Glass Reinforced Epoxy Casing: Lessons Learned After Cementing and Completion of 70 Wells

Abstract

The use of Glass Reinforced Epoxy (GRE) casing has increased significantly during the last decade, primarily on secondary recovery water injector wells. Corrosion resistance is this material main advantage when compared to steel. Almost one hundred wells have been completed in the Neuquén basin, Argentina, during the past five years.This paper presents the experience obtained after cementing and completion of 70 GRE cased wells. Improvements on cement slurry mix designs, mud cleaning preflushes systems and best practices to ensure successful stimulation conditions (acids and fractures) are provided.The work is supported by a laboratory study focused on the GRE casing to cement bonding performance evaluation and a finite element numerical simulation analysis of the down-hole service conditions achieved during stimulation jobs. This study considered the influence of GRE, cement and rock mechanical properties, the mud-cake removal conditions, as well as different bonding conditions. A comparison between GRE and steel cased wells is presented.Cementing results were improved by casing centralization, increasing the preflushes aggressiveness and using low density slurries. Bonding experimental results showed that original GRE external coating attempts against cement bonding strength.The numerical simulations show that when GRE casings are subjected to high internal pressures, its elastic behavior (Young modulus ten times lower than steel) generates overloading on the cement annulus. This condition could generate cracks that will propagate along the annulus creating communications paths between close perforated zones during stimulations treatments. This situation is even worst when poor formation mud-cake removal takes place.

An Update on the Use of Fiberglass Casing and Tubing in Oil and Gas Wells

“…Advances in fiberglass linings are not limited to fire-proof coatings, linings that provide protection against erosion and ultraviolet degradation have curtailed complaints against these issues that were common in the 1980's (Cowley and McCauley 2005). With current technology, the use of even high-density proppants has no noticeable eroding effect on fiberglass casing (Romera et al 2008). Additionally, a variety of intumescent paints, mastic coatings, and lightweight ceramic coatings (Williams 1988) for specific fire-retardant or erosion-protection purposes are available with the majority of fiberglass manufacturers (Sharif et al 2015 To reduce effects of static charge building up in chemical storage tanks and tubulars, water inlets have been designed and palced at the bottom of water tankers.…”

“…Abrasion and erosion resistant linings for fiberglass tubulars (see Fire Safety section) have been developed by manufacturers and are widely available for use in the field. Such tubulars have been effectively installed in Argentina, Oman, and Brunei with no reported complications (Romera et al 2008). …”

“…This debris can then cause further problems for other equipment like gauging instruments and packers. These issues are either remedied by using strictly shallow-penetration charges, hollow carrier guns, or using weight bars on baskets for gauging operations, so as to prevent them from getting stuck in perforation debris (Romera et al 2008). In addition to capsule-type perforation guns, other equipment unsuitable for fiberglass tubulars has also been identified.…”

“…These include slip-type casing elevators, power tongs, and button-type slips as these all cause damage to the fiberglass tubular. Instead, normal serrated slips, soft slings, strap wrenches ( Fig.9), and equipment from the pipe manufacturer have have been advised (Romera et al 2008). …”

“…Anchoring is required because the low density of fiberglass can lead to buoyancy/flotation issues during cementing, an alternative would be to use a lower-density cement slurry. The lower density also requires metal collars to be added to the end of fiberglass tubulars to add weight when pushing downhole (Romera et al 2008), however this would require special precautions as cited in the Joints and Standards section. When these collars are added, the crossover between fiberglass to steel material should be isolated as in the case of hybrid strings.…”