A New Approach to Facing Rod Pump Challenges

Worldwide, there are approximately 2 million oil wells and 37.5 percent of these use rod pumps as the artificial lift method. Alternative methods such as electrical submersible pumps, gas lift systems, and progressive cavity pumps are used on 12.5 percent of the wells.

Rod pumps face many operational challenges. Some of these challenges consist of:

• Mechanical wear
• Corrosion
• Pump failures
• Inefficient pumping

The most common challenges are mechanical wear and corrosion, both of which lead to a constant battle to decrease failures and workover costs, especially as a field matures and water production increases. Corrosion and wear management are an essential part of optimizing operations. There is extensive information available in literature about traditional mechanical wear and corrosion mitigation methods. Below are some examples of the most common mitigation methods:

• Use rod guides to prevent rods and rod couplings from contacting tubing
• Install rod rotators to distribute the wear equally
• Utilize pump-off controllers so the well is not pumped off, and only actively pumped when sufficient fluid is available
• Use corrosion inhibitors to oil-wet the tubing and rods in high water cut wells to provide lubrication

A new type of rod pump, the Linear Lift System (LLS), was recently developed. The LLS aids in directly addressing inefficient pumping and mechanical wear and indirectly addresses pump failure challenges; the LLS will be the focus of this blog.

Fig-1 Traditional Rod Pump

Fig-2 Linear Lift System - Mounted Unit

Linear Lift System (LLS)

Rod pumps are activated with a pumpjack as shown in Fig. 1. The LLS is an innovative design to pumpjacks as shown in Fig. 2. The downhole equipment is the same as a conventional rod pump system, essentially consisting of tubing, rods, and a pump. The difference is in the surface equipment, which is smaller in size and has an automatic pump-off controller and a self-adjusting, ultra-long variable speed stroke. These characteristics have several potential advantages over the traditional pumpjack and rod pump installation. These advantages include:

Characteristic	Advantage
Self-adjusting, ultra-long variable speed stroke	Leads to more efficient pumping
Automatic pump-off controller	Reduces rod and tubing mechanical wear
Smaller surface equipment / pad	Decreases environmental impact
Increased load range	Increases efficient pumping

The integrated pump-off controller software automatically senses downhole conditions and changing fluid levels. The pump-off controller also adjusts the unit speed to maintain optimum fluid levels, which prevents pump-off conditions and reduces the effects of fluid pound on the rod string. These result in a decrease in rod / tubing wear and pump failures and leads to more efficient pumping conditions. The benefits of these operational advantages are an increase in daily production and a reduction of downtime.

A Halliburton case study shows that production doubled after replacing the conventional pumpjack with the LLS. Production improved by the ability to control the speed of the downstroke and make real-time adjustments to provide more efficient pumping. Long-term use of the LLS is expected to provide additional data that will confirm some of the other advantages listed previously. The LLS is a relatively new technology with very few case studies compared to rod pumps, which have been used for decades. However the few case studies that do exist are proving this new linear lift technology to be very promising.

Final Thoughts

With 37.5 percent of today’s global wells using rod pumps, it is crucial that we optimize their operations. We live in an exciting time with the development of new technology that has the capability to more efficiently undertake a well’s operational challenges based on optimizing the design of surface equipment.