The electric submersible pump (ESP) industry is significant in size, with about 150,000 ESPs operational in the world today. Borets’ dedicated R&D department has focused its resources on the global land market, paying particular attention to unconventional shale plays. A focused team of engineers at the company is devoted to developing a whole new range of ESP technology centered on the concept of driving artificial lift from downhole rather than from surface. The team has developed a radically different platform based on the company’s permanent magnet motor (PMM) technology.

PMM
A decade ago, company engineers developed the concept of the PMM and have developed it into the mature product it is today. PMMs offer an alternative to the older and more established induction motor concept.

PMM and induction motor stators are similar: Both have three-phase armature winding, which generates a rotating magnetic field. Both have housings, heads and bases, shafts and bearings that are similar. However, PMM and induction motor electromagnetic processes, which participate in energy generation, have significant differences.

PMMs are about 15% more electrically efficient than induction motors, meaning that billions of dollars in savings could be achieved if PMMs were to be adopted industrywide and millions of megawatts of unnecessary power use could be avoided. In Europe in particular the adoption of PMMs would qualify a company for the award of carbon credits and reduce its environmental footprint considerably.

Because the PMM has much greater power density than the induction motor, considerably higher horsepower can be harnessed in a shorter component. For example, the company’s 5.62-in. diameter motor can deliver 1,000 hp in a single motor section. Currently, three sections of induction motors, 27 m (90 ft) long, are required to generate the same as one 9-m (30-ft) long PMM section. Therefore, PMMs are ideally designed for future use in offshore wells, where the absolute highest horsepower possible in the shortest package is advantageous.

Offshore wells and unconventional land wells often are deviated; therefore, shorter units can more successfully navigate these geometries. Additionally, in an offshore environment a 27-m motor will need to be handled and assembled in three pieces, resulting in more points of potential failure and increased time spent rigging up in an expensive offshore environment. Several large research projects aimed at exploring deepwater high horsepower applications are ongoing.

Borets has more than 7,000 PMMs sold into the oil field today, and the uptake of this technology in the industry is growing significantly.

New technologies based on PMM platform
Developed on the platform of already-operational PMMs are a number of new technologies applicable to the unconventional land market. One is the PMM progressive cavity pump (PMPCP).

Traditionally, when using a PCP, companies drive the pump from the surface with a drive head and drive rods. In highly deviated or crooked wells, this becomes the key wear point and main mode of failure in the system. The only truly effective way to run a PCP in a deviated well is with a downhole motor as opposed to a surface motor. Borets uses the PMM motor to turn at an acceptable rpm for a PCP pump without the need for a downhole gear box to reduce the speed of the motor, which has proven to be the least reliable component in previous bottom-driven PCP systems.

The concept of using a PMM to drive artificial lift from downhole rather than from the surface is a new idea made possible with PMM technology.

The PMPCP is essentially a PMM that is constructed in a way that allows it to rotate at a slow speed (in the 500-rpm to 700-rpm range) and that allows connection to a conventional PCP. It can be used in wells that are too deviated to accommodate traditional PCPs, which rapidly wear out in such environments. By operating the pump from downhole, the PMPCP eliminates
multiple well workovers over the course of a pump’s lifetime.

Also recently launched into this suite of technology is a new variable speed drive (VSD) that works in conjunction with the PMM, known in the industry as AXIOM II. A unique aspect of the AXIOM II is that it is capable of running both an induction motor and the PMM. It offers unique functionality that provides operators the flexibility to use PMMs and apply a VSD solution to optimize production while not creating inventory or training issues with existing equipment.

High-speed WR2 system
Another technology recently launched by the company is the high-speed wear-resistant/wide-range or “WR2” system. The system includes a high-speed pump, a PMM and a monitoring package. The manufacturing of the WR2 system uses metal-injection molding. This method was previously used on very small parts such as those found in medical devices. It has been scaled to a size large enough to be deployed in downhole oil and gas applications. The new method of pump manufacturing enables the development of unique hydraulic designs and new materials for stage manufacture.

The new patent-pending processes involved in metal-injection molding allow engineers to use geometries that cannot be economically produced in a foundry. Because the geometry is different to what can be made in a sand cast, it has a unique geometry that cannot be recreated in a conventional pump, resulting in better gas handling. When finished, the mold is close enough to the desired finished form and at the required tolerances that minimal machining is required. Therefore, a very hard material can be used, close in hardness to a ceramic bearing, enabling it to handle sand flowback yet survive for an acceptable runlife.

The WR2 system is a complete system built in combination with a PMM. As a result of the PMM and the way the pump is designed, it can be turned at a very high speed. Conventional ESPs run between 3,500 rpm and 3,600 rpm, but the WR2 system can run at 6,000 rpm. In pump terms, this means everything can be made shorter and more efficient, resulting in a much-improved tool for navigating deviated and horizontal wells. Its improved energy efficiency also results in lower power costs.

Eleven WR2 systems have been run outside North America so far and five within North America. The initially released pump has an efficient pump range from 400 bbl/d to 1,900 bbl/d and covers a wide range of operation at a high efficiency.

In the current industry climate of cutbacks and money-saving initiatives, completing a well now with a system that will use 15% less energy over its lifetime represents a significant saving, making it an appropriate time to transition to PMMs for new wells. The efficiency of the WR2 system allows clients to optimize their financial return in the early period of the well when they are looking to pay back the investment in the fastest way possible.

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