Openhole Completion Techniques for Horizontal Foam-Drilled Wells
Authors: Bybee Karen 
Published: February 2015

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 125642, ’Optimizing Openhole Completion Techniques for Horizontal Foam-Drilled Wells,’ by Dave Allison, SPE, Don Folds, SPE, David Harless, SPE, Matt Howell, SPE, and Greg Vargus, SPE, Halliburton, and Abby Stipetich, SPE, EQT Production, originally prepared for the 2009 SPE Eastern Regional Meeting, Charleston, West Virginia, 23-25 September. The paper has not been peer reviewed.

To overcome the issue of isolation in nongauge holes without damaging the shale formation, an interventionless solution was incorporated using sliding sleeves, swellable-elastomer packers (SEPs), and a specially developed shale-optimized fluid system to swell the packers. The shale-optimized fluid is an effective low-leakoff fluid that causes minimum physio/chemical damage to the shale while optimizing the swell time of the packers.

Introduction

In recent years, the North American land markets have seen a shift in focus toward developing shale-gas plays such as the Lower Huron, Marcellus, and Haynesville formations. This shift can be attributed largely to the development of new technologies that make the completion costs more economical. One of the technologies that has made a big impact on lowering completion costs is the combination of horizontal drilling and use of sliding-sleeve technology to provide an interventionless completion. The deployment of this type of system enables the operator to fracture separately several different intervals within the horizontal section without shutting down the pumps. Operators can simply drop a ball from surface to isolate the intervals that have been treated and open the next zone for treatment. This type of completion also maximizes production possibilities by optimizing and tailoring treatments for each interval throughout the horizontal section of the wellbore.

To compartmentalize the horizontal section and optimize the fracture treatments, zonal isolation is required in the annulus between each sliding sleeve. There are several ways to establish zonal isolation including traditional cement, openhole hydraulic-set packers, or inflatable packers, but each method adds a certain complexity whether by adding operations to complete the installation or by introducing more mechanical components, which increases the risks associated with installation. The introduction of SEPs as the method of zonal isolation greatly simplifies the installation process and decreases the associated risks. SEPs are simply positioned onto the production casing and spaced out as per the wellbore plan. Once in position, the swelling actuator—traditionally, liquid hydrocarbons, natural gas, or water—is introduced into the system, allowing the SEPs to begin to swell. Once actuated, the SEPs will continue to swell and conform to the inside diameter of the wellbore in which they are installed.

In areas where the horizontal wells are foam drilled instead of air drilled, because of the sensitivity of the shale, the wellbore may be nongauge, which may lead to operational failures when trying to isolate the wellbore with hydraulic-set packers because of the limitation of the expansion of the element package. The advances in the use of SEPs provide an ideal solution for isolating these nongauge holes for the completion process; however, the shale in these wellbores is sensitive, and applying the typical hydrocarbon fluid to the formation to swell the SEPs may have a detrimental effect on the formation.