Avoid intervention risks with rigless options.
by John Algeroy, Greg Nutter

As horizontal wells in the U.S. become more established and gradually age, operators are continually challenged to select the optimal forms of artificial lift to sustain maximum production. In the current market, increasing the overall value of a well has never been so vital. As a consequence, the artificial lift market will experience substantial growth over the next few years.

Essentially, there are seven types of artificial lift: electric submersible pumps (ESPs), sucker-rod lift, plunger lift, gas lift, chemical lift, progressive cavity pumps (PCPs) and hydraulic pumping systems, and each have their pros and cons and are suitable for use in different contexts.

Why Choose ESPs?

With all things considered, ESPs frequently emerge as the best artificial lift option open to operators looking to cost-effectively maximize their reservoir production. However, the full potential of ESPs in offshore and remote locations has been restricted
by the high cost of intervention associated with rig deployment, the loss of production that it brings with it, and an inability to access the reservoir without pulling the production tubing. Crucially, repairing a damaged ESP system can be very expensive. In many cases, (when the rig is offshore or beset by permitting, rig availability or accessibility issues), a rigless ESP offers a more cost-efficient solution.

Rigless ESP Conveyance

One provider of rigless electric submersible pump (ESP) conveyance solutions has a unique system offers a significant cost saving and added value, as it simplifies the ability of an operator to quickly and easily install and retrieve ESP systems on slickline, without a rig. It is designed specifically for high-value wells, where access to the location is difficult (such as onshore Alaska, offshore West Africa, the Middle East and Southeast Asia), rig interventions are cost-prohibitive and where delays in production need to be strictly avoided.

This rigless conveyance system combines a robust production-tubing landing string with a side-pocket-mounted downhole wet connector and a high-power permanent magnet motor (PMM).

Example of a permanent completionFigure 1. Example of a permanent completion. Click on the image for a larger version. (Graphics courtesy of AccessESP)

Permanent Completion System

The permanent completion is deployed with the production tubing and is formed of two components: the side-pocket-mounted downhole wet connector and the connector orientation and latching system. The side pocket wet connect system provides an electrical connection between the retrievable ESP assembly and the ESP power cable to surface. After deployment of the permanent completion, it only takes a few hours to complete the through tubing installation of the slickline assembly. The retrieval of the slickline assembly is the reverse of the installation and also only takes a few hours to complete. The connector orientation and latching mechanism ensures that the wet connector on the retrievable ESP assembly is aligned with the mating connector on the permanent completion before engagement. Mechanical supports are also provided by the permanent completion, which take the mechanical forces generated by the retrievable ESP system.

Slickline Retrievable ESP Assembly

The high power density, lightweight PMM is only a fifth of the weight and length of conventional ESP induction motors. The slickline retrievable assembly integrates the PMM and wet connect system with industry-standard ESP components (pumps, gas handling equipment, seals, cables) from all major ESP providers, allowing the operator to combine the system with ESP components from whichever supplier they wish. The PMM is also compatible with surface electrical equipment (variable speed drives, step up transformers, downhole cables and wellhead/packer penetrators) from all major suppliers, meaning the client’s surface electrical equipment can remain the same.

The system can be easily installed and retrieved through tubing, in shut-in or live wells, with a low-cost standard slickline.

System assemblyFigure 2. System assembly. Click on the image for a larger version.

The permanent completion and the slickline retrievable ESP system together form a reliable, lightweight and sturdy system to perform a rigless ESP replacement. The PMM and deployment architecture of the system ensures that it is light, (allowing slickline deployment), short (allowing easy lubricator deployment), with full-bore access and highly tolerant to debris. In wells with high deviation and installations depths beyond reach of typical slickline operations, the system has been deployed using coiled tubing, wireline tractor or pumpdown to reach the target installation depth. With the full-bore access to the lower completion or formation when the retrievable assembly is removed, coiled tubing can be used to remove sand plugs, pump acid or pump fracturing fluids to clean up or stimulate the wellbore. Additionally, the live well intervention enables deployment with no need for pumping kill fluids, adding cost savings with no reservoir damage.

A Cost-Saving System

Since the potential ramifications from failure in a production well are severe, the artificial lift segment of the oil and gas industry is understandably extremely conservative in regards to adapting and using new technology until it is proven. These slickline retrievable ESP systems are indeed now proven in a variety of environments, making them a commercially viable choice of technology that is successfully operating in fields around the world. The application of these unique retrievable ESP systems significantly reduces operating costs, capital expenditure (CAPEX) and cost per barrel for global ESP market operators, while increasing rates of production.

While choosing to deploy this system can cost more in the short term, it can significantly reduce the costs to replace the ESP in the long run. Operators using the system generally lower their overall cost per barrel by $2-5, versus a conventional ESP deployment. The retrievable ESP system lowers the cost of oil production per barrel and simultaneously provides simple and low cost access to the reservoir. This amount of flexibility and ease of use has not been possible with ESPs previously.