Within the oil industry worldwide, artificial lift (AL) has become necessary to achieve desired reservoir production and maintain commercial output levels. According to Spears and Associates, in 2005, about $50,000 was spent per every new well drilled, by the end of 2016 it is expected that this figure is above $300,000. Bear in mind that this is a figure to bring things into perspective, as part of that investment is in replacing equipment in older wells, however, it does tell an important story in terms of showcasing the evident growth of the service. In an ever-evolving industry, where the ultimate goal is reducing the costs per BOE lifted, being efficient is paramount to the overall success of an operation.
According to industry statistics (Spears 2016 Artificial Lift Market Analysis), wells fitted with electrical submersible pump (ESP) systems represent approximately 56% of the global AL market revenue-wise; representing the most common lifting method, followed by rod lifting, progressive cavity pumps (PCP), and gas lift in fourth place. Just as with any complex piece of equipment, these pumps must often be pulled out for maintenance or replacement, and retrieval is not a trivial task. Workover rigs are the usual workhorse for such operations; however, other equipment, such as hydraulic workover (HWO) units, can be used to perform the same task in a more efficient manner. The evaluation approach was based on analysis from operational times throughout the past year, comparing both the evolutionary improvement of the HWO interventions as well as the operations performed with a conventional workover unit.
HWO units offer several advantages compared to workover rigs when performing retrieval and deployment of ESPs. The most important are smaller footprint and shorter rigup times. Additionally, if a well exhibits wellhead pressure (WHP), only an HWO unit can be used to perform the work. For these reasons, in land operations in western Venezuela, HWO units have proven to be the method of choice for artificial lift equipment replacement operations. Because these wells produce from 1,000 to 3,000 BOPD, they are of paramount importance to Venezuela's production stream. This paper explains the necessary steps and procedures to complete such operations; additionally presented are study results showing decreased intervention time from 15 to 11 days, which is a significant increase in efficiency. Conversely, this study showed that it takes approximately 20 days to complete the same intervention using a conventional workover unit.
Lastly described is the evolutionary path of efficiency developed by the operations team to improve intervention results, which are based on key performance indicators and other qualitative data, providing solid evidence of improvement.