EFFECT OF POLYMER LATEX AND CEMENT DENSITY IN WELLBORE INTEGRITY

Due to pressure and temperature changes during the life of the well (from drilling to production); globally many Casing-Casing Annular (CCA) leaks could be observed in the annuli between surface and intermediate casings. A new approach to well cementing had to be developed, and advanced cement technologies considered, taking into account both short- and long-term design parameters. To assess the effect of pressure and temperature cycling on the long-term well integrity, intensive lab work was done to design cement polymer latex formulations at different densities to improve wellbore integrity. Experimental work in this study contained short term testing and long-term testing. The short-term testing included thickening time and rheology. The long-term testing included curing for 30 days and mechanical properties measurements. Analytical techniques, such as nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared analysis (FTIR), differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA), were used to help with understanding the structures and physical properties of the latex and its interaction with cement matrix. Conventional cements had values of static Young’s Modulus range between 3 and 3.5 million psi which indicated that the cement was too rigid to resist any type of pressure or temperature cycling. Adding polymer latex improved wellbore integrity by reducing Young’s Modulus. Reducing density resulted in reducing Young’s Modulus values. Combination of low densities and polymer latex should be investigated for future cementing for potential improved wellbore integrity.