Artificial Lift

Gas and sand interference remain one of the most common challenges in the vast majority of wells in the Permian Basin. Gas interference can lead to poor pump efficiency and severe sand issues can lead to sticking and excessive wear and tear to the pump – both of which lead to unnecessary operational expenses and even well failure. Recognizing the ineffectiveness and shortcomings of current models of gas and sand separator systems and other mitigation technologies, WellWorx set out to design a more effective system to combat the dual issues in rod pump wells.

Sucker rod pump or “rod pump” is a common method of artificial lift for oil and gas wells in the United States. For decades well analysts and production engineers have looked at surface and downhole dynamometer cards to diagnose various downhole and surface equipment issues alike. In more recent years, helpful rod pump diagnostic tools have aided well analysts and production engineers in training and the analysis of downhole dynamometers utilizing generalized libraries with known behavior for downhole dynamometer cards.

The most common well profiles for reciprocating rod lift applications are deviated and highly corrosive wells. Many newly drilled horizontal wells exhibit moderate to severe deviations which require the pump to be set in the curve to produce intended target zones; resulting in a challenging environment for rod lift systems to successfully operate. These wells tend to be accompanied by corrosion, furthering the possibility of premature failures on all downhole equipment: rods, tubing, and pumps. 

Longer laterals, better perforations and larger frac jobs have all enabled increased production capabilities, yet production optimization practices have remained stagnant and, in doing so, limit the ability to draw wells down more aggressively. The data provided in the most common fluid level processes does not meet the challenges generated by fluctuating well dynamics and conditions. The irregularity and inconsistency of current fluid level measurement systems provide an incomplete snapshot of the well conditions when a more complete solution is needed for optimization.

Deviated wells have now been the standard form of drilling, increasing well life and production but also creating challenges in the Artificial Lift System, specifically the Reciprocating Rod Lift (RRL). With aggressive drilling deviations rod string guiding becomes a requirement, landing pumps in 45+° zones a normal, and gas mitigation a complete necessity to achieve target productions. 

In the past 10 years, drilling methods have drastically reduced the time it takes to drill wells. This is especially true in today’s unconventional shale market where 20,000 ft wells are being drilled in under 14 days. This increase in drilling rates along with increasing depths and deviations has presented many challenges for the conventional rod lift system, which was designed to last for ten years but are now having issues within the first twenty-four months resulting in substantial increases in workover costs.

One requirement of a Class VI Underground Injection Control permit involves continuous monitoring and reporting of injection pressure. Wells in pilot and commercial scale carbon dioxide (CO2) storage sites are equipped with devices that measure pressure and flow rate during injection operations. Downhole device failures have occured during CO2 injection operations in projects, which prevent bottom hole pressure measurement and require time consuming repairs.

Two widely used methods of artificial lift are Electrical Submersible Pumps (ESP) and Sucker Rod Pumps (SRP. Each of these methods frequently require methods to avoid or handle gas for successful operations. Presented here are discussions of methods of gas separation for each method and graphical techniques for prediction of the gas separator performance that will allow the user to better select a workable gas separator system and predict maximum well drawdown with the selected method of lift. 
 

It is recognized in the industry that it is wise to have AL in place before liquid loading is expected for a number of reasons.  These reasons include no production loss when the well drops below critical, convenience as the rig may/may not be available when the well drops below critical later, and in some cases some uplift is observed when installing plunger other AL before the rate drops below a calculated predicted critical. The discussion here concerns installing plunger lift in deviated wells in advance of predictions from well-known methods that say the well is not liquid loaded.

In unconventional wells unstable dynamic behavior ensuing from an exchange of energy in the casing and tubing is the biggest challenge in gas lift design. As reservoir and tubing pressures decline from early conditions, wells show erratic behavior in decreasing fluid levels and hence unload and operate at variable depths. This case study presents the full workflow of creating an effective gas-lift design from concept initiation to execution and field installation.