Extendable/Releasable Washpipe Provides Opportunity For Improved Gravel-Pack Operations
Authors: Ross C.M. , Young Keith 
Published: October 2008

ABSTRACT
Many completion designs do not address fluid loss problems that can occur during performance of sand control operations. These fluid losses are experienced during workstring and production tubing trips that are made into the well, and subsequently, leave the well in a fluid-loss condition.
This paper discusses a new set of tools that has been developed to address this fluid-loss situation by using the wash pipe below the service tool to isolate the formation interval when gravel packing (Figure 1). These tools eliminate multiple trips into the well and reduce fluid loss.
Two tool designs that provide a positive mechanical latching of an isolation wash pipe assembly and a mechanical release to expand a travel joint for circulating-type gravel-pack operations have been developed. The positively-locked system design was developed from a shear-pinned version of a releasable wash pipe system.
Divergent systems have evolved as a result of the initial concept and will be discussed briefly to show other new completion options.

INTRODUCTION
Much has been written about the damaging effects to the formation that result from exposure to completion fluids.1,2,3 The time a formation is exposed to fluids can be critical to the eventual success of a well. Many gravel-packed wells are in a fluid-loss condition during completion operations, and this allows expensive completion fluids to leak off to the formation. This uncontrolled fluid loss presents a potential well-control problem.
Other wells are completed with lost circulation materials in place or are prepacked. The ability to wash out or through these materials is important to the eventual success of the completion. These problems can be further complicated when multiple trips are required for each phase of the completion and stimulation of each interval.
Over the years, the various completion operations have been accomplished by multiple trips into the wellbore. In addition, effective well control required the use of a mechanical or chemical control method during the trips. Rig time (trip time) has been, and still is, a significant part of the completion cost. Well control becomes even more important when completing two or more zones in the same well. If a significant difference exists in the bottomhole pressure between the two zones, interzone communication must be restricted. Fluid incompatibilities that could require isolation between zones may also exist. This problem is not adequately addressed by most fluid-loss-control methods and is further complicated if the zones are closely spaced.
Mechanical isolation methods such as flapper valves work well in single zones but do not allow reentry into multi-zone completions.4 The flapper must be broken or taken out of service to regain access to a lower zone. In addition, the valves are designed to hold pressure from only one direction, usually from above, and interzone communication is not restricted. Chemical fluid-loss methods (Pills) are effective when used to isolate short intervals. The chemicals, however, must be removed or chemically broken to regain permeability of the formation. The problems of well clean up and formation compatibility are of major concern.