SPE - Society of Petroleum Engineers Artificial Lift Systems Questions and Answers 1

Question 1

An engineer is selecting an artificial lift system for an offshore well characterized by a high production rate (>10,000 BPD), moderate depth, and a low gas-oil ratio (GOR). The wellbore is deviated. Which artificial lift system is most suitable for these conditions?

Accepted Answer

Electrical Submersible Pump (ESP)

Answer

Electrical Submersible Pumps (ESPs) are specifically designed for high-volume applications and are commonly used offshore due to their compact surface footprint and ability to generate the high horsepower required for large flow rates. Sucker rod pumps are generally unsuitable for deviated wells and have lower volume capabilities. Gas lift is more efficient in wells with higher GOR. Plunger lift is a low-volume system for high-GOR wells.

Question 2

In a continuous-flow gas lift design, what is the primary function of the deepest valve, also known as the operating valve?

Accepted Answer

To provide the primary and deepest point for continuous gas injection into the production tubing.

Answer

In a continuous gas lift system, shallower 'unloading' valves are used to start the well by displacing heavy fluids. However, once the well is operational, the operating valve, which is the deepest valve, serves as the primary and most efficient point for continuous gas injection to lighten the fluid column and sustain production.

Question 3

Which of the following conditions represents a significant operational limitation for Progressing Cavity Pumps (PCPs) due to the material properties of their standard components?

Accepted Answer

High bottom-hole temperature.

Answer

Standard Progressing Cavity Pumps use a stator made of a synthetic elastomer. High bottom-hole temperatures (typically >250-300°F) can cause this elastomer to swell, degrade, or otherwise fail, leading to rapid pump failure. While PCPs are an excellent choice for viscous and abrasive fluids, temperature is a critical material limitation.

Question 4

An operator analyzes a downhole dynamometer card from a sucker rod pump and observes a sharp drop on the downstroke that occurs before the plunger reaches the bottom of its stroke, followed by a sharp impact line. What is the most likely cause of this 'fluid pound' signature?

Accepted Answer

The pump's displacement capacity is greater than the well's inflow, causing incomplete pump fillage.

Answer

Fluid pound occurs when the pump barrel is not completely filled with liquid on the upstroke. On the subsequent downstroke, the plunger falls freely through the gas-filled void until it impacts the top of the liquid column, causing a damaging shock load. This condition is a classic sign that the pump is trying to lift more fluid than the reservoir can provide, also known as being 'pumped off'.

Question 5

Plunger lift is an artificial lift method that is most effective and economically advantageous under which specific set of reservoir and well conditions?

Accepted Answer

High gas-liquid ratio, sufficient bottom-hole pressure to lift the plunger, and a tendency for liquid loading.

Answer

Plunger lift harnesses the energy from a well's own produced gas. It is most effective in wells with a high gas-liquid ratio (GLR) that can build up enough casing pressure during a shut-in period to lift the plunger and the accumulated liquid slug to the surface. It is specifically applied to mitigate liquid loading in gas wells or produce high-GOR oil wells.

(SPE) Society of Petroleum Engineers Certification Practice Test

(SPE) Society of Petroleum Engineers Certification Practice Test

SPE - Society of Petroleum Engineers Artificial Lift Systems Questions and Answers 1