The recirculation method using a bottom hole choke to prevent intermittent production and prolong pump life in wells lifted with the Electric Submergible Pumps (ESPs) is a new technique that was developed in ARCO offshore North West Java Sea Contract Area.
In some of the new fields developed by ARCO, accurate well productivity data was not available at the time that ESP sizing operations were conducted. This limitation resulted in some wells having ESPs that were oversized in-comparison to the well's inflow liquid capacity.
This situation is undesirable in that the well intermits and causes the pump to operate outside its designed operating range. Pumps which operate out of the recommended range for a prolonged period of time will have a short run life in comparison to one that is properly sized.
In order to circumvent the problem either one of the following three options is available to the engineer.:
Allow the oversized pump to run until failure (if possible) at which point the ESP is extracted from the well.
Use the variable speed drive by reducing the frequency to get lower production rate.
Install a down hole choke to allow recirculation of well-bore fluids so the ESP well does not pump off. (i.e. the well does not intermit).
The last option has been pioneered in the ONWJ Contract Area and has saved a considerable amount of expense since the installation of a dowhhole choke only requires a slick line unit which is more cost effective than a work over or snubbing rig as option (1) above would require. Additionally, the use of the downhole choke has increased the average pump run life considerably field wide.