Well Servicing by Pump Down Techniques
Authors: Raulins G.M. 
Published: October 2008

A number of wells have been completed for and have been serviced by pump down techniques. The services performed with this first generation hardware indicates that these methods are not only practical and economical for satellite ocean floor completions but will have many applications on conventional completions. Present completions, operations performed to date, and operational hardware are discussed, along with present and future hardware developments.

INTRODUCTION

Means of drilling, completing, and producing wells in very deepwater (greater than 200') has received very much publicity during the past few months. 1,2,3,4,5,6,7 Available information indicates that design work is being actively pursued on most of these systems. The rash of new concepts and design activities directed primarily at water depths of200 to 2,000ft, although there are proposals for operation in as high as 12,000 ft. Estimated cost of a system ranges up into several millions of dollars. Which of these will become operational will be decided in the next few years.

The Pump Down method of servicing wells remotely by hydraulic means has been under active development for a number of years. 8,9,10,11,12 Many operating and service companies have invested varying amounts of manpower, time and capital in concepts and hardware developments in an attempt to have a technique available when completions in water depths beyond tie economic platform limitations were reached. Leasing in deep (over 200 feet) water in the last two years has had the catalytic effect of bringing much of this hardware out of the research and development phase and putting it into an operational position.

There are now ten (Table l) operational ocean floor completions in the Gulf of Mexico, equipped for servicing only by pump down methods. Chart l shows the present status of operational and test wells that have been setup by various operating companies to use and/or test pump down methods and tools. Pump Down Operations as used hereinwill include both servicing through flowlines (satellite completions) and servicing platform completed wells. (Figure 1) Although the original concept of hydraulic servicing was primarily for satellite completions, it has been found that the technique is just as applicable to many conventional completions as well.

PUMP DOWN OPERATIONS

The operations described below have been performed operationally in producing wells a sufficient number of times to be considered operational now.

Running and Pulling Subsurface Controls

Subsurface controls such as standing valves, safety valves, straddle packs, circulation control valves, etc., have been run and pulled many times using pump down methods. In service work, pump down techniques have several inherent advantages over comparable wire line service. For instance, the strength limitation of wire line is eliminated. One locomotive can develop the approximate force that can be pulled on a solid wire line (.082 or .092"). Since these locomotives can be run in series, the desired force that can be developed is limited only by the pressure limitation of the system.