Artificial lift is considered by oil and gas production companies mainly to increase production by reducing cost. This process requires clear understanding of hydraulic, mechanical and electrical basics of the artificial lift system in addition to strategic planning. Everyday companies are thriving and doing their best to reinvent technologies for achieving higher production at reduced cost. Artificial lift systems can be divided into three basic categories i.e. pump-assisted; fluid-assisted; and flow enhancement techniques. Within these three categories, 11 different types of lift technologies are used currently. However, following are the main types of Artificial lift systems popularly used in the industry:
In last two decades the demand for Artificial Lift system has been increased many folds. The requirement of artificial lift systems is expected to rise further with the new discoveries in offshore and onshore fields, unconventional shale gas fields and also with the increase in exploration and production activities worldwide. Market research says the global artificial lift market was valued at $10,197.4 million in 2013, and it is projected to reach a value of $17,730.2 million by 2019. North America is projected to be the largest market for artificial lift systems by 2020. Amongst various type artificial lift system, Electrical Submersible Pump (ESP) is the most dominant type in the global artificial lift systems market.
Technological issues with conventional artificial lift
Liquid loading below conventional down-hole pumps (sucker rod & ESP) is a major problem in wells with horizontal or deviated sections. Additionally, high gas to liquid ratios (GLRs), deep reservoirs, or long perforated intervals are some other challenges which operators are constantly trying to overcome. Operators generally prefer to install down-hole pumps in a well’s vertical section, above any perforations or deviations, to prevent high maintenance costs and inefficiencies resulting from frictional wear on tubular, solids sticking the down-hole pumps, and gas interference in the pump. In many instances, the pump is placed many hundreds to thousands of feet above the reservoir. Since down-hole pumps cannot recover liquids that exist below them, liquids build up above the reservoir and causes significant back pressure, reducing or even ceasing the production, resulting in a lower eventual ultimate recovery (EUR) and premature abandonment of the well.
Further plunger lift and soap strings only operate in a narrow range of well conditions and do not effectively lower the bottom hole pressure. Jet pumps are difficult to operate, have environmental concerns with power fluid, and are very inefficient with low BHP and high GLR’s. Hydraulic piston pumps also have environmental issues with power fluid and are inefficient at high GLRs.
Selection and Monitoring of Artificial Lift system
Selection of the most economical artificial lift method is necessary for the operator to realize the maximum profit from developing any oil or gas field. Historically the methods used to select the type of artificial lift for a particular field have varied broadly across the industry, including
- Determining what methods will lift at the desired rates and from the required depths.
- Evaluating lists of advantages and disadvantages.
- Use of “expert” systems to both eliminate and select systems.
- Evaluation of initial costs, operating costs, production capabilities, etc. using economics as a tool of selection.
Monitoring production data from installation of artificial lift system is very important to analyze flow enhancement, operational cost and other parameters. Real time monitoring of such system provides continual optimization of performance at the field and reservoir scale. This is considered as a major step forward which can introduce game-changing capabilities for producers.