GEOPOLYMER CEMENT SLURRIES WITH ENHANCED MECHANICAL AND PHYSICAL PROPERTIES FOR OILWELL CEMENTING Syahrir Ridha*, Utami Yerikania *Petroleum Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak, Malaysia, E-mail: syahrir.ridha@petronas.com.my Keywords: Geopolymer, flyash, permeability, compressive strength Abstract Cement integrity and durability in the wells is a major concern for oil industries in securing long term production especially after Macondo disaster. Recent studies show that there are several problems associated with the use of Portland cement such as permeability and strength degradation of well cement, susceptibility to chemical reactions, poor durability and leakage. In achieving these goals, the industries nowadays are seeking for cement systems that meet the technical requirements and at the same time can contribute to reduce greenhouse gas footprints. This paper evaluate the proposed geopolymer cement performance both in mechanical and physical properties under wellbore condition. Low calcium fly ash and silica fume were used as the main substitute materials varying in terms of mix proportion. The results of experimental investigations on geopolymer cement exhibit better properties compared to conventional cement. Superior performances of the new cement system are consistent up to 5 days of hydrations. 1 Introduction The main function of the cement is to mitigate and block fluid communication between the formations to attain long-term zonal barrier throughout the well life and also after its abandonment. The effective isolation between formation zones will boost the production in a safe manner and economically. Besides, cementing strengthens and keeps the borehole integrity from collapsing, mitigate corrosion and seals off problematic zones. To achieve this, once set in place, cement should conform to both short-term and long-term specification to safeguard well operation. The oil and gas industry generally used conventional Portland cement in their operation which then classified into 8 classes of well cement. However, recent studies [1] show that there are several problems associated with the use of Portland cement such as degradation of well cement, susceptibility to chemical reactions, poor durability and leakage. Therefore there is a dire need to develop a sustainable cement technology which possesses superior properties compared to the conventional Portland cement for oil well cementing. This paper focuses on the potential use of geopolymer cement to optimize mechanical and physical properties. 2 Cementing Review To safeguard the environment, to produce oil and gas without compromising the safety of workers and surrounding communities and to ensure that the well is able to provide effective barriers for containment of well fluids and pressures, it is important to properly design and construct wells. It is intended in cementing operation to provide a complete zonal isolation throughout the lifetime of the well to enable effective and economical production. In most cases, the cement would be able to preserve its integrity in the short term, but may lose its integrity as hydrocarbons are produced for several years due to materials degradation. 2.1 Oilwell Cement Oil well cement demanded to has rapid gain in strength and neither shrink due to heat, moisture, drying or dehydration. Early strength development is important in ensuring structural support to casing, hydraulic and mechanical isolation. It also can be set in the presence of sulphate water, be a pump able slurry and produces no lumps, remain fluid until close to setting time, do not produce excessive heat during setting of cement and has low permeability [2]. In down hole, conventional cement often expose to failure due to pressure and temperature changes inside the wellbore which might cause crack [3, 4]. High temperature resulted in loss of silica in cement. Inadequate presence of silica, will convert C-S-H phase into lime rich α -dicalcium silicate hydrate. α - dicalcium silicate hydrate create high permeability and strength retrogression in cement mix [2, 4]. Strength retrogression can be defined as reduction in cement strength to the point of failure due to exposure of high temperature [5] while permeability is the ability of fluid to flow at different temperature between cement particles [2]. Low permeability of cement will result in good long term performance of cement [2] while high permeability may lead gas percolation, result in pressure accumulation behind low portion of the well. It also may cause blow out, weaker zonal isolation and production losses [6]. Cement that have free water or settling tendencies can result in water channel on the