TESTING COCONUT SHELLS, SEASHELLS AND SARAWAK COAL AS CEMENT ADDITIVES FOR HPHT WELLS CEMENTING.

Coconut shells, seashells and Sarawak coal (research materials) are tested as cement additives for high pressure and high temperature (HPHT) wells. For the cement design in HPHT conditions, pozzolanic additives such as fly ash and silica fume are used to enhance the compressive strength and the durability of cement sheath. Due to the increased demand by the construction industry, the cost of silica fume and fly ash are very high and the supply is not constant (Lake, 2006). Moreover, those supplementary additives are known as hazardous materials.
The scope of this project is to obtain powder from the research materials, blend them in the cement without any other additives and test three cement slurry parameters: compressive strength, fluid loss and rheology. Cement slurry is prepared and cured at 250F temperature and 3,000 psig pressure in HPHT cement curing chamber. Compressive strengths are measured at one and seven days’ time. Slurry rheology and fluid loss were as well measured following API RP 10B specifications.
Results show that cement composition with seashell content has compressive strength values which are higher than the field requirements. 30% BWOC seashell has the compressive strength value of above 5,000 psi. Even though coal and coconut shell additives did not show good compressive strength results in high concentrations, they showed good rheology and fluid loss behaviors. API fluid loss of the cement slurry reduced with the increasing concentrations of coal and coconut shells to as low as 100 cc/min.