Technology Focus: Artificial Lift (October 2021)

What, a second artificial lift focus feature this year? What’s going on? Well, maybe I can answer your questions with another round of questions: Do you know how many of your organization’s wells are artificially lifted? Or, more importantly, do you know what fraction of your production volumes are dependent on artificial lift? I would wager that the percentages are higher than you would expect, and I encourage you to seek out that information and share it. Share it with your asset team, share it with other asset teams, share it with other functions, share it with your management, shout it from the rooftops! Seriously, though, this information can be quite useful to you and your organization. Did you ever wonder if someone else could be struggling with the same artificial lift selection, installation, operation, or reliability challenges that you are? The answer you’re looking for may be in the SPE archives, or it may be just down the road with a colleague in a different part of the region, country, or world. Do you have a novel new technique, system, or invention that you want to try out? Why not leverage the knowledge that others in your company could also benefit from? Maybe they would even like to participate and strengthen your pilot with a broader range of test conditions. Do you need more personnel or technical or financial support for artificial lift in your asset? Show precisely what those electrical submersible pumps (ESPs), rod pumps, gas-lift valves, and plungers (among others) are lifting to the flowline. Sometimes a step back to a higher-level view can motivate and reinforce the people behind the day-to-day efforts to extend the time between failures and chase optimum performance. I’m certain that you are now a (possibly unwilling) expert at videoconferencing. That’s why I would like to encourage you to attend the 2021 SPE Electric Submersible Pumps Symposium, to be held 4–8 October in The Woodlands, Texas. Of course, the technical presentations will be well worth it, but you may gain even more value from the networking, collaboration, and idea generation that happens between the events listed in the program. Not an ESP person? Do gas and sand separators, power cables, advanced materials, and downhole sensors apply to other lift methods or well systems in general? How about applied artificial intelligence, reliability studies, and predictive analytics? Maybe they don’t for you right now, but they could. I hope to see you there. Recommended additional reading at OnePetro: www.onepetro.org. SPE 201153 - Intermittent Gas Lift for Liquid-Loaded Horizontal Wells in Tight Gas Shale Reservoirs by Daniel David Croce, Colorado School of Mines SPE 202668 - Insert Sucker Rod Surface-Controlled Subsurface Safety Valve: A Step Ahead To Improve the Well Integrity for Sucker Rod Artificial Lift Retrofitting by Salvatore Pilone, Eni, et al. SPE 201136 - New Stage of Rodless Artificial Lift Operation: The First Field Application of Submersible Motor Cable Plug With Electric Submersible Progressing Cavity Pump in CNPC by Shijia Zhu, China National Petroleum Corporation, et al.

Comparative Analysis of Temperature Field Model and Design of Cooling System Structure Parameters of Submersible Motor

The reliability of submersible motor is the key to determining the stability of the middle and deep sea exploration and development equipment. In this paper, in view of different equivalent modes of convective heat transfer of housing surface, two temperature field models are established in the finite volume method (FVM). The unidirectional and bidirectional coupling mode between loss and temperature of motor are analyzed, and the temperature calculation results are compared when the oil friction loss and copper loss are constant and variable. Then, the bidirectional coupling mode between radiator temperature field and cooling system internal flow field is determined based on the structural parameters of radiator and cooling circulation impeller. The circulation flow is simulated and the influence of different loss unidirectional coupling modes on the temperature field is compared. Finally, the cooling system design procedure is proposed to obtain the matching relationship of the same cooling system structure parameters of the two temperature field models. Experimental validation is presented, and a more reasonable temperature field model is obtained under the coupling mode proposed. It provides the necessary theoretical basis for the research on the submersible motor cooling system.

Simulation of oil cooling of a submersible motor using a heat exchanger

Submersible motors are part of submersible oil production pumps that convert electrical energy, which is supplied through a cable from VSD, into mechanical energy of pump rotation. Currently, in about 30% of cases, the failure of an electrical submersible pump is due to a failure of the submersible motor. One of the main causes of failures is overheating of the stator winding insulation. Overheating of submersible oil-filled electric motors occurs because more heat is generated inside the motor than is removed through its outer surface. To intensify the heat removal, it is proposed to connect a heat exchanger in series with the motor and to organize the circulation of the oil in a closed loop. Both in the submersible motor and in the heat exchanger, oil flows along the annular gap along the inner surface of the housing, the oil channel is closed through a hole inside the shaft. The aim of the work is to select such a configuration of the annular channel, in which its length would be minimal. Intensification of heat removal by increasing the speed of the coolant is not advisable, because requires the motor to be equipped with a powerful pump for pumping oil, which will become an additional source of heat. Therefore, it was decided to increase the surface area of the annular channel through which heat, through the body of the installation, is removed to the well fluid. A series of calculations was performed for heat exchangers with smooth walls, with fins (perpendicular to the flow direction), and with spiral grooves (which additionally increase the length of the trajectory of oil particles and the time of their thermal contact with the stacks of the heat exchanger body). Computational fluid dynamics calculations showed that heat exchangers made according to the first two design options removed less than half of the heat. According to the third option, the oil was cooled practically to the temperature of the well fluid with a heat exchanger length of about 10% of the submersible motor length.

Calculation of winding temperature of a submersible motor

The article is devoted to the issue of control and regulation of the high-quality operation of a submersible motor with a long overhaul period. There are some complications of operating the electric submersible pump. One of them is the thermal interaction of the borehole fluid and components and parts of the electric submersible pump that leads to failure and repair. It is necessary to conduct research in the field of physical and hydrodynamic calculations to determine the effect of heat exposure. The article reveals one of the approaches to solving the problem of thermal interaction between a well and the electric submersible pump. We describe calculations of the winding temperature of a submersible electric motor for specific conditions in a particular well, including different modes of fluid flow, different loads of the submersible motor, and different concentrations of oil in water. The development of the described technique will allow creating special software aimed at determining the areas with the highest temperature of the motor winding, taking into account various parameters that affect the heat transfer process.

Recommendations for Long-Term Operation of High-Performance Submersible Motor Pumps in Mine Dewatering

Modern submersible pumps are high performance aggregates for long-term operation, which find application in open-pit mining. Dewatering of groundwater to run an open-pit mine with various conditions for submersible pumps often leads to short-term performance based on different circumstances in the well as well as in the general operation. These result in high maintenance and energy costs and decreases the drawdown in open-pit mining. To ensure a long-time performance, a proper selection of submersible pump and motor is required. It is also necessary to consider the geometry of different deep wells in order to take into account the initial conditions of the pumps. This paper shows recommendations for long-term operation of high-performance submersible pumps due to the conditions of the mining industry. Therefore, a holistic consideration of the aggregate takes place to receive recommendations, which minimize the rate of pump failures and increase the efficiency of the dewatering process. These recommendations are based on various failures found during an investigation. Furthermore, this paper recommends different methods to prevent these failures, for instance clogging and erosion through particles in the well. These recommendations are linked to the research of different submersible motor pumps from various manufacturers in different wells in German open-pit mines with short-term operation caused by several circumstances.