Artificial Lift

The most common form of artificial lift is sucker-rod pumping.  One of the main elements of rod lift system design is the selection of a downhole pump.  This study examines the various factors that affect the selection and design of downhole rod pumps. Downhole rod pumps are made up of five main components: barrel, plunger, balls and seats, seating assembly, and valve rod or pull tube.  Understanding the various well and system design factors that are examined when selecting each of these components is a crucial part in the design of the downhole pump.

Automation of rod pumping systems has been a part of the oil and gas industry for over 65 years.  Starting with time clocks in the 1950s, the invention of the pump-off controller in the 60s, and variable speed drives in the early 2000s, the amount of technology available to both control and analyze the system has increased and improved drastically. Several of the driving factors to automate include high initial production rates, followed by a steep decline, gas slugging, high degrees of rod and tubing friction, and paraffin build.

Rod wear and corrosion have a complex relationship that is often misunderstood of oversimplified.  This paper provides a technical framework and provides empirical evidence of principles that clarify this complex relationship.  In particular, this paper will review stress levels and metal failure mechanisms that dispel many commonly held beliefs.  A better understanding of these principles will lead to opportunities to reduce an operator’s total operating footprint.

Downhole sucker rod pump clearance changes from shop conditions to bottom hole conditions due to bottomhole pressure and temperature that the pump components are subjected to. Presented here are equations to estimate the change in dimensions of the plunger and barrel of top and bottom hold down pumps at bottomhole pressure and temperature conditions.

Pumping wells hard involves a tradeoff between operating cost and production. Increased idle time or holding additional back pressure on the reservoir can decrease production but pumping a well harder will likely increase failure frequency. The existing reservoir pressure has a significant impact on the potential change in production.  Pump-Off Controllers (POCs) are used to regulate run time on many wells operated in Permian Basin water floods and are accepted as a failure reducing and cost saving tool.

New unconventional wells have been a huge challenge for ESPs in the Permian Basin because in horizontal wells with high-formation GORs or GLRs, the pumped fluid can cause issues such as gas interference, gas locking, short run life, low production, poor energy efficiency, increased failure rates, shutdowns, so forth. A major problem is gas presence around the ESPs, it causes the motor to rapidly overheat because the gas is incapable of adequately cooling.

Failures due to solid particles flowing with the production fluid is one of the main causes of interventions in wells with beam pumping systems. When this problem is accompanied with chemical deposits like scale, the interventions become very common operation in the well. This paper proposes an analytical methodology that consists of evaluation of the particle size distribution, viability for the use of sand screens and centrifugal separation systems for sand control management in wells with short run time.

America needs energy. Good techniques (Vogel’s Method and Constant PI) exist for estimating production from wells. These are phrased in terms of pressure. Pressure is not easy to measure especially in deep gassy wells. Fluid level is a logical remedy for the problem and can be measured at virtually any depth. But this creates the need for a method for deriving pressure (PIP) from fluid level. Wally Gilbert derived the first method in 1955. It was not used widely because casing gas (mcf/d) had to be vented while measuring it. This was a pollution no-no, then and now. In 1983 Echometer (J.

Historically as many as 30% of bottom hold down pumps have been stuck. This can result in extra cost associated with pulling tubing on pump repairs or rod failures. This paper focuses on efforts with various tools and techniques that have been used to lessen the number of pumps stuck in tubing.

Relating Polished Rod Velocity and ratio of MPRL/PPRL to Failure Frequency. This study uses historical data to understand these relationships. The data is primarily from San Andres and Clearfork water floods and CO2 floods located in the Permian Basin.