New Multiple Path Gravel-Pack Screen System Provides Improved Installation and Operational Performance
Authors: McGregor Ron , Fitzpatrick Harvey , Crow Robert , Hejl David 
Published: October 2008

With the industry completing longer and more difficult intervals, both on- and offshore, completion techniques and equipment must support sand-free hydrocarbon flow to provide economic feasibility. Traditional equipment often has failed to meet these needs. For example, when horizontal wells with high permeability are gravel packed, problems relating to integrity of drill-in fluid wall cake, fracture initiation during pack placement, borehole instability, well bore failure, and hole-size irregularities can occur. These scenarios can prevent complete packing of the screen downstream, which can severely compromise production potentials and the life of the well equipment.

A unique multiple-path gravel-pack screen has been designed to address these needs and provide reliable horizontal gravel packs. The system is easy to run, and provides multiple flow paths - the traditional annular path, a concentric annular path between the screen and outer shroud, and integral channels surrounding the screen. The screen, channels and base-pipe connections are integral with each joint so that no additional assembly other than the standard pin-to-box makeup is required on the rig floor. Washpipe is run inside the screen to carry fluid circulation for alpha - beta wave annular packing. The channel slurry exit port configuration radially directs the slurry into the annulus and away from the screen. Candidates for the system include horizontal wells with high-permeability zones, zones prone to fracturing during gravel-pack treatment, and wells with active shale sections or hole-size irregularities that can result in blockages.

In full scale testing of 300 feet of screen, the assembly reliably demonstrated a 100% pack using two different gravel/gel systems. The multiple path screen enabled the slurry to flow past annular blockages using both a low-friction concentric annular pathway with fluid returns and controlled leakoff slurry channels to finish the packing process.

The Challenge

Reliability of sand-control completions continues to be a key factor in the economics of producing oil and gas from unconsolidated sand reservoirs. In many cases, gravel pack life can make or break the economic viability of a project. Areas with high cost of rig operation and well intervention are particularly affected. These locations include many of the more promising plays such as deep water, areas of new development (like China), and places where logistics and lack of infrastructure drive high costs. In these areas, economic success can hinge on the capability to complete long, deviated, complex or horizontal sand intervals to efficiently capture reserves. But, successful installation of the sand-control completion is only the first step to attaining economic success. Long-term production is also required to meet the high capital outlays and high production costs on these projects. Only by achieving the above requirements as well as eliminating the need for well intervention can the planned economic returns be realized.

New sand-control completion methods continue to evolve, and older completion techniques have been improved in an effort to help operators meet these challenges. Whereas gravel packs and bare-screen completions used to be considered the preferred completion techniques, frac packs and horizontal gravel packs now seem more capable of offering increased productivity and long-term reliability.