Deepwater Remotely Actuated Completions for the 21st Century
Authors: Smith Mike , Lowe Evan , Coull Craig 
Published: December 2007

With deepwater rig rates as high as $190,000 per day, the ability to minimize well completion time without compromising reliability or safety can substantially reduce operating expense. In the Gulf of Mexico, Atlantic Frontier and North Sea, a pressure pulse remote actuation system for setting completion tools has significantly reduced rig time.

Previous SPE papers on pressure pulse remote actuation of completion tools' served to introduce this new technology to the industry. This paper, by examination of eighteen deepwater completion case histories, will illustrate the challenges faced, milestones reached, efficiencies achieved, and the promising future of remotely actuated completions. This paper should be read in conjunction with the referenced OTC papers to fully appreciate the many challenges of subsea deepwater completions.

This paper will not attempt to prove the technology by case study, but rather will examine the successes, failures and subsequent lessons learned that prove the service companies' and the industry's commitment to making remote actuation of completion tools a viable 21st century technology.

Introduction

As the oil industry moves into the 21st century, the role of electronics in communicating with and actuating downhole deepwater completions is expanding rapidly. These remotely actuated completions can save days of rig time and hundreds of thousands of dollars over standard conventional completions, which require well intervention for actuation.

One of the more common conventional completion practices is to set a retrievable or permanent production packer to isolate and control the pressure and fluids from the producing zone. In deepwater completions, the preferred packer setting method is a one-trip hydraulic system. The packer is run in on the production string in a single trip. The tubing is plugged by landing a wireline or coiled tubing conveyed blanking plug into a seating nipple below the packer. The packer is then set using hydraulic pressure. The one-trip hydraulic system requires well intervention which can be time-intensive, from 12 hours to 2 days, and introduces the risk of losing the wireline or coiled tubing, and associated tools in the well.

A more fit-for-purpose deepwater setting system would include all the features of the existing one-trip hydraulic system but would eliminate both the need to plug the tubing and the associated well intervention. These capabilities currently exist in a one-trip, remotely actuated, hydrostatic-set completion system. The system, which relies on pressure-pulse communication for actuation, is currently being used in the Gulf of Mexico, the Atlantic Frontier, and the North Sea.

Pressure-Pulse, Wireless Remote Actuation System

System Basics. The pressure-pulse, wireless and control line-less, remote actuation system is based on a one-way, fluid-conveyed communication loop. The system consists of a surface module, a communications medium, which is the fluid column in the completion string, and a downhole module (i.e., a packer). The surface module's function is to transmit a preprogrammed frequency of pressure pulses. The fluid column carries the pulses to the electronically enhanced packer, which is pre-programmed to actuate upon receiving the correct frequency of pulses. (Figure 1)

Component Descriptions. The surface module consists of a computer-controlled pulse generating unit, an interface box with manual controls, and a computer controller. The pulse generating unit transmits a discreet pressure pulse of specific amplitude and frequency through the tubing fluid. Its components include two nitrogen accumulators, an air-driven water pump and two pneumatic actuator-operated valves that control discharge of fluid into and out of the well.

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