Well Servicing by Pump-Down Techniques

Abstract

A number of wells have been equipped for and serviced by pump-down techniques. The services performed with this first-generation hardware indicate that these methods not only are practical and economical for satellite ocean floor completions, but also may be used on many conventional completions. Introduction Means of drilling, completing, and producing wells in very deep water (greater than 200 ft) have received much publicity during the past year. Available information indicates that design work is being actively pursued on many of these systems. The new concepts pursued on many of these systems. The new concepts and designs are primarily intended for use in water depths of 200 to 2,000 ft, although there are proposals for operation in water as deep as 12,000 ft. proposals for operation in water as deep as 12,000 ft. Estimated cost of a system ranges up to several millions of dollars. Which of the proposed systems will be pursued to the point of commercial usage will be determined 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. Many operating and service companies have invested varying amounts of manpower, time and capital in developing concepts and hardware so that a technique would be available when completions in water depths beyond the economic platform limitations are reached. Leasing in deep water (over 200 ft) in the last 2 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. position. There are now 10 commercial ocean floor completions in the Gulf of Mexico, equipped to be serviced entirely by pump-down methods. The term "pump-down operations" as used here will include both servicing through flowlines (satellite completions) and servicing platform-completed wells (Fig. 1). Although the original concept of hydraulic servicing was primarily for satellite completions, it has been found primarily for satellite completions, it has been found that the technique is just as applicable to many conventional completions (Fig. 1). Pump-Down Operations Pump-Down Operations The following services have been performed in producing wells often enough to be considered more or producing wells often enough to be considered more or less routine now. Running and Pulling Subsurface Controls Subsurface controls, such as standing valves, safety valves, straddle packs and circulation control valves, have been run and pulled many times using pump-down methods. In service work, pump-down pump-down methods. In service work, pump-down techniques have several inherent advantages over comparable wireline methods. For instance, the strength limitation of wireline is eliminated. One locomotive can develop the approximate force that can be pulled on a solid wireline (0.082 or 0.092 in.). Since these locomotives can be run in series, the force that can be developed is limited only by the pressure limitation of the system. As shown in Fig. 11, if it is desired to create a pull of about 4,000 lb, four locomotives would be run, facing in the direction opposite that of the desired pull. Normally the same number of locomotives are run facing each direction. Both mechanical and hydraulic jars have been developed to give additional power for pulling stuck tools and for other fishing operations. JPT P. 161