimc

PC pumps are still a viable option in a deviated well as they can now be driven using a standard ESP motor.

There is the addition of two components 1. gear reducer, 2. flex shaft to isolate the eccentric motion of the PC pump from the motor.

Go look at

http://www.centrilift.com/PCPS/default.htm

and you will get some idea. Admittedly they are not cheap, but if you are continually fishing rods or working over the well because of the deviation, they provide another alternative to you.

All the best

dadfap