Rod Pump Assisted With Compression
While most operators are familiar with using a rod pump for artificial lift, many overlook the opportunity to reduce the bottom hole flowing pressure and increase production by assisting with a rotary screw compressor. Using this method of production, operators also see a decrease in gas locking in downhole pumps, which increases “fill-up” and pump operating efficiency.
How it works
Depending on the pad set up, operators can connect a rotary screw compressor to either the casing line of a single well, or the separator on a pad of wells. The compressor becomes a gathering system on all casing head gas, relieving and lowering the pressure at surface, and in turn increasing the differential pressure between the casing line and the bottom hole pressure. This allows reservoir fluids to flow more freely into the wellbore, resulting in an increase in both oil and gas.
Additionally, if the downhole pump is experiencing gas locking, the well is operating in inefficient conditions. Due to internal clearance and spacing, downhole pumps often leave un-swept areas. This creates space for gas to become trapped and expand on the upstroke. Rather than having fluid entering the pump, a cycle begins of gas expanding, preventing fluid to enter, and compressing back into the original space. Tying in a rotary screw compressor to the casing line help to alleviate this issue, allowing for increased pump fillage, as stated above.
Permian case study
A Flogistix customer had an eight well pad producing from the Sprayberry and decided to use rotary screw compression to gather all casing head gas. This lowered line pressure from 35psi to 17psi, resulting in an increase from 55 to 105 barrels of oil per day and gas increase of 370 to 659mcfd.
Always evaluate older or low production wells on rod pump to determine if they are a candidate for a compression assist. An easy addition of a rotary screw compressor could easily increase your recovery. For an even more in-depth look at this application, please see SPE paper 38211, which provides details of oil and gas recovery from the El Tordillo field in the Gulf of St. George Basin, Argentina. Please visit www.flogistix.com for further case studies and information.