Jeff Saponja and Corbin Coyes, Q2 ALS
Kell Coleman, Devon
Sucker rod pumping can experience reliability challenges when produced fluid contains solids. Any improvement in the ability for a sucker rod pumping system to handle solids would be highly beneficial.
The sucker rod pump is one component of a complex downhole system of components for sucker rod pumping. Other components of this system include a downhole gas separator, a downhole solids separator, a tubing anchor and sucker rods. To maximize the efficiency and performance of a sucker rod pump, all these components must act together harmoniously to effectively feed the pump on demand with liquid that has been gas and solids depleted – unfortunately, achieving this has been particularly challenging. Consequently, the sucker rod pump and sucker rods must still contend with gas and solids.
Solids that travel through a sucker rod pump can be transported or carried to surface only if the average liquid velocity inside the tubing exceeds the solids settling velocity. If the average liquid velocity is less than the solids settling velocity, solids that have travelled through the pump will accumulate inside the tubing. Inevitably, the well will need to be shut down and these accumulated solids can settle on top of the pump and/or around the sucker rods. Upon restarting of the pump, the pump or sucker rods can be seized by the settled solids, forcing a costly workover. This is a common problem for wells that have be hydraulically fracced with sand.
Electrical Submersible Pumps (ESP’s) have employed solids fallback protection tools, which have proven to be effective. They are simple designs; in that they prevent solids from settling in the tubing to the ESP after a shut down. Use of staggered collection chamber weirs and sand screens prevents solids from settling to the ESP. Upon restarting of the ESP, the solids collected are flushed from the chambers with aim to carry the solids to surface and out of the tubing. ESP’s generally are used for higher production rates and often have enough liquid velocity inside the tubing to efficiently carry the solids to surface. Therefore, these existing ESP oriented tools are not designed to permanently contain solids downhole.
For a rod pumping system where the liquid velocity is inadequate for carrying the solids to surface, a permanent “out of harms way” downhole containment solution would be required for a solids fallback prevention tool. Additional design challenges include the need for full tubing internal drift diameter to allow passage of the pump and the fact that there are reciprocating sucker rods inside the tubing.
A new patent pending solids fallback prevention tool has been developed for sucker rod pumping. Tool’s design features include:
• tubing conveyed with no moving parts,
• uses an external to the tubing eccentric solids collection chamber with multiple internal sub-chambers for permanent (large volume) downhole containment of solids until the tubing string is retrieved,
• multiple tools can be run in series above a sucker rod pump,
• has full tubing internal diameter for passage of rod pumps,
• 10,000 psi burst pressure rating, and
• does not interfere with the sucker rod string’s reciprocal motion.
Flow loop testing and field trials have indicated tool’s operability. The design process, prototyping and flow loop testing, and well trials/results will be shared.