A new formulation for lightweight oil well cement slurry using a natural pozzolan
Corresponding Author and Email:Saeid Norouzi Apourvari, snorouzi@uk.ac.ir; ORCID: https://orcid.org/0000-0002-0410-0485
Citation:Larki, O., Norouzi Apourvari, S., Schaffie, M., Farazmand, R. A new formulation for lightweight oil well cement slurry using a natural pozzolan. Advances in Geo-Energy Research, 2019, 3(3): 242-249, doi: 10.26804/ager.2019.03.02.
Article Type:Original article
Abstract:
Fluid loss during cementing operation in depleted reservoirs or deep wells of reservoirs with low breakdown pressure is a major concern for maintaining well integrity. This issue is usually handled by reducing the weight of cement slurry. Although various slurry formulations were proposed during the last decade, the cost and availability of required additives is still a concern, especially when the oil price is low. The objective of this study is to make lightweight cement slurry with a density of 105 lb/ft3, using the combination of natural pozzolan and API class G cement. This study proposes a new lightweight cement formulation based on the optimum amount of a natural pozzolan and other additives. Based on the results of 24-hour compressive strength tests and free water volume, an optimum 30% of cement powder was replaced with pozzolan. Addition of more pozzolan into the slurry reduces its pumping even at room temperature. The bottom-hole condition was simulated by increasing the temperature to 150 °F, and chemical additives were used to maintain the rheological properties of this slurry. Fluid loss control agent, dispersant and retarder were used at optimum values 0.5, 0.08 and 0.05 (%bwoc), respectively. The compressive strength of the cement rock was monitored at 3, 7 and 30 days, reaching to 3528 lb/in2 after 30 days.
Keywords:Fluid loss, natural pozzolan, lightweight cement slurry, drilling cement, cementing operation.
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