Pumpdown (TFL) Technology for Subsea Completions
Authors: Arendt H.P. , Dines C. , Heard T. 
Published: December 2007

Pumpdown (TFL) Technology for Pumpdown (TFL) Technology for Subsea Completions

This paper describes the latest innovations in pumpdown equipment and methods that provide economical, reliable solutions to offshore production well maintenance in deep or shallow subsea completions worldwide. Demands for full-bore tubing have led to tool designs that negotiate wellhead entry loops, thus making single and multizone completions, gas lift, and surface-controlled subsurface safety systems feasible.

Introduction

The search for oil has caused the oil industry to drill in deeper and less accessible waters. Costs for production and pipelines have increased accordingly. For a well to be profitable under these conditions, it must produce large profitable under these conditions, it must produce large amounts of oil and be maintained easily.

One solution has been an increased demand for pumpdown (TFL) completions with large bores specially pumpdown (TFL) completions with large bores specially designed for deep water. These completions must incorporate the basic TFL requirements and certain other features that include the following.One requirement is the ability to perform maintenance and service work on subsea wells with flowlines more than 5 miles long. This distance results when cluster and satellite wells must be placed far from fixed or floating production platforms.Another feature is the ability to locate down-hole equipment selectively. This is more difficult on the deep or long flowline wells, where pressure response is minimal.Pressure response must be maintained for deep and subsea wells.Pressure integrity must be maintained and fluid losses kept to a minimum while performing service operations. This is very important for wells with low bottomhole pressures or sensitive formations.Another feature is the compatibility of down-hole equipment in the entire system.A circulation path (H-member) must be incorporated both down hole and in the wellhead.Surface-controlled subsurface safety systems are required. This is a necessary safety precaution with the ever-present threat of damage to wellheads and flowlines.

As will be discussed in this paper, recent innovations in TFL equipment now provide these features and offer solutions for the problems of well maintenance.

Description of Equipment

In the past 3 to 4 years, much development work and testing has occurred to help answer the problems faced by deep-water completions. Developments include well-head plugs, pumpdown-retrievable ball valves, and tubing-retrievable safety valves for pumpdown use; pumpdown kickover tools with side-pocket mandrels and pumpdown kickover tools with side-pocket mandrels and H-members; Select-20 shifter and locater systems, upper H-members with emergency circulating shear disks, and sliding-sleeve H-members, for gas lift in tubingless completions (in this instance, an uncased hole with tubing cemented in place).

As wells were completed with multiple zones and greater depths and gas lift requirements, additional burdens fell on the pumpdown operator. How was he to determine where the tools were in the tubing string at deep depths or with gas in the system? Solving this problem led to one of the most recent innovations in the problem led to one of the most recent innovations in the pumpdown field - the Select-20 shifter-locator mandrel pumpdown field - the Select-20 shifter-locator mandrel and connector system.

JPT

P. 1481