Design of High Toughness Cement for Effective Long Lasting Well Isolations

Abstract

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractDuring the well service life the cement isolation is exposed to extreme conditions that can cause its premature failure. Certain well completion operation as perforating and hydraulic fracturing, the changes in temperature and pressure during secondary recovery or the mechanical stress originated by formation displacements may cause severe damage to the cement isolation. The mechanical properties (compressive and tensile strength, toughness, Young modulus and Poisson ratio) of different cements were evaluated in order to establish their best service performance. Typical slurry designs were tested focusing the attention on the effect of certain additives such as latex, fibers and other polymers used as fluid loss control or dispersants. The cement mechanical properties were determined according to ASTM and API standard test methods. The cement toughness was evaluated following the API RP 43 standard for testing well perforators. The experimental results show that the mechanical properties of cement are strongly dependant on the particular additives used when preparing the slurry. Even when cement with no admixtures presents high compressive strength it also shows a fragile behavior with limited strain and low toughness. The use of latex improves the cement elastic behavior although it does not better its impact resistance. On the other hand, the addition of polymer fibers improves the cement toughness and its elastic behavior. As it was demonstrated by well testing profiles run before and after perforating, the addition of fibers improves the cement performance when exposed to the different events that may damage the isolation during the well service life.

Enhancing the cement quality using polypropylene fiber

“…Several previous studies suggested the use of different types of fibers such as the Wollastonite, organic, monofilament, and silicic fibers to improve properties of oil well cement at different conditions, the evaluated fibers were able to improve the strength (Shi et al 1995;Heinold et al 2002;Morris et al 2003;Iremonger et al 2015) and mitigate the loss circulation (Elmoneim et al 2000;Ilyas et al 2012;Al Maskary et al 2014;Arshad et al 2014) of the cement.…”

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

“…Once these stresses reach the materials tensile strength, cement will crack longitudinally allowing fluids communication. This problem could be controlled, up to some extent, designing cement compositions with improved mechanical properties (Morris, 2003). These compositions present high elasticity and toughness in order to tolerate casing deformation effects.…”

Properties and application of oil-well cement enhanced with a novel composite toughening agent

“…A usual measure to overcome the fracture of cement sheath is to add fiber-toughening agent in cement to solve these problems. The ductility and deformation of the set cement enhanced with ordinary fiber-toughening agent are improved, while its crack resistance and Young's modulus decrease remarkably (Brothers, 2005;Dean and Torres, 2002;DiLollo and Rae, 2004;Mack and Dillenbeck, 2002;Marar, et al, 2001;Morris, et al, 2003;Wang, et al, 2004). The decrease in crack resistance is not helpful in improving toughness and it even reduces toughness.…”